/*
 * driver/dma/coh901318.c
 *
 * Copyright (C) 2007-2009 ST-Ericsson
 * License terms: GNU General Public License (GPL) version 2
 * DMA driver for COH 901 318
 * Author: Per Friden <per.friden@stericsson.com>
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h> /* printk() */
#include <linux/fs.h> /* everything... */
#include <linux/scatterlist.h>
#include <linux/slab.h> /* kmalloc() */
#include <linux/dmaengine.h>
#include <linux/platform_device.h>
#include <linux/device.h>
#include <linux/irqreturn.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/debugfs.h>
#include <mach/coh901318.h>

#include "coh901318_lli.h"
#include "dmaengine.h"

#define COHC_2_DEV(cohc) (&cohc->chan.dev->device)

#ifdef VERBOSE_DEBUG
#define COH_DBG(x) ({ if (1) x; 0; })
#else
#define COH_DBG(x) ({ if (0) x; 0; })
#endif

struct coh901318_desc {
        struct dma_async_tx_descriptor desc;
        struct list_head node;
        struct scatterlist *sg;
        unsigned int sg_len;
        struct coh901318_lli *lli;
        enum dma_transfer_direction dir;
        unsigned long flags;
        u32 head_config;
        u32 head_ctrl;
};

struct coh901318_base {
        struct device *dev;
        void __iomem *virtbase;
        struct coh901318_pool pool;
        struct powersave pm;
        struct dma_device dma_slave;
        struct dma_device dma_memcpy;
        struct coh901318_chan *chans;
        struct coh901318_platform *platform;
};

struct coh901318_chan {
        spinlock_t lock;
        int allocated;
        int id;
        int stopped;

        struct work_struct free_work;
        struct dma_chan chan;

        struct tasklet_struct tasklet;

        struct list_head active;
        struct list_head queue;
        struct list_head free;

        unsigned long nbr_active_done;
        unsigned long busy;

        u32 runtime_addr;
        u32 runtime_ctrl;

        struct coh901318_base *base;
};

static void coh901318_list_print(struct coh901318_chan *cohc,
                                 struct coh901318_lli *lli)
{
        struct coh901318_lli *l = lli;
        int i = 0;

        while (l) {
                dev_vdbg(COHC_2_DEV(cohc), "i %d, lli %p, ctrl 0x%x, src 0x%x"
                         ", dst 0x%x, link 0x%x virt_link_addr 0x%p\n",
                         i, l, l->control, l->src_addr, l->dst_addr,
                         l->link_addr, l->virt_link_addr);
                i++;
                l = l->virt_link_addr;
        }
}

#ifdef CONFIG_DEBUG_FS

#define COH901318_DEBUGFS_ASSIGN(x, y) (x = y)

static struct coh901318_base *debugfs_dma_base;
static struct dentry *dma_dentry;

static int coh901318_debugfs_read(struct file *file, char __user *buf,
                                  size_t count, loff_t *f_pos)
{
        u64 started_channels = debugfs_dma_base->pm.started_channels;
        int pool_count = debugfs_dma_base->pool.debugfs_pool_counter;
        int i;
        int ret = 0;
        char *dev_buf;
        char *tmp;
        int dev_size;

        dev_buf = kmalloc(4*1024, GFP_KERNEL);
        if (dev_buf == NULL)
                goto err_kmalloc;
        tmp = dev_buf;

        tmp += sprintf(tmp, "DMA -- enabled dma channels\n");

        for (i = 0; i < debugfs_dma_base->platform->max_channels; i++)
                if (started_channels & (1 << i))
                        tmp += sprintf(tmp, "channel %d\n", i);

        tmp += sprintf(tmp, "Pool alloc nbr %d\n", pool_count);
        dev_size = tmp  - dev_buf;

        /* No more to read if offset != 0 */
        if (*f_pos > dev_size)
                goto out;

        if (count > dev_size - *f_pos)
                count = dev_size - *f_pos;

        if (copy_to_user(buf, dev_buf + *f_pos, count))
                ret = -EINVAL;
        ret = count;
        *f_pos += count;

 out:
        kfree(dev_buf);
        return ret;

 err_kmalloc:
        return 0;
}

static const struct file_operations coh901318_debugfs_status_operations = {
        .owner          = THIS_MODULE,
        .open           = simple_open,
        .read           = coh901318_debugfs_read,
        .llseek         = default_llseek,
};


static int __init init_coh901318_debugfs(void)
{

        dma_dentry = debugfs_create_dir("dma", NULL);

        (void) debugfs_create_file("status",
                                   S_IFREG | S_IRUGO,
                                   dma_dentry, NULL,
                                   &coh901318_debugfs_status_operations);
        return 0;
}

static void __exit exit_coh901318_debugfs(void)
{
        debugfs_remove_recursive(dma_dentry);
}

module_init(init_coh901318_debugfs);
module_exit(exit_coh901318_debugfs);
#else

#define COH901318_DEBUGFS_ASSIGN(x, y)

#endif /* CONFIG_DEBUG_FS */

static inline struct coh901318_chan *to_coh901318_chan(struct dma_chan *chan)
{
        return container_of(chan, struct coh901318_chan, chan);
}

static inline dma_addr_t
cohc_dev_addr(struct coh901318_chan *cohc)
{
        /* Runtime supplied address will take precedence */
        if (cohc->runtime_addr)
                return cohc->runtime_addr;
        return cohc->base->platform->chan_conf[cohc->id].dev_addr;
}

static inline const struct coh901318_params *
cohc_chan_param(struct coh901318_chan *cohc)
{
        return &cohc->base->platform->chan_conf[cohc->id].param;
}

static inline const struct coh_dma_channel *
cohc_chan_conf(struct coh901318_chan *cohc)
{
        return &cohc->base->platform->chan_conf[cohc->id];
}

static void enable_powersave(struct coh901318_chan *cohc)
{
        unsigned long flags;
        struct powersave *pm = &cohc->base->pm;

        spin_lock_irqsave(&pm->lock, flags);

        pm->started_channels &= ~(1ULL << cohc->id);

        if (!pm->started_channels) {
                /* DMA no longer intends to access memory */
                cohc->base->platform->access_memory_state(cohc->base->dev,
                                                          false);
        }

