drm/i915: Refactor panel backlight controls

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / dma / pch_dma.c

/*
 * Topcliff PCH DMA controller driver
 * Copyright (c) 2010 Intel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/pch_dma.h>

#define DRV_NAME "pch-dma"

#define DMA_CTL0_DISABLE                0x0
#define DMA_CTL0_SG                     0x1
#define DMA_CTL0_ONESHOT                0x2
#define DMA_CTL0_MODE_MASK_BITS         0x3
#define DMA_CTL0_DIR_SHIFT_BITS         2
#define DMA_CTL0_BITS_PER_CH            4

#define DMA_CTL2_START_SHIFT_BITS       8
#define DMA_CTL2_IRQ_ENABLE_MASK        ((1UL << DMA_CTL2_START_SHIFT_BITS) - 1)

#define DMA_STATUS_IDLE                 0x0
#define DMA_STATUS_DESC_READ            0x1
#define DMA_STATUS_WAIT                 0x2
#define DMA_STATUS_ACCESS               0x3
#define DMA_STATUS_BITS_PER_CH          2
#define DMA_STATUS_MASK_BITS            0x3
#define DMA_STATUS_SHIFT_BITS           16
#define DMA_STATUS_IRQ(x)               (0x1 << (x))
#define DMA_STATUS_ERR(x)               (0x1 << ((x) + 8))

#define DMA_DESC_WIDTH_SHIFT_BITS       12
#define DMA_DESC_WIDTH_1_BYTE           (0x3 << DMA_DESC_WIDTH_SHIFT_BITS)
#define DMA_DESC_WIDTH_2_BYTES          (0x2 << DMA_DESC_WIDTH_SHIFT_BITS)
#define DMA_DESC_WIDTH_4_BYTES          (0x0 << DMA_DESC_WIDTH_SHIFT_BITS)
#define DMA_DESC_MAX_COUNT_1_BYTE       0x3FF
#define DMA_DESC_MAX_COUNT_2_BYTES      0x3FF
#define DMA_DESC_MAX_COUNT_4_BYTES      0x7FF
#define DMA_DESC_END_WITHOUT_IRQ        0x0
#define DMA_DESC_END_WITH_IRQ           0x1
#define DMA_DESC_FOLLOW_WITHOUT_IRQ     0x2
#define DMA_DESC_FOLLOW_WITH_IRQ        0x3

#define MAX_CHAN_NR                     8

static unsigned int init_nr_desc_per_channel = 64;
module_param(init_nr_desc_per_channel, uint, 0644);
MODULE_PARM_DESC(init_nr_desc_per_channel,
                 "initial descriptors per channel (default: 64)");

struct pch_dma_desc_regs {
        u32     dev_addr;
        u32     mem_addr;
        u32     size;
        u32     next;
};

struct pch_dma_regs {
        u32     dma_ctl0;
        u32     dma_ctl1;
        u32     dma_ctl2;
        u32     reserved1;
        u32     dma_sts0;
        u32     dma_sts1;
        u32     reserved2;
        u32     reserved3;
        struct pch_dma_desc_regs desc[0];
};

struct pch_dma_desc {
        struct pch_dma_desc_regs regs;
        struct dma_async_tx_descriptor txd;
        struct list_head        desc_node;
        struct list_head        tx_list;
};

struct pch_dma_chan {
        struct dma_chan         chan;
        void __iomem *membase;
        enum dma_data_direction dir;
        struct tasklet_struct   tasklet;
        unsigned long           err_status;

        spinlock_t              lock;

        dma_cookie_t            completed_cookie;
        struct list_head        active_list;
        struct list_head        queue;
        struct list_head        free_list;
        unsigned int            descs_allocated;
};

#define PDC_DEV_ADDR    0x00
#define PDC_MEM_ADDR    0x04
#define PDC_SIZE        0x08
#define PDC_NEXT        0x0C

#define channel_readl(pdc, name) \
        readl((pdc)->membase + PDC_##name)
#define channel_writel(pdc, name, val) \
        writel((val), (pdc)->membase + PDC_##name)

struct pch_dma {
        struct dma_device       dma;
        void __iomem *membase;
        struct pci_pool         *pool;
        struct pch_dma_regs     regs;
        struct pch_dma_desc_regs ch_regs[MAX_CHAN_NR];
        struct pch_dma_chan     channels[0];
};

