/*
 * 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.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/memory.h>
#include <plat/mv_xor.h>
#include "mv_xor.h"

static void mv_xor_issue_pending(struct dma_chan *chan);

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

#define to_mv_xor_device(dev)           \
        container_of(dev, struct mv_xor_device, common)

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

static void mv_desc_init(struct mv_xor_desc_slot *desc, unsigned long flags)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;

        hw_desc->status = (1 << 31);
        hw_desc->phy_next_desc = 0;
        hw_desc->desc_command = (1 << 31);
}

static u32 mv_desc_get_dest_addr(struct mv_xor_desc_slot *desc)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;
        return hw_desc->phy_dest_addr;
}

static u32 mv_desc_get_src_addr(struct mv_xor_desc_slot *desc,
                                int src_idx)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;
        return hw_desc->phy_src_addr[src_idx];
}


static void mv_desc_set_byte_count(struct mv_xor_desc_slot *desc,
                                   u32 byte_count)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;
        hw_desc->byte_count = byte_count;
}

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_clear_next_desc(struct mv_xor_desc_slot *desc)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;
        hw_desc->phy_next_desc = 0;
}

static void mv_desc_set_block_fill_val(struct mv_xor_desc_slot *desc, u32 val)
{
        desc->value = val;
}

static void mv_desc_set_dest_addr(struct mv_xor_desc_slot *desc,
                                  dma_addr_t addr)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;
        hw_desc->phy_dest_addr = addr;
}

static int mv_chan_memset_slot_count(size_t len)
{
        return 1;
}

#define mv_chan_memcpy_slot_count(c) mv_chan_memset_slot_count(c)

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[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 __raw_readl(XOR_CURR_DESC(chan));
}

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

static void mv_chan_set_dest_pointer(struct mv_xor_chan *chan, u32 desc_addr)
{
        __raw_writel(desc_addr, XOR_DEST_POINTER(chan));
}

static void mv_chan_set_block_size(struct mv_xor_chan *chan, u32 block_size)
{
        __raw_writel(block_size, XOR_BLOCK_SIZE(chan));
}

static void mv_chan_set_value(struct mv_xor_chan *chan, u32 value)
{
        __raw_writel(value, XOR_INIT_VALUE_LOW(chan));
        __raw_writel(value, XOR_INIT_VALUE_HIGH(chan));
}

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

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

static int mv_is_err_intr(u32 intr_cause)
{
        if (intr_cause & ((1<<4)|(1<<5)|(1<<6)|(1<<7)|(1<<8)|(1<<9)))
                return 1;

        return 0;
}

static void mv_xor_device_clear_eoc_cause(struct mv_xor_chan *chan)
{
        u32 val = (1 << (1 + (chan->idx * 16)));
        dev_dbg(chan->device->common.dev, "%s, val 0x%08x\n", __func__, val);
        __raw_writel(val, XOR_INTR_CAUSE(chan));
}

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

static int mv_can_chain(struct mv_xor_desc_slot *desc)
{
        struct mv_xor_desc_slot *chain_old_tail = list_entry(
                desc->chain_node.prev, struct mv_xor_desc_slot, chain_node);

        if (chain_old_tail->type != desc->type)
                return 0;
        if (desc->type == DMA_MEMSET)
                return 0;

        return 1;
}

static void mv_set_mode(struct mv_xor_chan *chan,
                               enum dma_transaction_type type)
{
        u32 op_mode;
        u32 config = __raw_readl(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;
        case DMA_MEMSET:
                op_mode = XOR_OPERATION_MODE_MEMSET;
                break;
        default:
                dev_printk(KERN_ERR, chan->device->common.dev,
                           "error: unsupported operation %d.\n",
                           type);
                BUG();
                return;
        }

        config &= ~0x7;
        config |= op_mode;
        __raw_writel(config, XOR_CONFIG(chan));
        chan->current_type = type;
}

static void mv_chan_activate(struct mv_xor_chan *chan)
{
        u32 activation;

        dev_dbg(chan->device->common.dev, " activate chan.\n");
        activation = __raw_readl(XOR_ACTIVATION(chan));
        activation |= 0x1;
        __raw_writel(activation, XOR_ACTIVATION(chan));
}