        spin_unlock_irqrestore(&pm->lock, flags);
}
static void disable_powersave(struct coh901318_chan *cohc)
{
        unsigned long flags;
        struct powersave *pm = &cohc->base->pm;

        spin_lock_irqsave(&pm->lock, flags);

        if (!pm->started_channels) {
                /* DMA intends to access memory */
                cohc->base->platform->access_memory_state(cohc->base->dev,
                                                          true);
        }

        pm->started_channels |= (1ULL << cohc->id);

        spin_unlock_irqrestore(&pm->lock, flags);
}

static inline int coh901318_set_ctrl(struct coh901318_chan *cohc, u32 control)
{
        int channel = cohc->id;
        void __iomem *virtbase = cohc->base->virtbase;

        writel(control,
               virtbase + COH901318_CX_CTRL +
               COH901318_CX_CTRL_SPACING * channel);
        return 0;
}

static inline int coh901318_set_conf(struct coh901318_chan *cohc, u32 conf)
{
        int channel = cohc->id;
        void __iomem *virtbase = cohc->base->virtbase;

        writel(conf,
               virtbase + COH901318_CX_CFG +
               COH901318_CX_CFG_SPACING*channel);
        return 0;
}


static int coh901318_start(struct coh901318_chan *cohc)
{
        u32 val;
        int channel = cohc->id;
        void __iomem *virtbase = cohc->base->virtbase;

        disable_powersave(cohc);

        val = readl(virtbase + COH901318_CX_CFG +
                    COH901318_CX_CFG_SPACING * channel);

        /* Enable channel */
        val |= COH901318_CX_CFG_CH_ENABLE;
        writel(val, virtbase + COH901318_CX_CFG +
               COH901318_CX_CFG_SPACING * channel);

        return 0;
}

static int coh901318_prep_linked_list(struct coh901318_chan *cohc,
                                      struct coh901318_lli *lli)
{
        int channel = cohc->id;
        void __iomem *virtbase = cohc->base->virtbase;

        BUG_ON(readl(virtbase + COH901318_CX_STAT +
                     COH901318_CX_STAT_SPACING*channel) &
               COH901318_CX_STAT_ACTIVE);

        writel(lli->src_addr,
               virtbase + COH901318_CX_SRC_ADDR +
               COH901318_CX_SRC_ADDR_SPACING * channel);

        writel(lli->dst_addr, virtbase +
               COH901318_CX_DST_ADDR +
               COH901318_CX_DST_ADDR_SPACING * channel);

        writel(lli->link_addr, virtbase + COH901318_CX_LNK_ADDR +
               COH901318_CX_LNK_ADDR_SPACING * channel);

        writel(lli->control, virtbase + COH901318_CX_CTRL +
               COH901318_CX_CTRL_SPACING * channel);

        return 0;
}

static struct coh901318_desc *
coh901318_desc_get(struct coh901318_chan *cohc)
{
        struct coh901318_desc *desc;

        if (list_empty(&cohc->free)) {
                /* alloc new desc because we're out of used ones
                 * TODO: alloc a pile of descs instead of just one,
                 * avoid many small allocations.
                 */
                desc = kzalloc(sizeof(struct coh901318_desc), GFP_NOWAIT);
                if (desc == NULL)
                        goto out;
                INIT_LIST_HEAD(&desc->node);
                dma_async_tx_descriptor_init(&desc->desc, &cohc->chan);
        } else {
                /* Reuse an old desc. */
                desc = list_first_entry(&cohc->free,
                                        struct coh901318_desc,
                                        node);
                list_del(&desc->node);
                /* Initialize it a bit so it's not insane */
                desc->sg = NULL;
                desc->sg_len = 0;
                desc->desc.callback = NULL;
                desc->desc.callback_param = NULL;
        }

 out:
        return desc;
}

static void
coh901318_desc_free(struct coh901318_chan *cohc, struct coh901318_desc *cohd)
{
        list_add_tail(&cohd->node, &cohc->free);
}

/* call with irq lock held */
static void
coh901318_desc_submit(struct coh901318_chan *cohc, struct coh901318_desc *desc)
{
        list_add_tail(&desc->node, &cohc->active);
}

static struct coh901318_desc *
coh901318_first_active_get(struct coh901318_chan *cohc)
{
        struct coh901318_desc *d;

        if (list_empty(&cohc->active))
                return NULL;

        d = list_first_entry(&cohc->active,
                             struct coh901318_desc,
                             node);
        return d;
}

static void
coh901318_desc_remove(struct coh901318_desc *cohd)
{
        list_del(&cohd->node);
}

static void
coh901318_desc_queue(struct coh901318_chan *cohc, struct coh901318_desc *desc)
{
        list_add_tail(&desc->node, &cohc->queue);
}

static struct coh901318_desc *
coh901318_first_queued(struct coh901318_chan *cohc)
{
        struct coh901318_desc *d;

        if (list_empty(&cohc->queue))
                return NULL;

        d = list_first_entry(&cohc->queue,
                             struct coh901318_desc,
                             node);
        return d;
}

static inline u32 coh901318_get_bytes_in_lli(struct coh901318_lli *in_lli)
{
        struct coh901318_lli *lli = in_lli;
        u32 bytes = 0;

        while (lli) {
                bytes += lli->control & COH901318_CX_CTRL_TC_VALUE_MASK;
                lli = lli->virt_link_addr;
        }
        return bytes;
}

/*
 * Get the number of bytes left to transfer on this channel,
 * it is unwise to call this before stopping the channel for
 * absolute measures, but for a rough guess you can still call
 * it.
 */
static u32 coh901318_get_bytes_left(struct dma_chan *chan)
{
        struct coh901318_chan *cohc = to_coh901318_chan(chan);
        struct coh901318_desc *cohd;
        struct list_head *pos;
        unsigned long flags;
        u32 left = 0;
        int i = 0;

        spin_lock_irqsave(&cohc->lock, flags);

        /*
         * If there are many queued jobs, we iterate and add the
         * size of them all. We take a special look on the first
         * job though, since it is probably active.
         */
        list_for_each(pos, &cohc->active) {
                /*
                 * The first job in the list will be working on the
                 * hardware. The job can be stopped but still active,
                 * so that the transfer counter is somewhere inside
                 * the buffer.
                 */
                cohd = list_entry(pos, struct coh901318_desc, node);

                if (i == 0) {
                        struct coh901318_lli *lli;
                        dma_addr_t ladd;

