/*
 * Copyright (C) 2017 Broadcom
 *
 * 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 version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

/*
 * Broadcom SBA RAID Driver
 *
 * The Broadcom stream buffer accelerator (SBA) provides offloading
 * capabilities for RAID operations. The SBA offload engine is accessible
 * via Broadcom SoC specific ring manager. Two or more offload engines
 * can share same Broadcom SoC specific ring manager due to this Broadcom
 * SoC specific ring manager driver is implemented as a mailbox controller
 * driver and offload engine drivers are implemented as mallbox clients.
 *
 * Typically, Broadcom SoC specific ring manager will implement larger
 * number of hardware rings over one or more SBA hardware devices. By
 * design, the internal buffer size of SBA hardware device is limited
 * but all offload operations supported by SBA can be broken down into
 * multiple small size requests and executed parallely on multiple SBA
 * hardware devices for achieving high through-put.
 *
 * The Broadcom SBA RAID driver does not require any register programming
 * except submitting request to SBA hardware device via mailbox channels.
 * This driver implements a DMA device with one DMA channel using a single
 * mailbox channel provided by Broadcom SoC specific ring manager driver.
 * For having more SBA DMA channels, we can create more SBA device nodes
 * in Broadcom SoC specific DTS based on number of hardware rings supported
 * by Broadcom SoC ring manager.
 */

#include <linux/bitops.h>
#include <linux/debugfs.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/list.h>
#include <linux/mailbox_client.h>
#include <linux/mailbox/brcm-message.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/slab.h>
#include <linux/raid/pq.h>

#include "dmaengine.h"

/* ====== Driver macros and defines ===== */

#define SBA_TYPE_SHIFT                                  48
#define SBA_TYPE_MASK                                   GENMASK(1, 0)
#define SBA_TYPE_A                                      0x0
#define SBA_TYPE_B                                      0x2
#define SBA_TYPE_C                                      0x3
#define SBA_USER_DEF_SHIFT                              32
#define SBA_USER_DEF_MASK                               GENMASK(15, 0)
#define SBA_R_MDATA_SHIFT                               24
#define SBA_R_MDATA_MASK                                GENMASK(7, 0)
#define SBA_C_MDATA_MS_SHIFT                            18
#define SBA_C_MDATA_MS_MASK                             GENMASK(1, 0)
#define SBA_INT_SHIFT                                   17
#define SBA_INT_MASK                                    BIT(0)
#define SBA_RESP_SHIFT                                  16
#define SBA_RESP_MASK                                   BIT(0)
#define SBA_C_MDATA_SHIFT                               8
#define SBA_C_MDATA_MASK                                GENMASK(7, 0)
#define SBA_C_MDATA_BNUMx_SHIFT(__bnum)                 (2 * (__bnum))
#define SBA_C_MDATA_BNUMx_MASK                          GENMASK(1, 0)
#define SBA_C_MDATA_DNUM_SHIFT                          5
#define SBA_C_MDATA_DNUM_MASK                           GENMASK(4, 0)
#define SBA_C_MDATA_LS(__v)                             ((__v) & 0xff)
#define SBA_C_MDATA_MS(__v)                             (((__v) >> 8) & 0x3)
#define SBA_CMD_SHIFT                                   0
#define SBA_CMD_MASK                                    GENMASK(3, 0)
#define SBA_CMD_ZERO_BUFFER                             0x4
#define SBA_CMD_ZERO_ALL_BUFFERS                        0x8
#define SBA_CMD_LOAD_BUFFER                             0x9
#define SBA_CMD_XOR                                     0xa
#define SBA_CMD_GALOIS_XOR                              0xb
#define SBA_CMD_WRITE_BUFFER                            0xc
#define SBA_CMD_GALOIS                                  0xe

#define SBA_MAX_REQ_PER_MBOX_CHANNEL                    8192
#define SBA_MAX_MSG_SEND_PER_MBOX_CHANNEL               8

/* Driver helper macros */
#define to_sba_request(tx)              \
        container_of(tx, struct sba_request, tx)
#define to_sba_device(dchan)            \
        container_of(dchan, struct sba_device, dma_chan)

/* ===== Driver data structures ===== */

enum sba_request_flags {
        SBA_REQUEST_STATE_FREE          = 0x001,
        SBA_REQUEST_STATE_ALLOCED       = 0x002,
        SBA_REQUEST_STATE_PENDING       = 0x004,
        SBA_REQUEST_STATE_ACTIVE        = 0x008,
        SBA_REQUEST_STATE_ABORTED       = 0x010,
        SBA_REQUEST_STATE_MASK          = 0x0ff,
        SBA_REQUEST_FENCE               = 0x100,
};

struct sba_request {
        /* Global state */
        struct list_head node;
        struct sba_device *sba;
        u32 flags;
        /* Chained requests management */
        struct sba_request *first;
        struct list_head next;
        atomic_t next_pending_count;
        /* BRCM message data */
        struct brcm_message msg;
        struct dma_async_tx_descriptor tx;
        /* SBA commands */
        struct brcm_sba_command cmds[0];
};

enum sba_version {
        SBA_VER_1 = 0,
        SBA_VER_2
};

struct sba_device {
        /* Underlying device */
        struct device *dev;
        /* DT configuration parameters */
        enum sba_version ver;
        /* Derived configuration parameters */
        u32 max_req;
        u32 hw_buf_size;
        u32 hw_resp_size;
        u32 max_pq_coefs;
        u32 max_pq_srcs;
        u32 max_cmd_per_req;
        u32 max_xor_srcs;
        u32 max_resp_pool_size;
        u32 max_cmds_pool_size;
        /* Maibox client and Mailbox channels */
        struct mbox_client client;
        struct mbox_chan *mchan;
        struct device *mbox_dev;
        /* DMA device and DMA channel */
        struct dma_device dma_dev;
        struct dma_chan dma_chan;
        /* DMA channel resources */
        void *resp_base;
        dma_addr_t resp_dma_base;
        void *cmds_base;
        dma_addr_t cmds_dma_base;
        spinlock_t reqs_lock;
        bool reqs_fence;
        struct list_head reqs_alloc_list;
        struct list_head reqs_pending_list;
        struct list_head reqs_active_list;
        struct list_head reqs_aborted_list;
        struct list_head reqs_free_list;
        /* DebugFS directory entries */
        struct dentry *root;
        struct dentry *stats;
};

/* ====== Command helper routines ===== */

static inline u64 __pure sba_cmd_enc(u64 cmd, u32 val, u32 shift, u32 mask)
{
        cmd &= ~((u64)mask << shift);
        cmd |= ((u64)(val & mask) << shift);
        return cmd;
}

static inline u32 __pure sba_cmd_load_c_mdata(u32 b0)
{
        return b0 & SBA_C_MDATA_BNUMx_MASK;
}

static inline u32 __pure sba_cmd_write_c_mdata(u32 b0)
{
        return b0 & SBA_C_MDATA_BNUMx_MASK;
}

static inline u32 __pure sba_cmd_xor_c_mdata(u32 b1, u32 b0)
{
        return (b0 & SBA_C_MDATA_BNUMx_MASK) |
               ((b1 & SBA_C_MDATA_BNUMx_MASK) << SBA_C_MDATA_BNUMx_SHIFT(1));
}

static inline u32 __pure sba_cmd_pq_c_mdata(u32 d, u32 b1, u32 b0)
{
        return (b0 & SBA_C_MDATA_BNUMx_MASK) |
               ((b1 & SBA_C_MDATA_BNUMx_MASK) << SBA_C_MDATA_BNUMx_SHIFT(1)) |
               ((d & SBA_C_MDATA_DNUM_MASK) << SBA_C_MDATA_DNUM_SHIFT);
}

