Linux 4.2.1

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

/*
 * timb_dma.c timberdale FPGA DMA 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.
 */

/* Supports:
 * Timberdale FPGA DMA engine
 */

#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include <linux/timb_dma.h>

#include "dmaengine.h"

#define DRIVER_NAME "timb-dma"

/* Global DMA registers */
#define TIMBDMA_ACR             0x34
#define TIMBDMA_32BIT_ADDR      0x01

#define TIMBDMA_ISR             0x080000
#define TIMBDMA_IPR             0x080004
#define TIMBDMA_IER             0x080008

/* Channel specific registers */
/* RX instances base addresses are 0x00, 0x40, 0x80 ...
 * TX instances base addresses are 0x18, 0x58, 0x98 ...
 */
#define TIMBDMA_INSTANCE_OFFSET         0x40
#define TIMBDMA_INSTANCE_TX_OFFSET      0x18

/* RX registers, relative the instance base */
#define TIMBDMA_OFFS_RX_DHAR    0x00
#define TIMBDMA_OFFS_RX_DLAR    0x04
#define TIMBDMA_OFFS_RX_LR      0x0C
#define TIMBDMA_OFFS_RX_BLR     0x10
#define TIMBDMA_OFFS_RX_ER      0x14
#define TIMBDMA_RX_EN           0x01
/* bytes per Row, video specific register
 * which is placed after the TX registers...
 */
#define TIMBDMA_OFFS_RX_BPRR    0x30

/* TX registers, relative the instance base */
#define TIMBDMA_OFFS_TX_DHAR    0x00
#define TIMBDMA_OFFS_TX_DLAR    0x04
#define TIMBDMA_OFFS_TX_BLR     0x0C
#define TIMBDMA_OFFS_TX_LR      0x14


#define TIMB_DMA_DESC_SIZE      8

struct timb_dma_desc {
        struct list_head                desc_node;
        struct dma_async_tx_descriptor  txd;
        u8                              *desc_list;
        unsigned int                    desc_list_len;
        bool                            interrupt;
};

struct timb_dma_chan {
        struct dma_chan         chan;
        void __iomem            *membase;
        spinlock_t              lock; /* Used to protect data structures,
                                        especially the lists and descriptors,
                                        from races between the tasklet and calls
                                        from above */
        bool                    ongoing;
        struct list_head        active_list;
        struct list_head        queue;
        struct list_head        free_list;
        unsigned int            bytes_per_line;
        enum dma_transfer_direction     direction;
        unsigned int            descs; /* Descriptors to allocate */
        unsigned int            desc_elems; /* number of elems per descriptor */
};

struct timb_dma {
        struct dma_device       dma;
        void __iomem            *membase;
        struct tasklet_struct   tasklet;
        struct timb_dma_chan    channels[0];
};

static struct device *chan2dev(struct dma_chan *chan)
{
        return &chan->dev->device;
}
static struct device *chan2dmadev(struct dma_chan *chan)
{
        return chan2dev(chan)->parent->parent;
}

static struct timb_dma *tdchantotd(struct timb_dma_chan *td_chan)
{
        int id = td_chan->chan.chan_id;
        return (struct timb_dma *)((u8 *)td_chan -
                id * sizeof(struct timb_dma_chan) - sizeof(struct timb_dma));
}

/* Must be called with the spinlock held */
static void __td_enable_chan_irq(struct timb_dma_chan *td_chan)
{
        int id = td_chan->chan.chan_id;
        struct timb_dma *td = tdchantotd(td_chan);
        u32 ier;

        /* enable interrupt for this channel */
        ier = ioread32(td->membase + TIMBDMA_IER);
        ier |= 1 << id;
        dev_dbg(chan2dev(&td_chan->chan), "Enabling irq: %d, IER: 0x%x\n", id,
                ier);
        iowrite32(ier, td->membase + TIMBDMA_IER);
}