#define PCH_DMA_CTL0    0x00
#define PCH_DMA_CTL1    0x04
#define PCH_DMA_CTL2    0x08
#define PCH_DMA_STS0    0x10
#define PCH_DMA_STS1    0x14

#define dma_readl(pd, name) \
        readl((pd)->membase + PCH_DMA_##name)
#define dma_writel(pd, name, val) \
        writel((val), (pd)->membase + PCH_DMA_##name)

static inline struct pch_dma_desc *to_pd_desc(struct dma_async_tx_descriptor *txd)
{
        return container_of(txd, struct pch_dma_desc, txd);
}

static inline struct pch_dma_chan *to_pd_chan(struct dma_chan *chan)
{
        return container_of(chan, struct pch_dma_chan, chan);
}

static inline struct pch_dma *to_pd(struct dma_device *ddev)
{
        return container_of(ddev, struct pch_dma, dma);
}

static inline struct device *chan2dev(struct dma_chan *chan)
{
        return &chan->dev->device;
}

static inline struct device *chan2parent(struct dma_chan *chan)
{
        return chan->dev->device.parent;
}

static inline struct pch_dma_desc *pdc_first_active(struct pch_dma_chan *pd_chan)
{
        return list_first_entry(&pd_chan->active_list,
                                struct pch_dma_desc, desc_node);
}

static inline struct pch_dma_desc *pdc_first_queued(struct pch_dma_chan *pd_chan)
{
        return list_first_entry(&pd_chan->queue,
                                struct pch_dma_desc, desc_node);
}

static void pdc_enable_irq(struct dma_chan *chan, int enable)
{
        struct pch_dma *pd = to_pd(chan->device);
        u32 val;

        val = dma_readl(pd, CTL2);

        if (enable)
                val |= 0x1 << chan->chan_id;
        else
                val &= ~(0x1 << chan->chan_id);

        dma_writel(pd, CTL2, val);

        dev_dbg(chan2dev(chan), "pdc_enable_irq: chan %d -> %x\n",
                chan->chan_id, val);
}

static void pdc_set_dir(struct dma_chan *chan)
{
        struct pch_dma_chan *pd_chan = to_pd_chan(chan);
        struct pch_dma *pd = to_pd(chan->device);
        u32 val;

        val = dma_readl(pd, CTL0);

        if (pd_chan->dir == DMA_TO_DEVICE)
                val |= 0x1 << (DMA_CTL0_BITS_PER_CH * chan->chan_id +
                               DMA_CTL0_DIR_SHIFT_BITS);
        else
                val &= ~(0x1 << (DMA_CTL0_BITS_PER_CH * chan->chan_id +
                                 DMA_CTL0_DIR_SHIFT_BITS));

        dma_writel(pd, CTL0, val);

        dev_dbg(chan2dev(chan), "pdc_set_dir: chan %d -> %x\n",
                chan->chan_id, val);
}

static void pdc_set_mode(struct dma_chan *chan, u32 mode)
{
        struct pch_dma *pd = to_pd(chan->device);
        u32 val;

        val = dma_readl(pd, CTL0);

        val &= ~(DMA_CTL0_MODE_MASK_BITS <<
                (DMA_CTL0_BITS_PER_CH * chan->chan_id));
        val |= mode << (DMA_CTL0_BITS_PER_CH * chan->chan_id);

        dma_writel(pd, CTL0, val);

        dev_dbg(chan2dev(chan), "pdc_set_mode: chan %d -> %x\n",
                chan->chan_id, val);
}

static u32 pdc_get_status(struct pch_dma_chan *pd_chan)
{
        struct pch_dma *pd = to_pd(pd_chan->chan.device);
        u32 val;

        val = dma_readl(pd, STS0);
        return DMA_STATUS_MASK_BITS & (val >> (DMA_STATUS_SHIFT_BITS +
                        DMA_STATUS_BITS_PER_CH * pd_chan->chan.chan_id));
}