/* ====== General helper routines ===== */

static struct sba_request *sba_alloc_request(struct sba_device *sba)
{
        bool found = false;
        unsigned long flags;
        struct sba_request *req = NULL;

        spin_lock_irqsave(&sba->reqs_lock, flags);
        list_for_each_entry(req, &sba->reqs_free_list, node) {
                if (async_tx_test_ack(&req->tx)) {
                        list_move_tail(&req->node, &sba->reqs_alloc_list);
                        found = true;
                        break;
                }
        }
        spin_unlock_irqrestore(&sba->reqs_lock, flags);

        if (!found) {
                /*
                 * We have no more free requests so, we peek
                 * mailbox channels hoping few active requests
                 * would have completed which will create more
                 * room for new requests.
                 */
                mbox_client_peek_data(sba->mchan);
                return NULL;
        }

        req->flags = SBA_REQUEST_STATE_ALLOCED;
        req->first = req;
        INIT_LIST_HEAD(&req->next);
        atomic_set(&req->next_pending_count, 1);

        dma_async_tx_descriptor_init(&req->tx, &sba->dma_chan);
        async_tx_ack(&req->tx);

        return req;
}

/* Note: Must be called with sba->reqs_lock held */
static void _sba_pending_request(struct sba_device *sba,
                                 struct sba_request *req)
{
        lockdep_assert_held(&sba->reqs_lock);
        req->flags &= ~SBA_REQUEST_STATE_MASK;
        req->flags |= SBA_REQUEST_STATE_PENDING;
        list_move_tail(&req->node, &sba->reqs_pending_list);
        if (list_empty(&sba->reqs_active_list))
                sba->reqs_fence = false;
}

/* Note: Must be called with sba->reqs_lock held */
static bool _sba_active_request(struct sba_device *sba,
                                struct sba_request *req)
{
        lockdep_assert_held(&sba->reqs_lock);
        if (list_empty(&sba->reqs_active_list))
                sba->reqs_fence = false;
        if (sba->reqs_fence)
                return false;
        req->flags &= ~SBA_REQUEST_STATE_MASK;
        req->flags |= SBA_REQUEST_STATE_ACTIVE;
        list_move_tail(&req->node, &sba->reqs_active_list);
        if (req->flags & SBA_REQUEST_FENCE)
                sba->reqs_fence = true;
        return true;
}

/* Note: Must be called with sba->reqs_lock held */
static void _sba_abort_request(struct sba_device *sba,
                               struct sba_request *req)
{
        lockdep_assert_held(&sba->reqs_lock);
        req->flags &= ~SBA_REQUEST_STATE_MASK;
        req->flags |= SBA_REQUEST_STATE_ABORTED;
        list_move_tail(&req->node, &sba->reqs_aborted_list);
        if (list_empty(&sba->reqs_active_list))
                sba->reqs_fence = false;
}

/* Note: Must be called with sba->reqs_lock held */
static void _sba_free_request(struct sba_device *sba,
                              struct sba_request *req)
{
        lockdep_assert_held(&sba->reqs_lock);
        req->flags &= ~SBA_REQUEST_STATE_MASK;
        req->flags |= SBA_REQUEST_STATE_FREE;
        list_move_tail(&req->node, &sba->reqs_free_list);
        if (list_empty(&sba->reqs_active_list))
                sba->reqs_fence = false;
}

static void sba_free_chained_requests(struct sba_request *req)
{
        unsigned long flags;
        struct sba_request *nreq;
        struct sba_device *sba = req->sba;

        spin_lock_irqsave(&sba->reqs_lock, flags);

        _sba_free_request(sba, req);
        list_for_each_entry(nreq, &req->next, next)
                _sba_free_request(sba, nreq);

        spin_unlock_irqrestore(&sba->reqs_lock, flags);
}

static void sba_chain_request(struct sba_request *first,
                              struct sba_request *req)
{
        unsigned long flags;
        struct sba_device *sba = req->sba;

        spin_lock_irqsave(&sba->reqs_lock, flags);

        list_add_tail(&req->next, &first->next);
        req->first = first;
        atomic_inc(&first->next_pending_count);

        spin_unlock_irqrestore(&sba->reqs_lock, flags);
}

static void sba_cleanup_nonpending_requests(struct sba_device *sba)
{
        unsigned long flags;
        struct sba_request *req, *req1;

        spin_lock_irqsave(&sba->reqs_lock, flags);

        /* Freeup all alloced request */
        list_for_each_entry_safe(req, req1, &sba->reqs_alloc_list, node)
                _sba_free_request(sba, req);

        /* Set all active requests as aborted */
        list_for_each_entry_safe(req, req1, &sba->reqs_active_list, node)
                _sba_abort_request(sba, req);

        /*
         * Note: We expect that aborted request will be eventually
         * freed by sba_receive_message()
         */

        spin_unlock_irqrestore(&sba->reqs_lock, flags);
}

static void sba_cleanup_pending_requests(struct sba_device *sba)
{
        unsigned long flags;
        struct sba_request *req, *req1;

        spin_lock_irqsave(&sba->reqs_lock, flags);

        /* Freeup all pending request */
        list_for_each_entry_safe(req, req1, &sba->reqs_pending_list, node)
                _sba_free_request(sba, req);

        spin_unlock_irqrestore(&sba->reqs_lock, flags);
}

static int sba_send_mbox_request(struct sba_device *sba,
                                 struct sba_request *req)
{
        int ret = 0;

        /* Send message for the request */
        req->msg.error = 0;
        ret = mbox_send_message(sba->mchan, &req->msg);
        if (ret < 0) {
                dev_err(sba->dev, "send message failed with error %d", ret);
                return ret;
        }

        /* Check error returned by mailbox controller */
        ret = req->msg.error;
        if (ret < 0) {
                dev_err(sba->dev, "message error %d", ret);
        }

        /* Signal txdone for mailbox channel */
        mbox_client_txdone(sba->mchan, ret);

        return ret;
}

/* Note: Must be called with sba->reqs_lock held */
static void _sba_process_pending_requests(struct sba_device *sba)
{
        int ret;
        u32 count;
        struct sba_request *req;

        /* Process few pending requests */
        count = SBA_MAX_MSG_SEND_PER_MBOX_CHANNEL;
        while (!list_empty(&sba->reqs_pending_list) && count) {
                /* Get the first pending request */
                req = list_first_entry(&sba->reqs_pending_list,
                                       struct sba_request, node);

                /* Try to make request active */
                if (!_sba_active_request(sba, req))
                        break;

