/*
 * offload engine driver for the Marvell XOR engine
 * Copyright (C) 2007, 2008, Marvell International Ltd.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/memory.h>
#include <linux/clk.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/irqdomain.h>
#include <linux/platform_data/dma-mv_xor.h>

#include "dmaengine.h"
#include "mv_xor.h"

enum mv_xor_mode {
        XOR_MODE_IN_REG,
        XOR_MODE_IN_DESC,
};

static void mv_xor_issue_pending(struct dma_chan *chan);

#define to_mv_xor_chan(chan)            \
        container_of(chan, struct mv_xor_chan, dmachan)

#define to_mv_xor_slot(tx)              \
        container_of(tx, struct mv_xor_desc_slot, async_tx)

#define mv_chan_to_devp(chan)           \
        ((chan)->dmadev.dev)

static void mv_desc_init(struct mv_xor_desc_slot *desc,
                         dma_addr_t addr, u32 byte_count,
                         enum dma_ctrl_flags flags)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;

        hw_desc->status = XOR_DESC_DMA_OWNED;
        hw_desc->phy_next_desc = 0;
        /* Enable end-of-descriptor interrupts only for DMA_PREP_INTERRUPT */
        hw_desc->desc_command = (flags & DMA_PREP_INTERRUPT) ?
                                XOR_DESC_EOD_INT_EN : 0;
        hw_desc->phy_dest_addr = addr;
        hw_desc->byte_count = byte_count;
}

static void mv_desc_set_mode(struct mv_xor_desc_slot *desc)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;

        switch (desc->type) {
        case DMA_XOR:
        case DMA_INTERRUPT:
                hw_desc->desc_command |= XOR_DESC_OPERATION_XOR;
                break;
        case DMA_MEMCPY:
                hw_desc->desc_command |= XOR_DESC_OPERATION_MEMCPY;
                break;
        default:
                BUG();
                return;
        }
}

static void mv_desc_set_next_desc(struct mv_xor_desc_slot *desc,
                                  u32 next_desc_addr)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;
        BUG_ON(hw_desc->phy_next_desc);
        hw_desc->phy_next_desc = next_desc_addr;
}

static void mv_desc_set_src_addr(struct mv_xor_desc_slot *desc,
                                 int index, dma_addr_t addr)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;
        hw_desc->phy_src_addr[mv_phy_src_idx(index)] = addr;
        if (desc->type == DMA_XOR)
                hw_desc->desc_command |= (1 << index);
}

static u32 mv_chan_get_current_desc(struct mv_xor_chan *chan)
{
        return readl_relaxed(XOR_CURR_DESC(chan));
}

static void mv_chan_set_next_descriptor(struct mv_xor_chan *chan,
                                        u32 next_desc_addr)
{
        writel_relaxed(next_desc_addr, XOR_NEXT_DESC(chan));
}

static void mv_chan_unmask_interrupts(struct mv_xor_chan *chan)
{
        u32 val = readl_relaxed(XOR_INTR_MASK(chan));
        val |= XOR_INTR_MASK_VALUE << (chan->idx * 16);
        writel_relaxed(val, XOR_INTR_MASK(chan));
}

static u32 mv_chan_get_intr_cause(struct mv_xor_chan *chan)
{
        u32 intr_cause = readl_relaxed(XOR_INTR_CAUSE(chan));
        intr_cause = (intr_cause >> (chan->idx * 16)) & 0xFFFF;
        return intr_cause;
}

static void mv_chan_clear_eoc_cause(struct mv_xor_chan *chan)
{
        u32 val;

        val = XOR_INT_END_OF_DESC | XOR_INT_END_OF_CHAIN | XOR_INT_STOPPED;
        val = ~(val << (chan->idx * 16));
        dev_dbg(mv_chan_to_devp(chan), "%s, val 0x%08x\n", __func__, val);
        writel_relaxed(val, XOR_INTR_CAUSE(chan));
}

static void mv_chan_clear_err_status(struct mv_xor_chan *chan)
{
        u32 val = 0xFFFF0000 >> (chan->idx * 16);
        writel_relaxed(val, XOR_INTR_CAUSE(chan));
}

static void mv_chan_set_mode(struct mv_xor_chan *chan,
                             enum dma_transaction_type type)
{
        u32 op_mode;
        u32 config = readl_relaxed(XOR_CONFIG(chan));

        switch (type) {
        case DMA_XOR:
                op_mode = XOR_OPERATION_MODE_XOR;
                break;
        case DMA_MEMCPY:
                op_mode = XOR_OPERATION_MODE_MEMCPY;
                break;
        default:
                dev_err(mv_chan_to_devp(chan),
                        "error: unsupported operation %d\n",
                        type);
                BUG();
                return;
        }

        config &= ~0x7;
        config |= op_mode;

#if defined(__BIG_ENDIAN)
        config |= XOR_DESCRIPTOR_SWAP;
#else
        config &= ~XOR_DESCRIPTOR_SWAP;
#endif

        writel_relaxed(config, XOR_CONFIG(chan));
        chan->current_type = type;
}

static void mv_chan_set_mode_to_desc(struct mv_xor_chan *chan)
{
        u32 op_mode;
        u32 config = readl_relaxed(XOR_CONFIG(chan));

        op_mode = XOR_OPERATION_MODE_IN_DESC;

        config &= ~0x7;
        config |= op_mode;

