diff options
| -rw-r--r-- | drivers/dma/of-dma.c | 35 | ||||
| -rw-r--r-- | include/linux/of_dma.h | 4 |
2 files changed, 39 insertions, 0 deletions
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c index e8fe9dc455f4..d5fbeaa1e7ba 100644 --- a/drivers/dma/of-dma.c +++ b/drivers/dma/of-dma.c @@ -218,3 +218,38 @@ struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec, &dma_spec->args[0]); } EXPORT_SYMBOL_GPL(of_dma_simple_xlate); + +/** + * 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 wants + * 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 upon. + * + * 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 dma_device *dev = ofdma->of_dma_data; + struct dma_chan *chan, *candidate = NULL; + + if (!dev || dma_spec->args_count != 1) + return NULL; + + list_for_each_entry(chan, &dev->channels, device_node) + if (chan->chan_id == dma_spec->args[0]) { + candidate = chan; + break; + } + + if (!candidate) + return NULL; + + return dma_get_slave_channel(candidate); +} +EXPORT_SYMBOL_GPL(of_dma_xlate_by_chan_id); diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h index ae36298ba076..56bc026c143f 100644 --- a/include/linux/of_dma.h +++ b/include/linux/of_dma.h @@ -41,6 +41,8 @@ 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) @@ -66,6 +68,8 @@ 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 */ |