                /* Send request to mailbox channel */
                ret = sba_send_mbox_request(sba, req);
                if (ret < 0) {
                        _sba_pending_request(sba, req);
                        break;
                }

                count--;
        }
}

static void sba_process_received_request(struct sba_device *sba,
                                         struct sba_request *req)
{
        unsigned long flags;
        struct dma_async_tx_descriptor *tx;
        struct sba_request *nreq, *first = req->first;

        /* Process only after all chained requests are received */
        if (!atomic_dec_return(&first->next_pending_count)) {
                tx = &first->tx;

                WARN_ON(tx->cookie < 0);
                if (tx->cookie > 0) {
                        spin_lock_irqsave(&sba->reqs_lock, flags);
                        dma_cookie_complete(tx);
                        spin_unlock_irqrestore(&sba->reqs_lock, flags);
                        dmaengine_desc_get_callback_invoke(tx, NULL);
                        dma_descriptor_unmap(tx);
                        tx->callback = NULL;
                        tx->callback_result = NULL;
                }

                dma_run_dependencies(tx);

                spin_lock_irqsave(&sba->reqs_lock, flags);

                /* Free all requests chained to first request */
                list_for_each_entry(nreq, &first->next, next)
                        _sba_free_request(sba, nreq);
                INIT_LIST_HEAD(&first->next);

                /* Free the first request */
                _sba_free_request(sba, first);

                /* Process pending requests */
                _sba_process_pending_requests(sba);

                spin_unlock_irqrestore(&sba->reqs_lock, flags);
        }
}

static void sba_write_stats_in_seqfile(struct sba_device *sba,
                                       struct seq_file *file)
{
        unsigned long flags;
        struct sba_request *req;
        u32 free_count = 0, alloced_count = 0;
        u32 pending_count = 0, active_count = 0, aborted_count = 0;

        spin_lock_irqsave(&sba->reqs_lock, flags);

        list_for_each_entry(req, &sba->reqs_free_list, node)
                if (async_tx_test_ack(&req->tx))
                        free_count++;

        list_for_each_entry(req, &sba->reqs_alloc_list, node)
                alloced_count++;

        list_for_each_entry(req, &sba->reqs_pending_list, node)
                pending_count++;

        list_for_each_entry(req, &sba->reqs_active_list, node)
                active_count++;

        list_for_each_entry(req, &sba->reqs_aborted_list, node)
                aborted_count++;

        spin_unlock_irqrestore(&sba->reqs_lock, flags);

        seq_printf(file, "maximum requests   = %d\n", sba->max_req);
        seq_printf(file, "free requests      = %d\n", free_count);
        seq_printf(file, "alloced requests   = %d\n", alloced_count);
        seq_printf(file, "pending requests   = %d\n", pending_count);
        seq_printf(file, "active requests    = %d\n", active_count);
        seq_printf(file, "aborted requests   = %d\n", aborted_count);
}

/* ====== DMAENGINE callbacks ===== */

static void sba_free_chan_resources(struct dma_chan *dchan)
{
        /*
         * Channel resources are pre-alloced so we just free-up
         * whatever we can so that we can re-use pre-alloced
         * channel resources next time.
         */
        sba_cleanup_nonpending_requests(to_sba_device(dchan));
}

static int sba_device_terminate_all(struct dma_chan *dchan)
{
        /* Cleanup all pending requests */
        sba_cleanup_pending_requests(to_sba_device(dchan));

        return 0;
}

static void sba_issue_pending(struct dma_chan *dchan)
{
        unsigned long flags;
        struct sba_device *sba = to_sba_device(dchan);

        /* Process pending requests */
        spin_lock_irqsave(&sba->reqs_lock, flags);
        _sba_process_pending_requests(sba);
        spin_unlock_irqrestore(&sba->reqs_lock, flags);
}

static dma_cookie_t sba_tx_submit(struct dma_async_tx_descriptor *tx)
{
        unsigned long flags;
        dma_cookie_t cookie;
        struct sba_device *sba;
        struct sba_request *req, *nreq;

        if (unlikely(!tx))
                return -EINVAL;

        sba = to_sba_device(tx->chan);
        req = to_sba_request(tx);

        /* Assign cookie and mark all chained requests pending */
        spin_lock_irqsave(&sba->reqs_lock, flags);
        cookie = dma_cookie_assign(tx);
        _sba_pending_request(sba, req);
        list_for_each_entry(nreq, &req->next, next)
                _sba_pending_request(sba, nreq);
        spin_unlock_irqrestore(&sba->reqs_lock, flags);

        return cookie;
}

static enum dma_status sba_tx_status(struct dma_chan *dchan,
                                     dma_cookie_t cookie,
                                     struct dma_tx_state *txstate)
{
        enum dma_status ret;
        struct sba_device *sba = to_sba_device(dchan);

        ret = dma_cookie_status(dchan, cookie, txstate);
        if (ret == DMA_COMPLETE)
                return ret;

        mbox_client_peek_data(sba->mchan);

        return dma_cookie_status(dchan, cookie, txstate);
}

static void sba_fillup_interrupt_msg(struct sba_request *req,
                                     struct brcm_sba_command *cmds,
                                     struct brcm_message *msg)
{
        u64 cmd;
        u32 c_mdata;
        dma_addr_t resp_dma = req->tx.phys;
        struct brcm_sba_command *cmdsp = cmds;

        /* Type-B command to load dummy data into buf0 */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, req->sba->hw_resp_size,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        c_mdata = sba_cmd_load_c_mdata(0);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                          SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_LOAD_BUFFER,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
        cmdsp->data = resp_dma;
        cmdsp->data_len = req->sba->hw_resp_size;
        cmdsp++;

        /* Type-A command to write buf0 to dummy location */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, req->sba->hw_resp_size,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        cmd = sba_cmd_enc(cmd, 0x1,
                          SBA_RESP_SHIFT, SBA_RESP_MASK);
        c_mdata = sba_cmd_write_c_mdata(0);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                          SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_WRITE_BUFFER,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
        if (req->sba->hw_resp_size) {
                cmdsp->flags |= BRCM_SBA_CMD_HAS_RESP;
                cmdsp->resp = resp_dma;
                cmdsp->resp_len = req->sba->hw_resp_size;
        }
        cmdsp->flags |= BRCM_SBA_CMD_HAS_OUTPUT;
        cmdsp->data = resp_dma;
        cmdsp->data_len = req->sba->hw_resp_size;
        cmdsp++;

        /* Fillup brcm_message */
        msg->type = BRCM_MESSAGE_SBA;
        msg->sba.cmds = cmds;
        msg->sba.cmds_count = cmdsp - cmds;
        msg->ctx = req;
        msg->error = 0;
}

static struct dma_async_tx_descriptor *
sba_prep_dma_interrupt(struct dma_chan *dchan, unsigned long flags)
{
        struct sba_request *req = NULL;
        struct sba_device *sba = to_sba_device(dchan);

        /* Alloc new request */
        req = sba_alloc_request(sba);
        if (!req)
                return NULL;

        /*
         * Force fence so that no requests are submitted
         * until DMA callback for this request is invoked.
         */
        req->flags |= SBA_REQUEST_FENCE;