static bool pdc_is_idle(struct pch_dma_chan *pd_chan)
{
        if (pdc_get_status(pd_chan) == DMA_STATUS_IDLE)
                return true;
        else
                return false;
}

static void pdc_dostart(struct pch_dma_chan *pd_chan, struct pch_dma_desc* desc)
{
        struct pch_dma *pd = to_pd(pd_chan->chan.device);
        u32 val;

        if (!pdc_is_idle(pd_chan)) {
                dev_err(chan2dev(&pd_chan->chan),
                        "BUG: Attempt to start non-idle channel\n");
                return;
        }

        channel_writel(pd_chan, DEV_ADDR, desc->regs.dev_addr);
        channel_writel(pd_chan, MEM_ADDR, desc->regs.mem_addr);
        channel_writel(pd_chan, SIZE, desc->regs.size);
        channel_writel(pd_chan, NEXT, desc->regs.next);

        dev_dbg(chan2dev(&pd_chan->chan), "chan %d -> dev_addr: %x\n",
                pd_chan->chan.chan_id, desc->regs.dev_addr);
        dev_dbg(chan2dev(&pd_chan->chan), "chan %d -> mem_addr: %x\n",
                pd_chan->chan.chan_id, desc->regs.mem_addr);
        dev_dbg(chan2dev(&pd_chan->chan), "chan %d -> size: %x\n",
                pd_chan->chan.chan_id, desc->regs.size);
        dev_dbg(chan2dev(&pd_chan->chan), "chan %d -> next: %x\n",
                pd_chan->chan.chan_id, desc->regs.next);

        if (list_empty(&desc->tx_list))
                pdc_set_mode(&pd_chan->chan, DMA_CTL0_ONESHOT);
        else
                pdc_set_mode(&pd_chan->chan, DMA_CTL0_SG);

        val = dma_readl(pd, CTL2);
        val |= 1 << (DMA_CTL2_START_SHIFT_BITS + pd_chan->chan.chan_id);
        dma_writel(pd, CTL2, val);
}

static void pdc_chain_complete(struct pch_dma_chan *pd_chan,
                               struct pch_dma_desc *desc)
{
        struct dma_async_tx_descriptor *txd = &desc->txd;
        dma_async_tx_callback callback = txd->callback;
        void *param = txd->callback_param;

        list_splice_init(&desc->tx_list, &pd_chan->free_list);
        list_move(&desc->desc_node, &pd_chan->free_list);

        if (callback)
                callback(param);
}

static void pdc_complete_all(struct pch_dma_chan *pd_chan)
{
        struct pch_dma_desc *desc, *_d;
        LIST_HEAD(list);

        BUG_ON(!pdc_is_idle(pd_chan));

        if (!list_empty(&pd_chan->queue))
                pdc_dostart(pd_chan, pdc_first_queued(pd_chan));

        list_splice_init(&pd_chan->active_list, &list);
        list_splice_init(&pd_chan->queue, &pd_chan->active_list);

        list_for_each_entry_safe(desc, _d, &list, desc_node)
                pdc_chain_complete(pd_chan, desc);
}

static void pdc_handle_error(struct pch_dma_chan *pd_chan)
{
        struct pch_dma_desc *bad_desc;

        bad_desc = pdc_first_active(pd_chan);
        list_del(&bad_desc->desc_node);

        list_splice_init(&pd_chan->queue, pd_chan->active_list.prev);

        if (!list_empty(&pd_chan->active_list))
                pdc_dostart(pd_chan, pdc_first_active(pd_chan));

        dev_crit(chan2dev(&pd_chan->chan), "Bad descriptor submitted\n");
        dev_crit(chan2dev(&pd_chan->chan), "descriptor cookie: %d\n",
                 bad_desc->txd.cookie);

        pdc_chain_complete(pd_chan, bad_desc);
}

static void pdc_advance_work(struct pch_dma_chan *pd_chan)
{
        if (list_empty(&pd_chan->active_list) ||
                list_is_singular(&pd_chan->active_list)) {
                pdc_complete_all(pd_chan);
        } else {
                pdc_chain_complete(pd_chan, pdc_first_active(pd_chan));
                pdc_dostart(pd_chan, pdc_first_active(pd_chan));
        }
}

