dma: Add timb-dma

Adds the support for the DMA engine withing the timberdale FPGA.

The DMA channels are strict device to host, or host to device
and can not be used for generic memcpy.

Signed-off-by: Richard Röjfors <richard.rojfors@pelagicore.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

3 files changed, 861 insertions, 0 deletions

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index c27f80e5d531..a2fcb2ead892 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -149,6 +149,13 @@ config AMCC_PPC440SPE_ADMA
         help
           Enable support for the AMCC PPC440SPe RAID engines.
 
+config TIMB_DMA
+        tristate "Timberdale FPGA DMA support"
+        depends on MFD_TIMBERDALE || HAS_IOMEM
+        select DMA_ENGINE
+        help
+          Enable support for the Timberdale FPGA DMA engine.
+
 config ARCH_HAS_ASYNC_TX_FIND_CHANNEL
         bool
 
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index 22bba3d5e2b6..40c627d8f73b 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
 obj-$(CONFIG_SH_DMAE) += shdma.o
 obj-$(CONFIG_COH901318) += coh901318.o coh901318_lli.o
 obj-$(CONFIG_AMCC_PPC440SPE_ADMA) += ppc4xx/
+obj-$(CONFIG_TIMB_DMA) += timb_dma.o
diff --git a/drivers/dma/timb_dma.c b/drivers/dma/timb_dma.c
new file mode 100644
index 000000000000..4dd710246c79
--- /dev/null
+++ b/drivers/dma/timb_dma.c
@@ -0,0 +1,853 @@
+/*
+ * 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/timb_dma.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 for mutual exclusion */
+        dma_cookie_t            last_completed_cookie;
+        bool                    ongoing;
+        struct list_head        active_list;
+        struct list_head        queue;
+        struct list_head        free_list;
+        unsigned int            bytes_per_line;
+        enum dma_data_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 void __td_unmap_desc(struct timb_dma_chan *td_chan, const u8 *dma_desc,
+        bool single)
+{
+        dma_addr_t addr;
+        int len;
+
+        addr = (dma_desc[7] << 24) | (dma_desc[6] << 16) | (dma_desc[5] << 8) |
+                dma_desc[4];
+
+        len = (dma_desc[3] << 8) | dma_desc[2];
+
+        if (single)
+                dma_unmap_single(chan2dev(&td_chan->chan), addr, len,
+                        td_chan->direction);
+        else
+                dma_unmap_page(chan2dev(&td_chan->chan), addr, len,
+                        td_chan->direction);
+}
+
+static void __td_unmap_descs(struct timb_dma_desc *td_desc, bool single)
+{
+        struct timb_dma_chan *td_chan = container_of(td_desc->txd.chan,
+                struct timb_dma_chan, chan);
+        u8 *descs;
+
+        for (descs = td_desc->desc_list; ; descs += TIMB_DMA_DESC_SIZE) {
+                __td_unmap_desc(td_chan, descs, single);
+                if (descs[0] & 0x02)
+                        break;
+        }
+}
+
+static int td_fill_desc(struct timb_dma_chan *td_chan, u8 *dma_desc,
+        struct scatterlist *sg, bool last)
+{
+        if (sg_dma_len(sg) > USHORT_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: %p\n",
+                dma_desc, (void *)(int)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_FROM_DEVICE) {
+
+                /* 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_FROM_DEVICE)
+                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);
+*/
+        td_chan->last_completed_cookie = txd->cookie;
+        td_chan->ongoing = false;
+
+        callback = txd->callback;
+        param = txd->callback_param;
+
+        list_move(&td_desc->desc_node, &td_chan->free_list);
+
+        if (!(txd->flags & DMA_COMPL_SKIP_SRC_UNMAP))
+                __td_unmap_descs(td_desc,
+                        txd->flags & DMA_COMPL_SRC_UNMAP_SINGLE);
+
+        /*
+         * 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 = txd->chan->cookie;
+        if (++cookie < 0)
+                cookie = 1;
+        txd->chan->cookie = cookie;
+        txd->cookie = cookie;
+
+        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 err;
+        }
+
+        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);
+
+        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);
+        td_chan->last_completed_cookie = 1;
+        chan->cookie = 1;
+        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_is_tx_complete(struct dma_chan *chan,
+        dma_cookie_t cookie, dma_cookie_t *done, dma_cookie_t *used)
+{
+        struct timb_dma_chan *td_chan =
+                container_of(chan, struct timb_dma_chan, chan);
+        dma_cookie_t            last_used;
+        dma_cookie_t            last_complete;
+        int                     ret;
+
+        dev_dbg(chan2dev(chan), "%s: Entry\n", __func__);
+
+        last_complete = td_chan->last_completed_cookie;
+        last_used = chan->cookie;
+
+        ret = dma_async_is_complete(cookie, last_complete, last_used);
+
+        if (done)
+                *done = last_complete;
+        if (used)
+                *used = last_used;
+
+        dev_dbg(chan2dev(chan),
+                "%s: exit, ret: %d, last_complete: %d, last_used: %d\n",
+                __func__, ret, last_complete, last_used);
+
+        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_data_direction direction, unsigned long flags)
+{
+        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_TO_DEVICE);
+
+        return &td_desc->txd;
+}
+
+static void 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 runnning */
+        __td_finish(td_chan);
+        spin_unlock_bh(&td_chan->lock);
+}
+
+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 __devinit td_probe(struct platform_device *pdev)
+{
+        struct timb_dma_platform_data *pdata = pdev->dev.platform_data;
+        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_is_tx_complete           = td_is_tx_complete;
+        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++, td->dma.chancnt++) {
+                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) || (!(i % 2) && !pchan->rx)) {
+                        dev_err(&pdev->dev, "Wrong channel configuration\n");
+                        err = -EINVAL;
+                        goto err_tasklet_kill;
+                }
+
+                td_chan->chan.device = &td->dma;
+                td_chan->chan.cookie = 1;
+                td_chan->chan.chan_id = i;
+                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_FROM_DEVICE :
+                        DMA_TO_DEVICE;
+
+                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 __devexit 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));
+
+        platform_set_drvdata(pdev, NULL);
+
+        dev_dbg(&pdev->dev, "Removed...\n");
+        return 0;
+}
+
+static struct platform_driver td_driver = {
+        .driver = {
+                .name   = DRIVER_NAME,
+                .owner  = THIS_MODULE,
+        },
+        .probe  = td_probe,
+        .remove = __exit_p(td_remove),
+};
+
+static int __init td_init(void)
+{
+        return platform_driver_register(&td_driver);
+}
+module_init(td_init);
+
+static void __exit td_exit(void)
+{
+        platform_driver_unregister(&td_driver);
+}
+module_exit(td_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Timberdale DMA controller driver");
+MODULE_AUTHOR("Pelagicore AB <info@pelagicore.com>");
+MODULE_ALIAS("platform:"DRIVER_NAME);