        /* Fillup request message */
        sba_fillup_interrupt_msg(req, req->cmds, &req->msg);

        /* Init async_tx descriptor */
        req->tx.flags = flags;
        req->tx.cookie = -EBUSY;

        return &req->tx;
}

static void sba_fillup_memcpy_msg(struct sba_request *req,
                                  struct brcm_sba_command *cmds,
                                  struct brcm_message *msg,
                                  dma_addr_t msg_offset, size_t msg_len,
                                  dma_addr_t dst, dma_addr_t src)
{
        u64 cmd;
        u32 c_mdata;
        dma_addr_t resp_dma = req->tx.phys;
        struct brcm_sba_command *cmdsp = cmds;

        /* Type-B command to load data into buf0 */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, msg_len,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        c_mdata = sba_cmd_load_c_mdata(0);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                          SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_LOAD_BUFFER,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
        cmdsp->data = src + msg_offset;
        cmdsp->data_len = msg_len;
        cmdsp++;

        /* Type-A command to write buf0 */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, msg_len,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        cmd = sba_cmd_enc(cmd, 0x1,
                          SBA_RESP_SHIFT, SBA_RESP_MASK);
        c_mdata = sba_cmd_write_c_mdata(0);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                          SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_WRITE_BUFFER,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
        if (req->sba->hw_resp_size) {
                cmdsp->flags |= BRCM_SBA_CMD_HAS_RESP;
                cmdsp->resp = resp_dma;
                cmdsp->resp_len = req->sba->hw_resp_size;
        }
        cmdsp->flags |= BRCM_SBA_CMD_HAS_OUTPUT;
        cmdsp->data = dst + msg_offset;
        cmdsp->data_len = msg_len;
        cmdsp++;

        /* Fillup brcm_message */
        msg->type = BRCM_MESSAGE_SBA;
        msg->sba.cmds = cmds;
        msg->sba.cmds_count = cmdsp - cmds;
        msg->ctx = req;
        msg->error = 0;
}

static struct sba_request *
sba_prep_dma_memcpy_req(struct sba_device *sba,
                        dma_addr_t off, dma_addr_t dst, dma_addr_t src,
                        size_t len, unsigned long flags)
{
        struct sba_request *req = NULL;

        /* Alloc new request */
        req = sba_alloc_request(sba);
        if (!req)
                return NULL;
        if (flags & DMA_PREP_FENCE)
                req->flags |= SBA_REQUEST_FENCE;

        /* Fillup request message */
        sba_fillup_memcpy_msg(req, req->cmds, &req->msg,
                              off, len, dst, src);

        /* Init async_tx descriptor */
        req->tx.flags = flags;
        req->tx.cookie = -EBUSY;

        return req;
}

static struct dma_async_tx_descriptor *
sba_prep_dma_memcpy(struct dma_chan *dchan, dma_addr_t dst, dma_addr_t src,
                    size_t len, unsigned long flags)
{
        size_t req_len;
        dma_addr_t off = 0;
        struct sba_device *sba = to_sba_device(dchan);
        struct sba_request *first = NULL, *req;

        /* Create chained requests where each request is upto hw_buf_size */
        while (len) {
                req_len = (len < sba->hw_buf_size) ? len : sba->hw_buf_size;

                req = sba_prep_dma_memcpy_req(sba, off, dst, src,
                                              req_len, flags);
                if (!req) {
                        if (first)
                                sba_free_chained_requests(first);
                        return NULL;
                }

                if (first)
                        sba_chain_request(first, req);
                else
                        first = req;

                off += req_len;
                len -= req_len;
        }

        return (first) ? &first->tx : NULL;
}

static void sba_fillup_xor_msg(struct sba_request *req,
                                struct brcm_sba_command *cmds,
                                struct brcm_message *msg,
                                dma_addr_t msg_offset, size_t msg_len,
                                dma_addr_t dst, dma_addr_t *src, u32 src_cnt)
{
        u64 cmd;
        u32 c_mdata;
        unsigned int i;
        dma_addr_t resp_dma = req->tx.phys;
        struct brcm_sba_command *cmdsp = cmds;

        /* Type-B command to load data into buf0 */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, msg_len,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        c_mdata = sba_cmd_load_c_mdata(0);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                          SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_LOAD_BUFFER,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
        cmdsp->data = src[0] + msg_offset;
        cmdsp->data_len = msg_len;
        cmdsp++;

        /* Type-B commands to xor data with buf0 and put it back in buf0 */
        for (i = 1; i < src_cnt; i++) {
                cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                c_mdata = sba_cmd_xor_c_mdata(0, 0);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                  SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_XOR,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
                cmdsp->data = src[i] + msg_offset;
                cmdsp->data_len = msg_len;
                cmdsp++;
        }

        /* Type-A command to write buf0 */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, msg_len,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        cmd = sba_cmd_enc(cmd, 0x1,
                          SBA_RESP_SHIFT, SBA_RESP_MASK);
        c_mdata = sba_cmd_write_c_mdata(0);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                          SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_WRITE_BUFFER,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
        if (req->sba->hw_resp_size) {
                cmdsp->flags |= BRCM_SBA_CMD_HAS_RESP;
                cmdsp->resp = resp_dma;
                cmdsp->resp_len = req->sba->hw_resp_size;
        }
        cmdsp->flags |= BRCM_SBA_CMD_HAS_OUTPUT;
        cmdsp->data = dst + msg_offset;
        cmdsp->data_len = msg_len;
        cmdsp++;

        /* Fillup brcm_message */
        msg->type = BRCM_MESSAGE_SBA;
        msg->sba.cmds = cmds;
        msg->sba.cmds_count = cmdsp - cmds;
        msg->ctx = req;
        msg->error = 0;
}

static struct sba_request *
sba_prep_dma_xor_req(struct sba_device *sba,
                     dma_addr_t off, dma_addr_t dst, dma_addr_t *src,
                     u32 src_cnt, size_t len, unsigned long flags)
{
        struct sba_request *req = NULL;

        /* Alloc new request */
        req = sba_alloc_request(sba);
        if (!req)
                return NULL;
        if (flags & DMA_PREP_FENCE)
                req->flags |= SBA_REQUEST_FENCE;

        /* Fillup request message */
        sba_fillup_xor_msg(req, req->cmds, &req->msg,
                           off, len, dst, src, src_cnt);

        /* Init async_tx descriptor */
        req->tx.flags = flags;
        req->tx.cookie = -EBUSY;

        return req;
}

static struct dma_async_tx_descriptor *
sba_prep_dma_xor(struct dma_chan *dchan, dma_addr_t dst, dma_addr_t *src,
                 u32 src_cnt, size_t len, unsigned long flags)
{
        size_t req_len;
        dma_addr_t off = 0;
        struct sba_device *sba = to_sba_device(dchan);
        struct sba_request *first = NULL, *req;

        /* Sanity checks */
        if (unlikely(src_cnt > sba->max_xor_srcs))
                return NULL;

