Linux 3.18.139

[linux/fpc-iii.git] / drivers / dma / mic_x100_dma.c

/*
 * Intel MIC Platform Software Stack (MPSS)
 *
 * Copyright(c) 2014 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.
 *
 * The full GNU General Public License is included in this distribution in
 * the file called "COPYING".
 *
 * Intel MIC X100 DMA Driver.
 *
 * Adapted from IOAT dma driver.
 */
#include <linux/module.h>
#include <linux/io.h>
#include <linux/seq_file.h>

#include "mic_x100_dma.h"

#define MIC_DMA_MAX_XFER_SIZE_CARD  (1 * 1024 * 1024 -\
                                       MIC_DMA_ALIGN_BYTES)
#define MIC_DMA_MAX_XFER_SIZE_HOST  (1 * 1024 * 1024 >> 1)
#define MIC_DMA_DESC_TYPE_SHIFT 60
#define MIC_DMA_MEMCPY_LEN_SHIFT 46
#define MIC_DMA_STAT_INTR_SHIFT 59

/* high-water mark for pushing dma descriptors */
static int mic_dma_pending_level = 4;

/* Status descriptor is used to write a 64 bit value to a memory location */
enum mic_dma_desc_format_type {
        MIC_DMA_MEMCPY = 1,
        MIC_DMA_STATUS,
};

static inline u32 mic_dma_hw_ring_inc(u32 val)
{
        return (val + 1) % MIC_DMA_DESC_RX_SIZE;
}

static inline u32 mic_dma_hw_ring_dec(u32 val)
{
        return val ? val - 1 : MIC_DMA_DESC_RX_SIZE - 1;
}

static inline void mic_dma_hw_ring_inc_head(struct mic_dma_chan *ch)
{
        ch->head = mic_dma_hw_ring_inc(ch->head);
}

/* Prepare a memcpy desc */
static inline void mic_dma_memcpy_desc(struct mic_dma_desc *desc,
        dma_addr_t src_phys, dma_addr_t dst_phys, u64 size)
{
        u64 qw0, qw1;

        qw0 = src_phys;
        qw0 |= (size >> MIC_DMA_ALIGN_SHIFT) << MIC_DMA_MEMCPY_LEN_SHIFT;
        qw1 = MIC_DMA_MEMCPY;
        qw1 <<= MIC_DMA_DESC_TYPE_SHIFT;
        qw1 |= dst_phys;
        desc->qw0 = qw0;
        desc->qw1 = qw1;
}

/* Prepare a status desc. with @data to be written at @dst_phys */
static inline void mic_dma_prep_status_desc(struct mic_dma_desc *desc, u64 data,
        dma_addr_t dst_phys, bool generate_intr)
{
        u64 qw0, qw1;

        qw0 = data;
        qw1 = (u64) MIC_DMA_STATUS << MIC_DMA_DESC_TYPE_SHIFT | dst_phys;
        if (generate_intr)
                qw1 |= (1ULL << MIC_DMA_STAT_INTR_SHIFT);
        desc->qw0 = qw0;
        desc->qw1 = qw1;
}

static void mic_dma_cleanup(struct mic_dma_chan *ch)
{
        struct dma_async_tx_descriptor *tx;
        u32 tail;
        u32 last_tail;

        spin_lock(&ch->cleanup_lock);
        tail = mic_dma_read_cmp_cnt(ch);
        /*
         * This is the barrier pair for smp_wmb() in fn.
         * mic_dma_tx_submit_unlock. It's required so that we read the
         * updated cookie value from tx->cookie.
         */
        smp_rmb();
        for (last_tail = ch->last_tail; tail != last_tail;) {
                tx = &ch->tx_array[last_tail];
                if (tx->cookie) {
                        dma_cookie_complete(tx);
                        if (tx->callback) {
                                tx->callback(tx->callback_param);
                                tx->callback = NULL;
                        }
                }
                last_tail = mic_dma_hw_ring_inc(last_tail);
        }
        /* finish all completion callbacks before incrementing tail */
        smp_mb();
        ch->last_tail = last_tail;
        spin_unlock(&ch->cleanup_lock);
}

static u32 mic_dma_ring_count(u32 head, u32 tail)
{
        u32 count;

        if (head >= tail)
                count = (tail - 0) + (MIC_DMA_DESC_RX_SIZE - head);
        else
                count = tail - head;
        return count - 1;
}