                        /* Read current transfer count value */
                        left = readl(cohc->base->virtbase +
                                     COH901318_CX_CTRL +
                                     COH901318_CX_CTRL_SPACING * cohc->id) &
                                COH901318_CX_CTRL_TC_VALUE_MASK;

                        /* See if the transfer is linked... */
                        ladd = readl(cohc->base->virtbase +
                                     COH901318_CX_LNK_ADDR +
                                     COH901318_CX_LNK_ADDR_SPACING *
                                     cohc->id) &
                                ~COH901318_CX_LNK_LINK_IMMEDIATE;
                        /* Single transaction */
                        if (!ladd)
                                continue;

                        /*
                         * Linked transaction, follow the lli, find the
                         * currently processing lli, and proceed to the next
                         */
                        lli = cohd->lli;
                        while (lli && lli->link_addr != ladd)
                                lli = lli->virt_link_addr;

                        if (lli)
                                lli = lli->virt_link_addr;

                        /*
                         * Follow remaining lli links around to count the total
                         * number of bytes left
                         */
                        left += coh901318_get_bytes_in_lli(lli);
                } else {
                        left += coh901318_get_bytes_in_lli(cohd->lli);
                }
                i++;
        }

        /* Also count bytes in the queued jobs */
        list_for_each(pos, &cohc->queue) {
                cohd = list_entry(pos, struct coh901318_desc, node);
                left += coh901318_get_bytes_in_lli(cohd->lli);
        }

        spin_unlock_irqrestore(&cohc->lock, flags);

        return left;
}

/*
 * Pauses a transfer without losing data. Enables power save.
 * Use this function in conjunction with coh901318_resume.
 */
static void coh901318_pause(struct dma_chan *chan)
{
        u32 val;
        unsigned long flags;
        struct coh901318_chan *cohc = to_coh901318_chan(chan);
        int channel = cohc->id;
        void __iomem *virtbase = cohc->base->virtbase;

        spin_lock_irqsave(&cohc->lock, flags);

        /* Disable channel in HW */
        val = readl(virtbase + COH901318_CX_CFG +
                    COH901318_CX_CFG_SPACING * channel);

        /* Stopping infinite transfer */
        if ((val & COH901318_CX_CTRL_TC_ENABLE) == 0 &&
            (val & COH901318_CX_CFG_CH_ENABLE))
                cohc->stopped = 1;


        val &= ~COH901318_CX_CFG_CH_ENABLE;
        /* Enable twice, HW bug work around */
        writel(val, virtbase + COH901318_CX_CFG +
               COH901318_CX_CFG_SPACING * channel);
        writel(val, virtbase + COH901318_CX_CFG +
               COH901318_CX_CFG_SPACING * channel);

        /* Spin-wait for it to actually go inactive */
        while (readl(virtbase + COH901318_CX_STAT+COH901318_CX_STAT_SPACING *
                     channel) & COH901318_CX_STAT_ACTIVE)
                cpu_relax();

        /* Check if we stopped an active job */
        if ((readl(virtbase + COH901318_CX_CTRL+COH901318_CX_CTRL_SPACING *
                   channel) & COH901318_CX_CTRL_TC_VALUE_MASK) > 0)
                cohc->stopped = 1;

        enable_powersave(cohc);

        spin_unlock_irqrestore(&cohc->lock, flags);
}

/* Resumes a transfer that has been stopped via 300_dma_stop(..).
   Power save is handled.
*/
static void coh901318_resume(struct dma_chan *chan)
{
        u32 val;
        unsigned long flags;
        struct coh901318_chan *cohc = to_coh901318_chan(chan);
        int channel = cohc->id;

        spin_lock_irqsave(&cohc->lock, flags);

        disable_powersave(cohc);

        if (cohc->stopped) {
                /* Enable channel in HW */
                val = readl(cohc->base->virtbase + COH901318_CX_CFG +
                            COH901318_CX_CFG_SPACING * channel);

                val |= COH901318_CX_CFG_CH_ENABLE;

                writel(val, cohc->base->virtbase + COH901318_CX_CFG +
                       COH901318_CX_CFG_SPACING*channel);

                cohc->stopped = 0;
        }

        spin_unlock_irqrestore(&cohc->lock, flags);
}

bool coh901318_filter_id(struct dma_chan *chan, void *chan_id)
{
        unsigned int ch_nr = (unsigned int) chan_id;

        if (ch_nr == to_coh901318_chan(chan)->id)
                return true;

        return false;
}
EXPORT_SYMBOL(coh901318_filter_id);

/*
 * DMA channel allocation
 */
static int coh901318_config(struct coh901318_chan *cohc,
                            struct coh901318_params *param)
{
        unsigned long flags;
        const struct coh901318_params *p;
        int channel = cohc->id;
        void __iomem *virtbase = cohc->base->virtbase;

        spin_lock_irqsave(&cohc->lock, flags);

        if (param)
                p = param;
        else
                p = &cohc->base->platform->chan_conf[channel].param;

        /* Clear any pending BE or TC interrupt */
        if (channel < 32) {
                writel(1 << channel, virtbase + COH901318_BE_INT_CLEAR1);
                writel(1 << channel, virtbase + COH901318_TC_INT_CLEAR1);
        } else {
                writel(1 << (channel - 32), virtbase +
                       COH901318_BE_INT_CLEAR2);
                writel(1 << (channel - 32), virtbase +
                       COH901318_TC_INT_CLEAR2);
        }

        coh901318_set_conf(cohc, p->config);
        coh901318_set_ctrl(cohc, p->ctrl_lli_last);

        spin_unlock_irqrestore(&cohc->lock, flags);

        return 0;
}

/* must lock when calling this function
 * start queued jobs, if any
 * TODO: start all queued jobs in one go
 *
 * Returns descriptor if queued job is started otherwise NULL.
 * If the queue is empty NULL is returned.
 */
static struct coh901318_desc *coh901318_queue_start(struct coh901318_chan *cohc)
{
        struct coh901318_desc *cohd;

