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    SubjectRe: [PATCH/RFC] DMA engine driver for Marvell XOR engine
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    Date

    On Mon, 2008-06-23 at 09:46 -0700, Nicolas Pitre wrote:
    > Here is a driver for the DMA/XOR engine found on many ARM SoCs from
    > Marvell, such as Orion and newly supported Kirkwood. Could interested
    > people (notably Maciej Sosnowski and Dan Williams who are listed as
    > maintainers for the DMA generic offload subsystem) review this patch,
    > and ultimately provide their ACK, so we could push this driver along
    > with additional ARM patches that depend on this one through the ARM git
    > tree.
    >
    > Thanks

    Sticking closely to the construction of iop-adma made this that much
    easier to read, thanks. See below for an 'inline' cleanup suggestion, a
    few questions, and a checkpatch escape, but other than that:

    Acked-by: Dan Williams <dan.j.williams@intel.com>
    >
    > -----
    > From: Saeed Bishara <saeed@marvell.com>
    >
    > The Marvell XOR engine found in Marvell's SoCs and system controllers
    > provides xor and DMA operation, iSCSI CRC32C calculation, memory initialization,
    > and memory ECC errors cleanup operation support.
    >
    > This driver implements the DMA engine API and support the following capabilities:
    > memcpy
    > xor
    > memset
    >
    > The XOR engine can be used by DMA engine clients implemented in the
    > kernel, one of those clients is the RAID module. in that case, I
    > observed 20% improvement in the raid5 writes throughput, and 40%
    > decrease in the CPU utilization when doing array construction, those
    > results performed on 5182 running at 500Mhz.
    >
    > when enabling the NET DMA client, the performance decreased, so
    > meanwhile it is recommended to keep this client off.

    Yes, I see this as well on iop platforms. The problem is that the cache
    flushes in get_user_pages are too expensive, leading to out of tree
    hacks like:

    http://git.kernel.org/?p=linux/kernel/git/djbw/xscaleiop.git;a=commitdiff;h=729ea28e581ca25197f3e92b263b0659d4bdc341

    ...this helps iop3xx but not iop13xx to a noticeable degree.

    > Signed-off-by: Saeed Bishara <saeed@marvell.com>
    > ---
    > drivers/dma/Kconfig | 11 +-
    > drivers/dma/Makefile | 1 +
    > drivers/dma/mv_xor.c | 1446 +++++++++++++++++++++++++++++++++++
    > drivers/dma/mv_xor.h | 187 +++++
    > include/asm-arm/plat-orion/mv_xor.h | 24 +
    > 5 files changed, 1668 insertions(+), 1 deletions(-)
    > create mode 100644 drivers/dma/mv_xor.c
    > create mode 100644 drivers/dma/mv_xor.h
    > create mode 100644 include/asm-arm/plat-orion/mv_xor.h
    >
    > diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
    > index 6239c3d..8665e39 100644
    > --- a/drivers/dma/Kconfig
    > +++ b/drivers/dma/Kconfig
    [..]


    > diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
    > index c8036d9..ee272fd 100644
    > --- a/drivers/dma/Makefile
    > +++ b/drivers/dma/Makefile
    [..]

    > diff --git a/drivers/dma/mv_xor.c b/drivers/dma/mv_xor.c
    > new file mode 100644
    > index 0000000..bc708b7
    > --- /dev/null
    > +++ b/drivers/dma/mv_xor.c
    > @@ -0,0 +1,1446 @@
    > +/*
    > + * offload engine driver for the XOR engines of the Marvell Feroceon processors
    > + * Copyright ?? 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/async_tx.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 <asm/plat-orion/mv_xor.h>
    > +#include "mv_xor.h"
    > +
    > +static void mv_xor_check_threshold(struct mv_xor_chan *mv_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 tx_to_mv_xor_slot(tx) \
    > + container_of(tx, struct mv_xor_desc_slot, async_tx)
    > +
    > +static inline void

    I can already hear Adrian writing up a 'remove inlines from .c files'
    patch. Is gcc's automatic inlining insufficient for all these routines?
    How about limiting it to just the routines are called from
    device_prep_dma.{xor,memcpy,memset}?

