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Subject[PATCH 1/2] dma: of: Add generic xlate function for matching by channel id
Date
This patch adds a new generic of dma xlate callback function which will match a
channel by its id.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
drivers/dma/of-dma.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/of_dma.h | 4 ++++
2 files changed, 51 insertions(+)

diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index 00db454..7cad4d7 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -269,3 +269,50 @@ struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
&dma_spec->args[0]);
}
EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
+
+struct of_dma_filter_by_chan_id_args {
+ struct dma_device *dev;
+ unsigned int chan_id;
+};
+
+static bool of_dma_filter_by_chan_id(struct dma_chan *chan, void *params)
+{
+ struct of_dma_filter_by_chan_id_args *args = params;
+
+ return chan->device == args->dev && chan->chan_id == args->chan_id;
+}
+
+/**
+ * of_dma_xlate_by_chan_id - Translate dt property to DMA channel by channel id
+ * @dma_spec: pointer to DMA specifier as found in the device tree
+ * @of_dma: pointer to DMA controller data
+ *
+ * This function can be used as the of xlate callback for DMA driver which want
+ * to match the channel based on the channel id. When using this xlate function
+ * the #dma-cells propety of the DMA controller dt node needs to be set to 1.
+ * The data parameter of of_dma_controller_register must be a pointer to the
+ * dma_device struct the function should match uppon.
+ *
+ * Returns pointer to appropriate dma channel on success or NULL on error.
+ */
+struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
+ struct of_dma *ofdma)
+{
+ struct of_dma_filter_by_chan_id_args args;
+ dma_cap_mask_t cap;
+
+ args.dev = ofdma->of_dma_data;
+ if (!args.dev)
+ return NULL;
+
+ if (dma_spec->args_count != 1)
+ return NULL;
+
+ dma_cap_zero(cap);
+ dma_cap_set(DMA_SLAVE, cap);
+
+ args.chan_id = dma_spec->args[0];
+
+ return dma_request_channel(cap, of_dma_filter_by_chan_id, &args);
+}
+EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id);
diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h
index ce6a8ab..46732d3 100644
--- a/include/linux/of_dma.h
+++ b/include/linux/of_dma.h
@@ -43,6 +43,8 @@ extern struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
const char *name);
extern struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma);
+extern struct dma_chan *of_dma_xlate_by_chan_id(struct of_phandle_args *dma_spec,
+ struct of_dma *ofdma);
#else
static inline int of_dma_controller_register(struct device_node *np,
struct dma_chan *(*of_dma_xlate)
@@ -69,6 +71,8 @@ static inline struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_s
return NULL;
}

+#define of_dma_xlate_by_chan_id NULL
+
#endif

#endif /* __LINUX_OF_DMA_H */
--
1.8.0


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