/* Should be called with the spinlock held */
static bool __td_dma_done_ack(struct timb_dma_chan *td_chan)
{
        int id = td_chan->chan.chan_id;
        struct timb_dma *td = (struct timb_dma *)((u8 *)td_chan -
                id * sizeof(struct timb_dma_chan) - sizeof(struct timb_dma));
        u32 isr;
        bool done = false;

        dev_dbg(chan2dev(&td_chan->chan), "Checking irq: %d, td: %p\n", id, td);

        isr = ioread32(td->membase + TIMBDMA_ISR) & (1 << id);
        if (isr) {
                iowrite32(isr, td->membase + TIMBDMA_ISR);
                done = true;
        }

        return done;
}

static int td_fill_desc(struct timb_dma_chan *td_chan, u8 *dma_desc,
        struct scatterlist *sg, bool last)
{
        if (sg_dma_len(sg) > USHRT_MAX) {
                dev_err(chan2dev(&td_chan->chan), "Too big sg element\n");
                return -EINVAL;
        }

        /* length must be word aligned */
        if (sg_dma_len(sg) % sizeof(u32)) {
                dev_err(chan2dev(&td_chan->chan), "Incorrect length: %d\n",
                        sg_dma_len(sg));
                return -EINVAL;
        }

        dev_dbg(chan2dev(&td_chan->chan), "desc: %p, addr: 0x%llx\n",
                dma_desc, (unsigned long long)sg_dma_address(sg));

        dma_desc[7] = (sg_dma_address(sg) >> 24) & 0xff;
        dma_desc[6] = (sg_dma_address(sg) >> 16) & 0xff;
        dma_desc[5] = (sg_dma_address(sg) >> 8) & 0xff;
        dma_desc[4] = (sg_dma_address(sg) >> 0) & 0xff;

        dma_desc[3] = (sg_dma_len(sg) >> 8) & 0xff;
        dma_desc[2] = (sg_dma_len(sg) >> 0) & 0xff;

        dma_desc[1] = 0x00;
        dma_desc[0] = 0x21 | (last ? 0x02 : 0); /* tran, valid */

        return 0;
}

/* Must be called with the spinlock held */
static void __td_start_dma(struct timb_dma_chan *td_chan)
{
        struct timb_dma_desc *td_desc;

        if (td_chan->ongoing) {
                dev_err(chan2dev(&td_chan->chan),
                        "Transfer already ongoing\n");
                return;
        }

        td_desc = list_entry(td_chan->active_list.next, struct timb_dma_desc,
                desc_node);

        dev_dbg(chan2dev(&td_chan->chan),
                "td_chan: %p, chan: %d, membase: %p\n",
                td_chan, td_chan->chan.chan_id, td_chan->membase);

        if (td_chan->direction == DMA_DEV_TO_MEM) {

                /* descriptor address */
                iowrite32(0, td_chan->membase + TIMBDMA_OFFS_RX_DHAR);
                iowrite32(td_desc->txd.phys, td_chan->membase +
                        TIMBDMA_OFFS_RX_DLAR);
                /* Bytes per line */
                iowrite32(td_chan->bytes_per_line, td_chan->membase +
                        TIMBDMA_OFFS_RX_BPRR);
                /* enable RX */
                iowrite32(TIMBDMA_RX_EN, td_chan->membase + TIMBDMA_OFFS_RX_ER);
        } else {
                /* address high */
                iowrite32(0, td_chan->membase + TIMBDMA_OFFS_TX_DHAR);
                iowrite32(td_desc->txd.phys, td_chan->membase +
                        TIMBDMA_OFFS_TX_DLAR);
        }

        td_chan->ongoing = true;

        if (td_desc->interrupt)
                __td_enable_chan_irq(td_chan);
}

static void __td_finish(struct timb_dma_chan *td_chan)
{
        dma_async_tx_callback           callback;
        void                            *param;
        struct dma_async_tx_descriptor  *txd;
        struct timb_dma_desc            *td_desc;

        /* can happen if the descriptor is canceled */
        if (list_empty(&td_chan->active_list))
                return;

        td_desc = list_entry(td_chan->active_list.next, struct timb_dma_desc,
                desc_node);
        txd = &td_desc->txd;

        dev_dbg(chan2dev(&td_chan->chan), "descriptor %u complete\n",
                txd->cookie);