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

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

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

static int mv_chan_xor_slot_count(size_t len, int src_cnt)
{
        return 1;
}

/**
 * mv_xor_free_slots - flags descriptor slots for reuse
 * @slot: Slot to free
 * Caller must hold &mv_chan->lock while calling this function
 */
static void mv_xor_free_slots(struct mv_xor_chan *mv_chan,
                              struct mv_xor_desc_slot *slot)
{
        dev_dbg(mv_chan->device->common.dev, "%s %d slot %p\n",
                __func__, __LINE__, slot);

        slot->slots_per_op = 0;

}

/*
 * mv_xor_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_xor_start_new_chain(struct mv_xor_chan *mv_chan,
                                   struct mv_xor_desc_slot *sw_desc)
{
        dev_dbg(mv_chan->device->common.dev, "%s %d: sw_desc %p\n",
                __func__, __LINE__, sw_desc);
        if (sw_desc->type != mv_chan->current_type)
                mv_set_mode(mv_chan, sw_desc->type);

        if (sw_desc->type == DMA_MEMSET) {
                /* for memset requests we need to program the engine, no
                 * descriptors used.
                 */
                struct mv_xor_desc *hw_desc = sw_desc->hw_desc;
                mv_chan_set_dest_pointer(mv_chan, hw_desc->phy_dest_addr);
                mv_chan_set_block_size(mv_chan, sw_desc->unmap_len);
                mv_chan_set_value(mv_chan, sw_desc->value);
        } else {
                /* set the hardware chain */
                mv_chan_set_next_descriptor(mv_chan, sw_desc->async_tx.phys);
        }
        mv_chan->pending += sw_desc->slot_cnt;
        mv_xor_issue_pending(&mv_chan->common);
}

static dma_cookie_t
mv_xor_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);

                /* unmap dma addresses
                 * (unmap_single vs unmap_page?)
                 */
                if (desc->group_head && desc->unmap_len) {
                        struct mv_xor_desc_slot *unmap = desc->group_head;
                        struct device *dev =
                                &mv_chan->device->pdev->dev;
                        u32 len = unmap->unmap_len;
                        enum dma_ctrl_flags flags = desc->async_tx.flags;
                        u32 src_cnt;
                        dma_addr_t addr;
                        dma_addr_t dest;

                        src_cnt = unmap->unmap_src_cnt;
                        dest = mv_desc_get_dest_addr(unmap);
                        if (!(flags & DMA_COMPL_SKIP_DEST_UNMAP)) {
                                enum dma_data_direction dir;

                                if (src_cnt > 1) /* is xor ? */
                                        dir = DMA_BIDIRECTIONAL;
                                else
                                        dir = DMA_FROM_DEVICE;
                                dma_unmap_page(dev, dest, len, dir);
                        }

                        if (!(flags & DMA_COMPL_SKIP_SRC_UNMAP)) {
                                while (src_cnt--) {
                                        addr = mv_desc_get_src_addr(unmap,
                                                                    src_cnt);
                                        if (addr == dest)
                                                continue;
                                        dma_unmap_page(dev, addr, len,
                                                       DMA_TO_DEVICE);
                                }
                        }
                        desc->group_head = NULL;
                }
        }

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

        return cookie;
}

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

        dev_dbg(mv_chan->device->common.dev, "%s %d\n", __func__, __LINE__);
        list_for_each_entry_safe(iter, _iter, &mv_chan->completed_slots,
                                 completed_node) {

                if (async_tx_test_ack(&iter->async_tx)) {
                        list_del(&iter->completed_node);
                        mv_xor_free_slots(mv_chan, iter);
                }
        }
        return 0;
}