    > +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;
    > + if (flags & DMA_PREP_INTERRUPT)
    > + hw_desc->desc_command = (1 << 31);
    > + else
    > + hw_desc->desc_command = 0;
    > +
    > + hw_desc->desc_command = (1 << 31);
    > +}
    > +
    > +static inline u32 mv_desc_get_dest_addr(struct mv_xor_desc_slot *desc,
    > + struct mv_xor_chan *chan)
    > +{
    > + struct mv_xor_desc *hw_desc = desc->hw_desc;
    > + return hw_desc->phy_dest_addr;
    > +}
    > +
    > +static inline u32 mv_desc_get_src_addr(struct mv_xor_desc_slot *desc,
    > + struct mv_xor_chan *chan,
    > + int src_idx)
    > +{
    > + struct mv_xor_desc *hw_desc = desc->hw_desc;
    > + return hw_desc->phy_src_addr[src_idx];
    > +}
    > +
    > +
    > +static inline void mv_desc_set_byte_count(struct mv_xor_desc_slot *desc,
    > + struct mv_xor_chan *chan,
    > + u32 byte_count)
    > +{
    > + struct mv_xor_desc *hw_desc = desc->hw_desc;
    > + hw_desc->byte_count = byte_count;
    > +}
    > +
    > +static inline 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 inline u32 mv_desc_get_next_desc(struct mv_xor_desc_slot *desc)
    > +{
    > + struct mv_xor_desc *hw_desc = desc->hw_desc;
    > + return hw_desc->phy_next_desc;
    > +}
    > +
    > +static inline 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 inline void mv_desc_set_block_fill_val(struct mv_xor_desc_slot *desc,
    > + u32 val)
    > +{
    > + desc->value = val;
    > +}
    > +
    > +static inline void mv_desc_set_dest_addr(struct mv_xor_desc_slot *desc,
    > + struct mv_xor_chan *chan,
    > + dma_addr_t addr)
    > +{
    > + struct mv_xor_desc *hw_desc = desc->hw_desc;
    > + hw_desc->phy_dest_addr = addr;
    > +}
    > +
    > +static inline 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 inline 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 inline u32 mv_chan_get_current_desc(struct mv_xor_chan *chan)
    > +{
    > + return __raw_readl(XOR_CURR_DESC(chan));
    > +}
    > +
    > +static inline 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 inline void mv_chan_set_dest_pointer(struct mv_xor_chan *chan,
    > + u32 desc_addr)
    > +{
    > + __raw_writel(desc_addr, XOR_DEST_POINTER(chan));
    > +}
    > +
    > +static inline void mv_chan_set_block_size(struct mv_xor_chan *chan,
    > + u32 block_size)
    > +{
    > + __raw_writel(block_size, XOR_BLOCK_SIZE(chan));
    > +}
    > +
    > +static inline 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 inline 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 inline 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 inline 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 inline 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 inline 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 inline int mv_can_chain(struct mv_xor_chan *chan,
    > + 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 inline 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 inline 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 inline void mv_chan_disable(struct mv_xor_chan *chan)
    > +{
    > + u32 activation;
    > +
    > + activation = __raw_readl(XOR_ACTIVATION(chan));
    > + activation |= (1 << 1);
    > + __raw_writel(activation, XOR_ACTIVATION(chan));
    > +}
    > +
    > +static inline void mv_chan_pause(struct mv_xor_chan *chan)
    > +{
    > + u32 activation;
    > + __raw_writel(1 << 2, XOR_ACTIVATION(chan));
    > + activation = __raw_readl(XOR_ACTIVATION(chan));
    > +}
    > +
    > +static inline void mv_chan_restart(struct mv_xor_chan *chan)
    > +{
    > + __raw_writel(1 << 3, XOR_ACTIVATION(chan));
    > +}
    > +
    > +static inline int mv_desc_get_zero_result(struct mv_xor_desc_slot *desc)
    > +{
    > + BUG();
    > + return 0;
    > +}
    > +
    > +static inline void mv_chan_idle(int busy, struct mv_xor_chan *chan)
    > +{
    > + do { } while (0);
    > +}
    > +
    > +static inline 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 inline int
    > +mv_chan_get_desc_align(struct mv_xor_chan *chan, int num_slots)
    > +{
    > + return 1;
    > +}
    > +
    > +static inline 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_check_threshold(mv_chan);
    > +}
    > +
    > +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;
    > + u32 src_cnt = unmap->unmap_src_cnt;
    > + dma_addr_t addr = mv_desc_get_dest_addr(unmap, mv_chan);
    > +
    > + dma_unmap_page(dev, addr, len, DMA_FROM_DEVICE);
    > + while (src_cnt--) {
    > + addr = mv_desc_get_src_addr(unmap, mv_chan,
    > + src_cnt);
    > + dma_unmap_page(dev, addr, len, DMA_TO_DEVICE);
    > + }
    > + desc->group_head = NULL;
    > + }
    > + }
    > +
    > + /* run dependent operations */
    > + async_tx_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);
    > + }

    This, and the fact that memset is done without a descriptor, are the
    only significant differences with the iop-adma driver.

    Just to check my understanding this driver waits for a 'idle hardware +
    pending descriptors' condition as an indication of when to start a new
    chain? Out of curiosity might there be a case, like an error condition,
    where the channel is idle but should not start a new chain? Any ill
    effects from not detecting that case?

    > +
    > + 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->async_tx.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;
    > +}
    > +
    > +static void mv_xor_check_threshold(struct mv_xor_chan *mv_chan)
    > +{
    > + if (mv_chan->pending >= MV_XOR_THRESHOLD) {
    > + mv_chan->pending = 0;
    > + mv_chan_activate(mv_chan);
    > + }
    > +}
    > +
    > +/************************ 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 = tx_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->async_tx.tx_list, &mv_chan->chain);
    > + else{

    Checkpatch missed the needed space after that '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->async_tx.tx_list,
    > + &old_chain_tail->chain_node);
    > +
    > + if (!mv_can_chain(mv_chan, 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 */
    > + do {
    > + idx = mv_chan->slots_allocated;
    > + if (idx == num_descs_in_pool)
    > + break;
    > +
    > + 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->async_tx.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++;
    > + list_add_tail(&slot->slot_node, &mv_chan->all_slots);
    > + spin_unlock_bh(&mv_chan->lock);
    > + } while (mv_chan->slots_allocated < num_descs_in_pool);
    > +
    > + if (idx && !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 (idx > 0) ? idx : -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, mv_chan, len);
    > + mv_desc_set_dest_addr(sw_desc->group_head, mv_chan, 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, mv_chan, len);
    > + mv_desc_set_dest_addr(sw_desc->group_head, mv_chan, 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, mv_chan, len);
    > + mv_desc_set_dest_addr(sw_desc->group_head, mv_chan, 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_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);
    > + INIT_RCU_HEAD(&mv_chan->common.rcu);
    > + 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) ||
    > + dma_has_cap(DMA_MEMSET, 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;
    > + }
    > + 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) ||
    > + dma_has_cap(DMA_MEMSET, 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 = 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_base_high = devm_ioremap(&pdev->dev, res->start,
    > + res->end - res->start + 1);
    > + if (!msp->xor_base_high)
    > + 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;
    > +}

    Curious, can you elaborate on why the code performs two registrations?

    [..]

    Thanks,
    Dan



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