dmaengine: split out virtual channel DMA support from sa11x0 driver
authorRussell King <rmk+kernel@arm.linux.org.uk>
Fri, 13 Apr 2012 11:07:23 +0000 (12:07 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Sun, 1 Jul 2012 13:15:21 +0000 (14:15 +0100)
Split the virtual slave channel DMA support from the sa11x0 driver so
this code can be shared with other slave DMA engine drivers.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
drivers/dma/Kconfig
drivers/dma/Makefile
drivers/dma/sa11x0-dma.c
drivers/dma/virt-dma.c [new file with mode: 0644]
drivers/dma/virt-dma.h [new file with mode: 0644]

index aadeb5b..eb2b60e 100644 (file)
@@ -255,6 +255,7 @@ config DMA_SA11X0
        tristate "SA-11x0 DMA support"
        depends on ARCH_SA1100
        select DMA_ENGINE
+       select DMA_VIRTUAL_CHANNELS
        help
          Support the DMA engine found on Intel StrongARM SA-1100 and
          SA-1110 SoCs.  This DMA engine can only be used with on-chip
@@ -263,6 +264,9 @@ config DMA_SA11X0
 config DMA_ENGINE
        bool
 
+config DMA_VIRTUAL_CHANNELS
+       tristate
+
 comment "DMA Clients"
        depends on DMA_ENGINE
 
index 86b795b..fc05f7d 100644 (file)
@@ -2,6 +2,7 @@ ccflags-$(CONFIG_DMADEVICES_DEBUG)  := -DDEBUG
 ccflags-$(CONFIG_DMADEVICES_VDEBUG) += -DVERBOSE_DEBUG
 
 obj-$(CONFIG_DMA_ENGINE) += dmaengine.o
+obj-$(CONFIG_DMA_VIRTUAL_CHANNELS) += virt-dma.o
 obj-$(CONFIG_NET_DMA) += iovlock.o
 obj-$(CONFIG_INTEL_MID_DMAC) += intel_mid_dma.o
 obj-$(CONFIG_DMATEST) += dmatest.o
index ec78cce..5f1d2e6 100644 (file)
@@ -21,6 +21,8 @@
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 
+#include "virt-dma.h"
+
 #define NR_PHY_CHAN    6
 #define DMA_ALIGN      3
 #define DMA_MAX_SIZE   0x1fff
@@ -72,12 +74,11 @@ struct sa11x0_dma_sg {
 };
 
 struct sa11x0_dma_desc {
-       struct dma_async_tx_descriptor tx;
+       struct virt_dma_desc    vd;
+
        u32                     ddar;
        size_t                  size;
 
-       /* maybe protected by c->lock */
-       struct list_head        node;
        unsigned                sglen;
        struct sa11x0_dma_sg    sg[0];
 };
@@ -85,15 +86,11 @@ struct sa11x0_dma_desc {
 struct sa11x0_dma_phy;
 
 struct sa11x0_dma_chan {
-       struct dma_chan         chan;
-       spinlock_t              lock;
-       dma_cookie_t            lc;
+       struct virt_dma_chan    vc;
 
-       /* protected by c->lock */
+       /* protected by c->vc.lock */
        struct sa11x0_dma_phy   *phy;
        enum dma_status         status;
-       struct list_head        desc_submitted;
-       struct list_head        desc_issued;
 
        /* protected by d->lock */
        struct list_head        node;
@@ -109,7 +106,7 @@ struct sa11x0_dma_phy {
 
        struct sa11x0_dma_chan  *vchan;
 
-       /* Protected by c->lock */
+       /* Protected by c->vc.lock */
        unsigned                sg_load;
        struct sa11x0_dma_desc  *txd_load;
        unsigned                sg_done;
@@ -127,13 +124,12 @@ struct sa11x0_dma_dev {
        spinlock_t              lock;
        struct tasklet_struct   task;
        struct list_head        chan_pending;
-       struct list_head        desc_complete;
        struct sa11x0_dma_phy   phy[NR_PHY_CHAN];
 };
 
 static struct sa11x0_dma_chan *to_sa11x0_dma_chan(struct dma_chan *chan)
 {
-       return container_of(chan, struct sa11x0_dma_chan, chan);
+       return container_of(chan, struct sa11x0_dma_chan, vc.chan);
 }
 
 static struct sa11x0_dma_dev *to_sa11x0_dma(struct dma_device *dmadev)
@@ -141,27 +137,26 @@ static struct sa11x0_dma_dev *to_sa11x0_dma(struct dma_device *dmadev)
        return container_of(dmadev, struct sa11x0_dma_dev, slave);
 }
 