#if defined(__BIG_ENDIAN)
        config |= XOR_DESCRIPTOR_SWAP;
#else
        config &= ~XOR_DESCRIPTOR_SWAP;
#endif

        writel_relaxed(config, XOR_CONFIG(chan));
}

static void mv_chan_activate(struct mv_xor_chan *chan)
{
        dev_dbg(mv_chan_to_devp(chan), " activate chan.\n");

        /* writel ensures all descriptors are flushed before activation */
        writel(BIT(0), XOR_ACTIVATION(chan));
}

static char mv_chan_is_busy(struct mv_xor_chan *chan)
{
        u32 state = readl_relaxed(XOR_ACTIVATION(chan));

        state = (state >> 4) & 0x3;

        return (state == 1) ? 1 : 0;
}

/*
 * mv_chan_start_new_chain - program the engine to operate on new
 * chain headed by sw_desc
 * Caller must hold &mv_chan->lock while calling this function
 */
static void mv_chan_start_new_chain(struct mv_xor_chan *mv_chan,
                                    struct mv_xor_desc_slot *sw_desc)
{
        dev_dbg(mv_chan_to_devp(mv_chan), "%s %d: sw_desc %p\n",
                __func__, __LINE__, sw_desc);

        /* set the hardware chain */
        mv_chan_set_next_descriptor(mv_chan, sw_desc->async_tx.phys);

        mv_chan->pending++;
        mv_xor_issue_pending(&mv_chan->dmachan);
}

static dma_cookie_t
mv_desc_run_tx_complete_actions(struct mv_xor_desc_slot *desc,
                                struct mv_xor_chan *mv_chan,
                                dma_cookie_t cookie)
{
        BUG_ON(desc->async_tx.cookie < 0);

        if (desc->async_tx.cookie > 0) {
                cookie = desc->async_tx.cookie;

                /* 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;
}

static int
mv_chan_clean_completed_slots(struct mv_xor_chan *mv_chan)
{
        struct mv_xor_desc_slot *iter, *_iter;

        dev_dbg(mv_chan_to_devp(mv_chan), "%s %d\n", __func__, __LINE__);
        list_for_each_entry_safe(iter, _iter, &mv_chan->completed_slots,
                                 node) {

                if (async_tx_test_ack(&iter->async_tx))
                        list_move_tail(&iter->node, &mv_chan->free_slots);
        }
        return 0;
}

static int
mv_desc_clean_slot(struct mv_xor_desc_slot *desc,
                   struct mv_xor_chan *mv_chan)
{
        dev_dbg(mv_chan_to_devp(mv_chan), "%s %d: desc %p flags %d\n",
                __func__, __LINE__, desc, desc->async_tx.flags);

        /* the client is allowed to attach dependent operations
         * until 'ack' is set
         */
        if (!async_tx_test_ack(&desc->async_tx))
                /* move this slot to the completed_slots */
                list_move_tail(&desc->node, &mv_chan->completed_slots);
        else
                list_move_tail(&desc->node, &mv_chan->free_slots);

        return 0;
}

/* This function must be called with the mv_xor_chan spinlock held */
static void mv_chan_slot_cleanup(struct mv_xor_chan *mv_chan)
{
        struct mv_xor_desc_slot *iter, *_iter;
        dma_cookie_t cookie = 0;
        int busy = mv_chan_is_busy(mv_chan);
        u32 current_desc = mv_chan_get_current_desc(mv_chan);
        int current_cleaned = 0;
        struct mv_xor_desc *hw_desc;

        dev_dbg(mv_chan_to_devp(mv_chan), "%s %d\n", __func__, __LINE__);
        dev_dbg(mv_chan_to_devp(mv_chan), "current_desc %x\n", current_desc);
        mv_chan_clean_completed_slots(mv_chan);

        /* free completed slots from the chain starting with
         * the oldest descriptor
         */

        list_for_each_entry_safe(iter, _iter, &mv_chan->chain,
                                 node) {

                /* clean finished descriptors */
                hw_desc = iter->hw_desc;
                if (hw_desc->status & XOR_DESC_SUCCESS) {
                        cookie = mv_desc_run_tx_complete_actions(iter, mv_chan,
                                                                 cookie);

                        /* done processing desc, clean slot */
                        mv_desc_clean_slot(iter, mv_chan);

                        /* break if we did cleaned the current */
                        if (iter->async_tx.phys == current_desc) {
                                current_cleaned = 1;
                                break;
                        }
                } else {
                        if (iter->async_tx.phys == current_desc) {
                                current_cleaned = 0;
                                break;
                        }
                }
        }

        if ((busy == 0) && !list_empty(&mv_chan->chain)) {
                if (current_cleaned) {
                        /*
                         * current descriptor cleaned and removed, run
                         * from list head
                         */
                        iter = list_entry(mv_chan->chain.next,
                                          struct mv_xor_desc_slot,
                                          node);
                        mv_chan_start_new_chain(mv_chan, iter);
                } else {
                        if (!list_is_last(&iter->node, &mv_chan->chain)) {
                                /*
                                 * descriptors are still waiting after
                                 * current, trigger them
                                 */
                                iter = list_entry(iter->node.next,
                                                  struct mv_xor_desc_slot,
                                                  node);
                                mv_chan_start_new_chain(mv_chan, iter);
                        } else {
                                /*
                                 * some descriptors are still waiting
                                 * to be cleaned
                                 */
                                tasklet_schedule(&mv_chan->irq_tasklet);
                        }
                }
        }

        if (cookie > 0)
                mv_chan->dmachan.completed_cookie = cookie;
}

static void mv_xor_tasklet(unsigned long data)
{
        struct mv_xor_chan *chan = (struct mv_xor_chan *) data;

        spin_lock_bh(&chan->lock);
        mv_chan_slot_cleanup(chan);
        spin_unlock_bh(&chan->lock);
}

static struct mv_xor_desc_slot *
mv_chan_alloc_slot(struct mv_xor_chan *mv_chan)
{
        struct mv_xor_desc_slot *iter;

        spin_lock_bh(&mv_chan->lock);

        if (!list_empty(&mv_chan->free_slots)) {
                iter = list_first_entry(&mv_chan->free_slots,
                                        struct mv_xor_desc_slot,
                                        node);

                list_move_tail(&iter->node, &mv_chan->allocated_slots);

                spin_unlock_bh(&mv_chan->lock);