static int
mv_xor_clean_slot(struct mv_xor_desc_slot *desc,
        struct mv_xor_chan *mv_chan)
{
        dev_dbg(mv_chan->device->common.dev, "%s %d: desc %p flags %d\n",
                __func__, __LINE__, desc, desc->async_tx.flags);
        list_del(&desc->chain_node);
        /* 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_add_tail(&desc->completed_node, &mv_chan->completed_slots);
                return 0;
        }

        mv_xor_free_slots(mv_chan, desc);
        return 0;
}

static void __mv_xor_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 seen_current = 0;

        dev_dbg(mv_chan->device->common.dev, "%s %d\n", __func__, __LINE__);
        dev_dbg(mv_chan->device->common.dev, "current_desc %x\n", current_desc);
        mv_xor_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,
                                        chain_node) {
                prefetch(_iter);
                prefetch(&_iter->async_tx);

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

                /* stop the search if we reach the current descriptor and the
                 * channel is busy
                 */
                if (iter->async_tx.phys == current_desc) {
                        seen_current = 1;
                        if (busy)
                                break;
                }

                cookie = mv_xor_run_tx_complete_actions(iter, mv_chan, cookie);

                if (mv_xor_clean_slot(iter, mv_chan))
                        break;
        }

        if ((busy == 0) && !list_empty(&mv_chan->chain)) {
                struct mv_xor_desc_slot *chain_head;
                chain_head = list_entry(mv_chan->chain.next,
                                        struct mv_xor_desc_slot,
                                        chain_node);

                mv_xor_start_new_chain(mv_chan, chain_head);
        }

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

static void
mv_xor_slot_cleanup(struct mv_xor_chan *mv_chan)
{
        spin_lock_bh(&mv_chan->lock);
        __mv_xor_slot_cleanup(mv_chan);
        spin_unlock_bh(&mv_chan->lock);
}

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

static struct mv_xor_desc_slot *
mv_xor_alloc_slots(struct mv_xor_chan *mv_chan, int num_slots,
                    int slots_per_op)
{
        struct mv_xor_desc_slot *iter, *_iter, *alloc_start = NULL;
        LIST_HEAD(chain);
        int slots_found, retry = 0;

        /* start search from the last allocated descrtiptor
         * if a contiguous allocation can not be found start searching
         * from the beginning of the list
         */
retry:
        slots_found = 0;
        if (retry == 0)
                iter = mv_chan->last_used;
        else
                iter = list_entry(&mv_chan->all_slots,
                        struct mv_xor_desc_slot,
                        slot_node);

        list_for_each_entry_safe_continue(
                iter, _iter, &mv_chan->all_slots, slot_node) {
                prefetch(_iter);
                prefetch(&_iter->async_tx);
                if (iter->slots_per_op) {
                        /* give up after finding the first busy slot
                         * on the second pass through the list
                         */
                        if (retry)
                                break;

                        slots_found = 0;
                        continue;
                }

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

                if (slots_found == num_slots) {
                        struct mv_xor_desc_slot *alloc_tail = NULL;
                        struct mv_xor_desc_slot *last_used = NULL;
                        iter = alloc_start;
                        while (num_slots) {
                                int i;

                                /* pre-ack all but the last descriptor */
                                async_tx_ack(&iter->async_tx);

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

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

        return NULL;
}

static dma_cookie_t
mv_desc_assign_cookie(struct mv_xor_chan *mv_chan,
                      struct mv_xor_desc_slot *desc)
{
        dma_cookie_t cookie = mv_chan->common.cookie;

        if (++cookie < 0)
                cookie = 1;
        mv_chan->common.cookie = desc->async_tx.cookie = cookie;
        return cookie;
}

/************************ 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 *grp_start, *old_chain_tail;
        dma_cookie_t cookie;
        int new_hw_chain = 1;

        dev_dbg(mv_chan->device->common.dev,
                "%s sw_desc %p: async_tx %p\n",
                __func__, sw_desc, &sw_desc->async_tx);

        grp_start = sw_desc->group_head;

        spin_lock_bh(&mv_chan->lock);
        cookie = mv_desc_assign_cookie(mv_chan, sw_desc);