        /*
         * start queued jobs, if any
         * TODO: transmit all queued jobs in one go
         */
        cohd = coh901318_first_queued(cohc);

        if (cohd != NULL) {
                /* Remove from queue */
                coh901318_desc_remove(cohd);
                /* initiate DMA job */
                cohc->busy = 1;

                coh901318_desc_submit(cohc, cohd);

                /* Program the transaction head */
                coh901318_set_conf(cohc, cohd->head_config);
                coh901318_set_ctrl(cohc, cohd->head_ctrl);
                coh901318_prep_linked_list(cohc, cohd->lli);

                /* start dma job on this channel */
                coh901318_start(cohc);

        }

        return cohd;
}

/*
 * This tasklet is called from the interrupt handler to
 * handle each descriptor (DMA job) that is sent to a channel.
 */
static void dma_tasklet(unsigned long data)
{
        struct coh901318_chan *cohc = (struct coh901318_chan *) data;
        struct coh901318_desc *cohd_fin;
        unsigned long flags;
        dma_async_tx_callback callback;
        void *callback_param;

        dev_vdbg(COHC_2_DEV(cohc), "[%s] chan_id %d"
                 " nbr_active_done %ld\n", __func__,
                 cohc->id, cohc->nbr_active_done);

        spin_lock_irqsave(&cohc->lock, flags);

        /* get first active descriptor entry from list */
        cohd_fin = coh901318_first_active_get(cohc);

        if (cohd_fin == NULL)
                goto err;

        /* locate callback to client */
        callback = cohd_fin->desc.callback;
        callback_param = cohd_fin->desc.callback_param;

        /* sign this job as completed on the channel */
        dma_cookie_complete(&cohd_fin->desc);

        /* release the lli allocation and remove the descriptor */
        coh901318_lli_free(&cohc->base->pool, &cohd_fin->lli);

        /* return desc to free-list */
        coh901318_desc_remove(cohd_fin);
        coh901318_desc_free(cohc, cohd_fin);

        spin_unlock_irqrestore(&cohc->lock, flags);

        /* Call the callback when we're done */
        if (callback)
                callback(callback_param);

        spin_lock_irqsave(&cohc->lock, flags);

        /*
         * If another interrupt fired while the tasklet was scheduling,
         * we don't get called twice, so we have this number of active
         * counter that keep track of the number of IRQs expected to
         * be handled for this channel. If there happen to be more than
         * one IRQ to be ack:ed, we simply schedule this tasklet again.
         */
        cohc->nbr_active_done--;
        if (cohc->nbr_active_done) {
                dev_dbg(COHC_2_DEV(cohc), "scheduling tasklet again, new IRQs "
                        "came in while we were scheduling this tasklet\n");
                if (cohc_chan_conf(cohc)->priority_high)
                        tasklet_hi_schedule(&cohc->tasklet);
                else
                        tasklet_schedule(&cohc->tasklet);
        }

        spin_unlock_irqrestore(&cohc->lock, flags);

        return;

 err:
        spin_unlock_irqrestore(&cohc->lock, flags);
        dev_err(COHC_2_DEV(cohc), "[%s] No active dma desc\n", __func__);
}


/* called from interrupt context */
static void dma_tc_handle(struct coh901318_chan *cohc)
{
        /*
         * If the channel is not allocated, then we shouldn't have
         * any TC interrupts on it.
         */
        if (!cohc->allocated) {
                dev_err(COHC_2_DEV(cohc), "spurious interrupt from "
                        "unallocated channel\n");
                return;
        }

        spin_lock(&cohc->lock);

        /*
         * When we reach this point, at least one queue item
         * should have been moved over from cohc->queue to
         * cohc->active and run to completion, that is why we're
         * getting a terminal count interrupt is it not?
         * If you get this BUG() the most probable cause is that
         * the individual nodes in the lli chain have IRQ enabled,
         * so check your platform config for lli chain ctrl.
         */
        BUG_ON(list_empty(&cohc->active));

        cohc->nbr_active_done++;

        /*
         * This attempt to take a job from cohc->queue, put it
         * into cohc->active and start it.
         */
        if (coh901318_queue_start(cohc) == NULL)
                cohc->busy = 0;

        spin_unlock(&cohc->lock);

        /*
         * This tasklet will remove items from cohc->active
         * and thus terminates them.
         */
        if (cohc_chan_conf(cohc)->priority_high)
                tasklet_hi_schedule(&cohc->tasklet);
        else
                tasklet_schedule(&cohc->tasklet);
}


static irqreturn_t dma_irq_handler(int irq, void *dev_id)
{
        u32 status1;
        u32 status2;
        int i;
        int ch;
        struct coh901318_base *base  = dev_id;
        struct coh901318_chan *cohc;
        void __iomem *virtbase = base->virtbase;

        status1 = readl(virtbase + COH901318_INT_STATUS1);
        status2 = readl(virtbase + COH901318_INT_STATUS2);

        if (unlikely(status1 == 0 && status2 == 0)) {
                dev_warn(base->dev, "spurious DMA IRQ from no channel!\n");
                return IRQ_HANDLED;
        }

        /* TODO: consider handle IRQ in tasklet here to
         *       minimize interrupt latency */

        /* Check the first 32 DMA channels for IRQ */
        while (status1) {
                /* Find first bit set, return as a number. */
                i = ffs(status1) - 1;
                ch = i;

                cohc = &base->chans[ch];
                spin_lock(&cohc->lock);

                /* Mask off this bit */
                status1 &= ~(1 << i);
                /* Check the individual channel bits */
                if (test_bit(i, virtbase + COH901318_BE_INT_STATUS1)) {
                        dev_crit(COHC_2_DEV(cohc),
                                 "DMA bus error on channel %d!\n", ch);
                        BUG_ON(1);
                        /* Clear BE interrupt */
                        __set_bit(i, virtbase + COH901318_BE_INT_CLEAR1);
                } else {
                        /* Caused by TC, really? */
                        if (unlikely(!test_bit(i, virtbase +
                                               COH901318_TC_INT_STATUS1))) {
                                dev_warn(COHC_2_DEV(cohc),
                                         "ignoring interrupt not caused by terminal count on channel %d\n", ch);
                                /* Clear TC interrupt */
                                BUG_ON(1);
                                __set_bit(i, virtbase + COH901318_TC_INT_CLEAR1);
                        } else {
                                /* Enable powersave if transfer has finished */
                                if (!(readl(virtbase + COH901318_CX_STAT +
                                            COH901318_CX_STAT_SPACING*ch) &
                                      COH901318_CX_STAT_ENABLED)) {
                                        enable_powersave(cohc);
                                }

