From fd5e191e7610eb7ecb5e35b2045ceb6554bea15a Mon Sep 17 00:00:00 2001 From: Mike Rapoport Date: Mon, 6 Apr 2009 19:00:56 -0700 Subject: [PATCH] SPI: add dma_alignment field to spi_master Some SPI controllers have restrictions on DMAable buffers alignemt. Currently if the buffer supplied by protocol driver is not properly aligned, the controller silently performs transfer in PIO mode. Addition of dma_alignment field to spi_master allows protocol drivers to perform proper alignment. Signed-off-by: Mike Rapoport Cc: Bryan Wu Cc: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/spi/spi.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 68bb1c501d0..2cc43fa380c 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -204,6 +204,7 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) * SPI slaves, and are numbered from zero to num_chipselects. * each slave has a chipselect signal, but it's common that not * every chipselect is connected to a slave. + * @dma_alignment: SPI controller constraint on DMA buffers alignment. * @setup: updates the device mode and clocking records used by a * device's SPI controller; protocol code may call this. This * must fail if an unrecognized or unsupported mode is requested. @@ -239,6 +240,11 @@ struct spi_master { */ u16 num_chipselect; + /* some SPI controllers pose alignment requirements on DMAable + * buffers; let protocol drivers know about these requirements. + */ + u16 dma_alignment; + /* setup mode and clock, etc (spi driver may call many times) */ int (*setup)(struct spi_device *spi); -- 2.20.1