/*
 * Copyright (C) 2006-2009 DENX Software Engineering.
 *
 * Author: Yuri Tikhonov <yur@emcraft.com>
 *
 * Further porting to arch/powerpc by
 *      Anatolij Gustschin <agust@denx.de>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * The full GNU General Public License is included in this distribution in the
 * file called COPYING.
 */

/*
 * This driver supports the asynchrounous DMA copy and RAID engines available
 * on the AMCC PPC440SPe Processors.
 * Based on the Intel Xscale(R) family of I/O Processors (IOP 32x, 33x, 134x)
 * ADMA driver written by D.Williams.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/async_tx.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/proc_fs.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <asm/dcr.h>
#include <asm/dcr-regs.h>
#include "adma.h"
#include "../dmaengine.h"

enum ppc_adma_init_code {
        PPC_ADMA_INIT_OK = 0,
        PPC_ADMA_INIT_MEMRES,
        PPC_ADMA_INIT_MEMREG,
        PPC_ADMA_INIT_ALLOC,
        PPC_ADMA_INIT_COHERENT,
        PPC_ADMA_INIT_CHANNEL,
        PPC_ADMA_INIT_IRQ1,
        PPC_ADMA_INIT_IRQ2,
        PPC_ADMA_INIT_REGISTER
};

static char *ppc_adma_errors[] = {
        [PPC_ADMA_INIT_OK] = "ok",
        [PPC_ADMA_INIT_MEMRES] = "failed to get memory resource",
        [PPC_ADMA_INIT_MEMREG] = "failed to request memory region",
        [PPC_ADMA_INIT_ALLOC] = "failed to allocate memory for adev "
                                "structure",
        [PPC_ADMA_INIT_COHERENT] = "failed to allocate coherent memory for "
                                   "hardware descriptors",
        [PPC_ADMA_INIT_CHANNEL] = "failed to allocate memory for channel",
        [PPC_ADMA_INIT_IRQ1] = "failed to request first irq",
        [PPC_ADMA_INIT_IRQ2] = "failed to request second irq",
        [PPC_ADMA_INIT_REGISTER] = "failed to register dma async device",
};

static enum ppc_adma_init_code
ppc440spe_adma_devices[PPC440SPE_ADMA_ENGINES_NUM];

struct ppc_dma_chan_ref {
        struct dma_chan *chan;
        struct list_head node;
};

/* The list of channels exported by ppc440spe ADMA */
struct list_head
ppc440spe_adma_chan_list = LIST_HEAD_INIT(ppc440spe_adma_chan_list);

/* This flag is set when want to refetch the xor chain in the interrupt
 * handler
 */
static u32 do_xor_refetch;

/* Pointer to DMA0, DMA1 CP/CS FIFO */
static void *ppc440spe_dma_fifo_buf;

/* Pointers to last submitted to DMA0, DMA1 CDBs */
static struct ppc440spe_adma_desc_slot *chan_last_sub[3];
static struct ppc440spe_adma_desc_slot *chan_first_cdb[3];

/* Pointer to last linked and submitted xor CB */
static struct ppc440spe_adma_desc_slot *xor_last_linked;
static struct ppc440spe_adma_desc_slot *xor_last_submit;

/* This array is used in data-check operations for storing a pattern */
static char ppc440spe_qword[16];

static atomic_t ppc440spe_adma_err_irq_ref;
static dcr_host_t ppc440spe_mq_dcr_host;
static unsigned int ppc440spe_mq_dcr_len;

/* Since RXOR operations use the common register (MQ0_CF2H) for setting-up
 * the block size in transactions, then we do not allow to activate more than
 * only one RXOR transactions simultaneously. So use this var to store
 * the information about is RXOR currently active (PPC440SPE_RXOR_RUN bit is
 * set) or not (PPC440SPE_RXOR_RUN is clear).
 */
static unsigned long ppc440spe_rxor_state;

/* These are used in enable & check routines
 */
static u32 ppc440spe_r6_enabled;
static struct ppc440spe_adma_chan *ppc440spe_r6_tchan;
static struct completion ppc440spe_r6_test_comp;

static int ppc440spe_adma_dma2rxor_prep_src(
                struct ppc440spe_adma_desc_slot *desc,
                struct ppc440spe_rxor *cursor, int index,
                int src_cnt, u32 addr);
static void ppc440spe_adma_dma2rxor_set_src(
                struct ppc440spe_adma_desc_slot *desc,
                int index, dma_addr_t addr);
static void ppc440spe_adma_dma2rxor_set_mult(
                struct ppc440spe_adma_desc_slot *desc,
                int index, u8 mult);

#ifdef ADMA_LL_DEBUG
#define ADMA_LL_DBG(x) ({ if (1) x; 0; })
#else
#define ADMA_LL_DBG(x) ({ if (0) x; 0; })
#endif

static void print_cb(struct ppc440spe_adma_chan *chan, void *block)
{
        struct dma_cdb *cdb;
        struct xor_cb *cb;
        int i;

        switch (chan->device->id) {
        case 0:
        case 1:
                cdb = block;

                pr_debug("CDB at %p [%d]:\n"
                        "\t attr 0x%02x opc 0x%02x cnt 0x%08x\n"
                        "\t sg1u 0x%08x sg1l 0x%08x\n"
                        "\t sg2u 0x%08x sg2l 0x%08x\n"
                        "\t sg3u 0x%08x sg3l 0x%08x\n",
                        cdb, chan->device->id,
                        cdb->attr, cdb->opc, le32_to_cpu(cdb->cnt),
                        le32_to_cpu(cdb->sg1u), le32_to_cpu(cdb->sg1l),
                        le32_to_cpu(cdb->sg2u), le32_to_cpu(cdb->sg2l),
                        le32_to_cpu(cdb->sg3u), le32_to_cpu(cdb->sg3l)
                );
                break;
        case 2:
                cb = block;

                pr_debug("CB at %p [%d]:\n"
                        "\t cbc 0x%08x cbbc 0x%08x cbs 0x%08x\n"
                        "\t cbtah 0x%08x cbtal 0x%08x\n"
                        "\t cblah 0x%08x cblal 0x%08x\n",
                        cb, chan->device->id,
                        cb->cbc, cb->cbbc, cb->cbs,
                        cb->cbtah, cb->cbtal,
                        cb->cblah, cb->cblal);
                for (i = 0; i < 16; i++) {
                        if (i && !cb->ops[i].h && !cb->ops[i].l)
                                continue;
                        pr_debug("\t ops[%2d]: h 0x%08x l 0x%08x\n",
                                i, cb->ops[i].h, cb->ops[i].l);
                }
                break;
        }
}

static void print_cb_list(struct ppc440spe_adma_chan *chan,
                          struct ppc440spe_adma_desc_slot *iter)
{
        for (; iter; iter = iter->hw_next)
                print_cb(chan, iter->hw_desc);
}

static void prep_dma_xor_dbg(int id, dma_addr_t dst, dma_addr_t *src,
                             unsigned int src_cnt)
{
        int i;

        pr_debug("\n%s(%d):\nsrc: ", __func__, id);
        for (i = 0; i < src_cnt; i++)
                pr_debug("\t0x%016llx ", src[i]);
        pr_debug("dst:\n\t0x%016llx\n", dst);
}

static void prep_dma_pq_dbg(int id, dma_addr_t *dst, dma_addr_t *src,
                            unsigned int src_cnt)
{
        int i;

        pr_debug("\n%s(%d):\nsrc: ", __func__, id);
        for (i = 0; i < src_cnt; i++)
                pr_debug("\t0x%016llx ", src[i]);
        pr_debug("dst: ");
        for (i = 0; i < 2; i++)
                pr_debug("\t0x%016llx ", dst[i]);
}

static void prep_dma_pqzero_sum_dbg(int id, dma_addr_t *src,
                                    unsigned int src_cnt,
                                    const unsigned char *scf)
{
        int i;

        pr_debug("\n%s(%d):\nsrc(coef): ", __func__, id);
        if (scf) {
                for (i = 0; i < src_cnt; i++)
                        pr_debug("\t0x%016llx(0x%02x) ", src[i], scf[i]);
        } else {
                for (i = 0; i < src_cnt; i++)
                        pr_debug("\t0x%016llx(no) ", src[i]);
        }

        pr_debug("dst: ");
        for (i = 0; i < 2; i++)
                pr_debug("\t0x%016llx ", src[src_cnt + i]);
}

/******************************************************************************
 * Command (Descriptor) Blocks low-level routines
 ******************************************************************************/
/**
 * ppc440spe_desc_init_interrupt - initialize the descriptor for INTERRUPT
 * pseudo operation
 */
static void ppc440spe_desc_init_interrupt(struct ppc440spe_adma_desc_slot *desc,
                                          struct ppc440spe_adma_chan *chan)
{
        struct xor_cb *p;

        switch (chan->device->id) {
        case PPC440SPE_XOR_ID:
                p = desc->hw_desc;
                memset(desc->hw_desc, 0, sizeof(struct xor_cb));
                /* NOP with Command Block Complete Enable */
                p->cbc = XOR_CBCR_CBCE_BIT;
                break;
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                memset(desc->hw_desc, 0, sizeof(struct dma_cdb));
                /* NOP with interrupt */
                set_bit(PPC440SPE_DESC_INT, &desc->flags);
                break;
        default:
                printk(KERN_ERR "Unsupported id %d in %s\n", chan->device->id,
                                __func__);
                break;
        }
}

/**
 * ppc440spe_desc_init_null_xor - initialize the descriptor for NULL XOR
 * pseudo operation
 */
static void ppc440spe_desc_init_null_xor(struct ppc440spe_adma_desc_slot *desc)
{
        memset(desc->hw_desc, 0, sizeof(struct xor_cb));
        desc->hw_next = NULL;
        desc->src_cnt = 0;
        desc->dst_cnt = 1;
}

/**
 * ppc440spe_desc_init_xor - initialize the descriptor for XOR operation
 */
static void ppc440spe_desc_init_xor(struct ppc440spe_adma_desc_slot *desc,
                                         int src_cnt, unsigned long flags)
{
        struct xor_cb *hw_desc = desc->hw_desc;

        memset(desc->hw_desc, 0, sizeof(struct xor_cb));
        desc->hw_next = NULL;
        desc->src_cnt = src_cnt;
        desc->dst_cnt = 1;

        hw_desc->cbc = XOR_CBCR_TGT_BIT | src_cnt;
        if (flags & DMA_PREP_INTERRUPT)
                /* Enable interrupt on completion */
                hw_desc->cbc |= XOR_CBCR_CBCE_BIT;
}

/**
 * ppc440spe_desc_init_dma2pq - initialize the descriptor for PQ
 * operation in DMA2 controller
 */
static void ppc440spe_desc_init_dma2pq(struct ppc440spe_adma_desc_slot *desc,
                int dst_cnt, int src_cnt, unsigned long flags)
{
        struct xor_cb *hw_desc = desc->hw_desc;

        memset(desc->hw_desc, 0, sizeof(struct xor_cb));
        desc->hw_next = NULL;
        desc->src_cnt = src_cnt;
        desc->dst_cnt = dst_cnt;
        memset(desc->reverse_flags, 0, sizeof(desc->reverse_flags));
        desc->descs_per_op = 0;

        hw_desc->cbc = XOR_CBCR_TGT_BIT;
        if (flags & DMA_PREP_INTERRUPT)
                /* Enable interrupt on completion */
                hw_desc->cbc |= XOR_CBCR_CBCE_BIT;
}

#define DMA_CTRL_FLAGS_LAST     DMA_PREP_FENCE
#define DMA_PREP_ZERO_P         (DMA_CTRL_FLAGS_LAST << 1)
#define DMA_PREP_ZERO_Q         (DMA_PREP_ZERO_P << 1)

/**
 * ppc440spe_desc_init_dma01pq - initialize the descriptors for PQ operation
 * with DMA0/1
 */
static void ppc440spe_desc_init_dma01pq(struct ppc440spe_adma_desc_slot *desc,
                                int dst_cnt, int src_cnt, unsigned long flags,
                                unsigned long op)
{
        struct dma_cdb *hw_desc;
        struct ppc440spe_adma_desc_slot *iter;
        u8 dopc;

        /* Common initialization of a PQ descriptors chain */
        set_bits(op, &desc->flags);
        desc->src_cnt = src_cnt;
        desc->dst_cnt = dst_cnt;

        /* WXOR MULTICAST if both P and Q are being computed
         * MV_SG1_SG2 if Q only
         */
        dopc = (desc->dst_cnt == DMA_DEST_MAX_NUM) ?
                DMA_CDB_OPC_MULTICAST : DMA_CDB_OPC_MV_SG1_SG2;

        list_for_each_entry(iter, &desc->group_list, chain_node) {
                hw_desc = iter->hw_desc;
                memset(iter->hw_desc, 0, sizeof(struct dma_cdb));

                if (likely(!list_is_last(&iter->chain_node,
                                &desc->group_list))) {
                        /* set 'next' pointer */
                        iter->hw_next = list_entry(iter->chain_node.next,
                                struct ppc440spe_adma_desc_slot, chain_node);
                        clear_bit(PPC440SPE_DESC_INT, &iter->flags);
                } else {
                        /* this is the last descriptor.
                         * this slot will be pasted from ADMA level
                         * each time it wants to configure parameters
                         * of the transaction (src, dst, ...)
                         */
                        iter->hw_next = NULL;
                        if (flags & DMA_PREP_INTERRUPT)
                                set_bit(PPC440SPE_DESC_INT, &iter->flags);
                        else
                                clear_bit(PPC440SPE_DESC_INT, &iter->flags);
                }
        }