                /* pre-ack descriptor */
                async_tx_ack(&iter->async_tx);
                iter->async_tx.cookie = -EBUSY;

                return iter;

        }

        spin_unlock_bh(&mv_chan->lock);

        /* try to free some slots if the allocation fails */
        tasklet_schedule(&mv_chan->irq_tasklet);

        return NULL;
}

/************************ DMA engine API functions ****************************/
static dma_cookie_t
mv_xor_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct mv_xor_desc_slot *sw_desc = to_mv_xor_slot(tx);
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(tx->chan);
        struct mv_xor_desc_slot *old_chain_tail;
        dma_cookie_t cookie;
        int new_hw_chain = 1;

        dev_dbg(mv_chan_to_devp(mv_chan),
                "%s sw_desc %p: async_tx %p\n",
                __func__, sw_desc, &sw_desc->async_tx);

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

        if (list_empty(&mv_chan->chain))
                list_move_tail(&sw_desc->node, &mv_chan->chain);
        else {
                new_hw_chain = 0;

                old_chain_tail = list_entry(mv_chan->chain.prev,
                                            struct mv_xor_desc_slot,
                                            node);
                list_move_tail(&sw_desc->node, &mv_chan->chain);

                dev_dbg(mv_chan_to_devp(mv_chan), "Append to last desc %pa\n",
                        &old_chain_tail->async_tx.phys);

                /* fix up the hardware chain */
                mv_desc_set_next_desc(old_chain_tail, sw_desc->async_tx.phys);

                /* if the channel is not busy */
                if (!mv_chan_is_busy(mv_chan)) {
                        u32 current_desc = mv_chan_get_current_desc(mv_chan);
                        /*
                         * and the curren desc is the end of the chain before
                         * the append, then we need to start the channel
                         */
                        if (current_desc == old_chain_tail->async_tx.phys)
                                new_hw_chain = 1;
                }
        }

        if (new_hw_chain)
                mv_chan_start_new_chain(mv_chan, sw_desc);

        spin_unlock_bh(&mv_chan->lock);

        return cookie;
}

/* returns the number of allocated descriptors */
static int mv_xor_alloc_chan_resources(struct dma_chan *chan)
{
        void *virt_desc;
        dma_addr_t dma_desc;
        int idx;
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        struct mv_xor_desc_slot *slot = NULL;
        int num_descs_in_pool = MV_XOR_POOL_SIZE/MV_XOR_SLOT_SIZE;

        /* Allocate descriptor slots */
        idx = mv_chan->slots_allocated;
        while (idx < num_descs_in_pool) {
                slot = kzalloc(sizeof(*slot), GFP_KERNEL);
                if (!slot) {
                        dev_info(mv_chan_to_devp(mv_chan),
                                 "channel only initialized %d descriptor slots",
                                 idx);
                        break;
                }
                virt_desc = mv_chan->dma_desc_pool_virt;
                slot->hw_desc = virt_desc + idx * MV_XOR_SLOT_SIZE;

                dma_async_tx_descriptor_init(&slot->async_tx, chan);
                slot->async_tx.tx_submit = mv_xor_tx_submit;
                INIT_LIST_HEAD(&slot->node);
                dma_desc = mv_chan->dma_desc_pool;
                slot->async_tx.phys = dma_desc + idx * MV_XOR_SLOT_SIZE;
                slot->idx = idx++;

                spin_lock_bh(&mv_chan->lock);
                mv_chan->slots_allocated = idx;
                list_add_tail(&slot->node, &mv_chan->free_slots);
                spin_unlock_bh(&mv_chan->lock);
        }

        dev_dbg(mv_chan_to_devp(mv_chan),
                "allocated %d descriptor slots\n",
                mv_chan->slots_allocated);

        return mv_chan->slots_allocated ? : -ENOMEM;
}

static struct dma_async_tx_descriptor *
mv_xor_prep_dma_xor(struct dma_chan *chan, dma_addr_t dest, dma_addr_t *src,
                    unsigned int src_cnt, size_t len, unsigned long flags)
{
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        struct mv_xor_desc_slot *sw_desc;

        if (unlikely(len < MV_XOR_MIN_BYTE_COUNT))
                return NULL;