        /* Create chained requests where each request is upto hw_buf_size */
        while (len) {
                req_len = (len < sba->hw_buf_size) ? len : sba->hw_buf_size;

                req = sba_prep_dma_xor_req(sba, off, dst, src, src_cnt,
                                           req_len, flags);
                if (!req) {
                        if (first)
                                sba_free_chained_requests(first);
                        return NULL;
                }

                if (first)
                        sba_chain_request(first, req);
                else
                        first = req;

                off += req_len;
                len -= req_len;
        }

        return (first) ? &first->tx : NULL;
}

static void sba_fillup_pq_msg(struct sba_request *req,
                                bool pq_continue,
                                struct brcm_sba_command *cmds,
                                struct brcm_message *msg,
                                dma_addr_t msg_offset, size_t msg_len,
                                dma_addr_t *dst_p, dma_addr_t *dst_q,
                                const u8 *scf, dma_addr_t *src, u32 src_cnt)
{
        u64 cmd;
        u32 c_mdata;
        unsigned int i;
        dma_addr_t resp_dma = req->tx.phys;
        struct brcm_sba_command *cmdsp = cmds;

        if (pq_continue) {
                /* Type-B command to load old P into buf0 */
                if (dst_p) {
                        cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                                SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                        cmd = sba_cmd_enc(cmd, msg_len,
                                SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                        c_mdata = sba_cmd_load_c_mdata(0);
                        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                        cmd = sba_cmd_enc(cmd, SBA_CMD_LOAD_BUFFER,
                                SBA_CMD_SHIFT, SBA_CMD_MASK);
                        cmdsp->cmd = cmd;
                        *cmdsp->cmd_dma = cpu_to_le64(cmd);
                        cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
                        cmdsp->data = *dst_p + msg_offset;
                        cmdsp->data_len = msg_len;
                        cmdsp++;
                }

                /* Type-B command to load old Q into buf1 */
                if (dst_q) {
                        cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                                SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                        cmd = sba_cmd_enc(cmd, msg_len,
                                SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                        c_mdata = sba_cmd_load_c_mdata(1);
                        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                        cmd = sba_cmd_enc(cmd, SBA_CMD_LOAD_BUFFER,
                                SBA_CMD_SHIFT, SBA_CMD_MASK);
                        cmdsp->cmd = cmd;
                        *cmdsp->cmd_dma = cpu_to_le64(cmd);
                        cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
                        cmdsp->data = *dst_q + msg_offset;
                        cmdsp->data_len = msg_len;
                        cmdsp++;
                }
        } else {
                /* Type-A command to zero all buffers */
                cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_ZERO_ALL_BUFFERS,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
                cmdsp++;
        }

        /* Type-B commands for generate P onto buf0 and Q onto buf1 */
        for (i = 0; i < src_cnt; i++) {
                cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                c_mdata = sba_cmd_pq_c_mdata(raid6_gflog[scf[i]], 1, 0);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                  SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_MS(c_mdata),
                                  SBA_C_MDATA_MS_SHIFT, SBA_C_MDATA_MS_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_GALOIS_XOR,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
                cmdsp->data = src[i] + msg_offset;
                cmdsp->data_len = msg_len;
                cmdsp++;
        }

        /* Type-A command to write buf0 */
        if (dst_p) {

                cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                cmd = sba_cmd_enc(cmd, 0x1,
                                  SBA_RESP_SHIFT, SBA_RESP_MASK);
                c_mdata = sba_cmd_write_c_mdata(0);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                  SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_WRITE_BUFFER,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
                if (req->sba->hw_resp_size) {
                        cmdsp->flags |= BRCM_SBA_CMD_HAS_RESP;
                        cmdsp->resp = resp_dma;
                        cmdsp->resp_len = req->sba->hw_resp_size;
                }
                cmdsp->flags |= BRCM_SBA_CMD_HAS_OUTPUT;
                cmdsp->data = *dst_p + msg_offset;
                cmdsp->data_len = msg_len;
                cmdsp++;
        }

        /* Type-A command to write buf1 */
        if (dst_q) {
                cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                cmd = sba_cmd_enc(cmd, 0x1,
                                  SBA_RESP_SHIFT, SBA_RESP_MASK);
                c_mdata = sba_cmd_write_c_mdata(1);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                  SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_WRITE_BUFFER,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
                if (req->sba->hw_resp_size) {
                        cmdsp->flags |= BRCM_SBA_CMD_HAS_RESP;
                        cmdsp->resp = resp_dma;
                        cmdsp->resp_len = req->sba->hw_resp_size;
                }
                cmdsp->flags |= BRCM_SBA_CMD_HAS_OUTPUT;
                cmdsp->data = *dst_q + msg_offset;
                cmdsp->data_len = msg_len;
                cmdsp++;
        }

        /* Fillup brcm_message */
        msg->type = BRCM_MESSAGE_SBA;
        msg->sba.cmds = cmds;
        msg->sba.cmds_count = cmdsp - cmds;
        msg->ctx = req;
        msg->error = 0;
}

static struct sba_request *
sba_prep_dma_pq_req(struct sba_device *sba, dma_addr_t off,
                    dma_addr_t *dst_p, dma_addr_t *dst_q, dma_addr_t *src,
                    u32 src_cnt, const u8 *scf, size_t len, unsigned long flags)
{
        struct sba_request *req = NULL;

        /* Alloc new request */
        req = sba_alloc_request(sba);
        if (!req)
                return NULL;
        if (flags & DMA_PREP_FENCE)
                req->flags |= SBA_REQUEST_FENCE;

        /* Fillup request messages */
        sba_fillup_pq_msg(req, dmaf_continue(flags),
                          req->cmds, &req->msg,
                          off, len, dst_p, dst_q, scf, src, src_cnt);

        /* Init async_tx descriptor */
        req->tx.flags = flags;
        req->tx.cookie = -EBUSY;

        return req;
}

static void sba_fillup_pq_single_msg(struct sba_request *req,
                                bool pq_continue,
                                struct brcm_sba_command *cmds,
                                struct brcm_message *msg,
                                dma_addr_t msg_offset, size_t msg_len,
                                dma_addr_t *dst_p, dma_addr_t *dst_q,
                                dma_addr_t src, u8 scf)
{
        u64 cmd;
        u32 c_mdata;
        u8 pos, dpos = raid6_gflog[scf];
        dma_addr_t resp_dma = req->tx.phys;
        struct brcm_sba_command *cmdsp = cmds;

        if (!dst_p)
                goto skip_p;

        if (pq_continue) {
                /* Type-B command to load old P into buf0 */
                cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                c_mdata = sba_cmd_load_c_mdata(0);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                  SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_LOAD_BUFFER,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
                cmdsp->data = *dst_p + msg_offset;
                cmdsp->data_len = msg_len;
                cmdsp++;

                /*
                 * Type-B commands to xor data with buf0 and put it
                 * back in buf0
                 */
                cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                c_mdata = sba_cmd_xor_c_mdata(0, 0);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                  SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_XOR,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
                cmdsp->data = src + msg_offset;
                cmdsp->data_len = msg_len;
                cmdsp++;
        } else {
                /* Type-B command to load old P into buf0 */
                cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                c_mdata = sba_cmd_load_c_mdata(0);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                  SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_LOAD_BUFFER,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
                cmdsp->data = src + msg_offset;
                cmdsp->data_len = msg_len;
                cmdsp++;
        }