/* Returns the num. of free descriptors on success, -ENOMEM on failure */
static int mic_dma_avail_desc_ring_space(struct mic_dma_chan *ch, int required)
{
        struct device *dev = mic_dma_ch_to_device(ch);
        u32 count;

        count = mic_dma_ring_count(ch->head, ch->last_tail);
        if (count < required) {
                mic_dma_cleanup(ch);
                count = mic_dma_ring_count(ch->head, ch->last_tail);
        }

        if (count < required) {
                dev_dbg(dev, "Not enough desc space");
                dev_dbg(dev, "%s %d required=%u, avail=%u\n",
                        __func__, __LINE__, required, count);
                return -ENOMEM;
        } else {
                return count;
        }
}

/* Program memcpy descriptors into the descriptor ring and update s/w head ptr*/
static int mic_dma_prog_memcpy_desc(struct mic_dma_chan *ch, dma_addr_t src,
                                    dma_addr_t dst, size_t len)
{
        size_t current_transfer_len;
        size_t max_xfer_size = to_mic_dma_dev(ch)->max_xfer_size;
        /* 3 is added to make sure we have enough space for status desc */
        int num_desc = len / max_xfer_size + 3;
        int ret;

        if (len % max_xfer_size)
                num_desc++;

        ret = mic_dma_avail_desc_ring_space(ch, num_desc);
        if (ret < 0)
                return ret;
        do {
                current_transfer_len = min(len, max_xfer_size);
                mic_dma_memcpy_desc(&ch->desc_ring[ch->head],
                                    src, dst, current_transfer_len);
                mic_dma_hw_ring_inc_head(ch);
                len -= current_transfer_len;
                dst = dst + current_transfer_len;
                src = src + current_transfer_len;
        } while (len > 0);
        return 0;
}

/* It's a h/w quirk and h/w needs 2 status descriptors for every status desc */
static void mic_dma_prog_intr(struct mic_dma_chan *ch)
{
        mic_dma_prep_status_desc(&ch->desc_ring[ch->head], 0,
                                 ch->status_dest_micpa, false);
        mic_dma_hw_ring_inc_head(ch);
        mic_dma_prep_status_desc(&ch->desc_ring[ch->head], 0,
                                 ch->status_dest_micpa, true);
        mic_dma_hw_ring_inc_head(ch);
}

/* Wrapper function to program memcpy descriptors/status descriptors */
static int mic_dma_do_dma(struct mic_dma_chan *ch, int flags, dma_addr_t src,
                          dma_addr_t dst, size_t len)
{
        if (-ENOMEM == mic_dma_prog_memcpy_desc(ch, src, dst, len))
                return -ENOMEM;
        /* Above mic_dma_prog_memcpy_desc() makes sure we have enough space */
        if (flags & DMA_PREP_FENCE) {
                mic_dma_prep_status_desc(&ch->desc_ring[ch->head], 0,
                                         ch->status_dest_micpa, false);
                mic_dma_hw_ring_inc_head(ch);
        }

        if (flags & DMA_PREP_INTERRUPT)
                mic_dma_prog_intr(ch);

        return 0;
}

static inline void mic_dma_issue_pending(struct dma_chan *ch)
{
        struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);

        spin_lock(&mic_ch->issue_lock);
        /*
         * Write to head triggers h/w to act on the descriptors.
         * On MIC, writing the same head value twice causes
         * a h/w error. On second write, h/w assumes we filled
         * the entire ring & overwrote some of the descriptors.
         */
        if (mic_ch->issued == mic_ch->submitted)
                goto out;
        mic_ch->issued = mic_ch->submitted;
        /*
         * make descriptor updates visible before advancing head,
         * this is purposefully not smp_wmb() since we are also
         * publishing the descriptor updates to a dma device
         */
        wmb();
        mic_dma_write_reg(mic_ch, MIC_DMA_REG_DHPR, mic_ch->issued);
out:
        spin_unlock(&mic_ch->issue_lock);
}

