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path: root/drivers/dma/dmaengine.c
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Diffstat (limited to 'drivers/dma/dmaengine.c')
-rw-r--r--drivers/dma/dmaengine.c84
1 files changed, 62 insertions, 22 deletions
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index e057935e3023..f15712f2fec6 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -222,31 +222,35 @@ static void balance_ref_count(struct dma_chan *chan)
*/
static int dma_chan_get(struct dma_chan *chan)
{
- int err = -ENODEV;
struct module *owner = dma_chan_to_owner(chan);
+ int ret;
+ /* The channel is already in use, update client count */
if (chan->client_count) {
__module_get(owner);
- err = 0;
- } else if (try_module_get(owner))
- err = 0;
+ goto out;
+ }
- if (err == 0)
- chan->client_count++;
+ if (!try_module_get(owner))
+ return -ENODEV;
/* allocate upon first client reference */
- if (chan->client_count == 1 && err == 0) {
- int desc_cnt = chan->device->device_alloc_chan_resources(chan);
-
- if (desc_cnt < 0) {
- err = desc_cnt;
- chan->client_count = 0;
- module_put(owner);
- } else if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
- balance_ref_count(chan);
+ if (chan->device->device_alloc_chan_resources) {
+ ret = chan->device->device_alloc_chan_resources(chan);
+ if (ret < 0)
+ goto err_out;
}
- return err;
+ if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
+ balance_ref_count(chan);
+
+out:
+ chan->client_count++;
+ return 0;
+
+err_out:
+ module_put(owner);
+ return ret;
}
/**
@@ -257,11 +261,15 @@ static int dma_chan_get(struct dma_chan *chan)
*/
static void dma_chan_put(struct dma_chan *chan)
{
+ /* This channel is not in use, bail out */
if (!chan->client_count)
- return; /* this channel failed alloc_chan_resources */
+ return;
+
chan->client_count--;
module_put(dma_chan_to_owner(chan));
- if (chan->client_count == 0)
+
+ /* This channel is not in use anymore, free it */
+ if (!chan->client_count && chan->device->device_free_chan_resources)
chan->device->device_free_chan_resources(chan);
}
@@ -471,6 +479,39 @@ static void dma_channel_rebalance(void)
}
}
+int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
+{
+ struct dma_device *device;
+
+ if (!chan || !caps)
+ return -EINVAL;
+
+ device = chan->device;
+
+ /* check if the channel supports slave transactions */
+ if (!test_bit(DMA_SLAVE, device->cap_mask.bits))
+ return -ENXIO;
+
+ /*
+ * Check whether it reports it uses the generic slave
+ * capabilities, if not, that means it doesn't support any
+ * kind of slave capabilities reporting.
+ */
+ if (!device->directions)
+ return -ENXIO;
+
+ caps->src_addr_widths = device->src_addr_widths;
+ caps->dst_addr_widths = device->dst_addr_widths;
+ caps->directions = device->directions;
+ caps->residue_granularity = device->residue_granularity;
+
+ caps->cmd_pause = !!device->device_pause;
+ caps->cmd_terminate = !!device->device_terminate_all;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(dma_get_slave_caps);
+
static struct dma_chan *private_candidate(const dma_cap_mask_t *mask,
struct dma_device *dev,
dma_filter_fn fn, void *fn_param)
@@ -811,17 +852,16 @@ int dma_async_device_register(struct dma_device *device)
!device->device_prep_dma_sg);
BUG_ON(dma_has_cap(DMA_CYCLIC, device->cap_mask) &&
!device->device_prep_dma_cyclic);
- BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) &&
- !device->device_control);
BUG_ON(dma_has_cap(DMA_INTERLEAVE, device->cap_mask) &&
!device->device_prep_interleaved_dma);
- BUG_ON(!device->device_alloc_chan_resources);
- BUG_ON(!device->device_free_chan_resources);
BUG_ON(!device->device_tx_status);
BUG_ON(!device->device_issue_pending);
BUG_ON(!device->dev);
+ WARN(dma_has_cap(DMA_SLAVE, device->cap_mask) && !device->directions,
+ "this driver doesn't support generic slave capabilities reporting\n");
+
/* note: this only matters in the
* CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH=n case
*/