-static struct sa11x0_dma_desc *to_sa11x0_dma_tx(struct dma_async_tx_descriptor *tx)
+static struct sa11x0_dma_desc *sa11x0_dma_next_desc(struct sa11x0_dma_chan *c)
 {
-       return container_of(tx, struct sa11x0_dma_desc, tx);
+       struct virt_dma_desc *vd = vchan_next_desc(&c->vc);
+
+       return vd ? container_of(vd, struct sa11x0_dma_desc, vd) : NULL;
 }
 
-static struct sa11x0_dma_desc *sa11x0_dma_next_desc(struct sa11x0_dma_chan *c)
+static void sa11x0_dma_free_desc(struct virt_dma_desc *vd)
 {
-       if (list_empty(&c->desc_issued))
-               return NULL;
-
-       return list_first_entry(&c->desc_issued, struct sa11x0_dma_desc, node);
+       kfree(container_of(vd, struct sa11x0_dma_desc, vd));
 }
 
 static void sa11x0_dma_start_desc(struct sa11x0_dma_phy *p, struct sa11x0_dma_desc *txd)
 {
-       list_del(&txd->node);
+       list_del(&txd->vd.node);
        p->txd_load = txd;
        p->sg_load = 0;
 
        dev_vdbg(p->dev->slave.dev, "pchan %u: txd %p[%x]: starting: DDAR:%x\n",
-               p->num, txd, txd->tx.cookie, txd->ddar);
+               p->num, &txd->vd, txd->vd.tx.cookie, txd->ddar);
 }
 
 static void noinline sa11x0_dma_start_sg(struct sa11x0_dma_phy *p,
@@ -229,21 +224,13 @@ static void noinline sa11x0_dma_complete(struct sa11x0_dma_phy *p,
        struct sa11x0_dma_desc *txd = p->txd_done;
 
        if (++p->sg_done == txd->sglen) {
-               struct sa11x0_dma_dev *d = p->dev;
-
-               dev_vdbg(d->slave.dev, "pchan %u: txd %p[%x]: completed\n",
-                       p->num, p->txd_done, p->txd_done->tx.cookie);
-
-               c->lc = txd->tx.cookie;
-
-               spin_lock(&d->lock);
-               list_add_tail(&txd->node, &d->desc_complete);
-               spin_unlock(&d->lock);
+               vchan_cookie_complete(&txd->vd);
 
                p->sg_done = 0;
                p->txd_done = p->txd_load;
 
-               tasklet_schedule(&d->task);
+               if (!p->txd_done)
+                       tasklet_schedule(&p->dev->task);
        }
 
        sa11x0_dma_start_sg(p, c);
@@ -280,7 +267,7 @@ static irqreturn_t sa11x0_dma_irq(int irq, void *dev_id)
        if (c) {
                unsigned long flags;
 
-               spin_lock_irqsave(&c->lock, flags);
+               spin_lock_irqsave(&c->vc.lock, flags);
                /*
                 * Now that we're holding the lock, check that the vchan
                 * really is associated with this pchan before touching the
@@ -294,7 +281,7 @@ static irqreturn_t sa11x0_dma_irq(int irq, void *dev_id)
                        if (dcsr & DCSR_DONEB)
                                sa11x0_dma_complete(p, c);
                }
-               spin_unlock_irqrestore(&c->lock, flags);
+               spin_unlock_irqrestore(&c->vc.lock, flags);
        }
 
        return IRQ_HANDLED;
@@ -332,28 +319,15 @@ static void sa11x0_dma_tasklet(unsigned long arg)
        struct sa11x0_dma_dev *d = (struct sa11x0_dma_dev *)arg;
        struct sa11x0_dma_phy *p;
        struct sa11x0_dma_chan *c;
-       struct sa11x0_dma_desc *txd, *txn;
-       LIST_HEAD(head);
        unsigned pch, pch_alloc = 0;
 
        dev_dbg(d->slave.dev, "tasklet enter\n");
 