                                /* Must clear TC interrupt before calling
                                 * dma_tc_handle
                                 * in case tc_handle initiate a new dma job
                                 */
                                __set_bit(i, virtbase + COH901318_TC_INT_CLEAR1);

                                dma_tc_handle(cohc);
                        }
                }
                spin_unlock(&cohc->lock);
        }

        /* Check the remaining 32 DMA channels for IRQ */
        while (status2) {
                /* Find first bit set, return as a number. */
                i = ffs(status2) - 1;
                ch = i + 32;
                cohc = &base->chans[ch];
                spin_lock(&cohc->lock);

                /* Mask off this bit */
                status2 &= ~(1 << i);
                /* Check the individual channel bits */
                if (test_bit(i, virtbase + COH901318_BE_INT_STATUS2)) {
                        dev_crit(COHC_2_DEV(cohc),
                                 "DMA bus error on channel %d!\n", ch);
                        /* Clear BE interrupt */
                        BUG_ON(1);
                        __set_bit(i, virtbase + COH901318_BE_INT_CLEAR2);
                } else {
                        /* Caused by TC, really? */
                        if (unlikely(!test_bit(i, virtbase +
                                               COH901318_TC_INT_STATUS2))) {
                                dev_warn(COHC_2_DEV(cohc),
                                         "ignoring interrupt not caused by terminal count on channel %d\n", ch);
                                /* Clear TC interrupt */
                                __set_bit(i, virtbase + COH901318_TC_INT_CLEAR2);
                                BUG_ON(1);
                        } else {
                                /* Enable powersave if transfer has finished */
                                if (!(readl(virtbase + COH901318_CX_STAT +
                                            COH901318_CX_STAT_SPACING*ch) &
                                      COH901318_CX_STAT_ENABLED)) {
                                        enable_powersave(cohc);
                                }
                                /* Must clear TC interrupt before calling
                                 * dma_tc_handle
                                 * in case tc_handle initiate a new dma job
                                 */
                                __set_bit(i, virtbase + COH901318_TC_INT_CLEAR2);

                                dma_tc_handle(cohc);
                        }
                }
                spin_unlock(&cohc->lock);
        }

        return IRQ_HANDLED;
}

static int coh901318_alloc_chan_resources(struct dma_chan *chan)
{
        struct coh901318_chan   *cohc = to_coh901318_chan(chan);
        unsigned long flags;

        dev_vdbg(COHC_2_DEV(cohc), "[%s] DMA channel %d\n",
                 __func__, cohc->id);

        if (chan->client_count > 1)
                return -EBUSY;

        spin_lock_irqsave(&cohc->lock, flags);

        coh901318_config(cohc, NULL);

        cohc->allocated = 1;
        dma_cookie_init(chan);

        spin_unlock_irqrestore(&cohc->lock, flags);

        return 1;
}

static void
coh901318_free_chan_resources(struct dma_chan *chan)
{
        struct coh901318_chan   *cohc = to_coh901318_chan(chan);
        int channel = cohc->id;
        unsigned long flags;

        spin_lock_irqsave(&cohc->lock, flags);

        /* Disable HW */
        writel(0x00000000U, cohc->base->virtbase + COH901318_CX_CFG +
               COH901318_CX_CFG_SPACING*channel);
        writel(0x00000000U, cohc->base->virtbase + COH901318_CX_CTRL +
               COH901318_CX_CTRL_SPACING*channel);

        cohc->allocated = 0;

        spin_unlock_irqrestore(&cohc->lock, flags);

        chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
}


static dma_cookie_t
coh901318_tx_submit(struct dma_async_tx_descriptor *tx)
{
        struct coh901318_desc *cohd = container_of(tx, struct coh901318_desc,
                                                   desc);
        struct coh901318_chan *cohc = to_coh901318_chan(tx->chan);
        unsigned long flags;
        dma_cookie_t cookie;

        spin_lock_irqsave(&cohc->lock, flags);
        cookie = dma_cookie_assign(tx);

        coh901318_desc_queue(cohc, cohd);

        spin_unlock_irqrestore(&cohc->lock, flags);

        return cookie;
}

static struct dma_async_tx_descriptor *
coh901318_prep_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
                      size_t size, unsigned long flags)
{
        struct coh901318_lli *lli;
        struct coh901318_desc *cohd;
        unsigned long flg;
        struct coh901318_chan *cohc = to_coh901318_chan(chan);
        int lli_len;
        u32 ctrl_last = cohc_chan_param(cohc)->ctrl_lli_last;
        int ret;

        spin_lock_irqsave(&cohc->lock, flg);

        dev_vdbg(COHC_2_DEV(cohc),
                 "[%s] channel %d src 0x%x dest 0x%x size %d\n",
                 __func__, cohc->id, src, dest, size);

        if (flags & DMA_PREP_INTERRUPT)
                /* Trigger interrupt after last lli */
                ctrl_last |= COH901318_CX_CTRL_TC_IRQ_ENABLE;

        lli_len = size >> MAX_DMA_PACKET_SIZE_SHIFT;
        if ((lli_len << MAX_DMA_PACKET_SIZE_SHIFT) < size)
                lli_len++;

        lli = coh901318_lli_alloc(&cohc->base->pool, lli_len);

        if (lli == NULL)
                goto err;

        ret = coh901318_lli_fill_memcpy(
                &cohc->base->pool, lli, src, size, dest,
                cohc_chan_param(cohc)->ctrl_lli_chained,
                ctrl_last);
        if (ret)
                goto err;

        COH_DBG(coh901318_list_print(cohc, lli));