static dma_cookie_t pdc_assign_cookie(struct pch_dma_chan *pd_chan,
                                      struct pch_dma_desc *desc)
{
        dma_cookie_t cookie = pd_chan->chan.cookie;

        if (++cookie < 0)
                cookie = 1;

        pd_chan->chan.cookie = cookie;
        desc->txd.cookie = cookie;

        return cookie;
}

static dma_cookie_t pd_tx_submit(struct dma_async_tx_descriptor *txd)
{
        struct pch_dma_desc *desc = to_pd_desc(txd);
        struct pch_dma_chan *pd_chan = to_pd_chan(txd->chan);
        dma_cookie_t cookie;

        spin_lock_bh(&pd_chan->lock);
        cookie = pdc_assign_cookie(pd_chan, desc);

        if (list_empty(&pd_chan->active_list)) {
                list_add_tail(&desc->desc_node, &pd_chan->active_list);
                pdc_dostart(pd_chan, desc);
        } else {
                list_add_tail(&desc->desc_node, &pd_chan->queue);
        }

        spin_unlock_bh(&pd_chan->lock);
        return 0;
}

static struct pch_dma_desc *pdc_alloc_desc(struct dma_chan *chan, gfp_t flags)
{
        struct pch_dma_desc *desc = NULL;
        struct pch_dma *pd = to_pd(chan->device);
        dma_addr_t addr;

        desc = pci_pool_alloc(pd->pool, GFP_KERNEL, &addr);
        if (desc) {
                memset(desc, 0, sizeof(struct pch_dma_desc));
                INIT_LIST_HEAD(&desc->tx_list);
                dma_async_tx_descriptor_init(&desc->txd, chan);
                desc->txd.tx_submit = pd_tx_submit;
                desc->txd.flags = DMA_CTRL_ACK;
                desc->txd.phys = addr;
        }

        return desc;
}

static struct pch_dma_desc *pdc_desc_get(struct pch_dma_chan *pd_chan)
{
        struct pch_dma_desc *desc, *_d;
        struct pch_dma_desc *ret = NULL;
        int i;

        spin_lock_bh(&pd_chan->lock);
        list_for_each_entry_safe(desc, _d, &pd_chan->free_list, desc_node) {
                i++;
                if (async_tx_test_ack(&desc->txd)) {
                        list_del(&desc->desc_node);
                        ret = desc;
                        break;
                }
                dev_dbg(chan2dev(&pd_chan->chan), "desc %p not ACKed\n", desc);
        }
        spin_unlock_bh(&pd_chan->lock);
        dev_dbg(chan2dev(&pd_chan->chan), "scanned %d descriptors\n", i);

        if (!ret) {
                ret = pdc_alloc_desc(&pd_chan->chan, GFP_NOIO);
                if (ret) {
                        spin_lock_bh(&pd_chan->lock);
                        pd_chan->descs_allocated++;
                        spin_unlock_bh(&pd_chan->lock);
                } else {
                        dev_err(chan2dev(&pd_chan->chan),
                                "failed to alloc desc\n");
                }
        }

        return ret;
}

static void pdc_desc_put(struct pch_dma_chan *pd_chan,
                         struct pch_dma_desc *desc)
{
        if (desc) {
                spin_lock_bh(&pd_chan->lock);
                list_splice_init(&desc->tx_list, &pd_chan->free_list);
                list_add(&desc->desc_node, &pd_chan->free_list);
                spin_unlock_bh(&pd_chan->lock);
        }
}

static int pd_alloc_chan_resources(struct dma_chan *chan)
{
        struct pch_dma_chan *pd_chan = to_pd_chan(chan);
        struct pch_dma_desc *desc;
        LIST_HEAD(tmp_list);
        int i;

        if (!pdc_is_idle(pd_chan)) {
                dev_dbg(chan2dev(chan), "DMA channel not idle ?\n");
                return -EIO;
        }

        if (!list_empty(&pd_chan->free_list))
                return pd_chan->descs_allocated;

        for (i = 0; i < init_nr_desc_per_channel; i++) {
                desc = pdc_alloc_desc(chan, GFP_KERNEL);

