From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Christophe PLAGNIOL-VILLARD Subject: [PATCH 1/4 v4] of_spi: add generic binding support to specify cs gpio Date: Wed, 7 Mar 2012 13:23:06 +0100 Message-ID: <1331122989-14451-1-git-send-email-plagnioj@jcrosoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org List-Id: linux-spi.vger.kernel.org This will allow to use gpio for chip select with no modification in the driver binding When use the cs-gpios, the gpio number will be passed via the cs_gpio field and the number of chip select will automatically increased. Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org --- v4: use cs_gpio to pass the gpio number Best Regards, J. Documentation/devicetree/bindings/spi/spi-bus.txt | 6 ++ drivers/spi/spi.c | 57 +++++++++++++++++++- include/linux/spi/spi.h | 6 ++ 3 files changed, 66 insertions(+), 3 deletions(-) diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt index e782add..c253379 100644 --- a/Documentation/devicetree/bindings/spi/spi-bus.txt +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt @@ -12,6 +12,7 @@ The SPI master node requires the following properties: - #size-cells - should be zero. - compatible - name of SPI bus controller following generic names recommended practice. +- cs-gpios - (optional) gpios chip select. No other properties are required in the SPI bus node. It is assumed that a driver for an SPI bus device will understand that it is an SPI bus. However, the binding does not attempt to define the specific method for @@ -21,6 +22,8 @@ assumption that board specific platform code will be used to manage chip selects. Individual drivers can define additional properties to support describing the chip select layout. +If cs-gpios is used the number of chip select will automatically increased. + SPI slave nodes must be children of the SPI master node and can contain the following properties. - reg - (required) chip select address of device. @@ -34,6 +37,9 @@ contain the following properties. - spi-cs-high - (optional) Empty property indicating device requires chip select active high +If a gpio chipselect is used for the SPI slave the gpio number will be passed +via the controller_data + SPI example for an MPC5200 SPI bus: spi@f00 { #address-cells = <1>; diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index b2ccdea..c1d0955 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include @@ -322,6 +323,7 @@ struct spi_device *spi_alloc_device(struct spi_master *master) spi->dev.parent = &master->dev; spi->dev.bus = &spi_bus_type; spi->dev.release = spidev_release; + spi->cs_gpio = -EINVAL; device_initialize(&spi->dev); return spi; } @@ -339,15 +341,16 @@ EXPORT_SYMBOL_GPL(spi_alloc_device); int spi_add_device(struct spi_device *spi) { static DEFINE_MUTEX(spi_add_lock); - struct device *dev = spi->master->dev.parent; + struct spi_master *master = spi->master; + struct device *dev = master->dev.parent; struct device *d; int status; /* Chipselects are numbered 0..max; validate. */ - if (spi->chip_select >= spi->master->num_chipselect) { + if (spi->chip_select >= master->num_chipselect) { dev_err(dev, "cs%d >= max %d\n", spi->chip_select, - spi->master->num_chipselect); + master->num_chipselect); return -EINVAL; } @@ -371,6 +374,13 @@ int spi_add_device(struct spi_device *spi) goto done; } + if (master->num_gpio_cs && + spi->chip_select >= master->first_gpio_cs) { + int num = spi->chip_select - master->first_gpio_cs; + + spi->cs_gpio = master->cs_gpios[num]; + } + /* Drivers may modify this initial i/o setup, but will * normally rely on the device being setup. Devices * using SPI_CS_HIGH can't coexist well otherwise... @@ -561,6 +571,43 @@ struct spi_master *spi_alloc_master(struct device *dev, unsigned size) } EXPORT_SYMBOL_GPL(spi_alloc_master); +#ifdef CONFIG_OF +static int of_spi_register_master(struct spi_master *master) +{ + int nb, i; + int *cs; + struct device_node *np = master->dev.of_node; + + if (!np) + return 0; + + nb = of_gpio_named_count(np, "cs-gpios"); + + if (nb < 1) + return 0; + + cs = devm_kzalloc(&master->dev, sizeof(int) * nb, GFP_KERNEL); + master->cs_gpios = cs; + + if (!master->cs_gpios) + return -ENOMEM; + + master->first_gpio_cs = master->num_chipselect; + master->num_chipselect += nb; + master->num_gpio_cs = nb; + + for (i = 0; i < nb; i++) + cs[i] = of_get_named_gpio(np, "cs-gpios", i); + + return 0; +} +#else +static int of_spi_register_master(struct spi_master *master) +{ + return 0; +} +#endif + /** * spi_register_master - register SPI master controller * @master: initialized master, originally from spi_alloc_master() @@ -592,6 +639,10 @@ int spi_register_master(struct spi_master *master) if (!dev) return -ENODEV; + status = of_spi_register_master(master); + if (status) + return status; + /* even if it's just one always-selected device, there must * be at least one chipselect */ diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 176fce9..7dcf031 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -89,6 +89,7 @@ struct spi_device { void *controller_state; void *controller_data; char modalias[SPI_NAME_SIZE]; + int cs_gpio; /* chip select gpio */ /* * likely need more hooks for more protocol options affecting how @@ -318,6 +319,11 @@ struct spi_master { /* called on release() to free memory provided by spi_master */ void (*cleanup)(struct spi_device *spi); + + /* gpio chip select */ + int *cs_gpios; + int first_gpio_cs; + int num_gpio_cs; }; static inline void *spi_master_get_devdata(struct spi_master *master) -- 1.7.7