        /* Pick a descriptor to handle this transfer */

        cohd = coh901318_desc_get(cohc);
        cohd->lli = lli;
        cohd->flags = flags;
        cohd->desc.tx_submit = coh901318_tx_submit;

        spin_unlock_irqrestore(&cohc->lock, flg);

        return &cohd->desc;
 err:
        spin_unlock_irqrestore(&cohc->lock, flg);
        return NULL;
}

static struct dma_async_tx_descriptor *
coh901318_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
                        unsigned int sg_len, enum dma_transfer_direction direction,
                        unsigned long flags, void *context)
{
        struct coh901318_chan *cohc = to_coh901318_chan(chan);
        struct coh901318_lli *lli;
        struct coh901318_desc *cohd;
        const struct coh901318_params *params;
        struct scatterlist *sg;
        int len = 0;
        int size;
        int i;
        u32 ctrl_chained = cohc_chan_param(cohc)->ctrl_lli_chained;
        u32 ctrl = cohc_chan_param(cohc)->ctrl_lli;
        u32 ctrl_last = cohc_chan_param(cohc)->ctrl_lli_last;
        u32 config;
        unsigned long flg;
        int ret;

        if (!sgl)
                goto out;
        if (sg_dma_len(sgl) == 0)
                goto out;

        spin_lock_irqsave(&cohc->lock, flg);

        dev_vdbg(COHC_2_DEV(cohc), "[%s] sg_len %d dir %d\n",
                 __func__, sg_len, direction);

        if (flags & DMA_PREP_INTERRUPT)
                /* Trigger interrupt after last lli */
                ctrl_last |= COH901318_CX_CTRL_TC_IRQ_ENABLE;

        params = cohc_chan_param(cohc);
        config = params->config;
        /*
         * Add runtime-specific control on top, make
         * sure the bits you set per peripheral channel are
         * cleared in the default config from the platform.
         */
        ctrl_chained |= cohc->runtime_ctrl;
        ctrl_last |= cohc->runtime_ctrl;
        ctrl |= cohc->runtime_ctrl;

        if (direction == DMA_MEM_TO_DEV) {
                u32 tx_flags = COH901318_CX_CTRL_PRDD_SOURCE |
                        COH901318_CX_CTRL_SRC_ADDR_INC_ENABLE;

                config |= COH901318_CX_CFG_RM_MEMORY_TO_PRIMARY;
                ctrl_chained |= tx_flags;
                ctrl_last |= tx_flags;
                ctrl |= tx_flags;
        } else if (direction == DMA_DEV_TO_MEM) {
                u32 rx_flags = COH901318_CX_CTRL_PRDD_DEST |
                        COH901318_CX_CTRL_DST_ADDR_INC_ENABLE;

                config |= COH901318_CX_CFG_RM_PRIMARY_TO_MEMORY;
                ctrl_chained |= rx_flags;
                ctrl_last |= rx_flags;
                ctrl |= rx_flags;
        } else
                goto err_direction;

        /* The dma only supports transmitting packages up to
         * MAX_DMA_PACKET_SIZE. Calculate to total number of
         * dma elemts required to send the entire sg list
         */
        for_each_sg(sgl, sg, sg_len, i) {
                unsigned int factor;
                size = sg_dma_len(sg);

                if (size <= MAX_DMA_PACKET_SIZE) {
                        len++;
                        continue;
                }

                factor = size >> MAX_DMA_PACKET_SIZE_SHIFT;
                if ((factor << MAX_DMA_PACKET_SIZE_SHIFT) < size)
                        factor++;

                len += factor;
        }

        pr_debug("Allocate %d lli:s for this transfer\n", len);
        lli = coh901318_lli_alloc(&cohc->base->pool, len);

        if (lli == NULL)
                goto err_dma_alloc;

        /* initiate allocated lli list */
        ret = coh901318_lli_fill_sg(&cohc->base->pool, lli, sgl, sg_len,
                                    cohc_dev_addr(cohc),
                                    ctrl_chained,
                                    ctrl,
                                    ctrl_last,
                                    direction, COH901318_CX_CTRL_TC_IRQ_ENABLE);
        if (ret)
                goto err_lli_fill;


        COH_DBG(coh901318_list_print(cohc, lli));

        /* Pick a descriptor to handle this transfer */
        cohd = coh901318_desc_get(cohc);
        cohd->head_config = config;
        /*
         * Set the default head ctrl for the channel to the one from the
         * lli, things may have changed due to odd buffer alignment
         * etc.
         */
        cohd->head_ctrl = lli->control;
        cohd->dir = direction;
        cohd->flags = flags;
        cohd->desc.tx_submit = coh901318_tx_submit;
        cohd->lli = lli;

        spin_unlock_irqrestore(&cohc->lock, flg);

        return &cohd->desc;
 err_lli_fill:
 err_dma_alloc:
 err_direction:
        spin_unlock_irqrestore(&cohc->lock, flg);
 out:
        return NULL;
}

static enum dma_status
coh901318_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
                 struct dma_tx_state *txstate)
{
        struct coh901318_chan *cohc = to_coh901318_chan(chan);
        enum dma_status ret;

        ret = dma_cookie_status(chan, cookie, txstate);
        /* FIXME: should be conditional on ret != DMA_SUCCESS? */
        dma_set_residue(txstate, coh901318_get_bytes_left(chan));

        if (ret == DMA_IN_PROGRESS && cohc->stopped)
                ret = DMA_PAUSED;

        return ret;
}

static void
coh901318_issue_pending(struct dma_chan *chan)
{
        struct coh901318_chan *cohc = to_coh901318_chan(chan);
        unsigned long flags;

        spin_lock_irqsave(&cohc->lock, flags);