        /* Set OPS depending on WXOR/RXOR type of operation */
        if (!test_bit(PPC440SPE_DESC_RXOR, &desc->flags)) {
                /* This is a WXOR only chain:
                 * - first descriptors are for zeroing destinations
                 *   if PPC440SPE_ZERO_P/Q set;
                 * - descriptors remained are for GF-XOR operations.
                 */
                iter = list_first_entry(&desc->group_list,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);

                if (test_bit(PPC440SPE_ZERO_P, &desc->flags)) {
                        hw_desc = iter->hw_desc;
                        hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;
                        iter = list_first_entry(&iter->chain_node,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);
                }

                if (test_bit(PPC440SPE_ZERO_Q, &desc->flags)) {
                        hw_desc = iter->hw_desc;
                        hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;
                        iter = list_first_entry(&iter->chain_node,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);
                }

                list_for_each_entry_from(iter, &desc->group_list, chain_node) {
                        hw_desc = iter->hw_desc;
                        hw_desc->opc = dopc;
                }
        } else {
                /* This is either RXOR-only or mixed RXOR/WXOR */

                /* The first 1 or 2 slots in chain are always RXOR,
                 * if need to calculate P & Q, then there are two
                 * RXOR slots; if only P or only Q, then there is one
                 */
                iter = list_first_entry(&desc->group_list,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);
                hw_desc = iter->hw_desc;
                hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;

                if (desc->dst_cnt == DMA_DEST_MAX_NUM) {
                        iter = list_first_entry(&iter->chain_node,
                                                struct ppc440spe_adma_desc_slot,
                                                chain_node);
                        hw_desc = iter->hw_desc;
                        hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;
                }

                /* The remaining descs (if any) are WXORs */
                if (test_bit(PPC440SPE_DESC_WXOR, &desc->flags)) {
                        iter = list_first_entry(&iter->chain_node,
                                                struct ppc440spe_adma_desc_slot,
                                                chain_node);
                        list_for_each_entry_from(iter, &desc->group_list,
                                                chain_node) {
                                hw_desc = iter->hw_desc;
                                hw_desc->opc = dopc;
                        }
                }
        }
}

/**
 * ppc440spe_desc_init_dma01pqzero_sum - initialize the descriptor
 * for PQ_ZERO_SUM operation
 */
static void ppc440spe_desc_init_dma01pqzero_sum(
                                struct ppc440spe_adma_desc_slot *desc,
                                int dst_cnt, int src_cnt)
{
        struct dma_cdb *hw_desc;
        struct ppc440spe_adma_desc_slot *iter;
        int i = 0;
        u8 dopc = (dst_cnt == 2) ? DMA_CDB_OPC_MULTICAST :
                                   DMA_CDB_OPC_MV_SG1_SG2;
        /*
         * Initialize starting from 2nd or 3rd descriptor dependent
         * on dst_cnt. First one or two slots are for cloning P
         * and/or Q to chan->pdest and/or chan->qdest as we have
         * to preserve original P/Q.
         */
        iter = list_first_entry(&desc->group_list,
                                struct ppc440spe_adma_desc_slot, chain_node);
        iter = list_entry(iter->chain_node.next,
                          struct ppc440spe_adma_desc_slot, chain_node);

        if (dst_cnt > 1) {
                iter = list_entry(iter->chain_node.next,
                                  struct ppc440spe_adma_desc_slot, chain_node);
        }
        /* initialize each source descriptor in chain */
        list_for_each_entry_from(iter, &desc->group_list, chain_node) {
                hw_desc = iter->hw_desc;
                memset(iter->hw_desc, 0, sizeof(struct dma_cdb));
                iter->src_cnt = 0;
                iter->dst_cnt = 0;

                /* This is a ZERO_SUM operation:
                 * - <src_cnt> descriptors starting from 2nd or 3rd
                 *   descriptor are for GF-XOR operations;
                 * - remaining <dst_cnt> descriptors are for checking the result
                 */
                if (i++ < src_cnt)
                        /* MV_SG1_SG2 if only Q is being verified
                         * MULTICAST if both P and Q are being verified
                         */
                        hw_desc->opc = dopc;
                else
                        /* DMA_CDB_OPC_DCHECK128 operation */
                        hw_desc->opc = DMA_CDB_OPC_DCHECK128;

                if (likely(!list_is_last(&iter->chain_node,
                                         &desc->group_list))) {
                        /* set 'next' pointer */
                        iter->hw_next = list_entry(iter->chain_node.next,
                                                struct ppc440spe_adma_desc_slot,
                                                chain_node);
                } else {
                        /* this is the last descriptor.
                         * this slot will be pasted from ADMA level
                         * each time it wants to configure parameters
                         * of the transaction (src, dst, ...)
                         */
                        iter->hw_next = NULL;
                        /* always enable interrupt generation since we get
                         * the status of pqzero from the handler
                         */
                        set_bit(PPC440SPE_DESC_INT, &iter->flags);
                }
        }
        desc->src_cnt = src_cnt;
        desc->dst_cnt = dst_cnt;
}

/**
 * ppc440spe_desc_init_memcpy - initialize the descriptor for MEMCPY operation
 */
static void ppc440spe_desc_init_memcpy(struct ppc440spe_adma_desc_slot *desc,
                                        unsigned long flags)
{
        struct dma_cdb *hw_desc = desc->hw_desc;

        memset(desc->hw_desc, 0, sizeof(struct dma_cdb));
        desc->hw_next = NULL;
        desc->src_cnt = 1;
        desc->dst_cnt = 1;

        if (flags & DMA_PREP_INTERRUPT)
                set_bit(PPC440SPE_DESC_INT, &desc->flags);
        else
                clear_bit(PPC440SPE_DESC_INT, &desc->flags);

        hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;
}

/**
 * ppc440spe_desc_set_src_addr - set source address into the descriptor
 */
static void ppc440spe_desc_set_src_addr(struct ppc440spe_adma_desc_slot *desc,
                                        struct ppc440spe_adma_chan *chan,
                                        int src_idx, dma_addr_t addrh,
                                        dma_addr_t addrl)
{
        struct dma_cdb *dma_hw_desc;
        struct xor_cb *xor_hw_desc;
        phys_addr_t addr64, tmplow, tmphi;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                if (!addrh) {
                        addr64 = addrl;
                        tmphi = (addr64 >> 32);
                        tmplow = (addr64 & 0xFFFFFFFF);
                } else {
                        tmphi = addrh;
                        tmplow = addrl;
                }
                dma_hw_desc = desc->hw_desc;
                dma_hw_desc->sg1l = cpu_to_le32((u32)tmplow);
                dma_hw_desc->sg1u |= cpu_to_le32((u32)tmphi);
                break;
        case PPC440SPE_XOR_ID:
                xor_hw_desc = desc->hw_desc;
                xor_hw_desc->ops[src_idx].l = addrl;
                xor_hw_desc->ops[src_idx].h |= addrh;
                break;
        }
}

/**
 * ppc440spe_desc_set_src_mult - set source address mult into the descriptor
 */
static void ppc440spe_desc_set_src_mult(struct ppc440spe_adma_desc_slot *desc,
                        struct ppc440spe_adma_chan *chan, u32 mult_index,
                        int sg_index, unsigned char mult_value)
{
        struct dma_cdb *dma_hw_desc;
        struct xor_cb *xor_hw_desc;
        u32 *psgu;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                dma_hw_desc = desc->hw_desc;

                switch (sg_index) {
                /* for RXOR operations set multiplier
                 * into source cued address
                 */
                case DMA_CDB_SG_SRC:
                        psgu = &dma_hw_desc->sg1u;
                        break;
                /* for WXOR operations set multiplier
                 * into destination cued address(es)
                 */
                case DMA_CDB_SG_DST1:
                        psgu = &dma_hw_desc->sg2u;
                        break;
                case DMA_CDB_SG_DST2:
                        psgu = &dma_hw_desc->sg3u;
                        break;
                default:
                        BUG();
                }

                *psgu |= cpu_to_le32(mult_value << mult_index);
                break;
        case PPC440SPE_XOR_ID:
                xor_hw_desc = desc->hw_desc;
                break;
        default:
                BUG();
        }
}

/**
 * ppc440spe_desc_set_dest_addr - set destination address into the descriptor
 */
static void ppc440spe_desc_set_dest_addr(struct ppc440spe_adma_desc_slot *desc,
                                struct ppc440spe_adma_chan *chan,
                                dma_addr_t addrh, dma_addr_t addrl,
                                u32 dst_idx)
{
        struct dma_cdb *dma_hw_desc;
        struct xor_cb *xor_hw_desc;
        phys_addr_t addr64, tmphi, tmplow;
        u32 *psgu, *psgl;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                if (!addrh) {
                        addr64 = addrl;
                        tmphi = (addr64 >> 32);
                        tmplow = (addr64 & 0xFFFFFFFF);
                } else {
                        tmphi = addrh;
                        tmplow = addrl;
                }
                dma_hw_desc = desc->hw_desc;

                psgu = dst_idx ? &dma_hw_desc->sg3u : &dma_hw_desc->sg2u;
                psgl = dst_idx ? &dma_hw_desc->sg3l : &dma_hw_desc->sg2l;

                *psgl = cpu_to_le32((u32)tmplow);
                *psgu |= cpu_to_le32((u32)tmphi);
                break;
        case PPC440SPE_XOR_ID:
                xor_hw_desc = desc->hw_desc;
                xor_hw_desc->cbtal = addrl;
                xor_hw_desc->cbtah |= addrh;
                break;
        }
}

/**
 * ppc440spe_desc_set_byte_count - set number of data bytes involved
 * into the operation
 */
static void ppc440spe_desc_set_byte_count(struct ppc440spe_adma_desc_slot *desc,
                                struct ppc440spe_adma_chan *chan,
                                u32 byte_count)
{
        struct dma_cdb *dma_hw_desc;
        struct xor_cb *xor_hw_desc;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                dma_hw_desc = desc->hw_desc;
                dma_hw_desc->cnt = cpu_to_le32(byte_count);
                break;
        case PPC440SPE_XOR_ID:
                xor_hw_desc = desc->hw_desc;
                xor_hw_desc->cbbc = byte_count;
                break;
        }
}

/**
 * ppc440spe_desc_set_rxor_block_size - set RXOR block size
 */
static inline void ppc440spe_desc_set_rxor_block_size(u32 byte_count)
{
        /* assume that byte_count is aligned on the 512-boundary;
         * thus write it directly to the register (bits 23:31 are
         * reserved there).
         */
        dcr_write(ppc440spe_mq_dcr_host, DCRN_MQ0_CF2H, byte_count);
}

/**
 * ppc440spe_desc_set_dcheck - set CHECK pattern
 */
static void ppc440spe_desc_set_dcheck(struct ppc440spe_adma_desc_slot *desc,
                                struct ppc440spe_adma_chan *chan, u8 *qword)
{
        struct dma_cdb *dma_hw_desc;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                dma_hw_desc = desc->hw_desc;
                iowrite32(qword[0], &dma_hw_desc->sg3l);
                iowrite32(qword[4], &dma_hw_desc->sg3u);
                iowrite32(qword[8], &dma_hw_desc->sg2l);
                iowrite32(qword[12], &dma_hw_desc->sg2u);
                break;
        default:
                BUG();
        }
}

/**
 * ppc440spe_xor_set_link - set link address in xor CB
 */
static void ppc440spe_xor_set_link(struct ppc440spe_adma_desc_slot *prev_desc,
                                struct ppc440spe_adma_desc_slot *next_desc)
{
        struct xor_cb *xor_hw_desc = prev_desc->hw_desc;

        if (unlikely(!next_desc || !(next_desc->phys))) {
                printk(KERN_ERR "%s: next_desc=0x%p; next_desc->phys=0x%llx\n",
                        __func__, next_desc,
                        next_desc ? next_desc->phys : 0);
                BUG();
        }

        xor_hw_desc->cbs = 0;
        xor_hw_desc->cblal = next_desc->phys;
        xor_hw_desc->cblah = 0;
        xor_hw_desc->cbc |= XOR_CBCR_LNK_BIT;
}

/**
 * ppc440spe_desc_set_link - set the address of descriptor following this
 * descriptor in chain
 */
static void ppc440spe_desc_set_link(struct ppc440spe_adma_chan *chan,
                                struct ppc440spe_adma_desc_slot *prev_desc,
                                struct ppc440spe_adma_desc_slot *next_desc)
{
        unsigned long flags;
        struct ppc440spe_adma_desc_slot *tail = next_desc;

        if (unlikely(!prev_desc || !next_desc ||
                (prev_desc->hw_next && prev_desc->hw_next != next_desc))) {
                /* If previous next is overwritten something is wrong.
                 * though we may refetch from append to initiate list
                 * processing; in this case - it's ok.
                 */
                printk(KERN_ERR "%s: prev_desc=0x%p; next_desc=0x%p; "
                        "prev->hw_next=0x%p\n", __func__, prev_desc,
                        next_desc, prev_desc ? prev_desc->hw_next : 0);
                BUG();
        }

        local_irq_save(flags);

        /* do s/w chaining both for DMA and XOR descriptors */
        prev_desc->hw_next = next_desc;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                break;
        case PPC440SPE_XOR_ID:
                /* bind descriptor to the chain */
                while (tail->hw_next)
                        tail = tail->hw_next;
                xor_last_linked = tail;

                if (prev_desc == xor_last_submit)
                        /* do not link to the last submitted CB */
                        break;
                ppc440spe_xor_set_link(prev_desc, next_desc);
                break;
        }

        local_irq_restore(flags);
}

/**
 * ppc440spe_desc_get_link - get the address of the descriptor that
 * follows this one
 */
static inline u32 ppc440spe_desc_get_link(struct ppc440spe_adma_desc_slot *desc,
                                        struct ppc440spe_adma_chan *chan)
{
        if (!desc->hw_next)
                return 0;

        return desc->hw_next->phys;
}

/**
 * ppc440spe_desc_is_aligned - check alignment
 */
static inline int ppc440spe_desc_is_aligned(
        struct ppc440spe_adma_desc_slot *desc, int num_slots)
{
        return (desc->idx & (num_slots - 1)) ? 0 : 1;
}

