Messages in this thread | | | Date | Tue, 9 Apr 2013 16:58:16 +0530 | From | Vinod Koul <> | Subject | Re: [PATCH 1/2] dma: of: Add generic xlate function for matching by channel id |
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On Sat, Mar 30, 2013 at 09:38:54AM +0100, Lars-Peter Clausen wrote: > On 03/29/2013 10:49 PM, Vinod Koul wrote: > > On Mon, Mar 25, 2013 at 02:16:51PM +0100, Lars-Peter Clausen wrote: > >> This patch adds a new generic of dma xlate callback function which will match a > >> channel by its id. > > how will the client know which "id" to request? > > The devicetree tells it, or what exactly do you mean? Is this global id? Anrd, what does the id mean in DT? > > - Lars > > > > >> > >> 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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