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[mirror_ubuntu-artful-kernel.git] / drivers / dma / mv_xor.c

/*
 * 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/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/cpumask.h>
#include <linux/platform_data/dma-mv_xor.h>

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

enum mv_xor_type {
        XOR_ORION,
        XOR_ARMADA_38X,
        XOR_ARMADA_37XX,
};

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;
}

/* Populate the descriptor */
static void mv_xor_config_sg_ll_desc(struct mv_xor_desc_slot *desc,
                                     dma_addr_t dma_src, dma_addr_t dma_dst,
                                     u32 len, struct mv_xor_desc_slot *prev)
{
        struct mv_xor_desc *hw_desc = desc->hw_desc;

        hw_desc->status = XOR_DESC_DMA_OWNED;
        hw_desc->phy_next_desc = 0;
        /* Configure for XOR with only one src address -> MEMCPY */
        hw_desc->desc_command = XOR_DESC_OPERATION_XOR | (0x1 << 0);
        hw_desc->phy_dest_addr = dma_dst;
        hw_desc->phy_src_addr[0] = dma_src;
        hw_desc->byte_count = len;

        if (prev) {
                struct mv_xor_desc *hw_prev = prev->hw_desc;

                hw_prev->phy_next_desc = desc->async_tx.phys;
        }
}

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

        /* Enable end-of-descriptor interrupt */
        hw_desc->desc_command |= XOR_DESC_EOD_INT_EN;
}

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,
                             u32 op_mode)
{
        u32 config = readl_relaxed(XOR_CONFIG(chan));

        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;

                dma_descriptor_unmap(&desc->async_tx);
                /* call the callback (must not sleep or submit new
                 * operations to this channel)
                 */
                dmaengine_desc_get_callback_invoke(&desc->async_tx, NULL);
        }

        /* 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);
                        if (!list_empty(&iter->sg_tx_list)) {
                                list_splice_tail_init(&iter->sg_tx_list,
                                                        &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);
                if (!list_empty(&desc->sg_tx_list)) {
                        list_splice_tail_init(&desc->sg_tx_list,
                                              &mv_chan->completed_slots);
                }
        } else {
                list_move_tail(&desc->node, &mv_chan->free_slots);
                if (!list_empty(&desc->sg_tx_list)) {
                        list_splice_tail_init(&desc->sg_tx_list,
                                              &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);
                INIT_LIST_HEAD(&slot->sg_tx_list);
                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;
}

/*
 * Check if source or destination is an PCIe/IO address (non-SDRAM) and add
 * a new MBus window if necessary. Use a cache for these check so that
 * the MMIO mapped registers don't have to be accessed for this check
 * to speed up this process.
 */
static int mv_xor_add_io_win(struct mv_xor_chan *mv_chan, u32 addr)
{
        struct mv_xor_device *xordev = mv_chan->xordev;
        void __iomem *base = mv_chan->mmr_high_base;
        u32 win_enable;
        u32 size;
        u8 target, attr;
        int ret;
        int i;

        /* Nothing needs to get done for the Armada 3700 */
        if (xordev->xor_type == XOR_ARMADA_37XX)
                return 0;

        /*
         * Loop over the cached windows to check, if the requested area
         * is already mapped. If this the case, nothing needs to be done
         * and we can return.
         */
        for (i = 0; i < WINDOW_COUNT; i++) {
                if (addr >= xordev->win_start[i] &&
                    addr <= xordev->win_end[i]) {
                        /* Window is already mapped */
                        return 0;
                }
        }

        /*
         * The window is not mapped, so we need to create the new mapping
         */

        /* If no IO window is found that addr has to be located in SDRAM */
        ret = mvebu_mbus_get_io_win_info(addr, &size, &target, &attr);
        if (ret < 0)
                return 0;

        /*
         * Mask the base addr 'addr' according to 'size' read back from the
         * MBus window. Otherwise we might end up with an address located
         * somewhere in the middle of this area here.
         */
        size -= 1;
        addr &= ~size;

        /*
         * Reading one of both enabled register is enough, as they are always
         * programmed to the identical values
         */
        win_enable = readl(base + WINDOW_BAR_ENABLE(0));

        /* Set 'i' to the first free window to write the new values to */
        i = ffs(~win_enable) - 1;
        if (i >= WINDOW_COUNT)
                return -ENOMEM;

        writel((addr & 0xffff0000) | (attr << 8) | target,
               base + WINDOW_BASE(i));
        writel(size & 0xffff0000, base + WINDOW_SIZE(i));

        /* Fill the caching variables for later use */
        xordev->win_start[i] = addr;
        xordev->win_end[i] = addr + size;

        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));

        return 0;
}

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;
        int ret;

        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: %zu dest %pad flags: %ld\n",
                __func__, src_cnt, len, &dest, flags);

        /* Check if a new window needs to get added for 'dest' */
        ret = mv_xor_add_io_win(mv_chan, dest);
        if (ret)
                return NULL;

        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--) {
                        /* Check if a new window needs to get added for 'src' */
                        ret = mv_xor_add_io_win(mv_chan, src[src_cnt]);
                        if (ret)
                                return NULL;
                        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);
}