        /*
         * Busy means that pending jobs are already being processed,
         * and then there is no point in starting the queue: the
         * terminal count interrupt on the channel will take the next
         * job on the queue and execute it anyway.
         */
        if (!cohc->busy)
                coh901318_queue_start(cohc);

        spin_unlock_irqrestore(&cohc->lock, flags);
}

/*
 * Here we wrap in the runtime dma control interface
 */
struct burst_table {
        int burst_8bit;
        int burst_16bit;
        int burst_32bit;
        u32 reg;
};

static const struct burst_table burst_sizes[] = {
        {
                .burst_8bit = 64,
                .burst_16bit = 32,
                .burst_32bit = 16,
                .reg = COH901318_CX_CTRL_BURST_COUNT_64_BYTES,
        },
        {
                .burst_8bit = 48,
                .burst_16bit = 24,
                .burst_32bit = 12,
                .reg = COH901318_CX_CTRL_BURST_COUNT_48_BYTES,
        },
        {
                .burst_8bit = 32,
                .burst_16bit = 16,
                .burst_32bit = 8,
                .reg = COH901318_CX_CTRL_BURST_COUNT_32_BYTES,
        },
        {
                .burst_8bit = 16,
                .burst_16bit = 8,
                .burst_32bit = 4,
                .reg = COH901318_CX_CTRL_BURST_COUNT_16_BYTES,
        },
        {
                .burst_8bit = 8,
                .burst_16bit = 4,
                .burst_32bit = 2,
                .reg = COH901318_CX_CTRL_BURST_COUNT_8_BYTES,
        },
        {
                .burst_8bit = 4,
                .burst_16bit = 2,
                .burst_32bit = 1,
                .reg = COH901318_CX_CTRL_BURST_COUNT_4_BYTES,
        },
        {
                .burst_8bit = 2,
                .burst_16bit = 1,
                .burst_32bit = 0,
                .reg = COH901318_CX_CTRL_BURST_COUNT_2_BYTES,
        },
        {
                .burst_8bit = 1,
                .burst_16bit = 0,
                .burst_32bit = 0,
                .reg = COH901318_CX_CTRL_BURST_COUNT_1_BYTE,
        },
};

static void coh901318_dma_set_runtimeconfig(struct dma_chan *chan,
                        struct dma_slave_config *config)
{
        struct coh901318_chan *cohc = to_coh901318_chan(chan);
        dma_addr_t addr;
        enum dma_slave_buswidth addr_width;
        u32 maxburst;
        u32 runtime_ctrl = 0;
        int i = 0;

        /* We only support mem to per or per to mem transfers */
        if (config->direction == DMA_DEV_TO_MEM) {
                addr = config->src_addr;
                addr_width = config->src_addr_width;
                maxburst = config->src_maxburst;
        } else if (config->direction == DMA_MEM_TO_DEV) {
                addr = config->dst_addr;
                addr_width = config->dst_addr_width;
                maxburst = config->dst_maxburst;
        } else {
                dev_err(COHC_2_DEV(cohc), "illegal channel mode\n");
                return;
        }

        dev_dbg(COHC_2_DEV(cohc), "configure channel for %d byte transfers\n",
                addr_width);
        switch (addr_width)  {
        case DMA_SLAVE_BUSWIDTH_1_BYTE:
                runtime_ctrl |=
                        COH901318_CX_CTRL_SRC_BUS_SIZE_8_BITS |
                        COH901318_CX_CTRL_DST_BUS_SIZE_8_BITS;

                while (i < ARRAY_SIZE(burst_sizes)) {
                        if (burst_sizes[i].burst_8bit <= maxburst)
                                break;
                        i++;
                }

                break;
        case DMA_SLAVE_BUSWIDTH_2_BYTES:
                runtime_ctrl |=
                        COH901318_CX_CTRL_SRC_BUS_SIZE_16_BITS |
                        COH901318_CX_CTRL_DST_BUS_SIZE_16_BITS;

                while (i < ARRAY_SIZE(burst_sizes)) {
                        if (burst_sizes[i].burst_16bit <= maxburst)
                                break;
                        i++;
                }

                break;
        case DMA_SLAVE_BUSWIDTH_4_BYTES:
                /* Direction doesn't matter here, it's 32/32 bits */
                runtime_ctrl |=
                        COH901318_CX_CTRL_SRC_BUS_SIZE_32_BITS |
                        COH901318_CX_CTRL_DST_BUS_SIZE_32_BITS;

                while (i < ARRAY_SIZE(burst_sizes)) {
                        if (burst_sizes[i].burst_32bit <= maxburst)
                                break;
                        i++;
                }

                break;
        default:
                dev_err(COHC_2_DEV(cohc),
                        "bad runtimeconfig: alien address width\n");
                return;
        }

        runtime_ctrl |= burst_sizes[i].reg;
        dev_dbg(COHC_2_DEV(cohc),
                "selected burst size %d bytes for address width %d bytes, maxburst %d\n",
                burst_sizes[i].burst_8bit, addr_width, maxburst);

        cohc->runtime_addr = addr;
        cohc->runtime_ctrl = runtime_ctrl;
}

static int
coh901318_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                  unsigned long arg)
{
        unsigned long flags;
        struct coh901318_chan *cohc = to_coh901318_chan(chan);
        struct coh901318_desc *cohd;
        void __iomem *virtbase = cohc->base->virtbase;

        if (cmd == DMA_SLAVE_CONFIG) {
                struct dma_slave_config *config =
                        (struct dma_slave_config *) arg;

                coh901318_dma_set_runtimeconfig(chan, config);
                return 0;
          }

        if (cmd == DMA_PAUSE) {
                coh901318_pause(chan);
                return 0;
        }

        if (cmd == DMA_RESUME) {
                coh901318_resume(chan);
                return 0;
        }

        if (cmd != DMA_TERMINATE_ALL)
                return -ENXIO;

        /* The remainder of this function terminates the transfer */
        coh901318_pause(chan);
        spin_lock_irqsave(&cohc->lock, flags);

        /* Clear any pending BE or TC interrupt */
        if (cohc->id < 32) {
                writel(1 << cohc->id, virtbase + COH901318_BE_INT_CLEAR1);
                writel(1 << cohc->id, virtbase + COH901318_TC_INT_CLEAR1);
        } else {
                writel(1 << (cohc->id - 32), virtbase +
                       COH901318_BE_INT_CLEAR2);
                writel(1 << (cohc->id - 32), virtbase +
                       COH901318_TC_INT_CLEAR2);
        }

        enable_powersave(cohc);

        while ((cohd = coh901318_first_active_get(cohc))) {
                /* release the lli allocation*/
                coh901318_lli_free(&cohc->base->pool, &cohd->lli);

                /* return desc to free-list */
                coh901318_desc_remove(cohd);
                coh901318_desc_free(cohc, cohd);
        }

        while ((cohd = coh901318_first_queued(cohc))) {
                /* release the lli allocation*/
                coh901318_lli_free(&cohc->base->pool, &cohd->lli);