        /* make sure to stop the transfer */
        if (td_chan->direction == DMA_DEV_TO_MEM)
                iowrite32(0, td_chan->membase + TIMBDMA_OFFS_RX_ER);
/* Currently no support for stopping DMA transfers
        else
                iowrite32(0, td_chan->membase + TIMBDMA_OFFS_TX_DLAR);
*/
        dma_cookie_complete(txd);
        td_chan->ongoing = false;

        callback = txd->callback;
        param = txd->callback_param;

        list_move(&td_desc->desc_node, &td_chan->free_list);

        dma_descriptor_unmap(txd);
        /*
         * The API requires that no submissions are done from a
         * callback, so we don't need to drop the lock here
         */
        if (callback)
                callback(param);
}

static u32 __td_ier_mask(struct timb_dma *td)
{
        int i;
        u32 ret = 0;

        for (i = 0; i < td->dma.chancnt; i++) {
                struct timb_dma_chan *td_chan = td->channels + i;
                if (td_chan->ongoing) {
                        struct timb_dma_desc *td_desc =
                                list_entry(td_chan->active_list.next,
                                struct timb_dma_desc, desc_node);
                        if (td_desc->interrupt)
                                ret |= 1 << i;
                }
        }

        return ret;
}

static void __td_start_next(struct timb_dma_chan *td_chan)
{
        struct timb_dma_desc *td_desc;

        BUG_ON(list_empty(&td_chan->queue));
        BUG_ON(td_chan->ongoing);

        td_desc = list_entry(td_chan->queue.next, struct timb_dma_desc,
                desc_node);

        dev_dbg(chan2dev(&td_chan->chan), "%s: started %u\n",
                __func__, td_desc->txd.cookie);

        list_move(&td_desc->desc_node, &td_chan->active_list);
        __td_start_dma(td_chan);
}

static dma_cookie_t td_tx_submit(struct dma_async_tx_descriptor *txd)
{
        struct timb_dma_desc *td_desc = container_of(txd, struct timb_dma_desc,
                txd);
        struct timb_dma_chan *td_chan = container_of(txd->chan,
                struct timb_dma_chan, chan);
        dma_cookie_t cookie;

        spin_lock_bh(&td_chan->lock);
        cookie = dma_cookie_assign(txd);

        if (list_empty(&td_chan->active_list)) {
                dev_dbg(chan2dev(txd->chan), "%s: started %u\n", __func__,
                        txd->cookie);
                list_add_tail(&td_desc->desc_node, &td_chan->active_list);
                __td_start_dma(td_chan);
        } else {
                dev_dbg(chan2dev(txd->chan), "tx_submit: queued %u\n",
                        txd->cookie);

                list_add_tail(&td_desc->desc_node, &td_chan->queue);
        }

        spin_unlock_bh(&td_chan->lock);

        return cookie;
}

static struct timb_dma_desc *td_alloc_init_desc(struct timb_dma_chan *td_chan)
{
        struct dma_chan *chan = &td_chan->chan;
        struct timb_dma_desc *td_desc;
        int err;

        td_desc = kzalloc(sizeof(struct timb_dma_desc), GFP_KERNEL);
        if (!td_desc) {
                dev_err(chan2dev(chan), "Failed to alloc descriptor\n");
                goto out;
        }

        td_desc->desc_list_len = td_chan->desc_elems * TIMB_DMA_DESC_SIZE;

        td_desc->desc_list = kzalloc(td_desc->desc_list_len, GFP_KERNEL);
        if (!td_desc->desc_list) {
                dev_err(chan2dev(chan), "Failed to alloc descriptor\n");
                goto err;
        }

        dma_async_tx_descriptor_init(&td_desc->txd, chan);
        td_desc->txd.tx_submit = td_tx_submit;
        td_desc->txd.flags = DMA_CTRL_ACK;

        td_desc->txd.phys = dma_map_single(chan2dmadev(chan),
                td_desc->desc_list, td_desc->desc_list_len, DMA_TO_DEVICE);

        err = dma_mapping_error(chan2dmadev(chan), td_desc->txd.phys);
        if (err) {
                dev_err(chan2dev(chan), "DMA mapping error: %d\n", err);
                goto err;
        }

        return td_desc;
err:
        kfree(td_desc->desc_list);
        kfree(td_desc);
out:
        return NULL;