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

                old_chain_tail = list_entry(mv_chan->chain.prev,
                                            struct mv_xor_desc_slot,
                                            chain_node);
                list_splice_init(&grp_start->tx_list,
                                 &old_chain_tail->chain_node);

                if (!mv_can_chain(grp_start))
                        goto submit_done;

                dev_dbg(mv_chan->device->common.dev, "Append to last desc %x\n",
                        old_chain_tail->async_tx.phys);

                /* fix up the hardware chain */
                mv_desc_set_next_desc(old_chain_tail, grp_start->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_xor_start_new_chain(mv_chan, grp_start);

submit_done:
        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)
{
        char *hw_desc;
        int idx;
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        struct mv_xor_desc_slot *slot = NULL;
        struct mv_xor_platform_data *plat_data =
                mv_chan->device->pdev->dev.platform_data;
        int num_descs_in_pool = plat_data->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) {
                        printk(KERN_INFO "MV XOR Channel only initialized"
                                " %d descriptor slots", idx);
                        break;
                }
                hw_desc = (char *) mv_chan->device->dma_desc_pool_virt;
                slot->hw_desc = (void *) &hw_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->chain_node);
                INIT_LIST_HEAD(&slot->slot_node);
                INIT_LIST_HEAD(&slot->tx_list);
                hw_desc = (char *) mv_chan->device->dma_desc_pool;
                slot->async_tx.phys =
                        (dma_addr_t) &hw_desc[idx * MV_XOR_SLOT_SIZE];
                slot->idx = idx++;

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

        if (mv_chan->slots_allocated && !mv_chan->last_used)
                mv_chan->last_used = list_entry(mv_chan->all_slots.next,
                                        struct mv_xor_desc_slot,
                                        slot_node);

        dev_dbg(mv_chan->device->common.dev,
                "allocated %d descriptor slots last_used: %p\n",
                mv_chan->slots_allocated, mv_chan->last_used);

        return mv_chan->slots_allocated ? : -ENOMEM;
}

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)
{
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        struct mv_xor_desc_slot *sw_desc, *grp_start;
        int slot_cnt;

        dev_dbg(mv_chan->device->common.dev,
                "%s dest: %x src %x len: %u flags: %ld\n",
                __func__, dest, src, len, flags);
        if (unlikely(len < MV_XOR_MIN_BYTE_COUNT))
                return NULL;

        BUG_ON(unlikely(len > MV_XOR_MAX_BYTE_COUNT));

        spin_lock_bh(&mv_chan->lock);
        slot_cnt = mv_chan_memcpy_slot_count(len);
        sw_desc = mv_xor_alloc_slots(mv_chan, slot_cnt, 1);
        if (sw_desc) {
                sw_desc->type = DMA_MEMCPY;
                sw_desc->async_tx.flags = flags;
                grp_start = sw_desc->group_head;
                mv_desc_init(grp_start, flags);
                mv_desc_set_byte_count(grp_start, len);
                mv_desc_set_dest_addr(sw_desc->group_head, dest);
                mv_desc_set_src_addr(grp_start, 0, src);
                sw_desc->unmap_src_cnt = 1;
                sw_desc->unmap_len = len;
        }
        spin_unlock_bh(&mv_chan->lock);

        dev_dbg(mv_chan->device->common.dev,
                "%s sw_desc %p async_tx %p\n",
                __func__, sw_desc, sw_desc ? &sw_desc->async_tx : 0);

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

static struct dma_async_tx_descriptor *
mv_xor_prep_dma_memset(struct dma_chan *chan, dma_addr_t dest, int value,
                       size_t len, unsigned long flags)
{
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        struct mv_xor_desc_slot *sw_desc, *grp_start;
        int slot_cnt;

        dev_dbg(mv_chan->device->common.dev,
                "%s dest: %x len: %u flags: %ld\n",
                __func__, dest, len, flags);
        if (unlikely(len < MV_XOR_MIN_BYTE_COUNT))
                return NULL;

