DMA client device driver usually needs to know at probe time whether
dma controller has been registered to deffer probe. So add a help
function of_dma_check_controller.
DMA request channel functions can also used to check it, but they
are usually called at open() time.
Signed-off-by: Richard Zhao <riz...@nvidia.com>
---
drivers/dma/of-dma.c | 39 +++++++++++++++++++++++++++++++++++++++
include/linux/of_dma.h | 6 ++++++
2 files changed, 45 insertions(+)
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index 8cd5f3f..0063ddf 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -189,6 +189,45 @@ struct dma_chan *of_dma_request_slave_channel(struct
device_node *np,
}
/**
+ * of_dma_check_controller - Check whether dma controller registered
+ * @dev: pointer to client device structure
+ * @name: slave channel name
+ */
+int of_dma_check_controller(struct device *dev, const char *name)
+{
+ struct device_node *np = dev->of_node;
+ struct of_phandle_args dma_spec;
+ struct of_dma *ofdma = NULL;
+ int count, i, ret = 0;
+
+ if (!np || !name)
+ return -EINVAL;
+
+ count = of_property_count_strings(np, "dma-names");
+ if (count < 0) {
+ dev_err(dev, "dma-names property missing or empty\n");
+ return -EINVAL;
+ }
+
+ for (i = 0; i < count; i++) {
+ ret = of_dma_match_channel(np, name, i, &dma_spec);
+ if (ret)
+ continue;
+
+ mutex_lock(&of_dma_lock);
+ ofdma = of_dma_find_controller(&dma_spec);
+ mutex_unlock(&of_dma_lock);
+ of_node_put(dma_spec.np);
+ if (!ofdma)
+ ret = -EPROBE_DEFER;
+ break;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(of_dma_check_controller);
+
+/**
* of_dma_simple_xlate - Simple DMA engine translation function
* @dma_spec: pointer to DMA specifier as found in the device tree
* @of_dma: pointer to DMA controller data
diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h
index ae36298..bc7195f 100644
--- a/include/linux/of_dma.h
+++ b/include/linux/of_dma.h
@@ -39,6 +39,7 @@ extern int of_dma_controller_register(struct device_node *np,
extern void of_dma_controller_free(struct device_node *np);
extern struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
const char *name);
+extern int of_dma_check_controller(struct device *dev, const char *name);
extern struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma);
#else
@@ -60,6 +61,11 @@ static inline struct dma_chan
*of_dma_request_slave_channel(struct device_node *
return NULL;
}
+static inline int of_dma_check_controller(struct device *dev, const char *name)
+{
+ return 0;
+}
+
static inline struct dma_chan *of_dma_simple_xlate(struct of_phandle_args
*dma_spec,
struct of_dma *ofdma)
{
--
1.8.1.5
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