                if (!desc) {
                        dev_warn(chan2dev(chan),
                                "Only allocated %d initial descriptors\n", i);
                        break;
                }

                list_add_tail(&desc->desc_node, &tmp_list);
        }

        spin_lock_bh(&pd_chan->lock);
        list_splice(&tmp_list, &pd_chan->free_list);
        pd_chan->descs_allocated = i;
        pd_chan->completed_cookie = chan->cookie = 1;
        spin_unlock_bh(&pd_chan->lock);

        pdc_enable_irq(chan, 1);
        pdc_set_dir(chan);

        return pd_chan->descs_allocated;
}

static void pd_free_chan_resources(struct dma_chan *chan)
{
        struct pch_dma_chan *pd_chan = to_pd_chan(chan);
        struct pch_dma *pd = to_pd(chan->device);
        struct pch_dma_desc *desc, *_d;
        LIST_HEAD(tmp_list);

        BUG_ON(!pdc_is_idle(pd_chan));
        BUG_ON(!list_empty(&pd_chan->active_list));
        BUG_ON(!list_empty(&pd_chan->queue));

        spin_lock_bh(&pd_chan->lock);
        list_splice_init(&pd_chan->free_list, &tmp_list);
        pd_chan->descs_allocated = 0;
        spin_unlock_bh(&pd_chan->lock);

        list_for_each_entry_safe(desc, _d, &tmp_list, desc_node)
                pci_pool_free(pd->pool, desc, desc->txd.phys);

        pdc_enable_irq(chan, 0);
}

static enum dma_status pd_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
                                    struct dma_tx_state *txstate)
{
        struct pch_dma_chan *pd_chan = to_pd_chan(chan);
        dma_cookie_t last_used;
        dma_cookie_t last_completed;
        int ret;

        spin_lock_bh(&pd_chan->lock);
        last_completed = pd_chan->completed_cookie;
        last_used = chan->cookie;
        spin_unlock_bh(&pd_chan->lock);

        ret = dma_async_is_complete(cookie, last_completed, last_used);

        dma_set_tx_state(txstate, last_completed, last_used, 0);

        return ret;
}

static void pd_issue_pending(struct dma_chan *chan)
{
        struct pch_dma_chan *pd_chan = to_pd_chan(chan);

        if (pdc_is_idle(pd_chan)) {
                spin_lock_bh(&pd_chan->lock);
                pdc_advance_work(pd_chan);
                spin_unlock_bh(&pd_chan->lock);
        }
}

static struct dma_async_tx_descriptor *pd_prep_slave_sg(struct dma_chan *chan,
                        struct scatterlist *sgl, unsigned int sg_len,
                        enum dma_data_direction direction, unsigned long flags)
{
        struct pch_dma_chan *pd_chan = to_pd_chan(chan);
        struct pch_dma_slave *pd_slave = chan->private;
        struct pch_dma_desc *first = NULL;
        struct pch_dma_desc *prev = NULL;
        struct pch_dma_desc *desc = NULL;
        struct scatterlist *sg;
        dma_addr_t reg;
        int i;

        if (unlikely(!sg_len)) {
                dev_info(chan2dev(chan), "prep_slave_sg: length is zero!\n");
                return NULL;
        }

        if (direction == DMA_FROM_DEVICE)
                reg = pd_slave->rx_reg;
        else if (direction == DMA_TO_DEVICE)
                reg = pd_slave->tx_reg;
        else
                return NULL;

        for_each_sg(sgl, sg, sg_len, i) {
                desc = pdc_desc_get(pd_chan);

                if (!desc)
                        goto err_desc_get;

                desc->regs.dev_addr = reg;
                desc->regs.mem_addr = sg_phys(sg);
                desc->regs.size = sg_dma_len(sg);
                desc->regs.next = DMA_DESC_FOLLOW_WITHOUT_IRQ;