-       /* Get the completed tx descriptors */
-       spin_lock_irq(&d->lock);
-       list_splice_init(&d->desc_complete, &head);
-       spin_unlock_irq(&d->lock);
-
-       list_for_each_entry(txd, &head, node) {
-               c = to_sa11x0_dma_chan(txd->tx.chan);
-
-               dev_dbg(d->slave.dev, "vchan %p: txd %p[%x] completed\n",
-                       c, txd, txd->tx.cookie);
-
-               spin_lock_irq(&c->lock);
+       list_for_each_entry(c, &d->slave.channels, vc.chan.device_node) {
+               spin_lock_irq(&c->vc.lock);
                p = c->phy;
-               if (p) {
-                       if (!p->txd_done)
-                               sa11x0_dma_start_txd(c);
+               if (p && !p->txd_done) {
+                       sa11x0_dma_start_txd(c);
                        if (!p->txd_done) {
                                /* No current txd associated with this channel */
                                dev_dbg(d->slave.dev, "pchan %u: free\n", p->num);
@@ -363,7 +337,7 @@ static void sa11x0_dma_tasklet(unsigned long arg)
                                p->vchan = NULL;
                        }
                }
-               spin_unlock_irq(&c->lock);
+               spin_unlock_irq(&c->vc.lock);
        }
 
        spin_lock_irq(&d->lock);
@@ -380,7 +354,7 @@ static void sa11x0_dma_tasklet(unsigned long arg)
                        /* Mark this channel allocated */
                        p->vchan = c;
 
-                       dev_dbg(d->slave.dev, "pchan %u: alloc vchan %p\n", pch, c);
+                       dev_dbg(d->slave.dev, "pchan %u: alloc vchan %p\n", pch, &c->vc);
                }
        }
        spin_unlock_irq(&d->lock);
@@ -390,42 +364,18 @@ static void sa11x0_dma_tasklet(unsigned long arg)
                        p = &d->phy[pch];
                        c = p->vchan;
 
-                       spin_lock_irq(&c->lock);
+                       spin_lock_irq(&c->vc.lock);
                        c->phy = p;
 
                        sa11x0_dma_start_txd(c);
-                       spin_unlock_irq(&c->lock);
+                       spin_unlock_irq(&c->vc.lock);
                }
        }
 
-       /* Now free the completed tx descriptor, and call their callbacks */
-       list_for_each_entry_safe(txd, txn, &head, node) {
-               dma_async_tx_callback callback = txd->tx.callback;
-               void *callback_param = txd->tx.callback_param;
-
-               dev_dbg(d->slave.dev, "txd %p[%x]: callback and free\n",
-                       txd, txd->tx.cookie);
-
-               kfree(txd);
-
-               if (callback)
-                       callback(callback_param);
-       }
-
        dev_dbg(d->slave.dev, "tasklet exit\n");
 }
 
 
-static void sa11x0_dma_desc_free(struct sa11x0_dma_dev *d, struct list_head *head)
-{
-       struct sa11x0_dma_desc *txd, *txn;
-
-       list_for_each_entry_safe(txd, txn, head, node) {
-               dev_dbg(d->slave.dev, "txd %p: freeing\n", txd);
-               kfree(txd);
-       }
-}
-
 static int sa11x0_dma_alloc_chan_resources(struct dma_chan *chan)
 {
        return 0;
@@ -436,18 +386,12 @@ static void sa11x0_dma_free_chan_resources(struct dma_chan *chan)
        struct sa11x0_dma_chan *c = to_sa11x0_dma_chan(chan);
        struct sa11x0_dma_dev *d = to_sa11x0_dma(chan->device);
        unsigned long flags;
-       LIST_HEAD(head);
 
-       spin_lock_irqsave(&c->lock, flags);
-       spin_lock(&d->lock);
+       spin_lock_irqsave(&d->lock, flags);
        list_del_init(&c->node);
-       spin_unlock(&d->lock);
-
-       list_splice_tail_init(&c->desc_submitted, &head);
-       list_splice_tail_init(&c->desc_issued, &head);
-       spin_unlock_irqrestore(&c->lock, flags);
+       spin_unlock_irqrestore(&d->lock, flags);
 