/**
 * mv_xor_prep_dma_sg - prepare descriptors for a memory sg transaction
 * @chan: DMA channel
 * @dst_sg: Destination scatter list
 * @dst_sg_len: Number of entries in destination scatter list
 * @src_sg: Source scatter list
 * @src_sg_len: Number of entries in source scatter list
 * @flags: transfer ack flags
 *
 * Return: Async transaction descriptor on success and NULL on failure
 */
static struct dma_async_tx_descriptor *
mv_xor_prep_dma_sg(struct dma_chan *chan, struct scatterlist *dst_sg,
                   unsigned int dst_sg_len, struct scatterlist *src_sg,
                   unsigned int src_sg_len, unsigned long flags)
{
        struct mv_xor_chan *mv_chan = to_mv_xor_chan(chan);
        struct mv_xor_desc_slot *new;
        struct mv_xor_desc_slot *first = NULL;
        struct mv_xor_desc_slot *prev = NULL;
        size_t len, dst_avail, src_avail;
        dma_addr_t dma_dst, dma_src;
        int desc_cnt = 0;
        int ret;

        dev_dbg(mv_chan_to_devp(mv_chan),
                "%s dst_sg_len: %d src_sg_len: %d flags: %ld\n",
                __func__, dst_sg_len, src_sg_len, flags);

        dst_avail = sg_dma_len(dst_sg);
        src_avail = sg_dma_len(src_sg);

        /* Run until we are out of scatterlist entries */
        while (true) {
                /* Allocate and populate the descriptor */
                desc_cnt++;
                new = mv_chan_alloc_slot(mv_chan);
                if (!new) {
                        dev_err(mv_chan_to_devp(mv_chan),
                                "Out of descriptors (desc_cnt=%d)!\n",
                                desc_cnt);
                        goto err;
                }

                len = min_t(size_t, src_avail, dst_avail);
                len = min_t(size_t, len, MV_XOR_MAX_BYTE_COUNT);
                if (len == 0)
                        goto fetch;

                if (len < MV_XOR_MIN_BYTE_COUNT) {
                        dev_err(mv_chan_to_devp(mv_chan),
                                "Transfer size of %zu too small!\n", len);
                        goto err;
                }

                dma_dst = sg_dma_address(dst_sg) + sg_dma_len(dst_sg) -
                        dst_avail;
                dma_src = sg_dma_address(src_sg) + sg_dma_len(src_sg) -
                        src_avail;

                /* Check if a new window needs to get added for 'dst' */
                ret = mv_xor_add_io_win(mv_chan, dma_dst);
                if (ret)
                        goto err;

                /* Check if a new window needs to get added for 'src' */
                ret = mv_xor_add_io_win(mv_chan, dma_src);
                if (ret)
                        goto err;

                /* Populate the descriptor */
                mv_xor_config_sg_ll_desc(new, dma_src, dma_dst, len, prev);
                prev = new;
                dst_avail -= len;
                src_avail -= len;

                if (!first)
                        first = new;
                else
                        list_move_tail(&new->node, &first->sg_tx_list);

fetch:
                /* Fetch the next dst scatterlist entry */
                if (dst_avail == 0) {
                        if (dst_sg_len == 0)
                                break;

                        /* Fetch the next entry: if there are no more: done */
                        dst_sg = sg_next(dst_sg);
                        if (dst_sg == NULL)
                                break;

                        dst_sg_len--;
                        dst_avail = sg_dma_len(dst_sg);
                }

                /* Fetch the next src scatterlist entry */
                if (src_avail == 0) {
                        if (src_sg_len == 0)
                                break;

                        /* Fetch the next entry: if there are no more: done */
                        src_sg = sg_next(src_sg);
                        if (src_sg == NULL)
                                break;

                        src_sg_len--;
                        src_avail = sg_dma_len(src_sg);
                }
        }

        /* Set the EOD flag in the last descriptor */
        mv_xor_desc_config_eod(new);
        first->async_tx.flags = flags;

        return &first->async_tx;

err:
        /* Cleanup: Move all descriptors back into the free list */
        spin_lock_bh(&mv_chan->lock);
        mv_desc_clean_slot(first, mv_chan);
        spin_unlock_bh(&mv_chan->lock);

        return 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;

        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),
                               offset_in_page(src), 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),
                                offset_in_page(dest), 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 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;
        if (xordev->xor_type == XOR_ORION)
                mv_chan->op_in_desc = XOR_MODE_IN_REG;
        else
                mv_chan->op_in_desc = XOR_MODE_IN_DESC;

        dma_dev = &mv_chan->dmadev;
        mv_chan->xordev = xordev;

        /*
         * 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_wc(&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_SG, dma_dev->cap_mask))
                dma_dev->device_prep_dma_sg = mv_xor_prep_dma_sg;
        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(mv_chan, XOR_OPERATION_MODE_IN_DESC);
        else
                mv_chan_set_mode(mv_chan, XOR_OPERATION_MODE_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%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_SG, dma_dev->cap_mask) ? "sg " : "",
                 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));