                switch (pd_slave->width) {
                case PCH_DMA_WIDTH_1_BYTE:
                        if (desc->regs.size > DMA_DESC_MAX_COUNT_1_BYTE)
                                goto err_desc_get;
                        desc->regs.size |= DMA_DESC_WIDTH_1_BYTE;
                        break;
                case PCH_DMA_WIDTH_2_BYTES:
                        if (desc->regs.size > DMA_DESC_MAX_COUNT_2_BYTES)
                                goto err_desc_get;
                        desc->regs.size |= DMA_DESC_WIDTH_2_BYTES;
                        break;
                case PCH_DMA_WIDTH_4_BYTES:
                        if (desc->regs.size > DMA_DESC_MAX_COUNT_4_BYTES)
                                goto err_desc_get;
                        desc->regs.size |= DMA_DESC_WIDTH_4_BYTES;
                        break;
                default:
                        goto err_desc_get;
                }


                if (!first) {
                        first = desc;
                } else {
                        prev->regs.next |= desc->txd.phys;
                        list_add_tail(&desc->desc_node, &first->tx_list);
                }

                prev = desc;
        }

        if (flags & DMA_PREP_INTERRUPT)
                desc->regs.next = DMA_DESC_END_WITH_IRQ;
        else
                desc->regs.next = DMA_DESC_END_WITHOUT_IRQ;

        first->txd.cookie = -EBUSY;
        desc->txd.flags = flags;

        return &first->txd;

err_desc_get:
        dev_err(chan2dev(chan), "failed to get desc or wrong parameters\n");
        pdc_desc_put(pd_chan, first);
        return NULL;
}

static int pd_device_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                             unsigned long arg)
{
        struct pch_dma_chan *pd_chan = to_pd_chan(chan);
        struct pch_dma_desc *desc, *_d;
        LIST_HEAD(list);

        if (cmd != DMA_TERMINATE_ALL)
                return -ENXIO;

        spin_lock_bh(&pd_chan->lock);

        pdc_set_mode(&pd_chan->chan, DMA_CTL0_DISABLE);

        list_splice_init(&pd_chan->active_list, &list);
        list_splice_init(&pd_chan->queue, &list);

        list_for_each_entry_safe(desc, _d, &list, desc_node)
                pdc_chain_complete(pd_chan, desc);

        spin_unlock_bh(&pd_chan->lock);


        return 0;
}

static void pdc_tasklet(unsigned long data)
{
        struct pch_dma_chan *pd_chan = (struct pch_dma_chan *)data;

        if (!pdc_is_idle(pd_chan)) {
                dev_err(chan2dev(&pd_chan->chan),
                        "BUG: handle non-idle channel in tasklet\n");
                return;
        }

        spin_lock_bh(&pd_chan->lock);
        if (test_and_clear_bit(0, &pd_chan->err_status))
                pdc_handle_error(pd_chan);
        else
                pdc_advance_work(pd_chan);
        spin_unlock_bh(&pd_chan->lock);
}

static irqreturn_t pd_irq(int irq, void *devid)
{
        struct pch_dma *pd = (struct pch_dma *)devid;
        struct pch_dma_chan *pd_chan;
        u32 sts0;
        int i;
        int ret = IRQ_NONE;

        sts0 = dma_readl(pd, STS0);

        dev_dbg(pd->dma.dev, "pd_irq sts0: %x\n", sts0);

        for (i = 0; i < pd->dma.chancnt; i++) {
                pd_chan = &pd->channels[i];

                if (sts0 & DMA_STATUS_IRQ(i)) {
                        if (sts0 & DMA_STATUS_ERR(i))
                                set_bit(0, &pd_chan->err_status);

                        tasklet_schedule(&pd_chan->tasklet);
                        ret = IRQ_HANDLED;
                }

        }

        /* clear interrupt bits in status register */
        dma_writel(pd, STS0, sts0);

        return ret;
}

static void pch_dma_save_regs(struct pch_dma *pd)
{
        struct pch_dma_chan *pd_chan;
        struct dma_chan *chan, *_c;
        int i = 0;

        pd->regs.dma_ctl0 = dma_readl(pd, CTL0);
        pd->regs.dma_ctl1 = dma_readl(pd, CTL1);
        pd->regs.dma_ctl2 = dma_readl(pd, CTL2);

        list_for_each_entry_safe(chan, _c, &pd->dma.channels, device_node) {
                pd_chan = to_pd_chan(chan);

