Merge branch 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma

Pull slave-dmaengine updates from Vinod Koul:
 "This pull brings:
   - Andy's DW driver updates
   - Guennadi's sh driver updates
   - Pl08x driver fixes from Tomasz & Alban
   - Improvements to mmp_pdma by Daniel
   - TI EDMA fixes by Joel
   - New drivers:
     - Hisilicon k3dma driver
     - Renesas rcar dma driver
  - New API for publishing slave driver capablities
  - Various fixes across the subsystem by Andy, Jingoo, Sachin etc..."

* 'for-linus' of git://git.infradead.org/users/vkoul/slave-dma: (94 commits)
  dma: edma: Remove limits on number of slots
  dma: edma: Leave linked to Null slot instead of DUMMY slot
  dma: edma: Find missed events and issue them
  ARM: edma: Add function to manually trigger an EDMA channel
  dma: edma: Write out and handle MAX_NR_SG at a given time
  dma: edma: Setup parameters to DMA MAX_NR_SG at a time
  dmaengine: pl330: use dma_set_max_seg_size to set the sg limit
  dmaengine: dma_slave_caps: remove sg entries
  dma: replace devm_request_and_ioremap by devm_ioremap_resource
  dma: ste_dma40: Fix potential null pointer dereference
  dma: ste_dma40: Remove duplicate const
  dma: imx-dma: Remove redundant NULL check
  dma: dmagengine: fix function names in comments
  dma: add driver for R-Car HPB-DMAC
  dma: k3dma: use devm_ioremap_resource() instead of devm_request_and_ioremap()
  dma: imx-sdma: Staticize sdma_driver_data structures
  pch_dma: Add MODULE_DEVICE_TABLE
  dmaengine: PL08x: Add cyclic transfer support
  dmaengine: PL08x: Fix reading the byte count in cctl
  dmaengine: PL08x: Add support for different maximum transfer size
  ...

1 files changed, 27 insertions, 1 deletions

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index eee16b01fa8..9162ac80c18 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -509,7 +509,33 @@ static struct dma_chan *private_candidate(const dma_cap_mask_t *mask,
 }
 
 /**
- * dma_request_channel - try to allocate an exclusive channel
+ * dma_request_slave_channel - try to get specific channel exclusively
+ * @chan: target channel
+ */
+struct dma_chan *dma_get_slave_channel(struct dma_chan *chan)
+{
+	int err = -EBUSY;
+
+	/* lock against __dma_request_channel */
+	mutex_lock(&dma_list_mutex);
+
+	if (chan->client_count == 0) {
+		err = dma_chan_get(chan);
+		if (err)
+			pr_debug("%s: failed to get %s: (%d)\n",
+				__func__, dma_chan_name(chan), err);
+	} else
+		chan = NULL;
+
+	mutex_unlock(&dma_list_mutex);
+
+
+	return chan;
+}
+EXPORT_SYMBOL_GPL(dma_get_slave_channel);
+
+/**
+ * __dma_request_channel - try to allocate an exclusive channel
  * @mask: capabilities that the channel must satisfy
  * @fn: optional callback to disposition available channels
  * @fn_param: opaque parameter to pass to dma_filter_fn