-       sa11x0_dma_desc_free(d, &head);
+       vchan_free_chan_resources(&c->vc);
 }
 
 static dma_addr_t sa11x0_dma_pos(struct sa11x0_dma_phy *p)
@@ -473,21 +417,15 @@ static enum dma_status sa11x0_dma_tx_status(struct dma_chan *chan,
        struct sa11x0_dma_dev *d = to_sa11x0_dma(chan->device);
        struct sa11x0_dma_phy *p;
        struct sa11x0_dma_desc *txd;
-       dma_cookie_t last_used, last_complete;
        unsigned long flags;
        enum dma_status ret;
        size_t bytes = 0;
 
-       last_used = c->chan.cookie;
-       last_complete = c->lc;
-
-       ret = dma_async_is_complete(cookie, last_complete, last_used);
-       if (ret == DMA_SUCCESS) {
-               dma_set_tx_state(state, last_complete, last_used, 0);
+       ret = dma_cookie_status(&c->vc.chan, cookie, state);
+       if (ret == DMA_SUCCESS)
                return ret;
-       }
 
-       spin_lock_irqsave(&c->lock, flags);
+       spin_lock_irqsave(&c->vc.lock, flags);
        p = c->phy;
        ret = c->status;
        if (p) {
@@ -524,12 +462,13 @@ static enum dma_status sa11x0_dma_tx_status(struct dma_chan *chan,
                if (txd != p->txd_load && p->txd_load)
                        bytes += p->txd_load->size;
        }
-       list_for_each_entry(txd, &c->desc_issued, node) {
+       list_for_each_entry(txd, &c->vc.desc_issued, vd.node) {
                bytes += txd->size;
        }
-       spin_unlock_irqrestore(&c->lock, flags);
+       spin_unlock_irqrestore(&c->vc.lock, flags);
 
-       dma_set_tx_state(state, last_complete, last_used, bytes);
+       if (state)
+               state->residue = bytes;
 
        dev_vdbg(d->slave.dev, "tx_status: bytes 0x%zx\n", bytes);
 
@@ -547,40 +486,20 @@ static void sa11x0_dma_issue_pending(struct dma_chan *chan)
        struct sa11x0_dma_dev *d = to_sa11x0_dma(chan->device);
        unsigned long flags;
 
-       spin_lock_irqsave(&c->lock, flags);
-       list_splice_tail_init(&c->desc_submitted, &c->desc_issued);
-       if (!list_empty(&c->desc_issued)) {
-               spin_lock(&d->lock);
-               if (!c->phy && list_empty(&c->node)) {
-                       list_add_tail(&c->node, &d->chan_pending);
-                       tasklet_schedule(&d->task);
-                       dev_dbg(d->slave.dev, "vchan %p: issued\n", c);
+       spin_lock_irqsave(&c->vc.lock, flags);
+       if (vchan_issue_pending(&c->vc)) {
+               if (!c->phy) {
+                       spin_lock(&d->lock);
+                       if (list_empty(&c->node)) {
+                               list_add_tail(&c->node, &d->chan_pending);
+                               tasklet_schedule(&d->task);
+                               dev_dbg(d->slave.dev, "vchan %p: issued\n", &c->vc);
+                       }
+                       spin_unlock(&d->lock);
                }
-               spin_unlock(&d->lock);
        } else
-               dev_dbg(d->slave.dev, "vchan %p: nothing to issue\n", c);
-       spin_unlock_irqrestore(&c->lock, flags);
-}
-
-static dma_cookie_t sa11x0_dma_tx_submit(struct dma_async_tx_descriptor *tx)
-{
-       struct sa11x0_dma_chan *c = to_sa11x0_dma_chan(tx->chan);
-       struct sa11x0_dma_desc *txd = to_sa11x0_dma_tx(tx);
-       unsigned long flags;
-
-       spin_lock_irqsave(&c->lock, flags);
-       c->chan.cookie += 1;
-       if (c->chan.cookie < 0)
-               c->chan.cookie = 1;
-       txd->tx.cookie = c->chan.cookie;
-
-       list_add_tail(&txd->node, &c->desc_submitted);
-       spin_unlock_irqrestore(&c->lock, flags);
-
-       dev_dbg(tx->chan->device->dev, "vchan %p: txd %p[%x]: submitted\n",
-               c, txd, txd->tx.cookie);
-
-       return txd->tx.cookie;
+               dev_dbg(d->slave.dev, "vchan %p: nothing to issue\n", &c->vc);
+       spin_unlock_irqrestore(&c->vc.lock, flags);
 }
 