/**
 * ppc440spe_chan_xor_slot_count - get the number of slots necessary for
 * XOR operation
 */
static int ppc440spe_chan_xor_slot_count(size_t len, int src_cnt,
                        int *slots_per_op)
{
        int slot_cnt;

        /* each XOR descriptor provides up to 16 source operands */
        slot_cnt = *slots_per_op = (src_cnt + XOR_MAX_OPS - 1)/XOR_MAX_OPS;

        if (likely(len <= PPC440SPE_ADMA_XOR_MAX_BYTE_COUNT))
                return slot_cnt;

        printk(KERN_ERR "%s: len %d > max %d !!\n",
                __func__, len, PPC440SPE_ADMA_XOR_MAX_BYTE_COUNT);
        BUG();
        return slot_cnt;
}

/**
 * ppc440spe_dma2_pq_slot_count - get the number of slots necessary for
 * DMA2 PQ operation
 */
static int ppc440spe_dma2_pq_slot_count(dma_addr_t *srcs,
                int src_cnt, size_t len)
{
        signed long long order = 0;
        int state = 0;
        int addr_count = 0;
        int i;
        for (i = 1; i < src_cnt; i++) {
                dma_addr_t cur_addr = srcs[i];
                dma_addr_t old_addr = srcs[i-1];
                switch (state) {
                case 0:
                        if (cur_addr == old_addr + len) {
                                /* direct RXOR */
                                order = 1;
                                state = 1;
                                if (i == src_cnt-1)
                                        addr_count++;
                        } else if (old_addr == cur_addr + len) {
                                /* reverse RXOR */
                                order = -1;
                                state = 1;
                                if (i == src_cnt-1)
                                        addr_count++;
                        } else {
                                state = 3;
                        }
                        break;
                case 1:
                        if (i == src_cnt-2 || (order == -1
                                && cur_addr != old_addr - len)) {
                                order = 0;
                                state = 0;
                                addr_count++;
                        } else if (cur_addr == old_addr + len*order) {
                                state = 2;
                                if (i == src_cnt-1)
                                        addr_count++;
                        } else if (cur_addr == old_addr + 2*len) {
                                state = 2;
                                if (i == src_cnt-1)
                                        addr_count++;
                        } else if (cur_addr == old_addr + 3*len) {
                                state = 2;
                                if (i == src_cnt-1)
                                        addr_count++;
                        } else {
                                order = 0;
                                state = 0;
                                addr_count++;
                        }
                        break;
                case 2:
                        order = 0;
                        state = 0;
                        addr_count++;
                                break;
                }
                if (state == 3)
                        break;
        }
        if (src_cnt <= 1 || (state != 1 && state != 2)) {
                pr_err("%s: src_cnt=%d, state=%d, addr_count=%d, order=%lld\n",
                        __func__, src_cnt, state, addr_count, order);
                for (i = 0; i < src_cnt; i++)
                        pr_err("\t[%d] 0x%llx \n", i, srcs[i]);
                BUG();
        }

        return (addr_count + XOR_MAX_OPS - 1) / XOR_MAX_OPS;
}


/******************************************************************************
 * ADMA channel low-level routines
 ******************************************************************************/

static u32
ppc440spe_chan_get_current_descriptor(struct ppc440spe_adma_chan *chan);
static void ppc440spe_chan_append(struct ppc440spe_adma_chan *chan);

/**
 * ppc440spe_adma_device_clear_eot_status - interrupt ack to XOR or DMA engine
 */
static void ppc440spe_adma_device_clear_eot_status(
                                        struct ppc440spe_adma_chan *chan)
{
        struct dma_regs *dma_reg;
        struct xor_regs *xor_reg;
        u8 *p = chan->device->dma_desc_pool_virt;
        struct dma_cdb *cdb;
        u32 rv, i;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                /* read FIFO to ack */
                dma_reg = chan->device->dma_reg;
                while ((rv = ioread32(&dma_reg->csfpl))) {
                        i = rv & DMA_CDB_ADDR_MSK;
                        cdb = (struct dma_cdb *)&p[i -
                            (u32)chan->device->dma_desc_pool];

                        /* Clear opcode to ack. This is necessary for
                         * ZeroSum operations only
                         */
                        cdb->opc = 0;

                        if (test_bit(PPC440SPE_RXOR_RUN,
                            &ppc440spe_rxor_state)) {
                                /* probably this is a completed RXOR op,
                                 * get pointer to CDB using the fact that
                                 * physical and virtual addresses of CDB
                                 * in pools have the same offsets
                                 */
                                if (le32_to_cpu(cdb->sg1u) &
                                    DMA_CUED_XOR_BASE) {
                                        /* this is a RXOR */
                                        clear_bit(PPC440SPE_RXOR_RUN,
                                                  &ppc440spe_rxor_state);
                                }
                        }

                        if (rv & DMA_CDB_STATUS_MSK) {
                                /* ZeroSum check failed
                                 */
                                struct ppc440spe_adma_desc_slot *iter;
                                dma_addr_t phys = rv & ~DMA_CDB_MSK;

                                /*
                                 * Update the status of corresponding
                                 * descriptor.
                                 */
                                list_for_each_entry(iter, &chan->chain,
                                    chain_node) {
                                        if (iter->phys == phys)
                                                break;
                                }
                                /*
                                 * if cannot find the corresponding
                                 * slot it's a bug
                                 */
                                BUG_ON(&iter->chain_node == &chan->chain);

                                if (iter->xor_check_result) {
                                        if (test_bit(PPC440SPE_DESC_PCHECK,
                                                     &iter->flags)) {
                                                *iter->xor_check_result |=
                                                        SUM_CHECK_P_RESULT;
                                        } else
                                        if (test_bit(PPC440SPE_DESC_QCHECK,
                                                     &iter->flags)) {
                                                *iter->xor_check_result |=
                                                        SUM_CHECK_Q_RESULT;
                                        } else
                                                BUG();
                                }
                        }
                }

                rv = ioread32(&dma_reg->dsts);
                if (rv) {
                        pr_err("DMA%d err status: 0x%x\n",
                               chan->device->id, rv);
                        /* write back to clear */
                        iowrite32(rv, &dma_reg->dsts);
                }
                break;
        case PPC440SPE_XOR_ID:
                /* reset status bits to ack */
                xor_reg = chan->device->xor_reg;
                rv = ioread32be(&xor_reg->sr);
                iowrite32be(rv, &xor_reg->sr);

                if (rv & (XOR_IE_ICBIE_BIT|XOR_IE_ICIE_BIT|XOR_IE_RPTIE_BIT)) {

                        if (rv & XOR_IE_RPTIE_BIT) {
                                /* Read PLB Timeout Error.
                                 * Try to resubmit the CB
                                 */
                                u32 val = ioread32be(&xor_reg->ccbalr);

                                iowrite32be(val, &xor_reg->cblalr);

                                val = ioread32be(&xor_reg->crsr);
                                iowrite32be(val | XOR_CRSR_XAE_BIT,
                                            &xor_reg->crsr);
                        } else
                                pr_err("XOR ERR 0x%x status\n", rv);
                        break;
                }

                /*  if the XORcore is idle, but there are unprocessed CBs
                 * then refetch the s/w chain here
                 */
                if (!(ioread32be(&xor_reg->sr) & XOR_SR_XCP_BIT) &&
                    do_xor_refetch)
                        ppc440spe_chan_append(chan);
                break;
        }
}

/**
 * ppc440spe_chan_is_busy - get the channel status
 */
static int ppc440spe_chan_is_busy(struct ppc440spe_adma_chan *chan)
{
        struct dma_regs *dma_reg;
        struct xor_regs *xor_reg;
        int busy = 0;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                dma_reg = chan->device->dma_reg;
                /*  if command FIFO's head and tail pointers are equal and
                 * status tail is the same as command, then channel is free
                 */
                if (ioread16(&dma_reg->cpfhp) != ioread16(&dma_reg->cpftp) ||
                    ioread16(&dma_reg->cpftp) != ioread16(&dma_reg->csftp))
                        busy = 1;
                break;
        case PPC440SPE_XOR_ID:
                /* use the special status bit for the XORcore
                 */
                xor_reg = chan->device->xor_reg;
                busy = (ioread32be(&xor_reg->sr) & XOR_SR_XCP_BIT) ? 1 : 0;
                break;
        }

        return busy;
}

/**
 * ppc440spe_chan_set_first_xor_descriptor -  init XORcore chain
 */
static void ppc440spe_chan_set_first_xor_descriptor(
                                struct ppc440spe_adma_chan *chan,
                                struct ppc440spe_adma_desc_slot *next_desc)
{
        struct xor_regs *xor_reg = chan->device->xor_reg;

        if (ioread32be(&xor_reg->sr) & XOR_SR_XCP_BIT)
                printk(KERN_INFO "%s: Warn: XORcore is running "
                        "when try to set the first CDB!\n",
                        __func__);

        xor_last_submit = xor_last_linked = next_desc;

        iowrite32be(XOR_CRSR_64BA_BIT, &xor_reg->crsr);

        iowrite32be(next_desc->phys, &xor_reg->cblalr);
        iowrite32be(0, &xor_reg->cblahr);
        iowrite32be(ioread32be(&xor_reg->cbcr) | XOR_CBCR_LNK_BIT,
                    &xor_reg->cbcr);

        chan->hw_chain_inited = 1;
}

/**
 * ppc440spe_dma_put_desc - put DMA0,1 descriptor to FIFO.
 * called with irqs disabled
 */
static void ppc440spe_dma_put_desc(struct ppc440spe_adma_chan *chan,
                struct ppc440spe_adma_desc_slot *desc)
{
        u32 pcdb;
        struct dma_regs *dma_reg = chan->device->dma_reg;

        pcdb = desc->phys;
        if (!test_bit(PPC440SPE_DESC_INT, &desc->flags))
                pcdb |= DMA_CDB_NO_INT;

        chan_last_sub[chan->device->id] = desc;

        ADMA_LL_DBG(print_cb(chan, desc->hw_desc));

        iowrite32(pcdb, &dma_reg->cpfpl);
}

/**
 * ppc440spe_chan_append - update the h/w chain in the channel
 */
static void ppc440spe_chan_append(struct ppc440spe_adma_chan *chan)
{
        struct xor_regs *xor_reg;
        struct ppc440spe_adma_desc_slot *iter;
        struct xor_cb *xcb;
        u32 cur_desc;
        unsigned long flags;

        local_irq_save(flags);

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                cur_desc = ppc440spe_chan_get_current_descriptor(chan);

                if (likely(cur_desc)) {
                        iter = chan_last_sub[chan->device->id];
                        BUG_ON(!iter);
                } else {
                        /* first peer */
                        iter = chan_first_cdb[chan->device->id];
                        BUG_ON(!iter);
                        ppc440spe_dma_put_desc(chan, iter);
                        chan->hw_chain_inited = 1;
                }

                /* is there something new to append */
                if (!iter->hw_next)
                        break;

                /* flush descriptors from the s/w queue to fifo */
                list_for_each_entry_continue(iter, &chan->chain, chain_node) {
                        ppc440spe_dma_put_desc(chan, iter);
                        if (!iter->hw_next)
                                break;
                }
                break;
        case PPC440SPE_XOR_ID:
                /* update h/w links and refetch */
                if (!xor_last_submit->hw_next)
                        break;

                xor_reg = chan->device->xor_reg;
                /* the last linked CDB has to generate an interrupt
                 * that we'd be able to append the next lists to h/w
                 * regardless of the XOR engine state at the moment of
                 * appending of these next lists
                 */
                xcb = xor_last_linked->hw_desc;
                xcb->cbc |= XOR_CBCR_CBCE_BIT;

                if (!(ioread32be(&xor_reg->sr) & XOR_SR_XCP_BIT)) {
                        /* XORcore is idle. Refetch now */
                        do_xor_refetch = 0;
                        ppc440spe_xor_set_link(xor_last_submit,
                                xor_last_submit->hw_next);

                        ADMA_LL_DBG(print_cb_list(chan,
                                xor_last_submit->hw_next));

                        xor_last_submit = xor_last_linked;
                        iowrite32be(ioread32be(&xor_reg->crsr) |
                                    XOR_CRSR_RCBE_BIT | XOR_CRSR_64BA_BIT,
                                    &xor_reg->crsr);
                } else {
                        /* XORcore is running. Refetch later in the handler */
                        do_xor_refetch = 1;
                }

                break;
        }

        local_irq_restore(flags);
}

/**
 * ppc440spe_chan_get_current_descriptor - get the currently executed descriptor
 */
static u32
ppc440spe_chan_get_current_descriptor(struct ppc440spe_adma_chan *chan)
{
        struct dma_regs *dma_reg;
        struct xor_regs *xor_reg;

        if (unlikely(!chan->hw_chain_inited))
                /* h/w descriptor chain is not initialized yet */
                return 0;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                dma_reg = chan->device->dma_reg;
                return ioread32(&dma_reg->acpl) & (~DMA_CDB_MSK);
        case PPC440SPE_XOR_ID:
                xor_reg = chan->device->xor_reg;
                return ioread32be(&xor_reg->ccbalr);
        }
        return 0;
}