        /* Type-A command to write buf0 */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, msg_len,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        cmd = sba_cmd_enc(cmd, 0x1,
                          SBA_RESP_SHIFT, SBA_RESP_MASK);
        c_mdata = sba_cmd_write_c_mdata(0);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                          SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_WRITE_BUFFER,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
        if (req->sba->hw_resp_size) {
                cmdsp->flags |= BRCM_SBA_CMD_HAS_RESP;
                cmdsp->resp = resp_dma;
                cmdsp->resp_len = req->sba->hw_resp_size;
        }
        cmdsp->flags |= BRCM_SBA_CMD_HAS_OUTPUT;
        cmdsp->data = *dst_p + msg_offset;
        cmdsp->data_len = msg_len;
        cmdsp++;

skip_p:
        if (!dst_q)
                goto skip_q;

        /* Type-A command to zero all buffers */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, msg_len,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_ZERO_ALL_BUFFERS,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
        cmdsp++;

        if (dpos == 255)
                goto skip_q_computation;
        pos = (dpos < req->sba->max_pq_coefs) ?
                dpos : (req->sba->max_pq_coefs - 1);

        /*
         * Type-B command to generate initial Q from data
         * and store output into buf0
         */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, msg_len,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        c_mdata = sba_cmd_pq_c_mdata(pos, 0, 0);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                          SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_MS(c_mdata),
                          SBA_C_MDATA_MS_SHIFT, SBA_C_MDATA_MS_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_GALOIS,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
        cmdsp->data = src + msg_offset;
        cmdsp->data_len = msg_len;
        cmdsp++;

        dpos -= pos;

        /* Multiple Type-A command to generate final Q */
        while (dpos) {
                pos = (dpos < req->sba->max_pq_coefs) ?
                        dpos : (req->sba->max_pq_coefs - 1);

                /*
                 * Type-A command to generate Q with buf0 and
                 * buf1 store result in buf0
                 */
                cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                c_mdata = sba_cmd_pq_c_mdata(pos, 0, 1);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                  SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_MS(c_mdata),
                                  SBA_C_MDATA_MS_SHIFT, SBA_C_MDATA_MS_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_GALOIS,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
                cmdsp++;

                dpos -= pos;
        }

skip_q_computation:
        if (pq_continue) {
                /*
                 * Type-B command to XOR previous output with
                 * buf0 and write it into buf0
                 */
                cmd = sba_cmd_enc(0x0, SBA_TYPE_B,
                                  SBA_TYPE_SHIFT, SBA_TYPE_MASK);
                cmd = sba_cmd_enc(cmd, msg_len,
                                  SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
                c_mdata = sba_cmd_xor_c_mdata(0, 0);
                cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                                  SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
                cmd = sba_cmd_enc(cmd, SBA_CMD_XOR,
                                  SBA_CMD_SHIFT, SBA_CMD_MASK);
                cmdsp->cmd = cmd;
                *cmdsp->cmd_dma = cpu_to_le64(cmd);
                cmdsp->flags = BRCM_SBA_CMD_TYPE_B;
                cmdsp->data = *dst_q + msg_offset;
                cmdsp->data_len = msg_len;
                cmdsp++;
        }

        /* Type-A command to write buf0 */
        cmd = sba_cmd_enc(0x0, SBA_TYPE_A,
                          SBA_TYPE_SHIFT, SBA_TYPE_MASK);
        cmd = sba_cmd_enc(cmd, msg_len,
                          SBA_USER_DEF_SHIFT, SBA_USER_DEF_MASK);
        cmd = sba_cmd_enc(cmd, 0x1,
                          SBA_RESP_SHIFT, SBA_RESP_MASK);
        c_mdata = sba_cmd_write_c_mdata(0);
        cmd = sba_cmd_enc(cmd, SBA_C_MDATA_LS(c_mdata),
                          SBA_C_MDATA_SHIFT, SBA_C_MDATA_MASK);
        cmd = sba_cmd_enc(cmd, SBA_CMD_WRITE_BUFFER,
                          SBA_CMD_SHIFT, SBA_CMD_MASK);
        cmdsp->cmd = cmd;
        *cmdsp->cmd_dma = cpu_to_le64(cmd);
        cmdsp->flags = BRCM_SBA_CMD_TYPE_A;
        if (req->sba->hw_resp_size) {
                cmdsp->flags |= BRCM_SBA_CMD_HAS_RESP;
                cmdsp->resp = resp_dma;
                cmdsp->resp_len = req->sba->hw_resp_size;
        }
        cmdsp->flags |= BRCM_SBA_CMD_HAS_OUTPUT;
        cmdsp->data = *dst_q + msg_offset;
        cmdsp->data_len = msg_len;
        cmdsp++;

skip_q:
        /* Fillup brcm_message */
        msg->type = BRCM_MESSAGE_SBA;
        msg->sba.cmds = cmds;
        msg->sba.cmds_count = cmdsp - cmds;
        msg->ctx = req;
        msg->error = 0;
}

static struct sba_request *
sba_prep_dma_pq_single_req(struct sba_device *sba, dma_addr_t off,
                           dma_addr_t *dst_p, dma_addr_t *dst_q,
                           dma_addr_t src, u8 scf, size_t len,
                           unsigned long flags)
{
        struct sba_request *req = NULL;

        /* Alloc new request */
        req = sba_alloc_request(sba);
        if (!req)
                return NULL;
        if (flags & DMA_PREP_FENCE)
                req->flags |= SBA_REQUEST_FENCE;

        /* Fillup request messages */
        sba_fillup_pq_single_msg(req,  dmaf_continue(flags),
                                 req->cmds, &req->msg, off, len,
                                 dst_p, dst_q, src, scf);

        /* Init async_tx descriptor */
        req->tx.flags = flags;
        req->tx.cookie = -EBUSY;

        return req;
}

static struct dma_async_tx_descriptor *
sba_prep_dma_pq(struct dma_chan *dchan, dma_addr_t *dst, dma_addr_t *src,
                u32 src_cnt, const u8 *scf, size_t len, unsigned long flags)
{
        u32 i, dst_q_index;
        size_t req_len;
        bool slow = false;
        dma_addr_t off = 0;
        dma_addr_t *dst_p = NULL, *dst_q = NULL;
        struct sba_device *sba = to_sba_device(dchan);
        struct sba_request *first = NULL, *req;

        /* Sanity checks */
        if (unlikely(src_cnt > sba->max_pq_srcs))
                return NULL;
        for (i = 0; i < src_cnt; i++)
                if (sba->max_pq_coefs <= raid6_gflog[scf[i]])
                        slow = true;

        /* Figure-out P and Q destination addresses */
        if (!(flags & DMA_PREP_PQ_DISABLE_P))
                dst_p = &dst[0];
        if (!(flags & DMA_PREP_PQ_DISABLE_Q))
                dst_q = &dst[1];

        /* Create chained requests where each request is upto hw_buf_size */
        while (len) {
                req_len = (len < sba->hw_buf_size) ? len : sba->hw_buf_size;

                if (slow) {
                        dst_q_index = src_cnt;