 static struct dma_async_tx_descriptor *sa11x0_dma_prep_slave_sg(
@@ -596,7 +515,7 @@ static struct dma_async_tx_descriptor *sa11x0_dma_prep_slave_sg(
        /* SA11x0 channels can only operate in their native direction */
        if (dir != (c->ddar & DDAR_RW ? DMA_DEV_TO_MEM : DMA_MEM_TO_DEV)) {
                dev_err(chan->device->dev, "vchan %p: bad DMA direction: DDAR:%08x dir:%u\n",
-                       c, c->ddar, dir);
+                       &c->vc, c->ddar, dir);
                return NULL;
        }
 
@@ -612,14 +531,14 @@ static struct dma_async_tx_descriptor *sa11x0_dma_prep_slave_sg(
                        j += DIV_ROUND_UP(len, DMA_MAX_SIZE & ~DMA_ALIGN) - 1;
                if (addr & DMA_ALIGN) {
                        dev_dbg(chan->device->dev, "vchan %p: bad buffer alignment: %08x\n",
-                               c, addr);
+                               &c->vc, addr);
                        return NULL;
                }
        }
 
        txd = kzalloc(sizeof(*txd) + j * sizeof(txd->sg[0]), GFP_ATOMIC);
        if (!txd) {
-               dev_dbg(chan->device->dev, "vchan %p: kzalloc failed\n", c);
+               dev_dbg(chan->device->dev, "vchan %p: kzalloc failed\n", &c->vc);
                return NULL;
        }
 
@@ -655,17 +574,14 @@ static struct dma_async_tx_descriptor *sa11x0_dma_prep_slave_sg(
                } while (len);
        }
 
-       dma_async_tx_descriptor_init(&txd->tx, &c->chan);
-       txd->tx.flags = flags;
-       txd->tx.tx_submit = sa11x0_dma_tx_submit;
        txd->ddar = c->ddar;
        txd->size = size;
        txd->sglen = j;
 
        dev_dbg(chan->device->dev, "vchan %p: txd %p: size %u nr %u\n",
-               c, txd, txd->size, txd->sglen);
+               &c->vc, &txd->vd, txd->size, txd->sglen);
 
-       return &txd->tx;
+       return vchan_tx_prep(&c->vc, &txd->vd, flags);
 }
 
 static int sa11x0_dma_slave_config(struct sa11x0_dma_chan *c, struct dma_slave_config *cfg)
@@ -695,8 +611,8 @@ static int sa11x0_dma_slave_config(struct sa11x0_dma_chan *c, struct dma_slave_c
        if (maxburst == 8)
                ddar |= DDAR_BS;
 
-       dev_dbg(c->chan.device->dev, "vchan %p: dma_slave_config addr %x width %u burst %u\n",
-               c, addr, width, maxburst);
+       dev_dbg(c->vc.chan.device->dev, "vchan %p: dma_slave_config addr %x width %u burst %u\n",
+               &c->vc, addr, width, maxburst);
 
        c->ddar = ddar | (addr & 0xf0000000) | (addr & 0x003ffffc) << 6;
 
@@ -718,16 +634,13 @@ static int sa11x0_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                return sa11x0_dma_slave_config(c, (struct dma_slave_config *)arg);
 
        case DMA_TERMINATE_ALL:
-               dev_dbg(d->slave.dev, "vchan %p: terminate all\n", c);
+               dev_dbg(d->slave.dev, "vchan %p: terminate all\n", &c->vc);
                /* Clear the tx descriptor lists */
-               spin_lock_irqsave(&c->lock, flags);
-               list_splice_tail_init(&c->desc_submitted, &head);
-               list_splice_tail_init(&c->desc_issued, &head);
+               spin_lock_irqsave(&c->vc.lock, flags);
+               vchan_get_all_descriptors(&c->vc, &head);
 
                p = c->phy;
                if (p) {
-                       struct sa11x0_dma_desc *txd, *txn;
-
                        dev_dbg(d->slave.dev, "pchan %u: terminating\n", p->num);
                        /* vchan is assigned to a pchan - stop the channel */
                        writel(DCSR_RUN | DCSR_IE |
@@ -735,17 +648,13 @@ static int sa11x0_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                                DCSR_STRTB | DCSR_DONEB,
                                p->base + DMA_DCSR_C);
 
