From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757229Ab3C2WQj (ORCPT ); Fri, 29 Mar 2013 18:16:39 -0400 Received: from mga03.intel.com ([143.182.124.21]:37280 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756793Ab3C2WQi (ORCPT ); Fri, 29 Mar 2013 18:16:38 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,375,1363158000"; d="scan'208";a="277800896" Date: Sat, 30 Mar 2013 03:19:51 +0530 From: Vinod Koul To: Lars-Peter Clausen , Arnd Bergmann Cc: 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 Message-ID: <20130329214951.GA10326@intel.com> References: <1364217412-31905-1-git-send-email-lars@metafoo.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1364217412-31905-1-git-send-email-lars@metafoo.de> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > --- > 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 >