                pd->ch_regs[i].dev_addr = channel_readl(pd_chan, DEV_ADDR);
                pd->ch_regs[i].mem_addr = channel_readl(pd_chan, MEM_ADDR);
                pd->ch_regs[i].size = channel_readl(pd_chan, SIZE);
                pd->ch_regs[i].next = channel_readl(pd_chan, NEXT);

                i++;
        }
}

static void pch_dma_restore_regs(struct pch_dma *pd)
{
        struct pch_dma_chan *pd_chan;
        struct dma_chan *chan, *_c;
        int i = 0;

        dma_writel(pd, CTL0, pd->regs.dma_ctl0);
        dma_writel(pd, CTL1, pd->regs.dma_ctl1);
        dma_writel(pd, CTL2, pd->regs.dma_ctl2);

        list_for_each_entry_safe(chan, _c, &pd->dma.channels, device_node) {
                pd_chan = to_pd_chan(chan);

                channel_writel(pd_chan, DEV_ADDR, pd->ch_regs[i].dev_addr);
                channel_writel(pd_chan, MEM_ADDR, pd->ch_regs[i].mem_addr);
                channel_writel(pd_chan, SIZE, pd->ch_regs[i].size);
                channel_writel(pd_chan, NEXT, pd->ch_regs[i].next);

                i++;
        }
}

static int pch_dma_suspend(struct pci_dev *pdev, pm_message_t state)
{
        struct pch_dma *pd = pci_get_drvdata(pdev);

        if (pd)
                pch_dma_save_regs(pd);

        pci_save_state(pdev);
        pci_disable_device(pdev);
        pci_set_power_state(pdev, pci_choose_state(pdev, state));

        return 0;
}

static int pch_dma_resume(struct pci_dev *pdev)
{
        struct pch_dma *pd = pci_get_drvdata(pdev);
        int err;

        pci_set_power_state(pdev, PCI_D0);
        pci_restore_state(pdev);

        err = pci_enable_device(pdev);
        if (err) {
                dev_dbg(&pdev->dev, "failed to enable device\n");
                return err;
        }

        if (pd)
                pch_dma_restore_regs(pd);

        return 0;
}

static int __devinit pch_dma_probe(struct pci_dev *pdev,
                                   const struct pci_device_id *id)
{
        struct pch_dma *pd;
        struct pch_dma_regs *regs;
        unsigned int nr_channels;
        int err;
        int i;

        nr_channels = id->driver_data;
        pd = kzalloc(sizeof(struct pch_dma)+
                sizeof(struct pch_dma_chan) * nr_channels, GFP_KERNEL);
        if (!pd)
                return -ENOMEM;

        pci_set_drvdata(pdev, pd);

        err = pci_enable_device(pdev);
        if (err) {
                dev_err(&pdev->dev, "Cannot enable PCI device\n");
                goto err_free_mem;
        }

        if (!(pci_resource_flags(pdev, 1) & IORESOURCE_MEM)) {
                dev_err(&pdev->dev, "Cannot find proper base address\n");
                goto err_disable_pdev;
        }

        err = pci_request_regions(pdev, DRV_NAME);
        if (err) {
                dev_err(&pdev->dev, "Cannot obtain PCI resources\n");
                goto err_disable_pdev;
        }

        err = pci_set_dma_mask(pdev, DMA_BIT_MASK(32));
        if (err) {
                dev_err(&pdev->dev, "Cannot set proper DMA config\n");
                goto err_free_res;
        }

        regs = pd->membase = pci_iomap(pdev, 1, 0);
        if (!pd->membase) {
                dev_err(&pdev->dev, "Cannot map MMIO registers\n");
                err = -ENOMEM;
                goto err_free_res;
        }

        pci_set_master(pdev);

        err = request_irq(pdev->irq, pd_irq, IRQF_SHARED, DRV_NAME, pd);
        if (err) {
                dev_err(&pdev->dev, "Failed to request IRQ\n");
                goto err_iounmap;
        }

        pd->pool = pci_pool_create("pch_dma_desc_pool", pdev,
                                   sizeof(struct pch_dma_desc), 4, 0);
        if (!pd->pool) {
                dev_err(&pdev->dev, "Failed to alloc DMA descriptors\n");
                err = -ENOMEM;
                goto err_free_irq;
        }

        pd->dma.dev = &pdev->dev;
        pd->dma.chancnt = nr_channels;