}

static void td_free_desc(struct timb_dma_desc *td_desc)
{
        dev_dbg(chan2dev(td_desc->txd.chan), "Freeing desc: %p\n", td_desc);
        dma_unmap_single(chan2dmadev(td_desc->txd.chan), td_desc->txd.phys,
                td_desc->desc_list_len, DMA_TO_DEVICE);

        kfree(td_desc->desc_list);
        kfree(td_desc);
}

static void td_desc_put(struct timb_dma_chan *td_chan,
        struct timb_dma_desc *td_desc)
{
        dev_dbg(chan2dev(&td_chan->chan), "Putting desc: %p\n", td_desc);

        spin_lock_bh(&td_chan->lock);
        list_add(&td_desc->desc_node, &td_chan->free_list);
        spin_unlock_bh(&td_chan->lock);
}

static struct timb_dma_desc *td_desc_get(struct timb_dma_chan *td_chan)
{
        struct timb_dma_desc *td_desc, *_td_desc;
        struct timb_dma_desc *ret = NULL;

        spin_lock_bh(&td_chan->lock);
        list_for_each_entry_safe(td_desc, _td_desc, &td_chan->free_list,
                desc_node) {
                if (async_tx_test_ack(&td_desc->txd)) {
                        list_del(&td_desc->desc_node);
                        ret = td_desc;
                        break;
                }
                dev_dbg(chan2dev(&td_chan->chan), "desc %p not ACKed\n",
                        td_desc);
        }
        spin_unlock_bh(&td_chan->lock);

        return ret;
}

static int td_alloc_chan_resources(struct dma_chan *chan)
{
        struct timb_dma_chan *td_chan =
                container_of(chan, struct timb_dma_chan, chan);
        int i;

        dev_dbg(chan2dev(chan), "%s: entry\n", __func__);

        BUG_ON(!list_empty(&td_chan->free_list));
        for (i = 0; i < td_chan->descs; i++) {
                struct timb_dma_desc *td_desc = td_alloc_init_desc(td_chan);
                if (!td_desc) {
                        if (i)
                                break;
                        else {
                                dev_err(chan2dev(chan),
                                        "Couldnt allocate any descriptors\n");
                                return -ENOMEM;
                        }
                }

                td_desc_put(td_chan, td_desc);
        }

        spin_lock_bh(&td_chan->lock);
        dma_cookie_init(chan);
        spin_unlock_bh(&td_chan->lock);

        return 0;
}

static void td_free_chan_resources(struct dma_chan *chan)
{
        struct timb_dma_chan *td_chan =
                container_of(chan, struct timb_dma_chan, chan);
        struct timb_dma_desc *td_desc, *_td_desc;
        LIST_HEAD(list);

        dev_dbg(chan2dev(chan), "%s: Entry\n", __func__);

        /* check that all descriptors are free */
        BUG_ON(!list_empty(&td_chan->active_list));
        BUG_ON(!list_empty(&td_chan->queue));

        spin_lock_bh(&td_chan->lock);
        list_splice_init(&td_chan->free_list, &list);
        spin_unlock_bh(&td_chan->lock);

        list_for_each_entry_safe(td_desc, _td_desc, &list, desc_node) {
                dev_dbg(chan2dev(chan), "%s: Freeing desc: %p\n", __func__,
                        td_desc);
                td_free_desc(td_desc);
        }
}

static enum dma_status td_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
                                    struct dma_tx_state *txstate)
{
        enum dma_status ret;

        dev_dbg(chan2dev(chan), "%s: Entry\n", __func__);

        ret = dma_cookie_status(chan, cookie, txstate);

        dev_dbg(chan2dev(chan), "%s: exit, ret: %d\n",  __func__, ret);

        return ret;
}

static void td_issue_pending(struct dma_chan *chan)
{
        struct timb_dma_chan *td_chan =
                container_of(chan, struct timb_dma_chan, chan);

        dev_dbg(chan2dev(chan), "%s: Entry\n", __func__);
        spin_lock_bh(&td_chan->lock);

        if (!list_empty(&td_chan->active_list))
                /* transfer ongoing */
                if (__td_dma_done_ack(td_chan))
                        __td_finish(td_chan);

        if (list_empty(&td_chan->active_list) && !list_empty(&td_chan->queue))
                __td_start_next(td_chan);

        spin_unlock_bh(&td_chan->lock);
}

static struct dma_async_tx_descriptor *td_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 timb_dma_chan *td_chan =
                container_of(chan, struct timb_dma_chan, chan);
        struct timb_dma_desc *td_desc;
        struct scatterlist *sg;
        unsigned int i;
        unsigned int desc_usage = 0;

        if (!sgl || !sg_len) {
                dev_err(chan2dev(chan), "%s: No SG list\n", __func__);
                return NULL;
        }