        BUG_ON(len > MV_XOR_MAX_BYTE_COUNT);

        dev_dbg(mv_chan_to_devp(mv_chan),
                "%s src_cnt: %d len: %u dest %pad flags: %ld\n",
                __func__, src_cnt, len, &dest, flags);

        sw_desc = mv_chan_alloc_slot(mv_chan);
        if (sw_desc) {
                sw_desc->type = DMA_XOR;
                sw_desc->async_tx.flags = flags;
                mv_desc_init(sw_desc, dest, len, flags);
                if (mv_chan->op_in_desc == XOR_MODE_IN_DESC)
                        mv_desc_set_mode(sw_desc);
                while (src_cnt--)
                        mv_desc_set_src_addr(sw_desc, src_cnt, src[src_cnt]);
        }

        dev_dbg(mv_chan_to_devp(mv_chan),
                "%s sw_desc %p async_tx %p \n",
                __func__, sw_desc, &sw_desc->async_tx);
        return sw_desc ? &sw_desc->async_tx : NULL;
}

static struct dma_async_tx_descriptor *
mv_xor_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
                size_t len, unsigned long flags)
{
        /*
         * A MEMCPY operation is identical to an XOR operation with only
         * a single source address.
         */
        return mv_xor_prep_dma_xor(chan, dest, &src, 1, len, flags);
}

static struct dma_async_tx_descriptor *
mv_xor_prep_dma_interrupt(struct dma_chan *chan, unsigned long flags)
{
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        dma_addr_t src, dest;
        size_t len;

        src = mv_chan->dummy_src_addr;
        dest = mv_chan->dummy_dst_addr;
        len = MV_XOR_MIN_BYTE_COUNT;

        /*
         * We implement the DMA_INTERRUPT operation as a minimum sized
         * XOR operation with a single dummy source address.
         */
        return mv_xor_prep_dma_xor(chan, dest, &src, 1, len, flags);
}

static void mv_xor_free_chan_resources(struct dma_chan *chan)
{
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        struct mv_xor_desc_slot *iter, *_iter;
        int in_use_descs = 0;

        spin_lock_bh(&mv_chan->lock);

        mv_chan_slot_cleanup(mv_chan);

        list_for_each_entry_safe(iter, _iter, &mv_chan->chain,
                                        node) {
                in_use_descs++;
                list_move_tail(&iter->node, &mv_chan->free_slots);
        }
        list_for_each_entry_safe(iter, _iter, &mv_chan->completed_slots,
                                 node) {
                in_use_descs++;
                list_move_tail(&iter->node, &mv_chan->free_slots);
        }
        list_for_each_entry_safe(iter, _iter, &mv_chan->allocated_slots,
                                 node) {
                in_use_descs++;
                list_move_tail(&iter->node, &mv_chan->free_slots);
        }
        list_for_each_entry_safe_reverse(
                iter, _iter, &mv_chan->free_slots, node) {
                list_del(&iter->node);
                kfree(iter);
                mv_chan->slots_allocated--;
        }

        dev_dbg(mv_chan_to_devp(mv_chan), "%s slots_allocated %d\n",
                __func__, mv_chan->slots_allocated);
        spin_unlock_bh(&mv_chan->lock);

        if (in_use_descs)
                dev_err(mv_chan_to_devp(mv_chan),
                        "freeing %d in use descriptors!\n", in_use_descs);
}

/**
 * mv_xor_status - poll the status of an XOR transaction
 * @chan: XOR channel handle
 * @cookie: XOR transaction identifier
 * @txstate: XOR transactions state holder (or NULL)
 */
static enum dma_status mv_xor_status(struct dma_chan *chan,
                                          dma_cookie_t cookie,
                                          struct dma_tx_state *txstate)
{
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        enum dma_status ret;

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

        spin_lock_bh(&mv_chan->lock);
        mv_chan_slot_cleanup(mv_chan);
        spin_unlock_bh(&mv_chan->lock);

        return dma_cookie_status(chan, cookie, txstate);
}

static void mv_chan_dump_regs(struct mv_xor_chan *chan)
{
        u32 val;

        val = readl_relaxed(XOR_CONFIG(chan));
        dev_err(mv_chan_to_devp(chan), "config       0x%08x\n", val);

        val = readl_relaxed(XOR_ACTIVATION(chan));
        dev_err(mv_chan_to_devp(chan), "activation   0x%08x\n", val);

        val = readl_relaxed(XOR_INTR_CAUSE(chan));
        dev_err(mv_chan_to_devp(chan), "intr cause   0x%08x\n", val);

        val = readl_relaxed(XOR_INTR_MASK(chan));
        dev_err(mv_chan_to_devp(chan), "intr mask    0x%08x\n", val);

        val = readl_relaxed(XOR_ERROR_CAUSE(chan));
        dev_err(mv_chan_to_devp(chan), "error cause  0x%08x\n", val);

        val = readl_relaxed(XOR_ERROR_ADDR(chan));
        dev_err(mv_chan_to_devp(chan), "error addr   0x%08x\n", val);
}

static void mv_chan_err_interrupt_handler(struct mv_xor_chan *chan,
                                          u32 intr_cause)
{
        if (intr_cause & XOR_INT_ERR_DECODE) {
                dev_dbg(mv_chan_to_devp(chan), "ignoring address decode error\n");
                return;
        }

        dev_err(mv_chan_to_devp(chan), "error on chan %d. intr cause 0x%08x\n",
                chan->idx, intr_cause);

        mv_chan_dump_regs(chan);
        WARN_ON(1);
}

static irqreturn_t mv_xor_interrupt_handler(int irq, void *data)
{
        struct mv_xor_chan *chan = data;
        u32 intr_cause = mv_chan_get_intr_cause(chan);

        dev_dbg(mv_chan_to_devp(chan), "intr cause %x\n", intr_cause);

        if (intr_cause & XOR_INTR_ERRORS)
                mv_chan_err_interrupt_handler(chan, intr_cause);

        tasklet_schedule(&chan->irq_tasklet);

        mv_chan_clear_eoc_cause(chan);

        return IRQ_HANDLED;
}

static void mv_xor_issue_pending(struct dma_chan *chan)
{
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);

        if (mv_chan->pending >= MV_XOR_THRESHOLD) {
                mv_chan->pending = 0;
                mv_chan_activate(mv_chan);
        }
}

