From mboxrd@z Thu Jan 1 00:00:00 1970 From: dan.j.williams@intel.com (Dan Williams) Date: Wed, 24 Mar 2010 14:25:35 -0700 Subject: [PATCH 1/5] ARM: define the PrimeCell DMA API In-Reply-To: <1268056327-16577-1-git-send-email-linus.walleij@stericsson.com> References: <1268056327-16577-1-git-send-email-linus.walleij@stericsson.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Mar 8, 2010 at 6:52 AM, Linus Walleij wrote: > This patch extends the DMA engine with a PrimeCell superset with > three functions: configure DMA channel, stop channel, and one for > getting the number of bytes pending on a channel. These have been > identified as the basic extensions needed to drive DMA on top of > the PL011 and PL180 PrimeCells. > > Signed-off-by: Linus Walleij > --- > ?include/linux/amba/dma.h | ? 44 ++++++++++++++++++++++++++++++++++++++++++++ > ?1 files changed, 44 insertions(+), 0 deletions(-) > ?create mode 100644 include/linux/amba/dma.h > > diff --git a/include/linux/amba/dma.h b/include/linux/amba/dma.h > new file mode 100644 > index 0000000..13196af > --- /dev/null > +++ b/include/linux/amba/dma.h > @@ -0,0 +1,44 @@ > +/* > + * ?linux/include/amba/dma.h > + * > + * ?Copyright (C) 2010 ST-Ericsson AB > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > +#if !defined(AMBA_DMA_H) && defined(CONFIG_DMADEVICES) > +#define AMBA_DMA_H > + > +/** > + * struct amba_dma_channel_request - this struct is passed in as > + * configuration data to a DMA engine in order to set up a certain > + * channel for DMA transport. Anything the DMA engine needs to > + * know about the PrimeCell shall be passed through this struct. > + * The DMA engine has to provide an additional function: > + * dma_set_ambaconfig() in order for it to work with PrimeCells. > + * @addr: this is the physical address where DMA data should be > + * read (RX) or written (TX) > + * @addr_width: this is the width of the source (RX) or target > + * (TX) register where DMA data shall be read/written, in bytes. > + * legal values: 1, 2, 4, 8. > + */ > +struct amba_dma_channel_config { > + ? ? ? dma_addr_t addr; > + ? ? ? u8 addr_width:4; > +}; The usages of this seem to be constant data based off something that comes from the platform data or 'slave' device. Could this constant data just be munged/merged into the platform data and we can look it up at runtime via chan->private. Or am I oversimplifying? None the of the usages seem to justify forking from core dmaengine at this point (I reserve the right to be proven wrong later). -- Dan