        BUG_ON(unlikely(len > MV_XOR_MAX_BYTE_COUNT));

        spin_lock_bh(&mv_chan->lock);
        slot_cnt = mv_chan_memset_slot_count(len);
        sw_desc = mv_xor_alloc_slots(mv_chan, slot_cnt, 1);
        if (sw_desc) {
                sw_desc->type = DMA_MEMSET;
                sw_desc->async_tx.flags = flags;
                grp_start = sw_desc->group_head;
                mv_desc_init(grp_start, flags);
                mv_desc_set_byte_count(grp_start, len);
                mv_desc_set_dest_addr(sw_desc->group_head, dest);
                mv_desc_set_block_fill_val(grp_start, value);
                sw_desc->unmap_src_cnt = 1;
                sw_desc->unmap_len = len;
        }
        spin_unlock_bh(&mv_chan->lock);
        dev_dbg(mv_chan->device->common.dev,
                "%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_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, *grp_start;
        int slot_cnt;

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

        BUG_ON(unlikely(len > MV_XOR_MAX_BYTE_COUNT));

        dev_dbg(mv_chan->device->common.dev,
                "%s src_cnt: %d len: dest %x %u flags: %ld\n",
                __func__, src_cnt, len, dest, flags);

        spin_lock_bh(&mv_chan->lock);
        slot_cnt = mv_chan_xor_slot_count(len, src_cnt);
        sw_desc = mv_xor_alloc_slots(mv_chan, slot_cnt, 1);
        if (sw_desc) {
                sw_desc->type = DMA_XOR;
                sw_desc->async_tx.flags = flags;
                grp_start = sw_desc->group_head;
                mv_desc_init(grp_start, flags);
                /* the byte count field is the same as in memcpy desc*/
                mv_desc_set_byte_count(grp_start, len);
                mv_desc_set_dest_addr(sw_desc->group_head, dest);
                sw_desc->unmap_src_cnt = src_cnt;
                sw_desc->unmap_len = len;
                while (src_cnt--)
                        mv_desc_set_src_addr(grp_start, src_cnt, src[src_cnt]);
        }
        spin_unlock_bh(&mv_chan->lock);
        dev_dbg(mv_chan->device->common.dev,
                "%s sw_desc %p async_tx %p \n",
                __func__, sw_desc, &sw_desc->async_tx);
        return sw_desc ? &sw_desc->async_tx : NULL;
}

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;

        mv_xor_slot_cleanup(mv_chan);

        spin_lock_bh(&mv_chan->lock);
        list_for_each_entry_safe(iter, _iter, &mv_chan->chain,
                                        chain_node) {
                in_use_descs++;
                list_del(&iter->chain_node);
        }
        list_for_each_entry_safe(iter, _iter, &mv_chan->completed_slots,
                                 completed_node) {
                in_use_descs++;
                list_del(&iter->completed_node);
        }
        list_for_each_entry_safe_reverse(
                iter, _iter, &mv_chan->all_slots, slot_node) {
                list_del(&iter->slot_node);
                kfree(iter);
                mv_chan->slots_allocated--;
        }
        mv_chan->last_used = NULL;

        dev_dbg(mv_chan->device->common.dev, "%s slots_allocated %d\n",
                __func__, mv_chan->slots_allocated);
        spin_unlock_bh(&mv_chan->lock);

        if (in_use_descs)
                dev_err(mv_chan->device->common.dev,
                        "freeing %d in use descriptors!\n", in_use_descs);
}

/**
 * mv_xor_is_complete - poll the status of an XOR transaction
 * @chan: XOR channel handle
 * @cookie: XOR transaction identifier
 */
static enum dma_status mv_xor_is_complete(struct dma_chan *chan,
                                          dma_cookie_t cookie,
                                          dma_cookie_t *done,
                                          dma_cookie_t *used)
{
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        dma_cookie_t last_used;
        dma_cookie_t last_complete;
        enum dma_status ret;

        last_used = chan->cookie;
        last_complete = mv_chan->completed_cookie;
        mv_chan->is_complete_cookie = cookie;
        if (done)
                *done = last_complete;
        if (used)
                *used = last_used;