/*
 * Perform a transaction to verify the HW works.
 */

static int mv_chan_memcpy_self_test(struct mv_xor_chan *mv_chan)
{
        int i, ret;
        void *src, *dest;
        dma_addr_t src_dma, dest_dma;
        struct dma_chan *dma_chan;
        dma_cookie_t cookie;
        struct dma_async_tx_descriptor *tx;
        struct dmaengine_unmap_data *unmap;
        int err = 0;

        src = kmalloc(sizeof(u8) * PAGE_SIZE, GFP_KERNEL);
        if (!src)
                return -ENOMEM;

        dest = kzalloc(sizeof(u8) * PAGE_SIZE, GFP_KERNEL);
        if (!dest) {
                kfree(src);
                return -ENOMEM;
        }

        /* Fill in src buffer */
        for (i = 0; i < PAGE_SIZE; i++)
                ((u8 *) src)[i] = (u8)i;

        dma_chan = &mv_chan->dmachan;
        if (mv_xor_alloc_chan_resources(dma_chan) < 1) {
                err = -ENODEV;
                goto out;
        }

        unmap = dmaengine_get_unmap_data(dma_chan->device->dev, 2, GFP_KERNEL);
        if (!unmap) {
                err = -ENOMEM;
                goto free_resources;
        }

        src_dma = dma_map_page(dma_chan->device->dev, virt_to_page(src), 0,
                                 PAGE_SIZE, DMA_TO_DEVICE);
        unmap->addr[0] = src_dma;

        ret = dma_mapping_error(dma_chan->device->dev, src_dma);
        if (ret) {
                err = -ENOMEM;
                goto free_resources;
        }
        unmap->to_cnt = 1;

        dest_dma = dma_map_page(dma_chan->device->dev, virt_to_page(dest), 0,
                                  PAGE_SIZE, DMA_FROM_DEVICE);
        unmap->addr[1] = dest_dma;

        ret = dma_mapping_error(dma_chan->device->dev, dest_dma);
        if (ret) {
                err = -ENOMEM;
                goto free_resources;
        }
        unmap->from_cnt = 1;
        unmap->len = PAGE_SIZE;

        tx = mv_xor_prep_dma_memcpy(dma_chan, dest_dma, src_dma,
                                    PAGE_SIZE, 0);
        if (!tx) {
                dev_err(dma_chan->device->dev,
                        "Self-test cannot prepare operation, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

        cookie = mv_xor_tx_submit(tx);
        if (dma_submit_error(cookie)) {
                dev_err(dma_chan->device->dev,
                        "Self-test submit error, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

        mv_xor_issue_pending(dma_chan);
        async_tx_ack(tx);
        msleep(1);

        if (mv_xor_status(dma_chan, cookie, NULL) !=
            DMA_COMPLETE) {
                dev_err(dma_chan->device->dev,
                        "Self-test copy timed out, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

        dma_sync_single_for_cpu(dma_chan->device->dev, dest_dma,
                                PAGE_SIZE, DMA_FROM_DEVICE);
        if (memcmp(src, dest, PAGE_SIZE)) {
                dev_err(dma_chan->device->dev,
                        "Self-test copy failed compare, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

free_resources:
        dmaengine_unmap_put(unmap);
        mv_xor_free_chan_resources(dma_chan);
out:
        kfree(src);
        kfree(dest);
        return err;
}

#define MV_XOR_NUM_SRC_TEST 4 /* must be <= 15 */
static int
mv_chan_xor_self_test(struct mv_xor_chan *mv_chan)
{
        int i, src_idx, ret;
        struct page *dest;
        struct page *xor_srcs[MV_XOR_NUM_SRC_TEST];
        dma_addr_t dma_srcs[MV_XOR_NUM_SRC_TEST];
        dma_addr_t dest_dma;
        struct dma_async_tx_descriptor *tx;
        struct dmaengine_unmap_data *unmap;
        struct dma_chan *dma_chan;
        dma_cookie_t cookie;
        u8 cmp_byte = 0;
        u32 cmp_word;
        int err = 0;
        int src_count = MV_XOR_NUM_SRC_TEST;

        for (src_idx = 0; src_idx < src_count; src_idx++) {
                xor_srcs[src_idx] = alloc_page(GFP_KERNEL);
                if (!xor_srcs[src_idx]) {
                        while (src_idx--)
                                __free_page(xor_srcs[src_idx]);
                        return -ENOMEM;
                }
        }

        dest = alloc_page(GFP_KERNEL);
        if (!dest) {
                while (src_idx--)
                        __free_page(xor_srcs[src_idx]);
                return -ENOMEM;
        }

        /* Fill in src buffers */
        for (src_idx = 0; src_idx < src_count; src_idx++) {
                u8 *ptr = page_address(xor_srcs[src_idx]);
                for (i = 0; i < PAGE_SIZE; i++)
                        ptr[i] = (1 << src_idx);
        }

        for (src_idx = 0; src_idx < src_count; src_idx++)
                cmp_byte ^= (u8) (1 << src_idx);

        cmp_word = (cmp_byte << 24) | (cmp_byte << 16) |
                (cmp_byte << 8) | cmp_byte;

        memset(page_address(dest), 0, PAGE_SIZE);

        dma_chan = &mv_chan->dmachan;
        if (mv_xor_alloc_chan_resources(dma_chan) < 1) {
                err = -ENODEV;
                goto out;
        }

        unmap = dmaengine_get_unmap_data(dma_chan->device->dev, src_count + 1,
                                         GFP_KERNEL);
        if (!unmap) {
                err = -ENOMEM;
                goto free_resources;
        }