-                       list_for_each_entry_safe(txd, txn, &d->desc_complete, node)
-                               if (txd->tx.chan == &c->chan)
-                                       list_move(&txd->node, &head);
-
                        if (p->txd_load) {
                                if (p->txd_load != p->txd_done)
-                                       list_add_tail(&p->txd_load->node, &head);
+                                       list_add_tail(&p->txd_load->vd.node, &head);
                                p->txd_load = NULL;
                        }
                        if (p->txd_done) {
-                               list_add_tail(&p->txd_done->node, &head);
+                               list_add_tail(&p->txd_done->vd.node, &head);
                                p->txd_done = NULL;
                        }
                        c->phy = NULL;
@@ -754,14 +663,14 @@ static int sa11x0_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                        spin_unlock(&d->lock);
                        tasklet_schedule(&d->task);
                }
-               spin_unlock_irqrestore(&c->lock, flags);
-               sa11x0_dma_desc_free(d, &head);
+               spin_unlock_irqrestore(&c->vc.lock, flags);
+               vchan_dma_desc_free_list(&c->vc, &head);
                ret = 0;
                break;
 
        case DMA_PAUSE:
-               dev_dbg(d->slave.dev, "vchan %p: pause\n", c);
-               spin_lock_irqsave(&c->lock, flags);
+               dev_dbg(d->slave.dev, "vchan %p: pause\n", &c->vc);
+               spin_lock_irqsave(&c->vc.lock, flags);
                if (c->status == DMA_IN_PROGRESS) {
                        c->status = DMA_PAUSED;
 
@@ -774,26 +683,26 @@ static int sa11x0_dma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
                                spin_unlock(&d->lock);
                        }
                }
-               spin_unlock_irqrestore(&c->lock, flags);
+               spin_unlock_irqrestore(&c->vc.lock, flags);
                ret = 0;
                break;
 
        case DMA_RESUME:
-               dev_dbg(d->slave.dev, "vchan %p: resume\n", c);
-               spin_lock_irqsave(&c->lock, flags);
+               dev_dbg(d->slave.dev, "vchan %p: resume\n", &c->vc);
+               spin_lock_irqsave(&c->vc.lock, flags);
                if (c->status == DMA_PAUSED) {
                        c->status = DMA_IN_PROGRESS;
 
                        p = c->phy;
                        if (p) {
                                writel(DCSR_RUN | DCSR_IE, p->base + DMA_DCSR_S);
-                       } else if (!list_empty(&c->desc_issued)) {
+                       } else if (!list_empty(&c->vc.desc_issued)) {
                                spin_lock(&d->lock);
                                list_add_tail(&c->node, &d->chan_pending);
                                spin_unlock(&d->lock);
                        }
                }
-               spin_unlock_irqrestore(&c->lock, flags);
+               spin_unlock_irqrestore(&c->vc.lock, flags);
                ret = 0;
                break;
 
@@ -853,15 +762,13 @@ static int __devinit sa11x0_dma_init_dmadev(struct dma_device *dmadev,
                        return -ENOMEM;
                }
 
-               c->chan.device = dmadev;
                c->status = DMA_IN_PROGRESS;
                c->ddar = chan_desc[i].ddar;
                c->name = chan_desc[i].name;
-               spin_lock_init(&c->lock);
-               INIT_LIST_HEAD(&c->desc_submitted);
-               INIT_LIST_HEAD(&c->desc_issued);
                INIT_LIST_HEAD(&c->node);
-               list_add_tail(&c->chan.device_node, &dmadev->channels);
+
+               c->vc.desc_free = sa11x0_dma_free_desc;
+               vchan_init(&c->vc, dmadev);
        }
 
        return dma_async_device_register(dmadev);
@@ -890,8 +797,9 @@ static void sa11x0_dma_free_channels(struct dma_device *dmadev)
 {
        struct sa11x0_dma_chan *c, *cn;
 
