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authorRussell King <rmk+kernel@arm.linux.org.uk>2012-05-14 15:17:20 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2012-07-01 14:15:23 +0100
commit571fa74034701391b1be2ad193f684acfdeb75d1 (patch)
treeb19b5fac263f5c23a053ac7db41d11ce634afb6b
parentfe045874aaf4480386c65baf1acae82af4c5e21f (diff)
downloadop-kernel-dev-571fa74034701391b1be2ad193f684acfdeb75d1.zip
op-kernel-dev-571fa74034701391b1be2ad193f684acfdeb75d1.tar.gz
dmaengine: virt-dma: add support for cyclic DMA periodic callbacks
Add support for cyclic DMA's periodic callbacks. Drivers are expected to call vchan_cyclic_callback() when a period has completed, which will schedule the tasklet to make the callback into the driver. As callbacks are made from tasklet context, it is important to realise that we don't guarantee a callback for each completed period, but for N completed periods where N may be greater than one. Tested-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--drivers/dma/virt-dma.c19
-rw-r--r--drivers/dma/virt-dma.h14
2 files changed, 29 insertions, 4 deletions
diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c
index a8054fc..6f80432 100644
--- a/drivers/dma/virt-dma.c
+++ b/drivers/dma/virt-dma.c
@@ -59,17 +59,28 @@ EXPORT_SYMBOL_GPL(vchan_find_desc);
static void vchan_complete(unsigned long arg)
{
struct virt_dma_chan *vc = (struct virt_dma_chan *)arg;
+ struct virt_dma_desc *vd;
+ dma_async_tx_callback cb = NULL;
+ void *cb_data = NULL;
LIST_HEAD(head);
spin_lock_irq(&vc->lock);
list_splice_tail_init(&vc->desc_completed, &head);
+ vd = vc->cyclic;
+ if (vd) {
+ vc->cyclic = NULL;
+ cb = vd->tx.callback;
+ cb_data = vd->tx.callback_param;
+ }
spin_unlock_irq(&vc->lock);
+ if (cb)
+ cb(cb_data);
+
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;
+ vd = list_first_entry(&head, struct virt_dma_desc, node);
+ cb = vd->tx.callback;
+ cb_data = vd->tx.callback_param;
list_del(&vd->node);
diff --git a/drivers/dma/virt-dma.h b/drivers/dma/virt-dma.h
index 44ec57e..85c19d6 100644
--- a/drivers/dma/virt-dma.h
+++ b/drivers/dma/virt-dma.h
@@ -32,6 +32,8 @@ struct virt_dma_chan {
struct list_head desc_submitted;
struct list_head desc_issued;
struct list_head desc_completed;
+
+ struct virt_dma_desc *cyclic;
};
static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
@@ -92,6 +94,18 @@ static inline void vchan_cookie_complete(struct virt_dma_desc *vd)
}
/**
+ * vchan_cyclic_callback - report the completion of a period
+ * vd: virtual descriptor
+ */
+static inline void vchan_cyclic_callback(struct virt_dma_desc *vd)
+{
+ struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
+
+ vc->cyclic = vd;
+ tasklet_schedule(&vc->task);
+}
+
+/**
* vchan_next_desc - peek at the next descriptor to be processed
* vc: virtual channel to obtain descriptor from
*
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