        /* test xor */
        for (i = 0; i < src_count; i++) {
                unmap->addr[i] = dma_map_page(dma_chan->device->dev, xor_srcs[i],
                                              0, PAGE_SIZE, DMA_TO_DEVICE);
                dma_srcs[i] = unmap->addr[i];
                ret = dma_mapping_error(dma_chan->device->dev, unmap->addr[i]);
                if (ret) {
                        err = -ENOMEM;
                        goto free_resources;
                }
                unmap->to_cnt++;
        }

        unmap->addr[src_count] = dma_map_page(dma_chan->device->dev, dest, 0, PAGE_SIZE,
                                      DMA_FROM_DEVICE);
        dest_dma = unmap->addr[src_count];
        ret = dma_mapping_error(dma_chan->device->dev, unmap->addr[src_count]);
        if (ret) {
                err = -ENOMEM;
                goto free_resources;
        }
        unmap->from_cnt = 1;
        unmap->len = PAGE_SIZE;

        tx = mv_xor_prep_dma_xor(dma_chan, dest_dma, dma_srcs,
                                 src_count, PAGE_SIZE, 0);
        if (!tx) {
                dev_err(dma_chan->device->dev,
                        "Self-test cannot prepare operation, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

        cookie = mv_xor_tx_submit(tx);
        if (dma_submit_error(cookie)) {
                dev_err(dma_chan->device->dev,
                        "Self-test submit error, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

        mv_xor_issue_pending(dma_chan);
        async_tx_ack(tx);
        msleep(8);

        if (mv_xor_status(dma_chan, cookie, NULL) !=
            DMA_COMPLETE) {
                dev_err(dma_chan->device->dev,
                        "Self-test xor timed out, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

        dma_sync_single_for_cpu(dma_chan->device->dev, dest_dma,
                                PAGE_SIZE, DMA_FROM_DEVICE);
        for (i = 0; i < (PAGE_SIZE / sizeof(u32)); i++) {
                u32 *ptr = page_address(dest);
                if (ptr[i] != cmp_word) {
                        dev_err(dma_chan->device->dev,
                                "Self-test xor failed compare, disabling. index %d, data %x, expected %x\n",
                                i, ptr[i], cmp_word);
                        err = -ENODEV;
                        goto free_resources;
                }
        }

free_resources:
        dmaengine_unmap_put(unmap);
        mv_xor_free_chan_resources(dma_chan);
out:
        src_idx = src_count;
        while (src_idx--)
                __free_page(xor_srcs[src_idx]);
        __free_page(dest);
        return err;
}

static int mv_xor_channel_remove(struct mv_xor_chan *mv_chan)
{
        struct dma_chan *chan, *_chan;
        struct device *dev = mv_chan->dmadev.dev;

        dma_async_device_unregister(&mv_chan->dmadev);

        dma_free_coherent(dev, MV_XOR_POOL_SIZE,
                          mv_chan->dma_desc_pool_virt, mv_chan->dma_desc_pool);
        dma_unmap_single(dev, mv_chan->dummy_src_addr,
                         MV_XOR_MIN_BYTE_COUNT, DMA_FROM_DEVICE);
        dma_unmap_single(dev, mv_chan->dummy_dst_addr,
                         MV_XOR_MIN_BYTE_COUNT, DMA_TO_DEVICE);

        list_for_each_entry_safe(chan, _chan, &mv_chan->dmadev.channels,
                                 device_node) {
                list_del(&chan->device_node);
        }

        free_irq(mv_chan->irq, mv_chan);

        return 0;
}

static struct mv_xor_chan *
mv_xor_channel_add(struct mv_xor_device *xordev,
                   struct platform_device *pdev,
                   int idx, dma_cap_mask_t cap_mask, int irq, int op_in_desc)
{
        int ret = 0;
        struct mv_xor_chan *mv_chan;
        struct dma_device *dma_dev;

        mv_chan = devm_kzalloc(&pdev->dev, sizeof(*mv_chan), GFP_KERNEL);
        if (!mv_chan)
                return ERR_PTR(-ENOMEM);

        mv_chan->idx = idx;
        mv_chan->irq = irq;
        mv_chan->op_in_desc = op_in_desc;

        dma_dev = &mv_chan->dmadev;

        /*
         * These source and destination dummy buffers are used to implement
         * a DMA_INTERRUPT operation as a minimum-sized XOR operation.
         * Hence, we only need to map the buffers at initialization-time.
         */
        mv_chan->dummy_src_addr = dma_map_single(dma_dev->dev,
                mv_chan->dummy_src, MV_XOR_MIN_BYTE_COUNT, DMA_FROM_DEVICE);
        mv_chan->dummy_dst_addr = dma_map_single(dma_dev->dev,
                mv_chan->dummy_dst, MV_XOR_MIN_BYTE_COUNT, DMA_TO_DEVICE);

        /* allocate coherent memory for hardware descriptors
         * note: writecombine gives slightly better performance, but
         * requires that we explicitly flush the writes