-       list_for_each_entry_safe(c, cn, &dmadev->channels, chan.device_node) {
-               list_del(&c->chan.device_node);
+       list_for_each_entry_safe(c, cn, &dmadev->channels, vc.chan.device_node) {
+               list_del(&c->vc.chan.device_node);
+               tasklet_kill(&c->vc.task);
                kfree(c);
        }
 }
@@ -915,7 +823,6 @@ static int __devinit sa11x0_dma_probe(struct platform_device *pdev)
 
        spin_lock_init(&d->lock);
        INIT_LIST_HEAD(&d->chan_pending);
-       INIT_LIST_HEAD(&d->desc_complete);
 
        d->base = ioremap(res->start, resource_size(res));
        if (!d->base) {
diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c
new file mode 100644 (file)
index 0000000..bd85b05
--- /dev/null
@@ -0,0 +1,99 @@
+/*
+ * Virtual DMA channel support for DMAengine
+ *
+ * Copyright (C) 2012 Russell King
+ *
+ * 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.
+ */
+#include <linux/device.h>
+#include <linux/dmaengine.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+
+#include "virt-dma.h"
+
+static struct virt_dma_desc *to_virt_desc(struct dma_async_tx_descriptor *tx)
+{
+       return container_of(tx, struct virt_dma_desc, tx);
+}
+
+dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *tx)
+{
+       struct virt_dma_chan *vc = to_virt_chan(tx->chan);
+       struct virt_dma_desc *vd = to_virt_desc(tx);
+       unsigned long flags;
+       dma_cookie_t cookie;
+
+       spin_lock_irqsave(&vc->lock, flags);
+       cookie = dma_cookie_assign(tx);
+
+       list_add_tail(&vd->node, &vc->desc_submitted);
+       spin_unlock_irqrestore(&vc->lock, flags);
+
+       dev_dbg(vc->chan.device->dev, "vchan %p: txd %p[%x]: submitted\n",
+               vc, vd, cookie);
+
+       return cookie;
+}
+EXPORT_SYMBOL_GPL(vchan_tx_submit);
+
+/*
+ * This tasklet handles the completion of a DMA descriptor by
+ * calling its callback and freeing it.
+ */
+static void vchan_complete(unsigned long arg)
+{
+       struct virt_dma_chan *vc = (struct virt_dma_chan *)arg;
+       LIST_HEAD(head);
+
+       spin_lock_irq(&vc->lock);
+       list_splice_tail_init(&vc->desc_completed, &head);
+       spin_unlock_irq(&vc->lock);
+
+       while (!list_empty(&head)) {
+               struct virt_dma_desc *vd = list_first_entry(&head,
+                               struct virt_dma_desc, node);
+               dma_async_tx_callback cb = vd->tx.callback;
+               void *cb_data = vd->tx.callback_param;
+
+               list_del(&vd->node);
+
+               vc->desc_free(vd);
+
+               if (cb)
+                       cb(cb_data);
+       }
+}
+
+void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head)
+{
+       while (!list_empty(head)) {
+               struct virt_dma_desc *vd = list_first_entry(head,
+                       struct virt_dma_desc, node);
+               list_del(&vd->node);
+               dev_dbg(vc->chan.device->dev, "txd %p: freeing\n", vd);
+               vc->desc_free(vd);
+       }
+}
+EXPORT_SYMBOL_GPL(vchan_dma_desc_free_list);
+
+void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
+{
+       dma_cookie_init(&vc->chan);
+
+       spin_lock_init(&vc->lock);
+       INIT_LIST_HEAD(&vc->desc_submitted);
+       INIT_LIST_HEAD(&vc->desc_issued);
+       INIT_LIST_HEAD(&vc->desc_completed);
+
+       tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
+
+       vc->chan.device = dmadev;
+       list_add_tail(&vc->chan.device_node, &dmadev->channels);
+}
+EXPORT_SYMBOL_GPL(vchan_init);
+
+MODULE_AUTHOR("Russell King");
+MODULE_LICENSE("GPL");
diff --git a/drivers/dma/virt-dma.h b/drivers/dma/virt-dma.h
new file mode 100644 (file)
index 0000000..825bb96
--- /dev/null
@@ -0,0 +1,138 @@
+/*
+ * Virtual DMA channel support for DMAengine