        INIT_LIST_HEAD(&pd->dma.channels);

        for (i = 0; i < nr_channels; i++) {
                struct pch_dma_chan *pd_chan = &pd->channels[i];

                pd_chan->chan.device = &pd->dma;
                pd_chan->chan.cookie = 1;
                pd_chan->chan.chan_id = i;

                pd_chan->membase = &regs->desc[i];

                pd_chan->dir = (i % 2) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;

                spin_lock_init(&pd_chan->lock);

                INIT_LIST_HEAD(&pd_chan->active_list);
                INIT_LIST_HEAD(&pd_chan->queue);
                INIT_LIST_HEAD(&pd_chan->free_list);

                tasklet_init(&pd_chan->tasklet, pdc_tasklet,
                             (unsigned long)pd_chan);
                list_add_tail(&pd_chan->chan.device_node, &pd->dma.channels);
        }

        dma_cap_zero(pd->dma.cap_mask);
        dma_cap_set(DMA_PRIVATE, pd->dma.cap_mask);
        dma_cap_set(DMA_SLAVE, pd->dma.cap_mask);

        pd->dma.device_alloc_chan_resources = pd_alloc_chan_resources;
        pd->dma.device_free_chan_resources = pd_free_chan_resources;
        pd->dma.device_tx_status = pd_tx_status;
        pd->dma.device_issue_pending = pd_issue_pending;
        pd->dma.device_prep_slave_sg = pd_prep_slave_sg;
        pd->dma.device_control = pd_device_control;

        err = dma_async_device_register(&pd->dma);
        if (err) {
                dev_err(&pdev->dev, "Failed to register DMA device\n");
                goto err_free_pool;
        }

        return 0;

err_free_pool:
        pci_pool_destroy(pd->pool);
err_free_irq:
        free_irq(pdev->irq, pd);
err_iounmap:
        pci_iounmap(pdev, pd->membase);
err_free_res:
        pci_release_regions(pdev);
err_disable_pdev:
        pci_disable_device(pdev);
err_free_mem:
        return err;
}

static void __devexit pch_dma_remove(struct pci_dev *pdev)
{
        struct pch_dma *pd = pci_get_drvdata(pdev);
        struct pch_dma_chan *pd_chan;
        struct dma_chan *chan, *_c;

        if (pd) {
                dma_async_device_unregister(&pd->dma);

                list_for_each_entry_safe(chan, _c, &pd->dma.channels,
                                         device_node) {
                        pd_chan = to_pd_chan(chan);

                        tasklet_disable(&pd_chan->tasklet);
                        tasklet_kill(&pd_chan->tasklet);
                }

                pci_pool_destroy(pd->pool);
                free_irq(pdev->irq, pd);
                pci_iounmap(pdev, pd->membase);
                pci_release_regions(pdev);
                pci_disable_device(pdev);
                kfree(pd);
        }
}

/* PCI Device ID of DMA device */
#define PCI_DEVICE_ID_PCH_DMA_8CH        0x8810
#define PCI_DEVICE_ID_PCH_DMA_4CH        0x8815

static const struct pci_device_id pch_dma_id_table[] = {
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_PCH_DMA_8CH), 8 },
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_PCH_DMA_4CH), 4 },
};

static struct pci_driver pch_dma_driver = {
        .name           = DRV_NAME,
        .id_table       = pch_dma_id_table,
        .probe          = pch_dma_probe,
        .remove         = __devexit_p(pch_dma_remove),
#ifdef CONFIG_PM
        .suspend        = pch_dma_suspend,
        .resume         = pch_dma_resume,
#endif
};

static int __init pch_dma_init(void)
{
        return pci_register_driver(&pch_dma_driver);
}

static void __exit pch_dma_exit(void)
{
        pci_unregister_driver(&pch_dma_driver);
}

module_init(pch_dma_init);
module_exit(pch_dma_exit);

MODULE_DESCRIPTION("Topcliff PCH DMA controller driver");
MODULE_AUTHOR("Yong Wang <yong.y.wang@intel.com>");
MODULE_LICENSE("GPL v2");