/**
 * ppc440spe_chan_run - enable the channel
 */
static void ppc440spe_chan_run(struct ppc440spe_adma_chan *chan)
{
        struct xor_regs *xor_reg;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                /* DMAs are always enabled, do nothing */
                break;
        case PPC440SPE_XOR_ID:
                /* drain write buffer */
                xor_reg = chan->device->xor_reg;

                /* fetch descriptor pointed to in <link> */
                iowrite32be(XOR_CRSR_64BA_BIT | XOR_CRSR_XAE_BIT,
                            &xor_reg->crsr);
                break;
        }
}

/******************************************************************************
 * ADMA device level
 ******************************************************************************/

static void ppc440spe_chan_start_null_xor(struct ppc440spe_adma_chan *chan);
static int ppc440spe_adma_alloc_chan_resources(struct dma_chan *chan);

static dma_cookie_t
ppc440spe_adma_tx_submit(struct dma_async_tx_descriptor *tx);

static void ppc440spe_adma_set_dest(struct ppc440spe_adma_desc_slot *tx,
                                    dma_addr_t addr, int index);
static void
ppc440spe_adma_memcpy_xor_set_src(struct ppc440spe_adma_desc_slot *tx,
                                  dma_addr_t addr, int index);

static void
ppc440spe_adma_pq_set_dest(struct ppc440spe_adma_desc_slot *tx,
                           dma_addr_t *paddr, unsigned long flags);
static void
ppc440spe_adma_pq_set_src(struct ppc440spe_adma_desc_slot *tx,
                          dma_addr_t addr, int index);
static void
ppc440spe_adma_pq_set_src_mult(struct ppc440spe_adma_desc_slot *tx,
                               unsigned char mult, int index, int dst_pos);
static void
ppc440spe_adma_pqzero_sum_set_dest(struct ppc440spe_adma_desc_slot *tx,
                                   dma_addr_t paddr, dma_addr_t qaddr);

static struct page *ppc440spe_rxor_srcs[32];

/**
 * ppc440spe_can_rxor - check if the operands may be processed with RXOR
 */
static int ppc440spe_can_rxor(struct page **srcs, int src_cnt, size_t len)
{
        int i, order = 0, state = 0;
        int idx = 0;

        if (unlikely(!(src_cnt > 1)))
                return 0;

        BUG_ON(src_cnt > ARRAY_SIZE(ppc440spe_rxor_srcs));

        /* Skip holes in the source list before checking */
        for (i = 0; i < src_cnt; i++) {
                if (!srcs[i])
                        continue;
                ppc440spe_rxor_srcs[idx++] = srcs[i];
        }
        src_cnt = idx;

        for (i = 1; i < src_cnt; i++) {
                char *cur_addr = page_address(ppc440spe_rxor_srcs[i]);
                char *old_addr = page_address(ppc440spe_rxor_srcs[i - 1]);

                switch (state) {
                case 0:
                        if (cur_addr == old_addr + len) {
                                /* direct RXOR */
                                order = 1;
                                state = 1;
                        } else if (old_addr == cur_addr + len) {
                                /* reverse RXOR */
                                order = -1;
                                state = 1;
                        } else
                                goto out;
                        break;
                case 1:
                        if ((i == src_cnt - 2) ||
                            (order == -1 && cur_addr != old_addr - len)) {
                                order = 0;
                                state = 0;
                        } else if ((cur_addr == old_addr + len * order) ||
                                   (cur_addr == old_addr + 2 * len) ||
                                   (cur_addr == old_addr + 3 * len)) {
                                state = 2;
                        } else {
                                order = 0;
                                state = 0;
                        }
                        break;
                case 2:
                        order = 0;
                        state = 0;
                        break;
                }
        }

out:
        if (state == 1 || state == 2)
                return 1;

        return 0;
}

/**
 * ppc440spe_adma_device_estimate - estimate the efficiency of processing
 *      the operation given on this channel. It's assumed that 'chan' is
 *      capable to process 'cap' type of operation.
 * @chan: channel to use
 * @cap: type of transaction
 * @dst_lst: array of destination pointers
 * @dst_cnt: number of destination operands
 * @src_lst: array of source pointers
 * @src_cnt: number of source operands
 * @src_sz: size of each source operand
 */
static int ppc440spe_adma_estimate(struct dma_chan *chan,
        enum dma_transaction_type cap, struct page **dst_lst, int dst_cnt,
        struct page **src_lst, int src_cnt, size_t src_sz)
{
        int ef = 1;

        if (cap == DMA_PQ || cap == DMA_PQ_VAL) {
                /* If RAID-6 capabilities were not activated don't try
                 * to use them
                 */
                if (unlikely(!ppc440spe_r6_enabled))
                        return -1;
        }
        /*  In the current implementation of ppc440spe ADMA driver it
         * makes sense to pick out only pq case, because it may be
         * processed:
         * (1) either using Biskup method on DMA2;
         * (2) or on DMA0/1.
         *  Thus we give a favour to (1) if the sources are suitable;
         * else let it be processed on one of the DMA0/1 engines.
         *  In the sum_product case where destination is also the
         * source process it on DMA0/1 only.
         */
        if (cap == DMA_PQ && chan->chan_id == PPC440SPE_XOR_ID) {

                if (dst_cnt == 1 && src_cnt == 2 && dst_lst[0] == src_lst[1])
                        ef = 0; /* sum_product case, process on DMA0/1 */
                else if (ppc440spe_can_rxor(src_lst, src_cnt, src_sz))
                        ef = 3; /* override (DMA0/1 + idle) */
                else
                        ef = 0; /* can't process on DMA2 if !rxor */
        }

        /* channel idleness increases the priority */
        if (likely(ef) &&
            !ppc440spe_chan_is_busy(to_ppc440spe_adma_chan(chan)))
                ef++;

        return ef;
}

struct dma_chan *
ppc440spe_async_tx_find_best_channel(enum dma_transaction_type cap,
        struct page **dst_lst, int dst_cnt, struct page **src_lst,
        int src_cnt, size_t src_sz)
{
        struct dma_chan *best_chan = NULL;
        struct ppc_dma_chan_ref *ref;
        int best_rank = -1;

        if (unlikely(!src_sz))
                return NULL;
        if (src_sz > PAGE_SIZE) {
                /*
                 * should a user of the api ever pass > PAGE_SIZE requests
                 * we sort out cases where temporary page-sized buffers
                 * are used.
                 */
                switch (cap) {
                case DMA_PQ:
                        if (src_cnt == 1 && dst_lst[1] == src_lst[0])
                                return NULL;
                        if (src_cnt == 2 && dst_lst[1] == src_lst[1])
                                return NULL;
                        break;
                case DMA_PQ_VAL:
                case DMA_XOR_VAL:
                        return NULL;
                default:
                        break;
                }
        }

        list_for_each_entry(ref, &ppc440spe_adma_chan_list, node) {
                if (dma_has_cap(cap, ref->chan->device->cap_mask)) {
                        int rank;

                        rank = ppc440spe_adma_estimate(ref->chan, cap, dst_lst,
                                        dst_cnt, src_lst, src_cnt, src_sz);
                        if (rank > best_rank) {
                                best_rank = rank;
                                best_chan = ref->chan;
                        }
                }
        }

        return best_chan;
}
EXPORT_SYMBOL_GPL(ppc440spe_async_tx_find_best_channel);

/**
 * ppc440spe_get_group_entry - get group entry with index idx
 * @tdesc: is the last allocated slot in the group.
 */
static struct ppc440spe_adma_desc_slot *
ppc440spe_get_group_entry(struct ppc440spe_adma_desc_slot *tdesc, u32 entry_idx)
{
        struct ppc440spe_adma_desc_slot *iter = tdesc->group_head;
        int i = 0;

        if (entry_idx < 0 || entry_idx >= (tdesc->src_cnt + tdesc->dst_cnt)) {
                printk("%s: entry_idx %d, src_cnt %d, dst_cnt %d\n",
                        __func__, entry_idx, tdesc->src_cnt, tdesc->dst_cnt);
                BUG();
        }

        list_for_each_entry(iter, &tdesc->group_list, chain_node) {
                if (i++ == entry_idx)
                        break;
        }
        return iter;
}

/**
 * ppc440spe_adma_free_slots - flags descriptor slots for reuse
 * @slot: Slot to free
 * Caller must hold &ppc440spe_chan->lock while calling this function
 */
static void ppc440spe_adma_free_slots(struct ppc440spe_adma_desc_slot *slot,
                                      struct ppc440spe_adma_chan *chan)
{
        int stride = slot->slots_per_op;

        while (stride--) {
                slot->slots_per_op = 0;
                slot = list_entry(slot->slot_node.next,
                                struct ppc440spe_adma_desc_slot,
                                slot_node);
        }
}

/**
 * ppc440spe_adma_run_tx_complete_actions - call functions to be called
 * upon completion
 */
static dma_cookie_t ppc440spe_adma_run_tx_complete_actions(
                struct ppc440spe_adma_desc_slot *desc,
                struct ppc440spe_adma_chan *chan,
                dma_cookie_t cookie)
{
        BUG_ON(desc->async_tx.cookie < 0);
        if (desc->async_tx.cookie > 0) {
                cookie = desc->async_tx.cookie;
                desc->async_tx.cookie = 0;

                /* call the callback (must not sleep or submit new
                 * operations to this channel)
                 */
                if (desc->async_tx.callback)
                        desc->async_tx.callback(
                                desc->async_tx.callback_param);

                dma_descriptor_unmap(&desc->async_tx);
        }

        /* run dependent operations */
        dma_run_dependencies(&desc->async_tx);

        return cookie;
}

/**
 * ppc440spe_adma_clean_slot - clean up CDB slot (if ack is set)
 */
static int ppc440spe_adma_clean_slot(struct ppc440spe_adma_desc_slot *desc,
                struct ppc440spe_adma_chan *chan)
{
        /* the client is allowed to attach dependent operations
         * until 'ack' is set
         */
        if (!async_tx_test_ack(&desc->async_tx))
                return 0;

        /* leave the last descriptor in the chain
         * so we can append to it
         */
        if (list_is_last(&desc->chain_node, &chan->chain) ||
            desc->phys == ppc440spe_chan_get_current_descriptor(chan))
                return 1;

        if (chan->device->id != PPC440SPE_XOR_ID) {
                /* our DMA interrupt handler clears opc field of
                 * each processed descriptor. For all types of
                 * operations except for ZeroSum we do not actually
                 * need ack from the interrupt handler. ZeroSum is a
                 * special case since the result of this operation
                 * is available from the handler only, so if we see
                 * such type of descriptor (which is unprocessed yet)
                 * then leave it in chain.
                 */
                struct dma_cdb *cdb = desc->hw_desc;
                if (cdb->opc == DMA_CDB_OPC_DCHECK128)
                        return 1;
        }

        dev_dbg(chan->device->common.dev, "\tfree slot %llx: %d stride: %d\n",
                desc->phys, desc->idx, desc->slots_per_op);

        list_del(&desc->chain_node);
        ppc440spe_adma_free_slots(desc, chan);
        return 0;
}

/**
 * __ppc440spe_adma_slot_cleanup - this is the common clean-up routine
 *      which runs through the channel CDBs list until reach the descriptor
 *      currently processed. When routine determines that all CDBs of group
 *      are completed then corresponding callbacks (if any) are called and slots
 *      are freed.
 */
static void __ppc440spe_adma_slot_cleanup(struct ppc440spe_adma_chan *chan)
{
        struct ppc440spe_adma_desc_slot *iter, *_iter, *group_start = NULL;
        dma_cookie_t cookie = 0;
        u32 current_desc = ppc440spe_chan_get_current_descriptor(chan);
        int busy = ppc440spe_chan_is_busy(chan);
        int seen_current = 0, slot_cnt = 0, slots_per_op = 0;

        dev_dbg(chan->device->common.dev, "ppc440spe adma%d: %s\n",
                chan->device->id, __func__);

        if (!current_desc) {
                /*  There were no transactions yet, so
                 * nothing to clean
                 */
                return;
        }

        /* free completed slots from the chain starting with
         * the oldest descriptor
         */
        list_for_each_entry_safe(iter, _iter, &chan->chain,
                                        chain_node) {
                dev_dbg(chan->device->common.dev, "\tcookie: %d slot: %d "
                    "busy: %d this_desc: %#llx next_desc: %#x "
                    "cur: %#x ack: %d\n",
                    iter->async_tx.cookie, iter->idx, busy, iter->phys,
                    ppc440spe_desc_get_link(iter, chan), current_desc,
                    async_tx_test_ack(&iter->async_tx));
                prefetch(_iter);
                prefetch(&_iter->async_tx);

                /* do not advance past the current descriptor loaded into the
                 * hardware channel,subsequent descriptors are either in process
                 * or have not been submitted
                 */
                if (seen_current)
                        break;

                /* stop the search if we reach the current descriptor and the
                 * channel is busy, or if it appears that the current descriptor
                 * needs to be re-read (i.e. has been appended to)
                 */
                if (iter->phys == current_desc) {
                        BUG_ON(seen_current++);
                        if (busy || ppc440spe_desc_get_link(iter, chan)) {
                                /* not all descriptors of the group have
                                 * been completed; exit.
                                 */
                                break;
                        }
                }

                /* detect the start of a group transaction */
                if (!slot_cnt && !slots_per_op) {
                        slot_cnt = iter->slot_cnt;
                        slots_per_op = iter->slots_per_op;
                        if (slot_cnt <= slots_per_op) {
                                slot_cnt = 0;
                                slots_per_op = 0;
                        }
                }

                if (slot_cnt) {
                        if (!group_start)
                                group_start = iter;
                        slot_cnt -= slots_per_op;
                }