static inline void mic_dma_update_pending(struct mic_dma_chan *ch)
{
        if (mic_dma_ring_count(ch->issued, ch->submitted)
                        > mic_dma_pending_level)
                mic_dma_issue_pending(&ch->api_ch);
}

static dma_cookie_t mic_dma_tx_submit_unlock(struct dma_async_tx_descriptor *tx)
{
        struct mic_dma_chan *mic_ch = to_mic_dma_chan(tx->chan);
        dma_cookie_t cookie;

        dma_cookie_assign(tx);
        cookie = tx->cookie;
        /*
         * We need an smp write barrier here because another CPU might see
         * an update to submitted and update h/w head even before we
         * assigned a cookie to this tx.
         */
        smp_wmb();
        mic_ch->submitted = mic_ch->head;
        spin_unlock(&mic_ch->prep_lock);
        mic_dma_update_pending(mic_ch);
        return cookie;
}

static inline struct dma_async_tx_descriptor *
allocate_tx(struct mic_dma_chan *ch)
{
        u32 idx = mic_dma_hw_ring_dec(ch->head);
        struct dma_async_tx_descriptor *tx = &ch->tx_array[idx];

        dma_async_tx_descriptor_init(tx, &ch->api_ch);
        tx->tx_submit = mic_dma_tx_submit_unlock;
        return tx;
}

/*
 * Prepare a memcpy descriptor to be added to the ring.
 * Note that the temporary descriptor adds an extra overhead of copying the
 * descriptor to ring. So, we copy directly to the descriptor ring
 */
static struct dma_async_tx_descriptor *
mic_dma_prep_memcpy_lock(struct dma_chan *ch, dma_addr_t dma_dest,
                         dma_addr_t dma_src, size_t len, unsigned long flags)
{
        struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);
        struct device *dev = mic_dma_ch_to_device(mic_ch);
        int result;

        if (!len && !flags)
                return NULL;

        spin_lock(&mic_ch->prep_lock);
        result = mic_dma_do_dma(mic_ch, flags, dma_src, dma_dest, len);
        if (result >= 0)
                return allocate_tx(mic_ch);
        dev_err(dev, "Error enqueueing dma, error=%d\n", result);
        spin_unlock(&mic_ch->prep_lock);
        return NULL;
}

static struct dma_async_tx_descriptor *
mic_dma_prep_interrupt_lock(struct dma_chan *ch, unsigned long flags)
{
        struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);
        int ret;

        spin_lock(&mic_ch->prep_lock);
        ret = mic_dma_do_dma(mic_ch, flags, 0, 0, 0);
        if (!ret)
                return allocate_tx(mic_ch);
        spin_unlock(&mic_ch->prep_lock);
        return NULL;
}

/* Return the status of the transaction */
static enum dma_status
mic_dma_tx_status(struct dma_chan *ch, dma_cookie_t cookie,
                  struct dma_tx_state *txstate)
{
        struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);

        if (DMA_COMPLETE != dma_cookie_status(ch, cookie, txstate))
                mic_dma_cleanup(mic_ch);

        return dma_cookie_status(ch, cookie, txstate);
}

static irqreturn_t mic_dma_thread_fn(int irq, void *data)
{
        mic_dma_cleanup((struct mic_dma_chan *)data);
        return IRQ_HANDLED;
}

static irqreturn_t mic_dma_intr_handler(int irq, void *data)
{
        struct mic_dma_chan *ch = ((struct mic_dma_chan *)data);

        mic_dma_ack_interrupt(ch);
        return IRQ_WAKE_THREAD;
}

static int mic_dma_alloc_desc_ring(struct mic_dma_chan *ch)
{
        u64 desc_ring_size = MIC_DMA_DESC_RX_SIZE * sizeof(*ch->desc_ring);
        struct device *dev = &to_mbus_device(ch)->dev;

        desc_ring_size = ALIGN(desc_ring_size, MIC_DMA_ALIGN_BYTES);
        ch->desc_ring = kzalloc(desc_ring_size, GFP_KERNEL);

        if (!ch->desc_ring)
                return -ENOMEM;

        ch->desc_ring_micpa = dma_map_single(dev, ch->desc_ring,
                                             desc_ring_size, DMA_BIDIRECTIONAL);
        if (dma_mapping_error(dev, ch->desc_ring_micpa))
                goto map_error;