        ret = dma_async_is_complete(cookie, last_complete, last_used);
        if (ret == DMA_SUCCESS) {
                mv_xor_clean_completed_slots(mv_chan);
                return ret;
        }
        mv_xor_slot_cleanup(mv_chan);

        last_used = chan->cookie;
        last_complete = mv_chan->completed_cookie;

        if (done)
                *done = last_complete;
        if (used)
                *used = last_used;

        return dma_async_is_complete(cookie, last_complete, last_used);
}

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

        val = __raw_readl(XOR_CONFIG(chan));
        dev_printk(KERN_ERR, chan->device->common.dev,
                   "config       0x%08x.\n", val);

        val = __raw_readl(XOR_ACTIVATION(chan));
        dev_printk(KERN_ERR, chan->device->common.dev,
                   "activation   0x%08x.\n", val);

        val = __raw_readl(XOR_INTR_CAUSE(chan));
        dev_printk(KERN_ERR, chan->device->common.dev,
                   "intr cause   0x%08x.\n", val);

        val = __raw_readl(XOR_INTR_MASK(chan));
        dev_printk(KERN_ERR, chan->device->common.dev,
                   "intr mask    0x%08x.\n", val);

        val = __raw_readl(XOR_ERROR_CAUSE(chan));
        dev_printk(KERN_ERR, chan->device->common.dev,
                   "error cause  0x%08x.\n", val);

        val = __raw_readl(XOR_ERROR_ADDR(chan));
        dev_printk(KERN_ERR, chan->device->common.dev,
                   "error addr   0x%08x.\n", val);
}

static void mv_xor_err_interrupt_handler(struct mv_xor_chan *chan,
                                         u32 intr_cause)
{
        if (intr_cause & (1 << 4)) {
             dev_dbg(chan->device->common.dev,
                     "ignore this error\n");
             return;
        }

        dev_printk(KERN_ERR, chan->device->common.dev,
                   "error on chan %d. intr cause 0x%08x.\n",
                   chan->idx, intr_cause);

        mv_dump_xor_regs(chan);
        BUG();
}

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(chan->device->common.dev, "intr cause %x\n", intr_cause);

        if (mv_is_err_intr(intr_cause))
                mv_xor_err_interrupt_handler(chan, intr_cause);

        tasklet_schedule(&chan->irq_tasklet);

        mv_xor_device_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.
 */
#define MV_XOR_TEST_SIZE 2000

static int __devinit mv_xor_memcpy_self_test(struct mv_xor_device *device)
{
        int i;
        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;
        int err = 0;
        struct mv_xor_chan *mv_chan;

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

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

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

        /* Start copy, using first DMA channel */
        dma_chan = container_of(device->common.channels.next,
                                struct dma_chan,
                                device_node);
        if (mv_xor_alloc_chan_resources(dma_chan) < 1) {
                err = -ENODEV;
                goto out;
        }

        dest_dma = dma_map_single(dma_chan->device->dev, dest,
                                  MV_XOR_TEST_SIZE, DMA_FROM_DEVICE);

        src_dma = dma_map_single(dma_chan->device->dev, src,
                                 MV_XOR_TEST_SIZE, DMA_TO_DEVICE);

        tx = mv_xor_prep_dma_memcpy(dma_chan, dest_dma, src_dma,
                                    MV_XOR_TEST_SIZE, 0);
        cookie = mv_xor_tx_submit(tx);
        mv_xor_issue_pending(dma_chan);
        async_tx_ack(tx);
        msleep(1);