                        if (dst_q) {
                                for (i = 0; i < src_cnt; i++) {
                                        if (*dst_q == src[i]) {
                                                dst_q_index = i;
                                                break;
                                        }
                                }
                        }

                        if (dst_q_index < src_cnt) {
                                i = dst_q_index;
                                req = sba_prep_dma_pq_single_req(sba,
                                        off, dst_p, dst_q, src[i], scf[i],
                                        req_len, flags | DMA_PREP_FENCE);
                                if (!req)
                                        goto fail;

                                if (first)
                                        sba_chain_request(first, req);
                                else
                                        first = req;

                                flags |= DMA_PREP_CONTINUE;
                        }

                        for (i = 0; i < src_cnt; i++) {
                                if (dst_q_index == i)
                                        continue;

                                req = sba_prep_dma_pq_single_req(sba,
                                        off, dst_p, dst_q, src[i], scf[i],
                                        req_len, flags | DMA_PREP_FENCE);
                                if (!req)
                                        goto fail;

                                if (first)
                                        sba_chain_request(first, req);
                                else
                                        first = req;

                                flags |= DMA_PREP_CONTINUE;
                        }
                } else {
                        req = sba_prep_dma_pq_req(sba, off,
                                                  dst_p, dst_q, src, src_cnt,
                                                  scf, req_len, flags);
                        if (!req)
                                goto fail;

                        if (first)
                                sba_chain_request(first, req);
                        else
                                first = req;
                }

                off += req_len;
                len -= req_len;
        }

        return (first) ? &first->tx : NULL;

fail:
        if (first)
                sba_free_chained_requests(first);
        return NULL;
}

/* ====== Mailbox callbacks ===== */

static void sba_receive_message(struct mbox_client *cl, void *msg)
{
        struct brcm_message *m = msg;
        struct sba_request *req = m->ctx;
        struct sba_device *sba = req->sba;

        /* Error count if message has error */
        if (m->error < 0)
                dev_err(sba->dev, "%s got message with error %d",
                        dma_chan_name(&sba->dma_chan), m->error);

        /* Process received request */
        sba_process_received_request(sba, req);
}

/* ====== Debugfs callbacks ====== */

static int sba_debugfs_stats_show(struct seq_file *file, void *offset)
{
        struct platform_device *pdev = to_platform_device(file->private);
        struct sba_device *sba = platform_get_drvdata(pdev);

        /* Write stats in file */
        sba_write_stats_in_seqfile(sba, file);

        return 0;
}

/* ====== Platform driver routines ===== */

static int sba_prealloc_channel_resources(struct sba_device *sba)
{
        int i, j, ret = 0;
        struct sba_request *req = NULL;

        sba->resp_base = dma_alloc_coherent(sba->mbox_dev,
                                            sba->max_resp_pool_size,
                                            &sba->resp_dma_base, GFP_KERNEL);
        if (!sba->resp_base)
                return -ENOMEM;

        sba->cmds_base = dma_alloc_coherent(sba->mbox_dev,
                                            sba->max_cmds_pool_size,
                                            &sba->cmds_dma_base, GFP_KERNEL);
        if (!sba->cmds_base) {
                ret = -ENOMEM;
                goto fail_free_resp_pool;
        }

        spin_lock_init(&sba->reqs_lock);
        sba->reqs_fence = false;
        INIT_LIST_HEAD(&sba->reqs_alloc_list);
        INIT_LIST_HEAD(&sba->reqs_pending_list);
        INIT_LIST_HEAD(&sba->reqs_active_list);
        INIT_LIST_HEAD(&sba->reqs_aborted_list);
        INIT_LIST_HEAD(&sba->reqs_free_list);

        for (i = 0; i < sba->max_req; i++) {
                req = devm_kzalloc(sba->dev,
                                   struct_size(req, cmds, sba->max_cmd_per_req),
                                   GFP_KERNEL);
                if (!req) {
                        ret = -ENOMEM;
                        goto fail_free_cmds_pool;
                }
                INIT_LIST_HEAD(&req->node);
                req->sba = sba;
                req->flags = SBA_REQUEST_STATE_FREE;
                INIT_LIST_HEAD(&req->next);
                atomic_set(&req->next_pending_count, 0);
                for (j = 0; j < sba->max_cmd_per_req; j++) {
                        req->cmds[j].cmd = 0;
                        req->cmds[j].cmd_dma = sba->cmds_base +
                                (i * sba->max_cmd_per_req + j) * sizeof(u64);
                        req->cmds[j].cmd_dma_addr = sba->cmds_dma_base +
                                (i * sba->max_cmd_per_req + j) * sizeof(u64);
                        req->cmds[j].flags = 0;
                }
                memset(&req->msg, 0, sizeof(req->msg));
                dma_async_tx_descriptor_init(&req->tx, &sba->dma_chan);
                async_tx_ack(&req->tx);
                req->tx.tx_submit = sba_tx_submit;
                req->tx.phys = sba->resp_dma_base + i * sba->hw_resp_size;
                list_add_tail(&req->node, &sba->reqs_free_list);
        }

        return 0;

fail_free_cmds_pool:
        dma_free_coherent(sba->mbox_dev,
                          sba->max_cmds_pool_size,
                          sba->cmds_base, sba->cmds_dma_base);
fail_free_resp_pool:
        dma_free_coherent(sba->mbox_dev,
                          sba->max_resp_pool_size,
                          sba->resp_base, sba->resp_dma_base);
        return ret;
}

static void sba_freeup_channel_resources(struct sba_device *sba)
{
        dmaengine_terminate_all(&sba->dma_chan);
        dma_free_coherent(sba->mbox_dev, sba->max_cmds_pool_size,
                          sba->cmds_base, sba->cmds_dma_base);
        dma_free_coherent(sba->mbox_dev, sba->max_resp_pool_size,
                          sba->resp_base, sba->resp_dma_base);
        sba->resp_base = NULL;
        sba->resp_dma_base = 0;
}

static int sba_async_register(struct sba_device *sba)
{
        int ret;
        struct dma_device *dma_dev = &sba->dma_dev;

        /* Initialize DMA channel cookie */
        sba->dma_chan.device = dma_dev;
        dma_cookie_init(&sba->dma_chan);

        /* Initialize DMA device capability mask */
        dma_cap_zero(dma_dev->cap_mask);
        dma_cap_set(DMA_INTERRUPT, dma_dev->cap_mask);
        dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
        dma_cap_set(DMA_XOR, dma_dev->cap_mask);
        dma_cap_set(DMA_PQ, dma_dev->cap_mask);

        /*
         * Set mailbox channel device as the base device of
         * our dma_device because the actual memory accesses
         * will be done by mailbox controller
         */
        dma_dev->dev = sba->mbox_dev;

        /* Set base prep routines */
        dma_dev->device_free_chan_resources = sba_free_chan_resources;
        dma_dev->device_terminate_all = sba_device_terminate_all;
        dma_dev->device_issue_pending = sba_issue_pending;
        dma_dev->device_tx_status = sba_tx_status;

        /* Set interrupt routine */
        if (dma_has_cap(DMA_INTERRUPT, dma_dev->cap_mask))
                dma_dev->device_prep_dma_interrupt = sba_prep_dma_interrupt;