                /* all the members of a group are complete */
                if (slots_per_op != 0 && slot_cnt == 0) {
                        struct ppc440spe_adma_desc_slot *grp_iter, *_grp_iter;
                        int end_of_chain = 0;

                        /* clean up the group */
                        slot_cnt = group_start->slot_cnt;
                        grp_iter = group_start;
                        list_for_each_entry_safe_from(grp_iter, _grp_iter,
                                &chan->chain, chain_node) {

                                cookie = ppc440spe_adma_run_tx_complete_actions(
                                        grp_iter, chan, cookie);

                                slot_cnt -= slots_per_op;
                                end_of_chain = ppc440spe_adma_clean_slot(
                                    grp_iter, chan);
                                if (end_of_chain && slot_cnt) {
                                        /* Should wait for ZeroSum completion */
                                        if (cookie > 0)
                                                chan->common.completed_cookie = cookie;
                                        return;
                                }

                                if (slot_cnt == 0 || end_of_chain)
                                        break;
                        }

                        /* the group should be complete at this point */
                        BUG_ON(slot_cnt);

                        slots_per_op = 0;
                        group_start = NULL;
                        if (end_of_chain)
                                break;
                        else
                                continue;
                } else if (slots_per_op) /* wait for group completion */
                        continue;

                cookie = ppc440spe_adma_run_tx_complete_actions(iter, chan,
                    cookie);

                if (ppc440spe_adma_clean_slot(iter, chan))
                        break;
        }

        BUG_ON(!seen_current);

        if (cookie > 0) {
                chan->common.completed_cookie = cookie;
                pr_debug("\tcompleted cookie %d\n", cookie);
        }

}

/**
 * ppc440spe_adma_tasklet - clean up watch-dog initiator
 */
static void ppc440spe_adma_tasklet(unsigned long data)
{
        struct ppc440spe_adma_chan *chan = (struct ppc440spe_adma_chan *) data;

        spin_lock_nested(&chan->lock, SINGLE_DEPTH_NESTING);
        __ppc440spe_adma_slot_cleanup(chan);
        spin_unlock(&chan->lock);
}

/**
 * ppc440spe_adma_slot_cleanup - clean up scheduled initiator
 */
static void ppc440spe_adma_slot_cleanup(struct ppc440spe_adma_chan *chan)
{
        spin_lock_bh(&chan->lock);
        __ppc440spe_adma_slot_cleanup(chan);
        spin_unlock_bh(&chan->lock);
}

/**
 * ppc440spe_adma_alloc_slots - allocate free slots (if any)
 */
static struct ppc440spe_adma_desc_slot *ppc440spe_adma_alloc_slots(
                struct ppc440spe_adma_chan *chan, int num_slots,
                int slots_per_op)
{
        struct ppc440spe_adma_desc_slot *iter = NULL, *_iter;
        struct ppc440spe_adma_desc_slot *alloc_start = NULL;
        struct list_head chain = LIST_HEAD_INIT(chain);
        int slots_found, retry = 0;


        BUG_ON(!num_slots || !slots_per_op);
        /* start search from the last allocated descrtiptor
         * if a contiguous allocation can not be found start searching
         * from the beginning of the list
         */
retry:
        slots_found = 0;
        if (retry == 0)
                iter = chan->last_used;
        else
                iter = list_entry(&chan->all_slots,
                                  struct ppc440spe_adma_desc_slot,
                                  slot_node);
        list_for_each_entry_safe_continue(iter, _iter, &chan->all_slots,
            slot_node) {
                prefetch(_iter);
                prefetch(&_iter->async_tx);
                if (iter->slots_per_op) {
                        slots_found = 0;
                        continue;
                }

                /* start the allocation if the slot is correctly aligned */
                if (!slots_found++)
                        alloc_start = iter;

                if (slots_found == num_slots) {
                        struct ppc440spe_adma_desc_slot *alloc_tail = NULL;
                        struct ppc440spe_adma_desc_slot *last_used = NULL;

                        iter = alloc_start;
                        while (num_slots) {
                                int i;
                                /* pre-ack all but the last descriptor */
                                if (num_slots != slots_per_op)
                                        async_tx_ack(&iter->async_tx);

                                list_add_tail(&iter->chain_node, &chain);
                                alloc_tail = iter;
                                iter->async_tx.cookie = 0;
                                iter->hw_next = NULL;
                                iter->flags = 0;
                                iter->slot_cnt = num_slots;
                                iter->xor_check_result = NULL;
                                for (i = 0; i < slots_per_op; i++) {
                                        iter->slots_per_op = slots_per_op - i;
                                        last_used = iter;
                                        iter = list_entry(iter->slot_node.next,
                                                struct ppc440spe_adma_desc_slot,
                                                slot_node);
                                }
                                num_slots -= slots_per_op;
                        }
                        alloc_tail->group_head = alloc_start;
                        alloc_tail->async_tx.cookie = -EBUSY;
                        list_splice(&chain, &alloc_tail->group_list);
                        chan->last_used = last_used;
                        return alloc_tail;
                }
        }
        if (!retry++)
                goto retry;

        /* try to free some slots if the allocation fails */
        tasklet_schedule(&chan->irq_tasklet);
        return NULL;
}

/**
 * ppc440spe_adma_alloc_chan_resources -  allocate pools for CDB slots
 */
static int ppc440spe_adma_alloc_chan_resources(struct dma_chan *chan)
{
        struct ppc440spe_adma_chan *ppc440spe_chan;
        struct ppc440spe_adma_desc_slot *slot = NULL;
        char *hw_desc;
        int i, db_sz;
        int init;

        ppc440spe_chan = to_ppc440spe_adma_chan(chan);
        init = ppc440spe_chan->slots_allocated ? 0 : 1;
        chan->chan_id = ppc440spe_chan->device->id;

        /* Allocate descriptor slots */
        i = ppc440spe_chan->slots_allocated;
        if (ppc440spe_chan->device->id != PPC440SPE_XOR_ID)
                db_sz = sizeof(struct dma_cdb);
        else
                db_sz = sizeof(struct xor_cb);

        for (; i < (ppc440spe_chan->device->pool_size / db_sz); i++) {
                slot = kzalloc(sizeof(struct ppc440spe_adma_desc_slot),
                               GFP_KERNEL);
                if (!slot) {
                        printk(KERN_INFO "SPE ADMA Channel only initialized"
                                " %d descriptor slots", i--);
                        break;
                }

                hw_desc = (char *) ppc440spe_chan->device->dma_desc_pool_virt;
                slot->hw_desc = (void *) &hw_desc[i * db_sz];
                dma_async_tx_descriptor_init(&slot->async_tx, chan);
                slot->async_tx.tx_submit = ppc440spe_adma_tx_submit;
                INIT_LIST_HEAD(&slot->chain_node);
                INIT_LIST_HEAD(&slot->slot_node);
                INIT_LIST_HEAD(&slot->group_list);
                slot->phys = ppc440spe_chan->device->dma_desc_pool + i * db_sz;
                slot->idx = i;

                spin_lock_bh(&ppc440spe_chan->lock);
                ppc440spe_chan->slots_allocated++;
                list_add_tail(&slot->slot_node, &ppc440spe_chan->all_slots);
                spin_unlock_bh(&ppc440spe_chan->lock);
        }

        if (i && !ppc440spe_chan->last_used) {
                ppc440spe_chan->last_used =
                        list_entry(ppc440spe_chan->all_slots.next,
                                struct ppc440spe_adma_desc_slot,
                                slot_node);
        }

        dev_dbg(ppc440spe_chan->device->common.dev,
                "ppc440spe adma%d: allocated %d descriptor slots\n",
                ppc440spe_chan->device->id, i);

        /* initialize the channel and the chain with a null operation */
        if (init) {
                switch (ppc440spe_chan->device->id) {
                case PPC440SPE_DMA0_ID:
                case PPC440SPE_DMA1_ID:
                        ppc440spe_chan->hw_chain_inited = 0;
                        /* Use WXOR for self-testing */
                        if (!ppc440spe_r6_tchan)
                                ppc440spe_r6_tchan = ppc440spe_chan;
                        break;
                case PPC440SPE_XOR_ID:
                        ppc440spe_chan_start_null_xor(ppc440spe_chan);
                        break;
                default:
                        BUG();
                }
                ppc440spe_chan->needs_unmap = 1;
        }

        return (i > 0) ? i : -ENOMEM;
}

/**
 * ppc440spe_rxor_set_region_data -
 */
static void ppc440spe_rxor_set_region(struct ppc440spe_adma_desc_slot *desc,
        u8 xor_arg_no, u32 mask)
{
        struct xor_cb *xcb = desc->hw_desc;

        xcb->ops[xor_arg_no].h |= mask;
}

/**
 * ppc440spe_rxor_set_src -
 */
static void ppc440spe_rxor_set_src(struct ppc440spe_adma_desc_slot *desc,
        u8 xor_arg_no, dma_addr_t addr)
{
        struct xor_cb *xcb = desc->hw_desc;

        xcb->ops[xor_arg_no].h |= DMA_CUED_XOR_BASE;
        xcb->ops[xor_arg_no].l = addr;
}

/**
 * ppc440spe_rxor_set_mult -
 */
static void ppc440spe_rxor_set_mult(struct ppc440spe_adma_desc_slot *desc,
        u8 xor_arg_no, u8 idx, u8 mult)
{
        struct xor_cb *xcb = desc->hw_desc;

        xcb->ops[xor_arg_no].h |= mult << (DMA_CUED_MULT1_OFF + idx * 8);
}

/**
 * ppc440spe_adma_check_threshold - append CDBs to h/w chain if threshold
 *      has been achieved
 */
static void ppc440spe_adma_check_threshold(struct ppc440spe_adma_chan *chan)
{
        dev_dbg(chan->device->common.dev, "ppc440spe adma%d: pending: %d\n",
                chan->device->id, chan->pending);

        if (chan->pending >= PPC440SPE_ADMA_THRESHOLD) {
                chan->pending = 0;
                ppc440spe_chan_append(chan);
        }
}

/**
 * ppc440spe_adma_tx_submit - submit new descriptor group to the channel
 *      (it's not necessary that descriptors will be submitted to the h/w
 *      chains too right now)
 */
static dma_cookie_t ppc440spe_adma_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct ppc440spe_adma_desc_slot *sw_desc;
        struct ppc440spe_adma_chan *chan = to_ppc440spe_adma_chan(tx->chan);
        struct ppc440spe_adma_desc_slot *group_start, *old_chain_tail;
        int slot_cnt;
        int slots_per_op;
        dma_cookie_t cookie;

        sw_desc = tx_to_ppc440spe_adma_slot(tx);

        group_start = sw_desc->group_head;
        slot_cnt = group_start->slot_cnt;
        slots_per_op = group_start->slots_per_op;

        spin_lock_bh(&chan->lock);
        cookie = dma_cookie_assign(tx);

        if (unlikely(list_empty(&chan->chain))) {
                /* first peer */
                list_splice_init(&sw_desc->group_list, &chan->chain);
                chan_first_cdb[chan->device->id] = group_start;
        } else {
                /* isn't first peer, bind CDBs to chain */
                old_chain_tail = list_entry(chan->chain.prev,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);
                list_splice_init(&sw_desc->group_list,
                    &old_chain_tail->chain_node);
                /* fix up the hardware chain */
                ppc440spe_desc_set_link(chan, old_chain_tail, group_start);
        }

        /* increment the pending count by the number of operations */
        chan->pending += slot_cnt / slots_per_op;
        ppc440spe_adma_check_threshold(chan);
        spin_unlock_bh(&chan->lock);

        dev_dbg(chan->device->common.dev,
                "ppc440spe adma%d: %s cookie: %d slot: %d tx %p\n",
                chan->device->id, __func__,
                sw_desc->async_tx.cookie, sw_desc->idx, sw_desc);

        return cookie;
}

/**
 * ppc440spe_adma_prep_dma_interrupt - prepare CDB for a pseudo DMA operation
 */
static struct dma_async_tx_descriptor *ppc440spe_adma_prep_dma_interrupt(
                struct dma_chan *chan, unsigned long flags)
{
        struct ppc440spe_adma_chan *ppc440spe_chan;
        struct ppc440spe_adma_desc_slot *sw_desc, *group_start;
        int slot_cnt, slots_per_op;

        ppc440spe_chan = to_ppc440spe_adma_chan(chan);

        dev_dbg(ppc440spe_chan->device->common.dev,
                "ppc440spe adma%d: %s\n", ppc440spe_chan->device->id,
                __func__);

        spin_lock_bh(&ppc440spe_chan->lock);
        slot_cnt = slots_per_op = 1;
        sw_desc = ppc440spe_adma_alloc_slots(ppc440spe_chan, slot_cnt,
                        slots_per_op);
        if (sw_desc) {
                group_start = sw_desc->group_head;
                ppc440spe_desc_init_interrupt(group_start, ppc440spe_chan);
                group_start->unmap_len = 0;
                sw_desc->async_tx.flags = flags;
        }
        spin_unlock_bh(&ppc440spe_chan->lock);

        return sw_desc ? &sw_desc->async_tx : NULL;
}

/**
 * ppc440spe_adma_prep_dma_memcpy - prepare CDB for a MEMCPY operation
 */
static struct dma_async_tx_descriptor *ppc440spe_adma_prep_dma_memcpy(
                struct dma_chan *chan, dma_addr_t dma_dest,
                dma_addr_t dma_src, size_t len, unsigned long flags)
{
        struct ppc440spe_adma_chan *ppc440spe_chan;
        struct ppc440spe_adma_desc_slot *sw_desc, *group_start;
        int slot_cnt, slots_per_op;

        ppc440spe_chan = to_ppc440spe_adma_chan(chan);

        if (unlikely(!len))
                return NULL;