        ch->tx_array = vzalloc(MIC_DMA_DESC_RX_SIZE * sizeof(*ch->tx_array));
        if (!ch->tx_array)
                goto tx_error;
        return 0;
tx_error:
        dma_unmap_single(dev, ch->desc_ring_micpa, desc_ring_size,
                         DMA_BIDIRECTIONAL);
map_error:
        kfree(ch->desc_ring);
        return -ENOMEM;
}

static void mic_dma_free_desc_ring(struct mic_dma_chan *ch)
{
        u64 desc_ring_size = MIC_DMA_DESC_RX_SIZE * sizeof(*ch->desc_ring);

        vfree(ch->tx_array);
        desc_ring_size = ALIGN(desc_ring_size, MIC_DMA_ALIGN_BYTES);
        dma_unmap_single(&to_mbus_device(ch)->dev, ch->desc_ring_micpa,
                         desc_ring_size, DMA_BIDIRECTIONAL);
        kfree(ch->desc_ring);
        ch->desc_ring = NULL;
}

static void mic_dma_free_status_dest(struct mic_dma_chan *ch)
{
        dma_unmap_single(&to_mbus_device(ch)->dev, ch->status_dest_micpa,
                         L1_CACHE_BYTES, DMA_BIDIRECTIONAL);
        kfree(ch->status_dest);
}

static int mic_dma_alloc_status_dest(struct mic_dma_chan *ch)
{
        struct device *dev = &to_mbus_device(ch)->dev;

        ch->status_dest = kzalloc(L1_CACHE_BYTES, GFP_KERNEL);
        if (!ch->status_dest)
                return -ENOMEM;
        ch->status_dest_micpa = dma_map_single(dev, ch->status_dest,
                                        L1_CACHE_BYTES, DMA_BIDIRECTIONAL);
        if (dma_mapping_error(dev, ch->status_dest_micpa)) {
                kfree(ch->status_dest);
                ch->status_dest = NULL;
                return -ENOMEM;
        }
        return 0;
}

static int mic_dma_check_chan(struct mic_dma_chan *ch)
{
        if (mic_dma_read_reg(ch, MIC_DMA_REG_DCHERR) ||
            mic_dma_read_reg(ch, MIC_DMA_REG_DSTAT) & MIC_DMA_CHAN_QUIESCE) {
                mic_dma_disable_chan(ch);
                mic_dma_chan_mask_intr(ch);
                dev_err(mic_dma_ch_to_device(ch),
                        "%s %d error setting up mic dma chan %d\n",
                        __func__, __LINE__, ch->ch_num);
                return -EBUSY;
        }
        return 0;
}

static int mic_dma_chan_setup(struct mic_dma_chan *ch)
{
        if (MIC_DMA_CHAN_MIC == ch->owner)
                mic_dma_chan_set_owner(ch);
        mic_dma_disable_chan(ch);
        mic_dma_chan_mask_intr(ch);
        mic_dma_write_reg(ch, MIC_DMA_REG_DCHERRMSK, 0);
        mic_dma_chan_set_desc_ring(ch);
        ch->last_tail = mic_dma_read_reg(ch, MIC_DMA_REG_DTPR);
        ch->head = ch->last_tail;
        ch->issued = 0;
        mic_dma_chan_unmask_intr(ch);
        mic_dma_enable_chan(ch);
        return mic_dma_check_chan(ch);
}

static void mic_dma_chan_destroy(struct mic_dma_chan *ch)
{
        mic_dma_disable_chan(ch);
        mic_dma_chan_mask_intr(ch);
}

static void mic_dma_unregister_dma_device(struct mic_dma_device *mic_dma_dev)
{
        dma_async_device_unregister(&mic_dma_dev->dma_dev);
}

static int mic_dma_setup_irq(struct mic_dma_chan *ch)
{
        ch->cookie =
                to_mbus_hw_ops(ch)->request_threaded_irq(to_mbus_device(ch),
                        mic_dma_intr_handler, mic_dma_thread_fn,
                        "mic dma_channel", ch, ch->ch_num);
        if (IS_ERR(ch->cookie))
                return IS_ERR(ch->cookie);
        return 0;
}

