The patch titled spi-gpio: allow operation without CS signal has been removed from the -mm tree. Its filename was spi-gpio-allow-operation-without-cs-signal.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: spi-gpio: allow operation without CS signal From: Michael Buesch <mb@xxxxxxxxx> Change spi-gpio so that it is possible to drive SPI communications over GPIO without the need for a chipselect signal. This is useful in very small setups where there's only one slave device on the bus. This patch does not affect existing setups. I use this for a tiny communication channel between an embedded device and a microcontroller. There are not enough GPIOs available for chipselect and it's not needed anyway in this case. Signed-off-by: Michael Buesch <mb@xxxxxxxxx> Cc: David Brownell <david-b@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/spi/spi_gpio.c | 21 +++++++++++++-------- include/linux/spi/spi_gpio.h | 6 ++++++ 2 files changed, 19 insertions(+), 8 deletions(-) diff -puN drivers/spi/spi_gpio.c~spi-gpio-allow-operation-without-cs-signal drivers/spi/spi_gpio.c --- a/drivers/spi/spi_gpio.c~spi-gpio-allow-operation-without-cs-signal +++ a/drivers/spi/spi_gpio.c @@ -178,8 +178,10 @@ static void spi_gpio_chipselect(struct s if (is_active) setsck(spi, spi->mode & SPI_CPOL); - /* SPI is normally active-low */ - gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active); + if (cs != SPI_GPIO_NO_CHIPSELECT) { + /* SPI is normally active-low */ + gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active); + } } static int spi_gpio_setup(struct spi_device *spi) @@ -191,15 +193,17 @@ static int spi_gpio_setup(struct spi_dev return -EINVAL; if (!spi->controller_state) { - status = gpio_request(cs, dev_name(&spi->dev)); - if (status) - return status; - status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH); + if (cs != SPI_GPIO_NO_CHIPSELECT) { + status = gpio_request(cs, dev_name(&spi->dev)); + if (status) + return status; + status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH); + } } if (!status) status = spi_bitbang_setup(spi); if (status) { - if (!spi->controller_state) + if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT) gpio_free(cs); } return status; @@ -209,7 +213,8 @@ static void spi_gpio_cleanup(struct spi_ { unsigned long cs = (unsigned long) spi->controller_data; - gpio_free(cs); + if (cs != SPI_GPIO_NO_CHIPSELECT) + gpio_free(cs); spi_bitbang_cleanup(spi); } diff -puN include/linux/spi/spi_gpio.h~spi-gpio-allow-operation-without-cs-signal include/linux/spi/spi_gpio.h --- a/include/linux/spi/spi_gpio.h~spi-gpio-allow-operation-without-cs-signal +++ a/include/linux/spi/spi_gpio.h @@ -25,10 +25,16 @@ * ... * }; * + * If chipselect is not used (there's only one device on the bus), assign + * SPI_GPIO_NO_CHIPSELECT to the controller_data: + * .controller_data = (void *) SPI_GPIO_NO_CHIPSELECT; + * * If the bitbanged bus is later switched to a "native" controller, * that platform_device and controller_data should be removed. */ +#define SPI_GPIO_NO_CHIPSELECT ((unsigned long)-1l) + /** * struct spi_gpio_platform_data - parameter for bitbanged SPI master * @sck: number of the GPIO used for clock output _ Patches currently in -mm which might be from mb@xxxxxxxxx are origin.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html