Messages in this thread | | | Date | Tue, 09 Apr 2013 14:36:24 +0200 | From | Lars-Peter Clausen <> | Subject | Re: [PATCH 1/2] dma: of: Add generic xlate function for matching by channel id |
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On 04/09/2013 01:28 PM, Vinod Koul wrote: > 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?
It's more or less a device specific cookie. And in this case we are using a 1 to 1 mapping to the channel number.
- Lars
>> >> - 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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