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?
>
> Signed-off-by: Lars-Peter Clausen <l...@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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