        /* even channels are for RX, odd for TX */
        if (td_chan->direction != direction) {
                dev_err(chan2dev(chan),
                        "Requesting channel in wrong direction\n");
                return NULL;
        }

        td_desc = td_desc_get(td_chan);
        if (!td_desc) {
                dev_err(chan2dev(chan), "Not enough descriptors available\n");
                return NULL;
        }

        td_desc->interrupt = (flags & DMA_PREP_INTERRUPT) != 0;

        for_each_sg(sgl, sg, sg_len, i) {
                int err;
                if (desc_usage > td_desc->desc_list_len) {
                        dev_err(chan2dev(chan), "No descriptor space\n");
                        return NULL;
                }

                err = td_fill_desc(td_chan, td_desc->desc_list + desc_usage, sg,
                        i == (sg_len - 1));
                if (err) {
                        dev_err(chan2dev(chan), "Failed to update desc: %d\n",
                                err);
                        td_desc_put(td_chan, td_desc);
                        return NULL;
                }
                desc_usage += TIMB_DMA_DESC_SIZE;
        }

        dma_sync_single_for_device(chan2dmadev(chan), td_desc->txd.phys,
                td_desc->desc_list_len, DMA_MEM_TO_DEV);

        return &td_desc->txd;
}

static int td_terminate_all(struct dma_chan *chan)
{
        struct timb_dma_chan *td_chan =
                container_of(chan, struct timb_dma_chan, chan);
        struct timb_dma_desc *td_desc, *_td_desc;

        dev_dbg(chan2dev(chan), "%s: Entry\n", __func__);

        /* first the easy part, put the queue into the free list */
        spin_lock_bh(&td_chan->lock);
        list_for_each_entry_safe(td_desc, _td_desc, &td_chan->queue,
                desc_node)
                list_move(&td_desc->desc_node, &td_chan->free_list);

        /* now tear down the running */
        __td_finish(td_chan);
        spin_unlock_bh(&td_chan->lock);

        return 0;
}

static void td_tasklet(unsigned long data)
{
        struct timb_dma *td = (struct timb_dma *)data;
        u32 isr;
        u32 ipr;
        u32 ier;
        int i;

        isr = ioread32(td->membase + TIMBDMA_ISR);
        ipr = isr & __td_ier_mask(td);

        /* ack the interrupts */
        iowrite32(ipr, td->membase + TIMBDMA_ISR);

        for (i = 0; i < td->dma.chancnt; i++)
                if (ipr & (1 << i)) {
                        struct timb_dma_chan *td_chan = td->channels + i;
                        spin_lock(&td_chan->lock);
                        __td_finish(td_chan);
                        if (!list_empty(&td_chan->queue))
                                __td_start_next(td_chan);
                        spin_unlock(&td_chan->lock);
                }

        ier = __td_ier_mask(td);
        iowrite32(ier, td->membase + TIMBDMA_IER);
}


static irqreturn_t td_irq(int irq, void *devid)
{
        struct timb_dma *td = devid;
        u32 ipr = ioread32(td->membase + TIMBDMA_IPR);

        if (ipr) {
                /* disable interrupts, will be re-enabled in tasklet */
                iowrite32(0, td->membase + TIMBDMA_IER);

                tasklet_schedule(&td->tasklet);

                return IRQ_HANDLED;
        } else
                return IRQ_NONE;
}


static int td_probe(struct platform_device *pdev)
{
        struct timb_dma_platform_data *pdata = dev_get_platdata(&pdev->dev);
        struct timb_dma *td;
        struct resource *iomem;
        int irq;
        int err;
        int i;

        if (!pdata) {
                dev_err(&pdev->dev, "No platform data\n");
                return -EINVAL;
        }

        iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!iomem)
                return -EINVAL;

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

        if (!request_mem_region(iomem->start, resource_size(iomem),
                DRIVER_NAME))
                return -EBUSY;

        td  = kzalloc(sizeof(struct timb_dma) +
                sizeof(struct timb_dma_chan) * pdata->nr_channels, GFP_KERNEL);
        if (!td) {
                err = -ENOMEM;
                goto err_release_region;
        }

        dev_dbg(&pdev->dev, "Allocated TD: %p\n", td);

        td->membase = ioremap(iomem->start, resource_size(iomem));
        if (!td->membase) {
                dev_err(&pdev->dev, "Failed to remap I/O memory\n");
                err = -ENOMEM;
                goto err_free_mem;
        }