        /* Set memcpy routine */
        if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask))
                dma_dev->device_prep_dma_memcpy = sba_prep_dma_memcpy;

        /* Set xor routine and capability */
        if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
                dma_dev->device_prep_dma_xor = sba_prep_dma_xor;
                dma_dev->max_xor = sba->max_xor_srcs;
        }

        /* Set pq routine and capability */
        if (dma_has_cap(DMA_PQ, dma_dev->cap_mask)) {
                dma_dev->device_prep_dma_pq = sba_prep_dma_pq;
                dma_set_maxpq(dma_dev, sba->max_pq_srcs, 0);
        }

        /* Initialize DMA device channel list */
        INIT_LIST_HEAD(&dma_dev->channels);
        list_add_tail(&sba->dma_chan.device_node, &dma_dev->channels);

        /* Register with Linux async DMA framework*/
        ret = dma_async_device_register(dma_dev);
        if (ret) {
                dev_err(sba->dev, "async device register error %d", ret);
                return ret;
        }

        dev_info(sba->dev, "%s capabilities: %s%s%s%s\n",
        dma_chan_name(&sba->dma_chan),
        dma_has_cap(DMA_INTERRUPT, dma_dev->cap_mask) ? "interrupt " : "",
        dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask) ? "memcpy " : "",
        dma_has_cap(DMA_XOR, dma_dev->cap_mask) ? "xor " : "",
        dma_has_cap(DMA_PQ, dma_dev->cap_mask) ? "pq " : "");

        return 0;
}

static int sba_probe(struct platform_device *pdev)
{
        int ret = 0;
        struct sba_device *sba;
        struct platform_device *mbox_pdev;
        struct of_phandle_args args;

        /* Allocate main SBA struct */
        sba = devm_kzalloc(&pdev->dev, sizeof(*sba), GFP_KERNEL);
        if (!sba)
                return -ENOMEM;

        sba->dev = &pdev->dev;
        platform_set_drvdata(pdev, sba);

        /* Number of mailbox channels should be atleast 1 */
        ret = of_count_phandle_with_args(pdev->dev.of_node,
                                         "mboxes", "#mbox-cells");
        if (ret <= 0)
                return -ENODEV;

        /* Determine SBA version from DT compatible string */
        if (of_device_is_compatible(sba->dev->of_node, "brcm,iproc-sba"))
                sba->ver = SBA_VER_1;
        else if (of_device_is_compatible(sba->dev->of_node,
                                         "brcm,iproc-sba-v2"))
                sba->ver = SBA_VER_2;
        else
                return -ENODEV;

        /* Derived Configuration parameters */
        switch (sba->ver) {
        case SBA_VER_1:
                sba->hw_buf_size = 4096;
                sba->hw_resp_size = 8;
                sba->max_pq_coefs = 6;
                sba->max_pq_srcs = 6;
                break;
        case SBA_VER_2:
                sba->hw_buf_size = 4096;
                sba->hw_resp_size = 8;
                sba->max_pq_coefs = 30;
                /*
                 * We can support max_pq_srcs == max_pq_coefs because
                 * we are limited by number of SBA commands that we can
                 * fit in one message for underlying ring manager HW.
                 */
                sba->max_pq_srcs = 12;
                break;
        default:
                return -EINVAL;
        }
        sba->max_req = SBA_MAX_REQ_PER_MBOX_CHANNEL;
        sba->max_cmd_per_req = sba->max_pq_srcs + 3;
        sba->max_xor_srcs = sba->max_cmd_per_req - 1;
        sba->max_resp_pool_size = sba->max_req * sba->hw_resp_size;
        sba->max_cmds_pool_size = sba->max_req *
                                  sba->max_cmd_per_req * sizeof(u64);

        /* Setup mailbox client */
        sba->client.dev                 = &pdev->dev;
        sba->client.rx_callback         = sba_receive_message;
        sba->client.tx_block            = false;
        sba->client.knows_txdone        = true;
        sba->client.tx_tout             = 0;

        /* Request mailbox channel */
        sba->mchan = mbox_request_channel(&sba->client, 0);
        if (IS_ERR(sba->mchan)) {
                ret = PTR_ERR(sba->mchan);
                goto fail_free_mchan;
        }

        /* Find-out underlying mailbox device */
        ret = of_parse_phandle_with_args(pdev->dev.of_node,
                                         "mboxes", "#mbox-cells", 0, &args);
        if (ret)
                goto fail_free_mchan;
        mbox_pdev = of_find_device_by_node(args.np);
        of_node_put(args.np);
        if (!mbox_pdev) {
                ret = -ENODEV;
                goto fail_free_mchan;
        }
        sba->mbox_dev = &mbox_pdev->dev;

        /* Prealloc channel resource */
        ret = sba_prealloc_channel_resources(sba);
        if (ret)
                goto fail_free_mchan;

        /* Check availability of debugfs */
        if (!debugfs_initialized())
                goto skip_debugfs;

        /* Create debugfs root entry */
        sba->root = debugfs_create_dir(dev_name(sba->dev), NULL);
        if (IS_ERR_OR_NULL(sba->root)) {
                dev_err(sba->dev, "failed to create debugfs root entry\n");
                sba->root = NULL;
                goto skip_debugfs;
        }

        /* Create debugfs stats entry */
        sba->stats = debugfs_create_devm_seqfile(sba->dev, "stats", sba->root,
                                                 sba_debugfs_stats_show);
        if (IS_ERR_OR_NULL(sba->stats))
                dev_err(sba->dev, "failed to create debugfs stats file\n");
skip_debugfs:

        /* Register DMA device with Linux async framework */
        ret = sba_async_register(sba);
        if (ret)
                goto fail_free_resources;

        /* Print device info */
        dev_info(sba->dev, "%s using SBAv%d mailbox channel from %s",
                 dma_chan_name(&sba->dma_chan), sba->ver+1,
                 dev_name(sba->mbox_dev));

        return 0;

fail_free_resources:
        debugfs_remove_recursive(sba->root);
        sba_freeup_channel_resources(sba);
fail_free_mchan:
        mbox_free_channel(sba->mchan);
        return ret;
}

static int sba_remove(struct platform_device *pdev)
{
        struct sba_device *sba = platform_get_drvdata(pdev);

        dma_async_device_unregister(&sba->dma_dev);

        debugfs_remove_recursive(sba->root);

        sba_freeup_channel_resources(sba);

        mbox_free_channel(sba->mchan);

        return 0;
}

static const struct of_device_id sba_of_match[] = {
        { .compatible = "brcm,iproc-sba", },
        { .compatible = "brcm,iproc-sba-v2", },
        {},
};
MODULE_DEVICE_TABLE(of, sba_of_match);

static struct platform_driver sba_driver = {
        .probe = sba_probe,
        .remove = sba_remove,
        .driver = {
                .name = "bcm-sba-raid",
                .of_match_table = sba_of_match,
        },
};
module_platform_driver(sba_driver);

MODULE_DESCRIPTION("Broadcom SBA RAID driver");
MODULE_AUTHOR("Anup Patel <anup.patel@broadcom.com>");
MODULE_LICENSE("GPL v2");