static inline void mic_dma_free_irq(struct mic_dma_chan *ch)
{
        to_mbus_hw_ops(ch)->free_irq(to_mbus_device(ch), ch->cookie, ch);
}

static int mic_dma_chan_init(struct mic_dma_chan *ch)
{
        int ret = mic_dma_alloc_desc_ring(ch);

        if (ret)
                goto ring_error;
        ret = mic_dma_alloc_status_dest(ch);
        if (ret)
                goto status_error;
        ret = mic_dma_chan_setup(ch);
        if (ret)
                goto chan_error;
        return ret;
chan_error:
        mic_dma_free_status_dest(ch);
status_error:
        mic_dma_free_desc_ring(ch);
ring_error:
        return ret;
}

static int mic_dma_drain_chan(struct mic_dma_chan *ch)
{
        struct dma_async_tx_descriptor *tx;
        int err = 0;
        dma_cookie_t cookie;

        tx = mic_dma_prep_memcpy_lock(&ch->api_ch, 0, 0, 0, DMA_PREP_FENCE);
        if (!tx) {
                err = -ENOMEM;
                goto error;
        }

        cookie = tx->tx_submit(tx);
        if (dma_submit_error(cookie))
                err = -ENOMEM;
        else
                err = dma_sync_wait(&ch->api_ch, cookie);
        if (err) {
                dev_err(mic_dma_ch_to_device(ch), "%s %d TO chan 0x%x\n",
                        __func__, __LINE__, ch->ch_num);
                err = -EIO;
        }
error:
        mic_dma_cleanup(ch);
        return err;
}

static inline void mic_dma_chan_uninit(struct mic_dma_chan *ch)
{
        mic_dma_chan_destroy(ch);
        mic_dma_cleanup(ch);
        mic_dma_free_status_dest(ch);
        mic_dma_free_desc_ring(ch);
}

static int mic_dma_init(struct mic_dma_device *mic_dma_dev,
                        enum mic_dma_chan_owner owner)
{
        int i, first_chan = mic_dma_dev->start_ch;
        struct mic_dma_chan *ch;
        int ret;

        for (i = first_chan; i < first_chan + MIC_DMA_NUM_CHAN; i++) {
                unsigned long data;
                ch = &mic_dma_dev->mic_ch[i];
                data = (unsigned long)ch;
                ch->ch_num = i;
                ch->owner = owner;
                spin_lock_init(&ch->cleanup_lock);
                spin_lock_init(&ch->prep_lock);
                spin_lock_init(&ch->issue_lock);
                ret = mic_dma_setup_irq(ch);
                if (ret)
                        goto error;
        }
        return 0;
error:
        for (i = i - 1; i >= first_chan; i--)
                mic_dma_free_irq(ch);
        return ret;
}

static void mic_dma_uninit(struct mic_dma_device *mic_dma_dev)
{
        int i, first_chan = mic_dma_dev->start_ch;
        struct mic_dma_chan *ch;

        for (i = first_chan; i < first_chan + MIC_DMA_NUM_CHAN; i++) {
                ch = &mic_dma_dev->mic_ch[i];
                mic_dma_free_irq(ch);
        }
}

static int mic_dma_alloc_chan_resources(struct dma_chan *ch)
{
        int ret = mic_dma_chan_init(to_mic_dma_chan(ch));
        if (ret)
                return ret;
        return MIC_DMA_DESC_RX_SIZE;
}

static void mic_dma_free_chan_resources(struct dma_chan *ch)
{
        struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);
        mic_dma_drain_chan(mic_ch);
        mic_dma_chan_uninit(mic_ch);
}

/* Set the fn. handlers and register the dma device with dma api */
static int mic_dma_register_dma_device(struct mic_dma_device *mic_dma_dev,
                                       enum mic_dma_chan_owner owner)
{
        int i, first_chan = mic_dma_dev->start_ch;

        dma_cap_zero(mic_dma_dev->dma_dev.cap_mask);
        /*
         * This dma engine is not capable of host memory to host memory
         * transfers
         */
        dma_cap_set(DMA_MEMCPY, mic_dma_dev->dma_dev.cap_mask);