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

        mv_chan = to_mv_xor_chan(dma_chan);
        dma_sync_single_for_cpu(&mv_chan->device->pdev->dev, dest_dma,
                                MV_XOR_TEST_SIZE, DMA_FROM_DEVICE);
        if (memcmp(src, dest, MV_XOR_TEST_SIZE)) {
                dev_printk(KERN_ERR, dma_chan->device->dev,
                           "Self-test copy failed compare, disabling\n");
                err = -ENODEV;
                goto free_resources;
        }

free_resources:
        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 __devinit
mv_xor_xor_self_test(struct mv_xor_device *device)
{
        int i, src_idx;
        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 dma_chan *dma_chan;
        dma_cookie_t cookie;
        u8 cmp_byte = 0;
        u32 cmp_word;
        int err = 0;
        struct mv_xor_chan *mv_chan;

        for (src_idx = 0; src_idx < MV_XOR_NUM_SRC_TEST; 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 < MV_XOR_NUM_SRC_TEST; 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 < MV_XOR_NUM_SRC_TEST; 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 = container_of(device->common.channels.next,
                                struct dma_chan,
                                device_node);
        if (mv_xor_alloc_chan_resources(dma_chan) < 1) {
                err = -ENODEV;
                goto out;
        }

        /* test xor */
        dest_dma = dma_map_page(dma_chan->device->dev, dest, 0, PAGE_SIZE,
                                DMA_FROM_DEVICE);

        for (i = 0; i < MV_XOR_NUM_SRC_TEST; i++)
                dma_srcs[i] = dma_map_page(dma_chan->device->dev, xor_srcs[i],
                                           0, PAGE_SIZE, DMA_TO_DEVICE);

        tx = mv_xor_prep_dma_xor(dma_chan, dest_dma, dma_srcs,
                                 MV_XOR_NUM_SRC_TEST, PAGE_SIZE, 0);

        cookie = mv_xor_tx_submit(tx);
        mv_xor_issue_pending(dma_chan);
        async_tx_ack(tx);
        msleep(8);

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

        mv_chan = to_mv_xor_chan(dma_chan);
        dma_sync_single_for_cpu(&mv_chan->device->pdev->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_printk(KERN_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:
        mv_xor_free_chan_resources(dma_chan);
out:
        src_idx = MV_XOR_NUM_SRC_TEST;
        while (src_idx--)
                __free_page(xor_srcs[src_idx]);
        __free_page(dest);
        return err;
}

static int __devexit mv_xor_remove(struct platform_device *dev)
{
        struct mv_xor_device *device = platform_get_drvdata(dev);
        struct dma_chan *chan, *_chan;
        struct mv_xor_chan *mv_chan;
        struct mv_xor_platform_data *plat_data = dev->dev.platform_data;

        dma_async_device_unregister(&device->common);

        dma_free_coherent(&dev->dev, plat_data->pool_size,
                        device->dma_desc_pool_virt, device->dma_desc_pool);

        list_for_each_entry_safe(chan, _chan, &device->common.channels,
                                device_node) {
                mv_chan = to_mv_xor_chan(chan);
                list_del(&chan->device_node);
        }

        return 0;
}

static int __devinit mv_xor_probe(struct platform_device *pdev)
{
        int ret = 0;
        int irq;
        struct mv_xor_device *adev;
        struct mv_xor_chan *mv_chan;
        struct dma_device *dma_dev;
        struct mv_xor_platform_data *plat_data = pdev->dev.platform_data;


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

        dma_dev = &adev->common;

        /* allocate coherent memory for hardware descriptors
         * note: writecombine gives slightly better performance, but
         * requires that we explicitly flush the writes
         */
        adev->dma_desc_pool_virt = dma_alloc_writecombine(&pdev->dev,
                                                          plat_data->pool_size,
                                                          &adev->dma_desc_pool,
                                                          GFP_KERNEL);
        if (!adev->dma_desc_pool_virt)
                return -ENOMEM;

        adev->id = plat_data->hw_id;

        /* discover transaction capabilites from the platform data */
        dma_dev->cap_mask = plat_data->cap_mask;
        adev->pdev = pdev;
        platform_set_drvdata(pdev, adev);

        adev->shared = platform_get_drvdata(plat_data->shared);