        BUG_ON(len > PPC440SPE_ADMA_DMA_MAX_BYTE_COUNT);

        spin_lock_bh(&ppc440spe_chan->lock);

        dev_dbg(ppc440spe_chan->device->common.dev,
                "ppc440spe adma%d: %s len: %u int_en %d\n",
                ppc440spe_chan->device->id, __func__, len,
                flags & DMA_PREP_INTERRUPT ? 1 : 0);
        slot_cnt = slots_per_op = 1;
        sw_desc = ppc440spe_adma_alloc_slots(ppc440spe_chan, slot_cnt,
                slots_per_op);
        if (sw_desc) {
                group_start = sw_desc->group_head;
                ppc440spe_desc_init_memcpy(group_start, flags);
                ppc440spe_adma_set_dest(group_start, dma_dest, 0);
                ppc440spe_adma_memcpy_xor_set_src(group_start, dma_src, 0);
                ppc440spe_desc_set_byte_count(group_start, ppc440spe_chan, len);
                sw_desc->unmap_len = len;
                sw_desc->async_tx.flags = flags;
        }
        spin_unlock_bh(&ppc440spe_chan->lock);

        return sw_desc ? &sw_desc->async_tx : NULL;
}

/**
 * ppc440spe_adma_prep_dma_xor - prepare CDB for a XOR operation
 */
static struct dma_async_tx_descriptor *ppc440spe_adma_prep_dma_xor(
                struct dma_chan *chan, dma_addr_t dma_dest,
                dma_addr_t *dma_src, u32 src_cnt, size_t len,
                unsigned long flags)
{
        struct ppc440spe_adma_chan *ppc440spe_chan;
        struct ppc440spe_adma_desc_slot *sw_desc, *group_start;
        int slot_cnt, slots_per_op;

        ppc440spe_chan = to_ppc440spe_adma_chan(chan);

        ADMA_LL_DBG(prep_dma_xor_dbg(ppc440spe_chan->device->id,
                                     dma_dest, dma_src, src_cnt));
        if (unlikely(!len))
                return NULL;
        BUG_ON(len > PPC440SPE_ADMA_XOR_MAX_BYTE_COUNT);

        dev_dbg(ppc440spe_chan->device->common.dev,
                "ppc440spe adma%d: %s src_cnt: %d len: %u int_en: %d\n",
                ppc440spe_chan->device->id, __func__, src_cnt, len,
                flags & DMA_PREP_INTERRUPT ? 1 : 0);

        spin_lock_bh(&ppc440spe_chan->lock);
        slot_cnt = ppc440spe_chan_xor_slot_count(len, src_cnt, &slots_per_op);
        sw_desc = ppc440spe_adma_alloc_slots(ppc440spe_chan, slot_cnt,
                        slots_per_op);
        if (sw_desc) {
                group_start = sw_desc->group_head;
                ppc440spe_desc_init_xor(group_start, src_cnt, flags);
                ppc440spe_adma_set_dest(group_start, dma_dest, 0);
                while (src_cnt--)
                        ppc440spe_adma_memcpy_xor_set_src(group_start,
                                dma_src[src_cnt], src_cnt);
                ppc440spe_desc_set_byte_count(group_start, ppc440spe_chan, len);
                sw_desc->unmap_len = len;
                sw_desc->async_tx.flags = flags;
        }
        spin_unlock_bh(&ppc440spe_chan->lock);

        return sw_desc ? &sw_desc->async_tx : NULL;
}

static inline void
ppc440spe_desc_set_xor_src_cnt(struct ppc440spe_adma_desc_slot *desc,
                                int src_cnt);
static void ppc440spe_init_rxor_cursor(struct ppc440spe_rxor *cursor);

/**
 * ppc440spe_adma_init_dma2rxor_slot -
 */
static void ppc440spe_adma_init_dma2rxor_slot(
                struct ppc440spe_adma_desc_slot *desc,
                dma_addr_t *src, int src_cnt)
{
        int i;

        /* initialize CDB */
        for (i = 0; i < src_cnt; i++) {
                ppc440spe_adma_dma2rxor_prep_src(desc, &desc->rxor_cursor, i,
                                                 desc->src_cnt, (u32)src[i]);
        }
}

/**
 * ppc440spe_dma01_prep_mult -
 * for Q operation where destination is also the source
 */
static struct ppc440spe_adma_desc_slot *ppc440spe_dma01_prep_mult(
                struct ppc440spe_adma_chan *ppc440spe_chan,
                dma_addr_t *dst, int dst_cnt, dma_addr_t *src, int src_cnt,
                const unsigned char *scf, size_t len, unsigned long flags)
{
        struct ppc440spe_adma_desc_slot *sw_desc = NULL;
        unsigned long op = 0;
        int slot_cnt;

        set_bit(PPC440SPE_DESC_WXOR, &op);
        slot_cnt = 2;

        spin_lock_bh(&ppc440spe_chan->lock);

        /* use WXOR, each descriptor occupies one slot */
        sw_desc = ppc440spe_adma_alloc_slots(ppc440spe_chan, slot_cnt, 1);
        if (sw_desc) {
                struct ppc440spe_adma_chan *chan;
                struct ppc440spe_adma_desc_slot *iter;
                struct dma_cdb *hw_desc;

                chan = to_ppc440spe_adma_chan(sw_desc->async_tx.chan);
                set_bits(op, &sw_desc->flags);
                sw_desc->src_cnt = src_cnt;
                sw_desc->dst_cnt = dst_cnt;
                /* First descriptor, zero data in the destination and copy it
                 * to q page using MULTICAST transfer.
                 */
                iter = list_first_entry(&sw_desc->group_list,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);
                memset(iter->hw_desc, 0, sizeof(struct dma_cdb));
                /* set 'next' pointer */
                iter->hw_next = list_entry(iter->chain_node.next,
                                           struct ppc440spe_adma_desc_slot,
                                           chain_node);
                clear_bit(PPC440SPE_DESC_INT, &iter->flags);
                hw_desc = iter->hw_desc;
                hw_desc->opc = DMA_CDB_OPC_MULTICAST;

                ppc440spe_desc_set_dest_addr(iter, chan,
                                             DMA_CUED_XOR_BASE, dst[0], 0);
                ppc440spe_desc_set_dest_addr(iter, chan, 0, dst[1], 1);
                ppc440spe_desc_set_src_addr(iter, chan, 0, DMA_CUED_XOR_HB,
                                            src[0]);
                ppc440spe_desc_set_byte_count(iter, ppc440spe_chan, len);
                iter->unmap_len = len;

                /*
                 * Second descriptor, multiply data from the q page
                 * and store the result in real destination.
                 */
                iter = list_first_entry(&iter->chain_node,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);
                memset(iter->hw_desc, 0, sizeof(struct dma_cdb));
                iter->hw_next = NULL;
                if (flags & DMA_PREP_INTERRUPT)
                        set_bit(PPC440SPE_DESC_INT, &iter->flags);
                else
                        clear_bit(PPC440SPE_DESC_INT, &iter->flags);

                hw_desc = iter->hw_desc;
                hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;
                ppc440spe_desc_set_src_addr(iter, chan, 0,
                                            DMA_CUED_XOR_HB, dst[1]);
                ppc440spe_desc_set_dest_addr(iter, chan,
                                             DMA_CUED_XOR_BASE, dst[0], 0);

                ppc440spe_desc_set_src_mult(iter, chan, DMA_CUED_MULT1_OFF,
                                            DMA_CDB_SG_DST1, scf[0]);
                ppc440spe_desc_set_byte_count(iter, ppc440spe_chan, len);
                iter->unmap_len = len;
                sw_desc->async_tx.flags = flags;
        }

        spin_unlock_bh(&ppc440spe_chan->lock);

        return sw_desc;
}

/**
 * ppc440spe_dma01_prep_sum_product -
 * Dx = A*(P+Pxy) + B*(Q+Qxy) operation where destination is also
 * the source.
 */
static struct ppc440spe_adma_desc_slot *ppc440spe_dma01_prep_sum_product(
                struct ppc440spe_adma_chan *ppc440spe_chan,
                dma_addr_t *dst, dma_addr_t *src, int src_cnt,
                const unsigned char *scf, size_t len, unsigned long flags)
{
        struct ppc440spe_adma_desc_slot *sw_desc = NULL;
        unsigned long op = 0;
        int slot_cnt;

        set_bit(PPC440SPE_DESC_WXOR, &op);
        slot_cnt = 3;

        spin_lock_bh(&ppc440spe_chan->lock);

        /* WXOR, each descriptor occupies one slot */
        sw_desc = ppc440spe_adma_alloc_slots(ppc440spe_chan, slot_cnt, 1);
        if (sw_desc) {
                struct ppc440spe_adma_chan *chan;
                struct ppc440spe_adma_desc_slot *iter;
                struct dma_cdb *hw_desc;

                chan = to_ppc440spe_adma_chan(sw_desc->async_tx.chan);
                set_bits(op, &sw_desc->flags);
                sw_desc->src_cnt = src_cnt;
                sw_desc->dst_cnt = 1;
                /* 1st descriptor, src[1] data to q page and zero destination */
                iter = list_first_entry(&sw_desc->group_list,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);
                memset(iter->hw_desc, 0, sizeof(struct dma_cdb));
                iter->hw_next = list_entry(iter->chain_node.next,
                                           struct ppc440spe_adma_desc_slot,
                                           chain_node);
                clear_bit(PPC440SPE_DESC_INT, &iter->flags);
                hw_desc = iter->hw_desc;
                hw_desc->opc = DMA_CDB_OPC_MULTICAST;

                ppc440spe_desc_set_dest_addr(iter, chan, DMA_CUED_XOR_BASE,
                                             *dst, 0);
                ppc440spe_desc_set_dest_addr(iter, chan, 0,
                                             ppc440spe_chan->qdest, 1);
                ppc440spe_desc_set_src_addr(iter, chan, 0, DMA_CUED_XOR_HB,
                                            src[1]);
                ppc440spe_desc_set_byte_count(iter, ppc440spe_chan, len);
                iter->unmap_len = len;

                /* 2nd descriptor, multiply src[1] data and store the
                 * result in destination */
                iter = list_first_entry(&iter->chain_node,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);
                memset(iter->hw_desc, 0, sizeof(struct dma_cdb));
                /* set 'next' pointer */
                iter->hw_next = list_entry(iter->chain_node.next,
                                           struct ppc440spe_adma_desc_slot,
                                           chain_node);
                if (flags & DMA_PREP_INTERRUPT)
                        set_bit(PPC440SPE_DESC_INT, &iter->flags);
                else
                        clear_bit(PPC440SPE_DESC_INT, &iter->flags);

                hw_desc = iter->hw_desc;
                hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;
                ppc440spe_desc_set_src_addr(iter, chan, 0, DMA_CUED_XOR_HB,
                                            ppc440spe_chan->qdest);
                ppc440spe_desc_set_dest_addr(iter, chan, DMA_CUED_XOR_BASE,
                                             *dst, 0);
                ppc440spe_desc_set_src_mult(iter, chan, DMA_CUED_MULT1_OFF,
                                            DMA_CDB_SG_DST1, scf[1]);
                ppc440spe_desc_set_byte_count(iter, ppc440spe_chan, len);
                iter->unmap_len = len;

                /*
                 * 3rd descriptor, multiply src[0] data and xor it
                 * with destination
                 */
                iter = list_first_entry(&iter->chain_node,
                                        struct ppc440spe_adma_desc_slot,
                                        chain_node);
                memset(iter->hw_desc, 0, sizeof(struct dma_cdb));
                iter->hw_next = NULL;
                if (flags & DMA_PREP_INTERRUPT)
                        set_bit(PPC440SPE_DESC_INT, &iter->flags);
                else
                        clear_bit(PPC440SPE_DESC_INT, &iter->flags);

                hw_desc = iter->hw_desc;
                hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;
                ppc440spe_desc_set_src_addr(iter, chan, 0, DMA_CUED_XOR_HB,
                                            src[0]);
                ppc440spe_desc_set_dest_addr(iter, chan, DMA_CUED_XOR_BASE,
                                             *dst, 0);
                ppc440spe_desc_set_src_mult(iter, chan, DMA_CUED_MULT1_OFF,
                                            DMA_CDB_SG_DST1, scf[0]);
                ppc440spe_desc_set_byte_count(iter, ppc440spe_chan, len);
                iter->unmap_len = len;
                sw_desc->async_tx.flags = flags;
        }

        spin_unlock_bh(&ppc440spe_chan->lock);

        return sw_desc;
}

static struct ppc440spe_adma_desc_slot *ppc440spe_dma01_prep_pq(
                struct ppc440spe_adma_chan *ppc440spe_chan,
                dma_addr_t *dst, int dst_cnt, dma_addr_t *src, int src_cnt,
                const unsigned char *scf, size_t len, unsigned long flags)
{
        int slot_cnt;
        struct ppc440spe_adma_desc_slot *sw_desc = NULL, *iter;
        unsigned long op = 0;
        unsigned char mult = 1;

        pr_debug("%s: dst_cnt %d, src_cnt %d, len %d\n",
                 __func__, dst_cnt, src_cnt, len);
        /*  select operations WXOR/RXOR depending on the
         * source addresses of operators and the number
         * of destinations (RXOR support only Q-parity calculations)
         */
        set_bit(PPC440SPE_DESC_WXOR, &op);
        if (!test_and_set_bit(PPC440SPE_RXOR_RUN, &ppc440spe_rxor_state)) {
                /* no active RXOR;
                 * do RXOR if:
                 * - there are more than 1 source,
                 * - len is aligned on 512-byte boundary,
                 * - source addresses fit to one of 4 possible regions.
                 */
                if (src_cnt > 1 &&
                    !(len & MQ0_CF2H_RXOR_BS_MASK) &&
                    (src[0] + len) == src[1]) {
                        /* may do RXOR R1 R2 */
                        set_bit(PPC440SPE_DESC_RXOR, &op);
                        if (src_cnt != 2) {
                                /* may try to enhance region of RXOR */
                                if ((src[1] + len) == src[2]) {
                                        /* do RXOR R1 R2 R3 */
                                        set_bit(PPC440SPE_DESC_RXOR123,
                                                &op);
                                } else if ((src[1] + len * 2) == src[2]) {
                                        /* do RXOR R1 R2 R4 */
                                        set_bit(PPC440SPE_DESC_RXOR124, &op);
                                } else if ((src[1] + len * 3) == src[2]) {
                                        /* do RXOR R1 R2 R5 */
                                        set_bit(PPC440SPE_DESC_RXOR125,
                                                &op);
                                } else {
                                        /* do RXOR R1 R2 */
                                        set_bit(PPC440SPE_DESC_RXOR12,
                                                &op);
                                }
                        } else {
                                /* do RXOR R1 R2 */
                                set_bit(PPC440SPE_DESC_RXOR12, &op);
                        }
                }

                if (!test_bit(PPC440SPE_DESC_RXOR, &op)) {
                        /* can not do this operation with RXOR */
                        clear_bit(PPC440SPE_RXOR_RUN,
                                &ppc440spe_rxor_state);
                } else {
                        /* can do; set block size right now */
                        ppc440spe_desc_set_rxor_block_size(len);
                }
        }