        if (MIC_DMA_CHAN_HOST == owner)
                dma_cap_set(DMA_PRIVATE, mic_dma_dev->dma_dev.cap_mask);
        mic_dma_dev->dma_dev.device_alloc_chan_resources =
                mic_dma_alloc_chan_resources;
        mic_dma_dev->dma_dev.device_free_chan_resources =
                mic_dma_free_chan_resources;
        mic_dma_dev->dma_dev.device_tx_status = mic_dma_tx_status;
        mic_dma_dev->dma_dev.device_prep_dma_memcpy = mic_dma_prep_memcpy_lock;
        mic_dma_dev->dma_dev.device_prep_dma_interrupt =
                mic_dma_prep_interrupt_lock;
        mic_dma_dev->dma_dev.device_issue_pending = mic_dma_issue_pending;
        mic_dma_dev->dma_dev.copy_align = MIC_DMA_ALIGN_SHIFT;
        INIT_LIST_HEAD(&mic_dma_dev->dma_dev.channels);
        for (i = first_chan; i < first_chan + MIC_DMA_NUM_CHAN; i++) {
                mic_dma_dev->mic_ch[i].api_ch.device = &mic_dma_dev->dma_dev;
                dma_cookie_init(&mic_dma_dev->mic_ch[i].api_ch);
                list_add_tail(&mic_dma_dev->mic_ch[i].api_ch.device_node,
                              &mic_dma_dev->dma_dev.channels);
        }
        return dma_async_device_register(&mic_dma_dev->dma_dev);
}

/*
 * Initializes dma channels and registers the dma device with the
 * dma engine api.
 */
static struct mic_dma_device *mic_dma_dev_reg(struct mbus_device *mbdev,
                                              enum mic_dma_chan_owner owner)
{
        struct mic_dma_device *mic_dma_dev;
        int ret;
        struct device *dev = &mbdev->dev;

        mic_dma_dev = kzalloc(sizeof(*mic_dma_dev), GFP_KERNEL);
        if (!mic_dma_dev) {
                ret = -ENOMEM;
                goto alloc_error;
        }
        mic_dma_dev->mbdev = mbdev;
        mic_dma_dev->dma_dev.dev = dev;
        mic_dma_dev->mmio = mbdev->mmio_va;
        if (MIC_DMA_CHAN_HOST == owner) {
                mic_dma_dev->start_ch = 0;
                mic_dma_dev->max_xfer_size = MIC_DMA_MAX_XFER_SIZE_HOST;
        } else {
                mic_dma_dev->start_ch = 4;
                mic_dma_dev->max_xfer_size = MIC_DMA_MAX_XFER_SIZE_CARD;
        }
        ret = mic_dma_init(mic_dma_dev, owner);
        if (ret)
                goto init_error;
        ret = mic_dma_register_dma_device(mic_dma_dev, owner);
        if (ret)
                goto reg_error;
        return mic_dma_dev;
reg_error:
        mic_dma_uninit(mic_dma_dev);
init_error:
        kfree(mic_dma_dev);
        mic_dma_dev = NULL;
alloc_error:
        dev_err(dev, "Error at %s %d ret=%d\n", __func__, __LINE__, ret);
        return mic_dma_dev;
}

static void mic_dma_dev_unreg(struct mic_dma_device *mic_dma_dev)
{
        mic_dma_unregister_dma_device(mic_dma_dev);
        mic_dma_uninit(mic_dma_dev);
        kfree(mic_dma_dev);
}

/* DEBUGFS CODE */
static int mic_dma_reg_seq_show(struct seq_file *s, void *pos)
{
        struct mic_dma_device *mic_dma_dev = s->private;
        int i, chan_num, first_chan = mic_dma_dev->start_ch;
        struct mic_dma_chan *ch;