         */
        mv_chan->dma_desc_pool_virt =
          dma_alloc_writecombine(&pdev->dev, MV_XOR_POOL_SIZE,
                                 &mv_chan->dma_desc_pool, GFP_KERNEL);
        if (!mv_chan->dma_desc_pool_virt)
                return ERR_PTR(-ENOMEM);

        /* discover transaction capabilites from the platform data */
        dma_dev->cap_mask = cap_mask;

        INIT_LIST_HEAD(&dma_dev->channels);

        /* set base routines */
        dma_dev->device_alloc_chan_resources = mv_xor_alloc_chan_resources;
        dma_dev->device_free_chan_resources = mv_xor_free_chan_resources;
        dma_dev->device_tx_status = mv_xor_status;
        dma_dev->device_issue_pending = mv_xor_issue_pending;
        dma_dev->dev = &pdev->dev;

        /* set prep routines based on capability */
        if (dma_has_cap(DMA_INTERRUPT, dma_dev->cap_mask))
                dma_dev->device_prep_dma_interrupt = mv_xor_prep_dma_interrupt;
        if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask))
                dma_dev->device_prep_dma_memcpy = mv_xor_prep_dma_memcpy;
        if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
                dma_dev->max_xor = 8;
                dma_dev->device_prep_dma_xor = mv_xor_prep_dma_xor;
        }

        mv_chan->mmr_base = xordev->xor_base;
        mv_chan->mmr_high_base = xordev->xor_high_base;
        tasklet_init(&mv_chan->irq_tasklet, mv_xor_tasklet, (unsigned long)
                     mv_chan);

        /* clear errors before enabling interrupts */
        mv_chan_clear_err_status(mv_chan);

        ret = request_irq(mv_chan->irq, mv_xor_interrupt_handler,
                          0, dev_name(&pdev->dev), mv_chan);
        if (ret)
                goto err_free_dma;

        mv_chan_unmask_interrupts(mv_chan);

        if (mv_chan->op_in_desc == XOR_MODE_IN_DESC)
                mv_chan_set_mode_to_desc(mv_chan);
        else
                mv_chan_set_mode(mv_chan, DMA_XOR);

        spin_lock_init(&mv_chan->lock);
        INIT_LIST_HEAD(&mv_chan->chain);
        INIT_LIST_HEAD(&mv_chan->completed_slots);
        INIT_LIST_HEAD(&mv_chan->free_slots);
        INIT_LIST_HEAD(&mv_chan->allocated_slots);
        mv_chan->dmachan.device = dma_dev;
        dma_cookie_init(&mv_chan->dmachan);

        list_add_tail(&mv_chan->dmachan.device_node, &dma_dev->channels);

        if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask)) {
                ret = mv_chan_memcpy_self_test(mv_chan);
                dev_dbg(&pdev->dev, "memcpy self test returned %d\n", ret);
                if (ret)
                        goto err_free_irq;
        }

        if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
                ret = mv_chan_xor_self_test(mv_chan);
                dev_dbg(&pdev->dev, "xor self test returned %d\n", ret);
                if (ret)
                        goto err_free_irq;
        }

        dev_info(&pdev->dev, "Marvell XOR (%s): ( %s%s%s)\n",
                 mv_chan->op_in_desc ? "Descriptor Mode" : "Registers Mode",
                 dma_has_cap(DMA_XOR, dma_dev->cap_mask) ? "xor " : "",
                 dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask) ? "cpy " : "",
                 dma_has_cap(DMA_INTERRUPT, dma_dev->cap_mask) ? "intr " : "");

        dma_async_device_register(dma_dev);
        return mv_chan;

err_free_irq:
        free_irq(mv_chan->irq, mv_chan);
 err_free_dma:
        dma_free_coherent(&pdev->dev, MV_XOR_POOL_SIZE,
                          mv_chan->dma_desc_pool_virt, mv_chan->dma_desc_pool);
        return ERR_PTR(ret);
}

static void
mv_xor_conf_mbus_windows(struct mv_xor_device *xordev,
                         const struct mbus_dram_target_info *dram)
{
        void __iomem *base = xordev->xor_high_base;
        u32 win_enable = 0;
        int i;

        for (i = 0; i < 8; i++) {
                writel(0, base + WINDOW_BASE(i));
                writel(0, base + WINDOW_SIZE(i));
                if (i < 4)
                        writel(0, base + WINDOW_REMAP_HIGH(i));
        }

        for (i = 0; i < dram->num_cs; i++) {
                const struct mbus_dram_window *cs = dram->cs + i;

                writel((cs->base & 0xffff0000) |
                       (cs->mbus_attr << 8) |
                       dram->mbus_dram_target_id, base + WINDOW_BASE(i));
                writel((cs->size - 1) & 0xffff0000, base + WINDOW_SIZE(i));

                win_enable |= (1 << i);
                win_enable |= 3 << (16 + (2 * i));
        }

        writel(win_enable, base + WINDOW_BAR_ENABLE(0));
        writel(win_enable, base + WINDOW_BAR_ENABLE(1));
        writel(0, base + WINDOW_OVERRIDE_CTRL(0));
        writel(0, base + WINDOW_OVERRIDE_CTRL(1));
}

static const struct of_device_id mv_xor_dt_ids[] = {
        { .compatible = "marvell,orion-xor", .data = (void *)XOR_MODE_IN_REG },
        { .compatible = "marvell,armada-380-xor", .data = (void *)XOR_MODE_IN_DESC },
        {},
};
MODULE_DEVICE_TABLE(of, mv_xor_dt_ids);