        /* 32bit addressing */
        iowrite32(TIMBDMA_32BIT_ADDR, td->membase + TIMBDMA_ACR);

        /* disable and clear any interrupts */
        iowrite32(0x0, td->membase + TIMBDMA_IER);
        iowrite32(0xFFFFFFFF, td->membase + TIMBDMA_ISR);

        tasklet_init(&td->tasklet, td_tasklet, (unsigned long)td);

        err = request_irq(irq, td_irq, IRQF_SHARED, DRIVER_NAME, td);
        if (err) {
                dev_err(&pdev->dev, "Failed to request IRQ\n");
                goto err_tasklet_kill;
        }

        td->dma.device_alloc_chan_resources     = td_alloc_chan_resources;
        td->dma.device_free_chan_resources      = td_free_chan_resources;
        td->dma.device_tx_status                = td_tx_status;
        td->dma.device_issue_pending            = td_issue_pending;

        dma_cap_set(DMA_SLAVE, td->dma.cap_mask);
        dma_cap_set(DMA_PRIVATE, td->dma.cap_mask);
        td->dma.device_prep_slave_sg = td_prep_slave_sg;
        td->dma.device_terminate_all = td_terminate_all;

        td->dma.dev = &pdev->dev;

        INIT_LIST_HEAD(&td->dma.channels);

        for (i = 0; i < pdata->nr_channels; i++) {
                struct timb_dma_chan *td_chan = &td->channels[i];
                struct timb_dma_platform_data_channel *pchan =
                        pdata->channels + i;

                /* even channels are RX, odd are TX */
                if ((i % 2) == pchan->rx) {
                        dev_err(&pdev->dev, "Wrong channel configuration\n");
                        err = -EINVAL;
                        goto err_free_irq;
                }

                td_chan->chan.device = &td->dma;
                dma_cookie_init(&td_chan->chan);
                spin_lock_init(&td_chan->lock);
                INIT_LIST_HEAD(&td_chan->active_list);
                INIT_LIST_HEAD(&td_chan->queue);
                INIT_LIST_HEAD(&td_chan->free_list);

                td_chan->descs = pchan->descriptors;
                td_chan->desc_elems = pchan->descriptor_elements;
                td_chan->bytes_per_line = pchan->bytes_per_line;
                td_chan->direction = pchan->rx ? DMA_DEV_TO_MEM :
                        DMA_MEM_TO_DEV;

                td_chan->membase = td->membase +
                        (i / 2) * TIMBDMA_INSTANCE_OFFSET +
                        (pchan->rx ? 0 : TIMBDMA_INSTANCE_TX_OFFSET);

                dev_dbg(&pdev->dev, "Chan: %d, membase: %p\n",
                        i, td_chan->membase);

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

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

        platform_set_drvdata(pdev, td);

        dev_dbg(&pdev->dev, "Probe result: %d\n", err);
        return err;

err_free_irq:
        free_irq(irq, td);
err_tasklet_kill:
        tasklet_kill(&td->tasklet);
        iounmap(td->membase);
err_free_mem:
        kfree(td);
err_release_region:
        release_mem_region(iomem->start, resource_size(iomem));

        return err;

}

static int td_remove(struct platform_device *pdev)
{
        struct timb_dma *td = platform_get_drvdata(pdev);
        struct resource *iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        int irq = platform_get_irq(pdev, 0);

        dma_async_device_unregister(&td->dma);
        free_irq(irq, td);
        tasklet_kill(&td->tasklet);
        iounmap(td->membase);
        kfree(td);
        release_mem_region(iomem->start, resource_size(iomem));

        dev_dbg(&pdev->dev, "Removed...\n");
        return 0;
}

static struct platform_driver td_driver = {
        .driver = {
                .name   = DRIVER_NAME,
        },
        .probe  = td_probe,
        .remove = td_remove,
};

module_platform_driver(td_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Timberdale DMA controller driver");
MODULE_AUTHOR("Pelagicore AB <info@pelagicore.com>");
MODULE_ALIAS("platform:"DRIVER_NAME);