        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_is_tx_complete = mv_xor_is_complete;
        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_MEMCPY, dma_dev->cap_mask))
                dma_dev->device_prep_dma_memcpy = mv_xor_prep_dma_memcpy;
        if (dma_has_cap(DMA_MEMSET, dma_dev->cap_mask))
                dma_dev->device_prep_dma_memset = mv_xor_prep_dma_memset;
        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 = devm_kzalloc(&pdev->dev, sizeof(*mv_chan), GFP_KERNEL);
        if (!mv_chan) {
                ret = -ENOMEM;
                goto err_free_dma;
        }
        mv_chan->device = adev;
        mv_chan->idx = plat_data->hw_id;
        mv_chan->mmr_base = adev->shared->xor_base;

        if (!mv_chan->mmr_base) {
                ret = -ENOMEM;
                goto err_free_dma;
        }
        tasklet_init(&mv_chan->irq_tasklet, mv_xor_tasklet, (unsigned long)
                     mv_chan);

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

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                ret = irq;
                goto err_free_dma;
        }
        ret = devm_request_irq(&pdev->dev, irq,
                               mv_xor_interrupt_handler,
                               0, dev_name(&pdev->dev), mv_chan);
        if (ret)
                goto err_free_dma;

        mv_chan_unmask_interrupts(mv_chan);

        mv_set_mode(mv_chan, DMA_MEMCPY);

        spin_lock_init(&mv_chan->lock);
        INIT_LIST_HEAD(&mv_chan->chain);
        INIT_LIST_HEAD(&mv_chan->completed_slots);
        INIT_LIST_HEAD(&mv_chan->all_slots);
        mv_chan->common.device = dma_dev;

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

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

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

        dev_printk(KERN_INFO, &pdev->dev, "Marvell XOR: "
          "( %s%s%s%s)\n",
          dma_has_cap(DMA_XOR, dma_dev->cap_mask) ? "xor " : "",
          dma_has_cap(DMA_MEMSET, dma_dev->cap_mask)  ? "fill " : "",
          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);
        goto out;

 err_free_dma:
        dma_free_coherent(&adev->pdev->dev, plat_data->pool_size,
                        adev->dma_desc_pool_virt, adev->dma_desc_pool);
 out:
        return ret;
}

static void
mv_xor_conf_mbus_windows(struct mv_xor_shared_private *msp,
                         struct mbus_dram_target_info *dram)
{
        void __iomem *base = msp->xor_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++) {
                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));
}

static struct platform_driver mv_xor_driver = {
        .probe          = mv_xor_probe,
        .remove         = __devexit_p(mv_xor_remove),
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = MV_XOR_NAME,
        },
};

static int mv_xor_shared_probe(struct platform_device *pdev)
{
        struct mv_xor_platform_shared_data *msd = pdev->dev.platform_data;
        struct mv_xor_shared_private *msp;
        struct resource *res;

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

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

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

        msp->xor_base = devm_ioremap(&pdev->dev, res->start,
                                     res->end - res->start + 1);
        if (!msp->xor_base)
                return -EBUSY;

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

        msp->xor_high_base = devm_ioremap(&pdev->dev, res->start,
                                          res->end - res->start + 1);
        if (!msp->xor_high_base)
                return -EBUSY;

        platform_set_drvdata(pdev, msp);

        /*
         * (Re-)program MBUS remapping windows if we are asked to.
         */
        if (msd != NULL && msd->dram != NULL)
                mv_xor_conf_mbus_windows(msp, msd->dram);

        return 0;
}

static int mv_xor_shared_remove(struct platform_device *pdev)
{
        return 0;
}

static struct platform_driver mv_xor_shared_driver = {
        .probe          = mv_xor_shared_probe,
        .remove         = mv_xor_shared_remove,
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = MV_XOR_SHARED_NAME,
        },
};


static int __init mv_xor_init(void)
{
        int rc;

        rc = platform_driver_register(&mv_xor_shared_driver);
        if (!rc) {
                rc = platform_driver_register(&mv_xor_driver);
                if (rc)
                        platform_driver_unregister(&mv_xor_shared_driver);
        }
        return rc;
}
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);
        platform_driver_unregister(&mv_xor_shared_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");