                /* return desc to free-list */
                coh901318_desc_remove(cohd);
                coh901318_desc_free(cohc, cohd);
        }


        cohc->nbr_active_done = 0;
        cohc->busy = 0;

        spin_unlock_irqrestore(&cohc->lock, flags);

        return 0;
}

void coh901318_base_init(struct dma_device *dma, const int *pick_chans,
                         struct coh901318_base *base)
{
        int chans_i;
        int i = 0;
        struct coh901318_chan *cohc;

        INIT_LIST_HEAD(&dma->channels);

        for (chans_i = 0; pick_chans[chans_i] != -1; chans_i += 2) {
                for (i = pick_chans[chans_i]; i <= pick_chans[chans_i+1]; i++) {
                        cohc = &base->chans[i];

                        cohc->base = base;
                        cohc->chan.device = dma;
                        cohc->id = i;

                        /* TODO: do we really need this lock if only one
                         * client is connected to each channel?
                         */

                        spin_lock_init(&cohc->lock);

                        cohc->nbr_active_done = 0;
                        cohc->busy = 0;
                        INIT_LIST_HEAD(&cohc->free);
                        INIT_LIST_HEAD(&cohc->active);
                        INIT_LIST_HEAD(&cohc->queue);

                        tasklet_init(&cohc->tasklet, dma_tasklet,
                                     (unsigned long) cohc);

                        list_add_tail(&cohc->chan.device_node,
                                      &dma->channels);
                }
        }
}

static int __init coh901318_probe(struct platform_device *pdev)
{
        int err = 0;
        struct coh901318_platform *pdata;
        struct coh901318_base *base;
        int irq;
        struct resource *io;

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

        /* Map DMA controller registers to virtual memory */
        if (devm_request_mem_region(&pdev->dev,
                                    io->start,
                                    resource_size(io),
                                    pdev->dev.driver->name) == NULL)
                return -ENOMEM;

        pdata = pdev->dev.platform_data;
        if (!pdata)
                return -ENODEV;

        base = devm_kzalloc(&pdev->dev,
                            ALIGN(sizeof(struct coh901318_base), 4) +
                            pdata->max_channels *
                            sizeof(struct coh901318_chan),
                            GFP_KERNEL);
        if (!base)
                return -ENOMEM;

        base->chans = ((void *)base) + ALIGN(sizeof(struct coh901318_base), 4);

        base->virtbase = devm_ioremap(&pdev->dev, io->start, resource_size(io));
        if (!base->virtbase)
                return -ENOMEM;

        base->dev = &pdev->dev;
        base->platform = pdata;
        spin_lock_init(&base->pm.lock);
        base->pm.started_channels = 0;

        COH901318_DEBUGFS_ASSIGN(debugfs_dma_base, base);

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        err = devm_request_irq(&pdev->dev, irq, dma_irq_handler, IRQF_DISABLED,
                               "coh901318", base);
        if (err)
                return err;

        err = coh901318_pool_create(&base->pool, &pdev->dev,
                                    sizeof(struct coh901318_lli),
                                    32);
        if (err)
                return err;

        /* init channels for device transfers */
        coh901318_base_init(&base->dma_slave,  base->platform->chans_slave,
                            base);

        dma_cap_zero(base->dma_slave.cap_mask);
        dma_cap_set(DMA_SLAVE, base->dma_slave.cap_mask);

        base->dma_slave.device_alloc_chan_resources = coh901318_alloc_chan_resources;
        base->dma_slave.device_free_chan_resources = coh901318_free_chan_resources;
        base->dma_slave.device_prep_slave_sg = coh901318_prep_slave_sg;
        base->dma_slave.device_tx_status = coh901318_tx_status;
        base->dma_slave.device_issue_pending = coh901318_issue_pending;
        base->dma_slave.device_control = coh901318_control;
        base->dma_slave.dev = &pdev->dev;

        err = dma_async_device_register(&base->dma_slave);

        if (err)
                goto err_register_slave;

        /* init channels for memcpy */
        coh901318_base_init(&base->dma_memcpy, base->platform->chans_memcpy,
                            base);

        dma_cap_zero(base->dma_memcpy.cap_mask);
        dma_cap_set(DMA_MEMCPY, base->dma_memcpy.cap_mask);

        base->dma_memcpy.device_alloc_chan_resources = coh901318_alloc_chan_resources;
        base->dma_memcpy.device_free_chan_resources = coh901318_free_chan_resources;
        base->dma_memcpy.device_prep_dma_memcpy = coh901318_prep_memcpy;
        base->dma_memcpy.device_tx_status = coh901318_tx_status;
        base->dma_memcpy.device_issue_pending = coh901318_issue_pending;
        base->dma_memcpy.device_control = coh901318_control;
        base->dma_memcpy.dev = &pdev->dev;
        /*
         * This controller can only access address at even 32bit boundaries,
         * i.e. 2^2
         */
        base->dma_memcpy.copy_align = 2;
        err = dma_async_device_register(&base->dma_memcpy);

        if (err)
                goto err_register_memcpy;

        platform_set_drvdata(pdev, base);
        dev_info(&pdev->dev, "Initialized COH901318 DMA on virtual base 0x%08x\n",
                (u32) base->virtbase);

        return err;

 err_register_memcpy:
        dma_async_device_unregister(&base->dma_slave);
 err_register_slave:
        coh901318_pool_destroy(&base->pool);
        return err;
}

static int __exit coh901318_remove(struct platform_device *pdev)
{
        struct coh901318_base *base = platform_get_drvdata(pdev);

        dma_async_device_unregister(&base->dma_memcpy);
        dma_async_device_unregister(&base->dma_slave);
        coh901318_pool_destroy(&base->pool);
        return 0;
}


static struct platform_driver coh901318_driver = {
        .remove = __exit_p(coh901318_remove),
        .driver = {
                .name   = "coh901318",
        },
};

int __init coh901318_init(void)
{
        return platform_driver_probe(&coh901318_driver, coh901318_probe);
}
subsys_initcall(coh901318_init);

void __exit coh901318_exit(void)
{
        platform_driver_unregister(&coh901318_driver);
}
module_exit(coh901318_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Per Friden");