                /* Fill the caching variables for later use */
                xordev->win_start[i] = cs->base;
                xordev->win_end[i] = cs->base + cs->size - 1;

                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 void
mv_xor_conf_mbus_windows_a3700(struct mv_xor_device *xordev)
{
        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 Armada3700 open default 4GB Mbus window. The dram
         * related configuration are done at AXIS level.
         */
        writel(0xffff0000, base + WINDOW_SIZE(0));
        win_enable |= 1;
        win_enable |= 3 << 16;

        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));
}

/*
 * Since this XOR driver is basically used only for RAID5, we don't
 * need to care about synchronizing ->suspend with DMA activity,
 * because the DMA engine will naturally be quiet due to the block
 * devices being suspended.
 */
static int mv_xor_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct mv_xor_device *xordev = platform_get_drvdata(pdev);
        int i;

        for (i = 0; i < MV_XOR_MAX_CHANNELS; i++) {
                struct mv_xor_chan *mv_chan = xordev->channels[i];

                if (!mv_chan)
                        continue;

                mv_chan->saved_config_reg =
                        readl_relaxed(XOR_CONFIG(mv_chan));
                mv_chan->saved_int_mask_reg =
                        readl_relaxed(XOR_INTR_MASK(mv_chan));
        }

        return 0;
}

static int mv_xor_resume(struct platform_device *dev)
{
        struct mv_xor_device *xordev = platform_get_drvdata(dev);
        const struct mbus_dram_target_info *dram;
        int i;

        for (i = 0; i < MV_XOR_MAX_CHANNELS; i++) {
                struct mv_xor_chan *mv_chan = xordev->channels[i];

                if (!mv_chan)
                        continue;

                writel_relaxed(mv_chan->saved_config_reg,
                               XOR_CONFIG(mv_chan));
                writel_relaxed(mv_chan->saved_int_mask_reg,
                               XOR_INTR_MASK(mv_chan));
        }

        if (xordev->xor_type == XOR_ARMADA_37XX) {
                mv_xor_conf_mbus_windows_a3700(xordev);
                return 0;
        }

        dram = mv_mbus_dram_info();
        if (dram)
                mv_xor_conf_mbus_windows(xordev, dram);

        return 0;
}

static const struct of_device_id mv_xor_dt_ids[] = {
        { .compatible = "marvell,orion-xor", .data = (void *)XOR_ORION },
        { .compatible = "marvell,armada-380-xor", .data = (void *)XOR_ARMADA_38X },
        { .compatible = "marvell,armada-3700-xor", .data = (void *)XOR_ARMADA_37XX },
        {},
};

static unsigned int mv_xor_engine_count;

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;
        unsigned int max_engines, max_channels;
        int i, ret;

        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);


        /*
         * We need to know which type of XOR device we use before
         * setting up. In non-dt case it can only be the legacy one.
         */
        xordev->xor_type = XOR_ORION;
        if (pdev->dev.of_node) {
                const struct of_device_id *of_id =
                        of_match_device(mv_xor_dt_ids,
                                        &pdev->dev);

                xordev->xor_type = (uintptr_t)of_id->data;
        }

        /*
         * (Re-)program MBUS remapping windows if we are asked to.
         */
        if (xordev->xor_type == XOR_ARMADA_37XX) {
                mv_xor_conf_mbus_windows_a3700(xordev);
        } else {
                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);

        /*
         * We don't want to have more than one channel per CPU in
         * order for async_tx to perform well. So we limit the number
         * of engines and channels so that we take into account this
         * constraint. Note that we also want to use channels from
         * separate engines when possible.  For dual-CPU Armada 3700
         * SoC with single XOR engine allow using its both channels.
         */
        max_engines = num_present_cpus();
        if (xordev->xor_type == XOR_ARMADA_37XX)
                max_channels =  num_present_cpus();
        else
                max_channels = min_t(unsigned int,
                                     MV_XOR_MAX_CHANNELS,
                                     DIV_ROUND_UP(num_present_cpus(), 2));

        if (mv_xor_engine_count >= max_engines)
                return 0;

        if (pdev->dev.of_node) {
                struct device_node *np;
                int i = 0;

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

                        if (i >= max_channels)
                                continue;

                        dma_cap_zero(cap_mask);
                        dma_cap_set(DMA_MEMCPY, cap_mask);
                        dma_cap_set(DMA_SG, cap_mask);
                        dma_cap_set(DMA_XOR, cap_mask);
                        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);
                        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 < max_channels; i++) {
                        struct mv_xor_channel_data *cd;
                        struct mv_xor_chan *chan;
                        int irq;

                        cd = &pdata->channels[i];
                        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);
                        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 struct platform_driver mv_xor_driver = {
        .probe          = mv_xor_probe,
        .suspend        = mv_xor_suspend,
        .resume         = mv_xor_resume,
        .driver         = {
                .name           = MV_XOR_NAME,
                .of_match_table = of_match_ptr(mv_xor_dt_ids),
        },
};

builtin_platform_driver(mv_xor_driver);

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