        /* Number of necessary slots depends on operation type selected */
        if (!test_bit(PPC440SPE_DESC_RXOR, &op)) {
                /*  This is a WXOR only chain. Need descriptors for each
                 * source to GF-XOR them with WXOR, and need descriptors
                 * for each destination to zero them with WXOR
                 */
                slot_cnt = src_cnt;

                if (flags & DMA_PREP_ZERO_P) {
                        slot_cnt++;
                        set_bit(PPC440SPE_ZERO_P, &op);
                }
                if (flags & DMA_PREP_ZERO_Q) {
                        slot_cnt++;
                        set_bit(PPC440SPE_ZERO_Q, &op);
                }
        } else {
                /*  Need 1/2 descriptor for RXOR operation, and
                 * need (src_cnt - (2 or 3)) for WXOR of sources
                 * remained (if any)
                 */
                slot_cnt = dst_cnt;

                if (flags & DMA_PREP_ZERO_P)
                        set_bit(PPC440SPE_ZERO_P, &op);
                if (flags & DMA_PREP_ZERO_Q)
                        set_bit(PPC440SPE_ZERO_Q, &op);

                if (test_bit(PPC440SPE_DESC_RXOR12, &op))
                        slot_cnt += src_cnt - 2;
                else
                        slot_cnt += src_cnt - 3;

                /*  Thus we have either RXOR only chain or
                 * mixed RXOR/WXOR
                 */
                if (slot_cnt == dst_cnt)
                        /* RXOR only chain */
                        clear_bit(PPC440SPE_DESC_WXOR, &op);
        }

        spin_lock_bh(&ppc440spe_chan->lock);
        /* for both RXOR/WXOR each descriptor occupies one slot */
        sw_desc = ppc440spe_adma_alloc_slots(ppc440spe_chan, slot_cnt, 1);
        if (sw_desc) {
                ppc440spe_desc_init_dma01pq(sw_desc, dst_cnt, src_cnt,
                                flags, op);

                /* setup dst/src/mult */
                pr_debug("%s: set dst descriptor 0, 1: 0x%016llx, 0x%016llx\n",
                         __func__, dst[0], dst[1]);
                ppc440spe_adma_pq_set_dest(sw_desc, dst, flags);
                while (src_cnt--) {
                        ppc440spe_adma_pq_set_src(sw_desc, src[src_cnt],
                                                  src_cnt);

                        /* NOTE: "Multi = 0 is equivalent to = 1" as it
                         * stated in 440SPSPe_RAID6_Addendum_UM_1_17.pdf
                         * doesn't work for RXOR with DMA0/1! Instead, multi=0
                         * leads to zeroing source data after RXOR.
                         * So, for P case set-up mult=1 explicitly.
                         */
                        if (!(flags & DMA_PREP_PQ_DISABLE_Q))
                                mult = scf[src_cnt];
                        ppc440spe_adma_pq_set_src_mult(sw_desc,
                                mult, src_cnt,  dst_cnt - 1);
                }

                /* Setup byte count foreach slot just allocated */
                sw_desc->async_tx.flags = flags;
                list_for_each_entry(iter, &sw_desc->group_list,
                                chain_node) {
                        ppc440spe_desc_set_byte_count(iter,
                                ppc440spe_chan, len);
                        iter->unmap_len = len;
                }
        }
        spin_unlock_bh(&ppc440spe_chan->lock);

        return sw_desc;
}

static struct ppc440spe_adma_desc_slot *ppc440spe_dma2_prep_pq(
                struct ppc440spe_adma_chan *ppc440spe_chan,
                dma_addr_t *dst, int dst_cnt, dma_addr_t *src, int src_cnt,
                const unsigned char *scf, size_t len, unsigned long flags)
{
        int slot_cnt, descs_per_op;
        struct ppc440spe_adma_desc_slot *sw_desc = NULL, *iter;
        unsigned long op = 0;
        unsigned char mult = 1;

        BUG_ON(!dst_cnt);
        /*pr_debug("%s: dst_cnt %d, src_cnt %d, len %d\n",
                 __func__, dst_cnt, src_cnt, len);*/

        spin_lock_bh(&ppc440spe_chan->lock);
        descs_per_op = ppc440spe_dma2_pq_slot_count(src, src_cnt, len);
        if (descs_per_op < 0) {
                spin_unlock_bh(&ppc440spe_chan->lock);
                return NULL;
        }

        /* depending on number of sources we have 1 or 2 RXOR chains */
        slot_cnt = descs_per_op * dst_cnt;

        sw_desc = ppc440spe_adma_alloc_slots(ppc440spe_chan, slot_cnt, 1);
        if (sw_desc) {
                op = slot_cnt;
                sw_desc->async_tx.flags = flags;
                list_for_each_entry(iter, &sw_desc->group_list, chain_node) {
                        ppc440spe_desc_init_dma2pq(iter, dst_cnt, src_cnt,
                                --op ? 0 : flags);
                        ppc440spe_desc_set_byte_count(iter, ppc440spe_chan,
                                len);
                        iter->unmap_len = len;

                        ppc440spe_init_rxor_cursor(&(iter->rxor_cursor));
                        iter->rxor_cursor.len = len;
                        iter->descs_per_op = descs_per_op;
                }
                op = 0;
                list_for_each_entry(iter, &sw_desc->group_list, chain_node) {
                        op++;
                        if (op % descs_per_op == 0)
                                ppc440spe_adma_init_dma2rxor_slot(iter, src,
                                                                  src_cnt);
                        if (likely(!list_is_last(&iter->chain_node,
                                                 &sw_desc->group_list))) {
                                /* set 'next' pointer */
                                iter->hw_next =
                                        list_entry(iter->chain_node.next,
                                                struct ppc440spe_adma_desc_slot,
                                                chain_node);
                                ppc440spe_xor_set_link(iter, iter->hw_next);
                        } else {
                                /* this is the last descriptor. */
                                iter->hw_next = NULL;
                        }
                }

                /* fixup head descriptor */
                sw_desc->dst_cnt = dst_cnt;
                if (flags & DMA_PREP_ZERO_P)
                        set_bit(PPC440SPE_ZERO_P, &sw_desc->flags);
                if (flags & DMA_PREP_ZERO_Q)
                        set_bit(PPC440SPE_ZERO_Q, &sw_desc->flags);

                /* setup dst/src/mult */
                ppc440spe_adma_pq_set_dest(sw_desc, dst, flags);

                while (src_cnt--) {
                        /* handle descriptors (if dst_cnt == 2) inside
                         * the ppc440spe_adma_pq_set_srcxxx() functions
                         */
                        ppc440spe_adma_pq_set_src(sw_desc, src[src_cnt],
                                                  src_cnt);
                        if (!(flags & DMA_PREP_PQ_DISABLE_Q))
                                mult = scf[src_cnt];
                        ppc440spe_adma_pq_set_src_mult(sw_desc,
                                        mult, src_cnt, dst_cnt - 1);
                }
        }
        spin_unlock_bh(&ppc440spe_chan->lock);
        ppc440spe_desc_set_rxor_block_size(len);
        return sw_desc;
}

/**
 * ppc440spe_adma_prep_dma_pq - prepare CDB (group) for a GF-XOR operation
 */
static struct dma_async_tx_descriptor *ppc440spe_adma_prep_dma_pq(
                struct dma_chan *chan, dma_addr_t *dst, dma_addr_t *src,
                unsigned int src_cnt, const unsigned char *scf,
                size_t len, unsigned long flags)
{
        struct ppc440spe_adma_chan *ppc440spe_chan;
        struct ppc440spe_adma_desc_slot *sw_desc = NULL;
        int dst_cnt = 0;

        ppc440spe_chan = to_ppc440spe_adma_chan(chan);

        ADMA_LL_DBG(prep_dma_pq_dbg(ppc440spe_chan->device->id,
                                    dst, src, src_cnt));
        BUG_ON(!len);
        BUG_ON(len > PPC440SPE_ADMA_XOR_MAX_BYTE_COUNT);
        BUG_ON(!src_cnt);

        if (src_cnt == 1 && dst[1] == src[0]) {
                dma_addr_t dest[2];

                /* dst[1] is real destination (Q) */
                dest[0] = dst[1];
                /* this is the page to multicast source data to */
                dest[1] = ppc440spe_chan->qdest;
                sw_desc = ppc440spe_dma01_prep_mult(ppc440spe_chan,
                                dest, 2, src, src_cnt, scf, len, flags);
                return sw_desc ? &sw_desc->async_tx : NULL;
        }

        if (src_cnt == 2 && dst[1] == src[1]) {
                sw_desc = ppc440spe_dma01_prep_sum_product(ppc440spe_chan,
                                        &dst[1], src, 2, scf, len, flags);
                return sw_desc ? &sw_desc->async_tx : NULL;
        }

        if (!(flags & DMA_PREP_PQ_DISABLE_P)) {
                BUG_ON(!dst[0]);
                dst_cnt++;
                flags |= DMA_PREP_ZERO_P;
        }

        if (!(flags & DMA_PREP_PQ_DISABLE_Q)) {
                BUG_ON(!dst[1]);
                dst_cnt++;
                flags |= DMA_PREP_ZERO_Q;
        }

        BUG_ON(!dst_cnt);

        dev_dbg(ppc440spe_chan->device->common.dev,
                "ppc440spe adma%d: %s src_cnt: %d len: %u int_en: %d\n",
                ppc440spe_chan->device->id, __func__, src_cnt, len,
                flags & DMA_PREP_INTERRUPT ? 1 : 0);

        switch (ppc440spe_chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                sw_desc = ppc440spe_dma01_prep_pq(ppc440spe_chan,
                                dst, dst_cnt, src, src_cnt, scf,
                                len, flags);
                break;

        case PPC440SPE_XOR_ID:
                sw_desc = ppc440spe_dma2_prep_pq(ppc440spe_chan,
                                dst, dst_cnt, src, src_cnt, scf,
                                len, flags);
                break;
        }

        return sw_desc ? &sw_desc->async_tx : NULL;
}

/**
 * ppc440spe_adma_prep_dma_pqzero_sum - prepare CDB group for
 * a PQ_ZERO_SUM operation
 */
static struct dma_async_tx_descriptor *ppc440spe_adma_prep_dma_pqzero_sum(
                struct dma_chan *chan, dma_addr_t *pq, dma_addr_t *src,
                unsigned int src_cnt, const unsigned char *scf, size_t len,
                enum sum_check_flags *pqres, unsigned long flags)
{
        struct ppc440spe_adma_chan *ppc440spe_chan;
        struct ppc440spe_adma_desc_slot *sw_desc, *iter;
        dma_addr_t pdest, qdest;
        int slot_cnt, slots_per_op, idst, dst_cnt;

        ppc440spe_chan = to_ppc440spe_adma_chan(chan);

        if (flags & DMA_PREP_PQ_DISABLE_P)
                pdest = 0;
        else
                pdest = pq[0];

        if (flags & DMA_PREP_PQ_DISABLE_Q)
                qdest = 0;
        else
                qdest = pq[1];

        ADMA_LL_DBG(prep_dma_pqzero_sum_dbg(ppc440spe_chan->device->id,
                                            src, src_cnt, scf));

        /* Always use WXOR for P/Q calculations (two destinations).
         * Need 1 or 2 extra slots to verify results are zero.
         */
        idst = dst_cnt = (pdest && qdest) ? 2 : 1;

        /* One additional slot per destination to clone P/Q
         * before calculation (we have to preserve destinations).
         */
        slot_cnt = src_cnt + dst_cnt * 2;
        slots_per_op = 1;

        spin_lock_bh(&ppc440spe_chan->lock);
        sw_desc = ppc440spe_adma_alloc_slots(ppc440spe_chan, slot_cnt,
                                             slots_per_op);
        if (sw_desc) {
                ppc440spe_desc_init_dma01pqzero_sum(sw_desc, dst_cnt, src_cnt);

