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-rw-r--r--drivers/dma/dmaengine.c35
-rw-r--r--drivers/dma/of-dma.c15
-rw-r--r--include/linux/dmaengine.h8
3 files changed, 48 insertions, 10 deletions
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index ea806bdc12ef..e17e9b22d85e 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -540,6 +540,8 @@ EXPORT_SYMBOL_GPL(dma_get_slave_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
+ *
+ * Returns pointer to appropriate DMA channel on success or NULL.
*/
struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
dma_filter_fn fn, void *fn_param)
@@ -591,18 +593,43 @@ EXPORT_SYMBOL_GPL(__dma_request_channel);
* dma_request_slave_channel - try to allocate an exclusive slave channel
* @dev: pointer to client device structure
* @name: slave channel name
+ *
+ * Returns pointer to appropriate DMA channel on success or an error pointer.
*/
-struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name)
+struct dma_chan *dma_request_slave_channel_reason(struct device *dev,
+ const char *name)
{
+ struct dma_chan *chan;
+
/* If device-tree is present get slave info from here */
if (dev->of_node)
return of_dma_request_slave_channel(dev->of_node, name);
/* If device was enumerated by ACPI get slave info from here */
- if (ACPI_HANDLE(dev))
- return acpi_dma_request_slave_chan_by_name(dev, name);
+ if (ACPI_HANDLE(dev)) {
+ chan = acpi_dma_request_slave_chan_by_name(dev, name);
+ if (chan)
+ return chan;
+ }
- return NULL;
+ return ERR_PTR(-ENODEV);
+}
+EXPORT_SYMBOL_GPL(dma_request_slave_channel_reason);
+
+/**
+ * dma_request_slave_channel - try to allocate an exclusive slave channel
+ * @dev: pointer to client device structure
+ * @name: slave channel name
+ *
+ * Returns pointer to appropriate DMA channel on success or NULL.
+ */
+struct dma_chan *dma_request_slave_channel(struct device *dev,
+ const char *name)
+{
+ struct dma_chan *ch = dma_request_slave_channel_reason(dev, name);
+ if (IS_ERR(ch))
+ return NULL;
+ return ch;
}
EXPORT_SYMBOL_GPL(dma_request_slave_channel);
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index 0b88dd3d05f4..e8fe9dc455f4 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -143,7 +143,7 @@ static int of_dma_match_channel(struct device_node *np, const char *name,
* @np: device node to get DMA request from
* @name: name of desired channel
*
- * Returns pointer to appropriate dma channel on success or NULL on error.
+ * Returns pointer to appropriate DMA channel on success or an error pointer.
*/
struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
const char *name)
@@ -152,17 +152,18 @@ struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
struct of_dma *ofdma;
struct dma_chan *chan;
int count, i;
+ int ret_no_channel = -ENODEV;
if (!np || !name) {
pr_err("%s: not enough information provided\n", __func__);
- return NULL;
+ return ERR_PTR(-ENODEV);
}
count = of_property_count_strings(np, "dma-names");
if (count < 0) {
pr_err("%s: dma-names property of node '%s' missing or empty\n",
__func__, np->full_name);
- return NULL;
+ return ERR_PTR(-ENODEV);
}
for (i = 0; i < count; i++) {
@@ -172,10 +173,12 @@ struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
mutex_lock(&of_dma_lock);
ofdma = of_dma_find_controller(&dma_spec);
- if (ofdma)
+ if (ofdma) {
chan = ofdma->of_dma_xlate(&dma_spec, ofdma);
- else
+ } else {
+ ret_no_channel = -EPROBE_DEFER;
chan = NULL;
+ }
mutex_unlock(&of_dma_lock);
@@ -185,7 +188,7 @@ struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
return chan;
}
- return NULL;
+ return ERR_PTR(ret_no_channel);
}
/**
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index bd6b88222ced..de550c61ba43 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -22,6 +22,7 @@
#define LINUX_DMAENGINE_H
#include <linux/device.h>
+#include <linux/err.h>
#include <linux/uio.h>
#include <linux/bug.h>
#include <linux/scatterlist.h>
@@ -1039,6 +1040,8 @@ enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
void dma_issue_pending_all(void);
struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
dma_filter_fn fn, void *fn_param);
+struct dma_chan *dma_request_slave_channel_reason(struct device *dev,
+ const char *name);
struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name);
void dma_release_channel(struct dma_chan *chan);
#else
@@ -1062,6 +1065,11 @@ static inline struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
{
return NULL;
}
+static inline struct dma_chan *dma_request_slave_channel_reason(
+ struct device *dev, const char *name)
+{
+ return ERR_PTR(-ENODEV);
+}
static inline struct dma_chan *dma_request_slave_channel(struct device *dev,
const char *name)
{