From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755869Ab3C3Igk (ORCPT ); Sat, 30 Mar 2013 04:36:40 -0400 Received: from mailhost.informatik.uni-hamburg.de ([134.100.9.70]:38297 "EHLO mailhost.informatik.uni-hamburg.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751343Ab3C3Igi (ORCPT ); Sat, 30 Mar 2013 04:36:38 -0400 Message-ID: <5156A49E.5030901@metafoo.de> Date: Sat, 30 Mar 2013 09:38:54 +0100 From: Lars-Peter Clausen User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20121215 Icedove/3.0.11 MIME-Version: 1.0 To: Vinod Koul CC: Arnd Bergmann , Dan Williams , Jon Hunter , Padmavathi Venna , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] dma: of: Add generic xlate function for matching by channel id References: <1364217412-31905-1-git-send-email-lars@metafoo.de> <20130329214951.GA10326@intel.com> In-Reply-To: <20130329214951.GA10326@intel.com> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? - Lars > >> >> Signed-off-by: Lars-Peter Clausen >> --- >> 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 >>