                /* Setup byte count for each slot just allocated */
                sw_desc->async_tx.flags = flags;
                list_for_each_entry(iter, &sw_desc->group_list, chain_node) {
                        ppc440spe_desc_set_byte_count(iter, ppc440spe_chan,
                                                      len);
                        iter->unmap_len = len;
                }

                if (pdest) {
                        struct dma_cdb *hw_desc;
                        struct ppc440spe_adma_chan *chan;

                        iter = sw_desc->group_head;
                        chan = to_ppc440spe_adma_chan(iter->async_tx.chan);
                        memset(iter->hw_desc, 0, sizeof(struct dma_cdb));
                        iter->hw_next = list_entry(iter->chain_node.next,
                                                struct ppc440spe_adma_desc_slot,
                                                chain_node);
                        hw_desc = iter->hw_desc;
                        hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;
                        iter->src_cnt = 0;
                        iter->dst_cnt = 0;
                        ppc440spe_desc_set_dest_addr(iter, chan, 0,
                                                     ppc440spe_chan->pdest, 0);
                        ppc440spe_desc_set_src_addr(iter, chan, 0, 0, pdest);
                        ppc440spe_desc_set_byte_count(iter, ppc440spe_chan,
                                                      len);
                        iter->unmap_len = 0;
                        /* override pdest to preserve original P */
                        pdest = ppc440spe_chan->pdest;
                }
                if (qdest) {
                        struct dma_cdb *hw_desc;
                        struct ppc440spe_adma_chan *chan;

                        iter = list_first_entry(&sw_desc->group_list,
                                                struct ppc440spe_adma_desc_slot,
                                                chain_node);
                        chan = to_ppc440spe_adma_chan(iter->async_tx.chan);

                        if (pdest) {
                                iter = list_entry(iter->chain_node.next,
                                                struct ppc440spe_adma_desc_slot,
                                                chain_node);
                        }

                        memset(iter->hw_desc, 0, sizeof(struct dma_cdb));
                        iter->hw_next = list_entry(iter->chain_node.next,
                                                struct ppc440spe_adma_desc_slot,
                                                chain_node);
                        hw_desc = iter->hw_desc;
                        hw_desc->opc = DMA_CDB_OPC_MV_SG1_SG2;
                        iter->src_cnt = 0;
                        iter->dst_cnt = 0;
                        ppc440spe_desc_set_dest_addr(iter, chan, 0,
                                                     ppc440spe_chan->qdest, 0);
                        ppc440spe_desc_set_src_addr(iter, chan, 0, 0, qdest);
                        ppc440spe_desc_set_byte_count(iter, ppc440spe_chan,
                                                      len);
                        iter->unmap_len = 0;
                        /* override qdest to preserve original Q */
                        qdest = ppc440spe_chan->qdest;
                }

                /* Setup destinations for P/Q ops */
                ppc440spe_adma_pqzero_sum_set_dest(sw_desc, pdest, qdest);

                /* Setup zero QWORDs into DCHECK CDBs */
                idst = dst_cnt;
                list_for_each_entry_reverse(iter, &sw_desc->group_list,
                                            chain_node) {
                        /*
                         * The last CDB corresponds to Q-parity check,
                         * the one before last CDB corresponds
                         * P-parity check
                         */
                        if (idst == DMA_DEST_MAX_NUM) {
                                if (idst == dst_cnt) {
                                        set_bit(PPC440SPE_DESC_QCHECK,
                                                &iter->flags);
                                } else {
                                        set_bit(PPC440SPE_DESC_PCHECK,
                                                &iter->flags);
                                }
                        } else {
                                if (qdest) {
                                        set_bit(PPC440SPE_DESC_QCHECK,
                                                &iter->flags);
                                } else {
                                        set_bit(PPC440SPE_DESC_PCHECK,
                                                &iter->flags);
                                }
                        }
                        iter->xor_check_result = pqres;

                        /*
                         * set it to zero, if check fail then result will
                         * be updated
                         */
                        *iter->xor_check_result = 0;
                        ppc440spe_desc_set_dcheck(iter, ppc440spe_chan,
                                ppc440spe_qword);

                        if (!(--dst_cnt))
                                break;
                }

                /* Setup sources and mults for P/Q ops */
                list_for_each_entry_continue_reverse(iter, &sw_desc->group_list,
                                                     chain_node) {
                        struct ppc440spe_adma_chan *chan;
                        u32 mult_dst;

                        chan = to_ppc440spe_adma_chan(iter->async_tx.chan);
                        ppc440spe_desc_set_src_addr(iter, chan, 0,
                                                    DMA_CUED_XOR_HB,
                                                    src[src_cnt - 1]);
                        if (qdest) {
                                mult_dst = (dst_cnt - 1) ? DMA_CDB_SG_DST2 :
                                                           DMA_CDB_SG_DST1;
                                ppc440spe_desc_set_src_mult(iter, chan,
                                                            DMA_CUED_MULT1_OFF,
                                                            mult_dst,
                                                            scf[src_cnt - 1]);
                        }
                        if (!(--src_cnt))
                                break;
                }
        }
        spin_unlock_bh(&ppc440spe_chan->lock);
        return sw_desc ? &sw_desc->async_tx : NULL;
}

/**
 * ppc440spe_adma_prep_dma_xor_zero_sum - prepare CDB group for
 * XOR ZERO_SUM operation
 */
static struct dma_async_tx_descriptor *ppc440spe_adma_prep_dma_xor_zero_sum(
                struct dma_chan *chan, dma_addr_t *src, unsigned int src_cnt,
                size_t len, enum sum_check_flags *result, unsigned long flags)
{
        struct dma_async_tx_descriptor *tx;
        dma_addr_t pq[2];

        /* validate P, disable Q */
        pq[0] = src[0];
        pq[1] = 0;
        flags |= DMA_PREP_PQ_DISABLE_Q;

        tx = ppc440spe_adma_prep_dma_pqzero_sum(chan, pq, &src[1],
                                                src_cnt - 1, 0, len,
                                                result, flags);
        return tx;
}

/**
 * ppc440spe_adma_set_dest - set destination address into descriptor
 */
static void ppc440spe_adma_set_dest(struct ppc440spe_adma_desc_slot *sw_desc,
                dma_addr_t addr, int index)
{
        struct ppc440spe_adma_chan *chan;

        BUG_ON(index >= sw_desc->dst_cnt);

        chan = to_ppc440spe_adma_chan(sw_desc->async_tx.chan);

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                /* to do: support transfers lengths >
                 * PPC440SPE_ADMA_DMA/XOR_MAX_BYTE_COUNT
                 */
                ppc440spe_desc_set_dest_addr(sw_desc->group_head,
                        chan, 0, addr, index);
                break;
        case PPC440SPE_XOR_ID:
                sw_desc = ppc440spe_get_group_entry(sw_desc, index);
                ppc440spe_desc_set_dest_addr(sw_desc,
                        chan, 0, addr, index);
                break;
        }
}

static void ppc440spe_adma_pq_zero_op(struct ppc440spe_adma_desc_slot *iter,
                struct ppc440spe_adma_chan *chan, dma_addr_t addr)
{
        /*  To clear destinations update the descriptor
         * (P or Q depending on index) as follows:
         * addr is destination (0 corresponds to SG2):
         */
        ppc440spe_desc_set_dest_addr(iter, chan, DMA_CUED_XOR_BASE, addr, 0);

        /* ... and the addr is source: */
        ppc440spe_desc_set_src_addr(iter, chan, 0, DMA_CUED_XOR_HB, addr);

        /* addr is always SG2 then the mult is always DST1 */
        ppc440spe_desc_set_src_mult(iter, chan, DMA_CUED_MULT1_OFF,
                                    DMA_CDB_SG_DST1, 1);
}

/**
 * ppc440spe_adma_pq_set_dest - set destination address into descriptor
 * for the PQXOR operation
 */
static void ppc440spe_adma_pq_set_dest(struct ppc440spe_adma_desc_slot *sw_desc,
                dma_addr_t *addrs, unsigned long flags)
{
        struct ppc440spe_adma_desc_slot *iter;
        struct ppc440spe_adma_chan *chan;
        dma_addr_t paddr, qaddr;
        dma_addr_t addr = 0, ppath, qpath;
        int index = 0, i;

        chan = to_ppc440spe_adma_chan(sw_desc->async_tx.chan);

        if (flags & DMA_PREP_PQ_DISABLE_P)
                paddr = 0;
        else
                paddr = addrs[0];

        if (flags & DMA_PREP_PQ_DISABLE_Q)
                qaddr = 0;
        else
                qaddr = addrs[1];

        if (!paddr || !qaddr)
                addr = paddr ? paddr : qaddr;

        switch (chan->device->id) {
        case PPC440SPE_DMA0_ID:
        case PPC440SPE_DMA1_ID:
                /* walk through the WXOR source list and set P/Q-destinations
                 * for each slot:
                 */
                if (!test_bit(PPC440SPE_DESC_RXOR, &sw_desc->flags)) {
                        /* This is WXOR-only chain; may have 1/2 zero descs */
                        if (test_bit(PPC440SPE_ZERO_P, &sw_desc->flags))
                                index++;
                        if (test_bit(PPC440SPE_ZERO_Q, &sw_desc->flags))
                                index++;

                        iter = ppc440spe_get_group_entry(sw_desc, index);
                        if (addr) {
                                /* one destination */
                                list_for_each_entry_from(iter,
                                        &sw_desc->group_list, chain_node)
                                        ppc440spe_desc_set_dest_addr(iter, chan,
                                                DMA_CUED_XOR_BASE, addr, 0);
                        } else {
                                /* two destinations */
                                list_for_each_entry_from(iter,
                                        &sw_desc->group_list, chain_node) {
                                        ppc440spe_desc_set_dest_addr(iter, chan,
                                                DMA_CUED_XOR_BASE, paddr, 0);
                                        ppc440spe_desc_set_dest_addr(iter, chan,
                                                DMA_CUED_XOR_BASE, qaddr, 1);
                                }
                        }

                        if (index) {
                                /*  To clear destinations update the descriptor
                                 * (1st,2nd, or both depending on flags)
                                 */
                                index = 0;
                                if (test_bit(PPC440SPE_ZERO_P,
                                                &sw_desc->flags)) {
                                        iter = ppc440spe_get_group_entry(
                                                        sw_desc, index++);
                                        ppc440spe_adma_pq_zero_op(iter, chan,
                                                        paddr);
                                }

                                if (test_bit(PPC440SPE_ZERO_Q,
                                                &sw_desc->flags)) {
                                        iter = ppc440spe_get_group_entry(
                                                        sw_desc, index++);
                                        ppc440spe_adma_pq_zero_op(iter, chan,
                                                        qaddr);
                                }

                                return;
                        }
                } else {
                        /* This is RXOR-only or RXOR/WXOR mixed chain */

                        /* If we want to include destination into calculations,
                         * then make dest addresses cued with mult=1 (XOR).
                         */
                        ppath = test_bit(PPC440SPE_ZERO_P, &sw_desc->flags) ?
                                        DMA_CUED_XOR_HB :
                                        DMA_CUED_XOR_BASE |
                                                (1 << DMA_CUED_MULT1_OFF);
                        qpath = test_bit(PPC440SPE_ZERO_Q, &sw_desc->flags) ?
                                        DMA_CUED_XOR_HB :
                                        DMA_CUED_XOR_BASE |
                                                (1 << DMA_CUED_MULT1_OFF);

                        /* Setup destination(s) in RXOR slot(s) */
                        iter = ppc440spe_get_group_entry(sw_desc, index++);
                        ppc440spe_desc_set_dest_addr(iter, chan,
                                                paddr ? ppath : qpath,
                                                paddr ? paddr : qaddr, 0);
                        if (!addr) {
                                /* two destinations */
                                iter = ppc440spe_get_group_entry(sw_desc,
                                                                 index++);
                                ppc440spe_desc_set_dest_addr(iter, chan,
                                                qpath, qaddr, 0);
                        }

                        if (test_bit(PPC440SPE_DESC_WXOR, &sw_desc->flags)) {
                                /* Setup destination(s) in remaining WXOR
                                 * slots
                                 */
                                iter = ppc440spe_get_group_entry(sw_desc,
                                                                 index);
                                if (addr) {
                                        /* one destination */
                                        list_for_each_entry_from(iter,
                                            &sw_desc->group_list,
                                            chain_node)
                                                ppc440spe_desc_set_dest_addr(
                                                        iter, chan,
                                                        DMA_CUED_XOR_BASE,
                                                        addr, 0);

                                } else {
                                        /* two destinations */
                                        list_for_each_entry_from(iter,
                                            &sw_desc->group_list,
                                            chain_node) {
                                                ppc440spe_desc_set_dest_addr(
                                                        iter, chan,
                                                        DMA_CUED_XOR_BASE,
                                                        paddr, 0);
                                                ppc440spe_desc_set_dest_addr(
                                                        iter, chan,
                                                        DMA_CUED_XOR_BASE,
                                                        qaddr, 1);
                                        }
                                }
                        }

                }
                break;

        case PPC440SPE_XOR_ID:
                /* DMA2 descriptors have only 1 destination, so there are
                 * two chains - one for each dest.
                 * If we want to include destination into calculations,
                 * then make dest addresses cued with mult=1 (XOR).
                 */
                ppath = test_bit(PPC440SPE_ZERO_P, &sw_desc->flags) ?
                                DMA_CUED_XOR_HB :
                                DMA_CUED_XOR_BASE |
                                        (1 << DMA_CUED_MULT1_OFF);

                qpath = test_bit(PPC440SPE_ZERO_Q, &sw_desc->flags) ?