        seq_printf(s, "SBOX_DCR: %#x\n",
                   mic_dma_mmio_read(&mic_dma_dev->mic_ch[first_chan],
                                     MIC_DMA_SBOX_BASE + MIC_DMA_SBOX_DCR));
        seq_puts(s, "DMA Channel Registers\n");
        seq_printf(s, "%-10s| %-10s %-10s %-10s %-10s %-10s",
                   "Channel", "DCAR", "DTPR", "DHPR", "DRAR_HI", "DRAR_LO");
        seq_printf(s, " %-11s %-14s %-10s\n", "DCHERR", "DCHERRMSK", "DSTAT");
        for (i = first_chan; i < first_chan + MIC_DMA_NUM_CHAN; i++) {
                ch = &mic_dma_dev->mic_ch[i];
                chan_num = ch->ch_num;
                seq_printf(s, "%-10i| %-#10x %-#10x %-#10x %-#10x",
                           chan_num,
                           mic_dma_read_reg(ch, MIC_DMA_REG_DCAR),
                           mic_dma_read_reg(ch, MIC_DMA_REG_DTPR),
                           mic_dma_read_reg(ch, MIC_DMA_REG_DHPR),
                           mic_dma_read_reg(ch, MIC_DMA_REG_DRAR_HI));
                seq_printf(s, " %-#10x %-#10x %-#14x %-#10x\n",
                           mic_dma_read_reg(ch, MIC_DMA_REG_DRAR_LO),
                           mic_dma_read_reg(ch, MIC_DMA_REG_DCHERR),
                           mic_dma_read_reg(ch, MIC_DMA_REG_DCHERRMSK),
                           mic_dma_read_reg(ch, MIC_DMA_REG_DSTAT));
        }
        return 0;
}

static int mic_dma_reg_debug_open(struct inode *inode, struct file *file)
{
        return single_open(file, mic_dma_reg_seq_show, inode->i_private);
}

static int mic_dma_reg_debug_release(struct inode *inode, struct file *file)
{
        return single_release(inode, file);
}

static const struct file_operations mic_dma_reg_ops = {
        .owner   = THIS_MODULE,
        .open    = mic_dma_reg_debug_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = mic_dma_reg_debug_release
};

/* Debugfs parent dir */
static struct dentry *mic_dma_dbg;

static int mic_dma_driver_probe(struct mbus_device *mbdev)
{
        struct mic_dma_device *mic_dma_dev;
        enum mic_dma_chan_owner owner;

        if (MBUS_DEV_DMA_MIC == mbdev->id.device)
                owner = MIC_DMA_CHAN_MIC;
        else
                owner = MIC_DMA_CHAN_HOST;

        mic_dma_dev = mic_dma_dev_reg(mbdev, owner);
        dev_set_drvdata(&mbdev->dev, mic_dma_dev);

        if (mic_dma_dbg) {
                mic_dma_dev->dbg_dir = debugfs_create_dir(dev_name(&mbdev->dev),
                                                          mic_dma_dbg);
                if (mic_dma_dev->dbg_dir)
                        debugfs_create_file("mic_dma_reg", 0444,
                                            mic_dma_dev->dbg_dir, mic_dma_dev,
                                            &mic_dma_reg_ops);
        }
        return 0;
}

static void mic_dma_driver_remove(struct mbus_device *mbdev)
{
        struct mic_dma_device *mic_dma_dev;

        mic_dma_dev = dev_get_drvdata(&mbdev->dev);
        debugfs_remove_recursive(mic_dma_dev->dbg_dir);
        mic_dma_dev_unreg(mic_dma_dev);
}

static struct mbus_device_id id_table[] = {
        {MBUS_DEV_DMA_MIC, MBUS_DEV_ANY_ID},
        {MBUS_DEV_DMA_HOST, MBUS_DEV_ANY_ID},
        {0},
};

static struct mbus_driver mic_dma_driver = {
        .driver.name =  KBUILD_MODNAME,
        .driver.owner = THIS_MODULE,
        .id_table = id_table,
        .probe = mic_dma_driver_probe,
        .remove = mic_dma_driver_remove,
};

static int __init mic_x100_dma_init(void)
{
        int rc = mbus_register_driver(&mic_dma_driver);
        if (rc)
                return rc;
        mic_dma_dbg = debugfs_create_dir(KBUILD_MODNAME, NULL);
        return 0;
}

static void __exit mic_x100_dma_exit(void)
{
        debugfs_remove_recursive(mic_dma_dbg);
        mbus_unregister_driver(&mic_dma_driver);
}

module_init(mic_x100_dma_init);
module_exit(mic_x100_dma_exit);

MODULE_DEVICE_TABLE(mbus, id_table);
MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("Intel(R) MIC X100 DMA Driver");
MODULE_LICENSE("GPL v2");