+ *
+ * Copyright (C) 2012 Russell King
+ *
+ * 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.
+ */
+#ifndef VIRT_DMA_H
+#define VIRT_DMA_H
+
+#include <linux/dmaengine.h>
+#include <linux/interrupt.h>
+
+#include "dmaengine.h"
+
+struct virt_dma_desc {
+       struct dma_async_tx_descriptor tx;
+       /* protected by vc.lock */
+       struct list_head node;
+};
+
+struct virt_dma_chan {
+       struct dma_chan chan;
+       struct tasklet_struct task;
+       void (*desc_free)(struct virt_dma_desc *);
+
+       spinlock_t lock;
+
+       /* protected by vc.lock */
+       struct list_head desc_submitted;
+       struct list_head desc_issued;
+       struct list_head desc_completed;
+};
+
+static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
+{
+       return container_of(chan, struct virt_dma_chan, chan);
+}
+
+void vchan_dma_desc_free_list(struct virt_dma_chan *vc, struct list_head *head);
+
+void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev);
+
+/**
+ * vchan_tx_prep - prepare a descriptor
+ * vc: virtual channel allocating this descriptor
+ * vd: virtual descriptor to prepare
+ * tx_flags: flags argument passed in to prepare function
+ */
+static inline struct dma_async_tx_descriptor *vchan_tx_prep(struct virt_dma_chan *vc,
+       struct virt_dma_desc *vd, unsigned long tx_flags)
+{
+       extern dma_cookie_t vchan_tx_submit(struct dma_async_tx_descriptor *);
+
+       dma_async_tx_descriptor_init(&vd->tx, &vc->chan);
+       vd->tx.flags = tx_flags;
+       vd->tx.tx_submit = vchan_tx_submit;
+
+       return &vd->tx;
+}
+
+/**
+ * vchan_issue_pending - move submitted descriptors to issued list
+ * vc: virtual channel to update
+ *
+ * vc.lock must be held by caller
+ */
+static inline bool vchan_issue_pending(struct virt_dma_chan *vc)
+{
+       list_splice_tail_init(&vc->desc_submitted, &vc->desc_issued);
+       return !list_empty(&vc->desc_issued);
+}
+
+/**
+ * vchan_cookie_complete - report completion of a descriptor
+ * vd: virtual descriptor to update
+ *
+ * vc.lock must be held by caller
+ */
+static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
+{
+       struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
+
+       dma_cookie_complete(&vd->tx);
+       dev_vdbg(vc->chan.device->dev, "txd %p[%x]: marked complete\n",
+               vd, vd->tx.cookie);
+       list_add_tail(&vd->node, &vc->desc_completed);
+
+       tasklet_schedule(&vc->task);
+}
+
+/**
+ * vchan_next_desc - peek at the next descriptor to be processed
+ * vc: virtual channel to obtain descriptor from
+ *
+ * vc.lock must be held by caller
+ */
+static inline struct virt_dma_desc *vchan_next_desc(struct virt_dma_chan *vc)
+{
+       if (list_empty(&vc->desc_issued))
+               return NULL;
+
+       return list_first_entry(&vc->desc_issued, struct virt_dma_desc, node);
+}
+
+/**
+ * vchan_get_all_descriptors - obtain all submitted and issued descriptors
+ * vc: virtual channel to get descriptors from
+ * head: list of descriptors found
+ *
+ * vc.lock must be held by caller
+ *
+ * Removes all submitted and issued descriptors from internal lists, and
+ * provides a list of all descriptors found
+ */
+static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
+       struct list_head *head)
+{
+       list_splice_tail_init(&vc->desc_submitted, head);
+       list_splice_tail_init(&vc->desc_issued, head);
+       list_splice_tail_init(&vc->desc_completed, head);
+}
+
+static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
+{
+       unsigned long flags;
+       LIST_HEAD(head);
+
+       spin_lock_irqsave(&vc->lock, flags);
+       vchan_get_all_descriptors(vc, &head);
+       spin_unlock_irqrestore(&vc->lock, flags);
+
+       vchan_dma_desc_free_list(vc, &head);
+}
+
+#endif