static int mv_xor_probe(struct platform_device *pdev)
{
        const struct mbus_dram_target_info *dram;
        struct mv_xor_device *xordev;
        struct mv_xor_platform_data *pdata = dev_get_platdata(&pdev->dev);
        struct resource *res;
        int i, ret;
        int op_in_desc;

        dev_notice(&pdev->dev, "Marvell shared XOR driver\n");

        xordev = devm_kzalloc(&pdev->dev, sizeof(*xordev), GFP_KERNEL);
        if (!xordev)
                return -ENOMEM;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res)
                return -ENODEV;

        xordev->xor_base = devm_ioremap(&pdev->dev, res->start,
                                        resource_size(res));
        if (!xordev->xor_base)
                return -EBUSY;

        res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (!res)
                return -ENODEV;

        xordev->xor_high_base = devm_ioremap(&pdev->dev, res->start,
                                             resource_size(res));
        if (!xordev->xor_high_base)
                return -EBUSY;

        platform_set_drvdata(pdev, xordev);

        /*
         * (Re-)program MBUS remapping windows if we are asked to.
         */
        dram = mv_mbus_dram_info();
        if (dram)
                mv_xor_conf_mbus_windows(xordev, dram);

        /* Not all platforms can gate the clock, so it is not
         * an error if the clock does not exists.
         */
        xordev->clk = clk_get(&pdev->dev, NULL);
        if (!IS_ERR(xordev->clk))
                clk_prepare_enable(xordev->clk);

        if (pdev->dev.of_node) {
                struct device_node *np;
                int i = 0;
                const struct of_device_id *of_id =
                        of_match_device(mv_xor_dt_ids,
                                        &pdev->dev);

                for_each_child_of_node(pdev->dev.of_node, np) {
                        struct mv_xor_chan *chan;
                        dma_cap_mask_t cap_mask;
                        int irq;
                        op_in_desc = (int)of_id->data;

                        dma_cap_zero(cap_mask);
                        if (of_property_read_bool(np, "dmacap,memcpy"))
                                dma_cap_set(DMA_MEMCPY, cap_mask);
                        if (of_property_read_bool(np, "dmacap,xor"))
                                dma_cap_set(DMA_XOR, cap_mask);
                        if (of_property_read_bool(np, "dmacap,interrupt"))
                                dma_cap_set(DMA_INTERRUPT, cap_mask);

                        irq = irq_of_parse_and_map(np, 0);
                        if (!irq) {
                                ret = -ENODEV;
                                goto err_channel_add;
                        }

                        chan = mv_xor_channel_add(xordev, pdev, i,
                                                  cap_mask, irq, op_in_desc);
                        if (IS_ERR(chan)) {
                                ret = PTR_ERR(chan);
                                irq_dispose_mapping(irq);
                                goto err_channel_add;
                        }

                        xordev->channels[i] = chan;
                        i++;
                }
        } else if (pdata && pdata->channels) {
                for (i = 0; i < MV_XOR_MAX_CHANNELS; i++) {
                        struct mv_xor_channel_data *cd;
                        struct mv_xor_chan *chan;
                        int irq;

                        cd = &pdata->channels[i];
                        if (!cd) {
                                ret = -ENODEV;
                                goto err_channel_add;
                        }

                        irq = platform_get_irq(pdev, i);
                        if (irq < 0) {
                                ret = irq;
                                goto err_channel_add;
                        }

                        chan = mv_xor_channel_add(xordev, pdev, i,
                                                  cd->cap_mask, irq,
                                                  XOR_MODE_IN_REG);
                        if (IS_ERR(chan)) {
                                ret = PTR_ERR(chan);
                                goto err_channel_add;
                        }

                        xordev->channels[i] = chan;
                }
        }

        return 0;

err_channel_add:
        for (i = 0; i < MV_XOR_MAX_CHANNELS; i++)
                if (xordev->channels[i]) {
                        mv_xor_channel_remove(xordev->channels[i]);
                        if (pdev->dev.of_node)
                                irq_dispose_mapping(xordev->channels[i]->irq);
                }

        if (!IS_ERR(xordev->clk)) {
                clk_disable_unprepare(xordev->clk);
                clk_put(xordev->clk);
        }

        return ret;
}

static int mv_xor_remove(struct platform_device *pdev)
{
        struct mv_xor_device *xordev = platform_get_drvdata(pdev);
        int i;

        for (i = 0; i < MV_XOR_MAX_CHANNELS; i++) {
                if (xordev->channels[i])
                        mv_xor_channel_remove(xordev->channels[i]);
        }

        if (!IS_ERR(xordev->clk)) {
                clk_disable_unprepare(xordev->clk);
                clk_put(xordev->clk);
        }

        return 0;
}

static struct platform_driver mv_xor_driver = {
        .probe          = mv_xor_probe,
        .remove         = mv_xor_remove,
        .driver         = {
                .name           = MV_XOR_NAME,
                .of_match_table = of_match_ptr(mv_xor_dt_ids),
        },
};


static int __init mv_xor_init(void)
{
        return platform_driver_register(&mv_xor_driver);
}
module_init(mv_xor_init);

/* it's currently unsafe to unload this module */
#if 0
static void __exit mv_xor_exit(void)
{
        platform_driver_unregister(&mv_xor_driver);
        return;
}

module_exit(mv_xor_exit);
#endif

MODULE_AUTHOR("Saeed Bishara <saeed@marvell.com>");
MODULE_DESCRIPTION("DMA engine driver for Marvell's XOR engine");
MODULE_LICENSE("GPL");