This will allow to use gpio for chip select with no modification in the driver binding
When use the ncs-gpios, the gpio number will be passed via the controller_data and the number of chip select will automatically increased. Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <[email protected]> Cc: [email protected] Cc: [email protected] --- Documentation/devicetree/bindings/spi/spi-bus.txt | 6 +++ drivers/of/of_spi.c | 27 ++++++++--- drivers/spi/spi.c | 51 +++++++++++++++++++- include/linux/spi/spi.h | 5 ++ 4 files changed, 78 insertions(+), 11 deletions(-) diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt index e782add..5a24729 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. +- ncs-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 ncs-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/of/of_spi.c b/drivers/of/of_spi.c index 6dbc074..0d41407 100644 --- a/drivers/of/of_spi.c +++ b/drivers/of/of_spi.c @@ -12,6 +12,7 @@ #include <linux/spi/spi.h> #include <linux/of_irq.h> #include <linux/of_spi.h> +#include <linux/of_gpio.h> /** * of_register_spi_devices - Register child devices onto the SPI bus @@ -27,6 +28,7 @@ void of_register_spi_devices(struct spi_master *master) const __be32 *prop; int rc; int len; + int ncs_pin; if (!master->dev.of_node) return; @@ -50,15 +52,24 @@ void of_register_spi_devices(struct spi_master *master) continue; } - /* Device address */ - prop = of_get_property(nc, "reg", &len); - if (!prop || len < sizeof(*prop)) { - dev_err(&master->dev, "%s has no 'reg' property\n", - nc->full_name); - spi_dev_put(spi); - continue; + /* ncs gpio */ + ncs_pin = of_get_named_gpio(nc, "ncs-gpio", 0); + + if (gpio_is_valid(ncs_pin)) { + spi->controller_data = (void *)ncs_pin; + spi->chip_select = master->num_chipselect; + master->num_chipselect++; + } else { + /* Device address */ + prop = of_get_property(nc, "reg", &len); + if (!prop || len < sizeof(*prop)) { + dev_err(&master->dev, "%s has no 'reg' property\n", + nc->full_name); + spi_dev_put(spi); + continue; + } + spi->chip_select = be32_to_cpup(prop); } - spi->chip_select = be32_to_cpup(prop); /* Mode (clock phase/polarity/etc.) */ if (of_find_property(nc, "spi-cpha", NULL)) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index e2f4ca0..1f5ffa6 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -28,6 +28,7 @@ #include <linux/mod_devicetable.h> #include <linux/spi/spi.h> #include <linux/of_spi.h> +#include <linux/of_gpio.h> #include <linux/pm_runtime.h> #include <linux/export.h> @@ -339,15 +340,16 @@ 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 +373,13 @@ int spi_add_device(struct spi_device *spi) goto done; } + if (master->num_gpio_chipselect && + spi->chip_select >= master->first_gpio_chipselect) { + int num = spi->chip_select = master->first_gpio_chipselect; + + spi->controller_data = (void*)master->chipselect_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... @@ -562,6 +571,38 @@ struct spi_master *spi_alloc_master(struct device *dev, unsigned size) } EXPORT_SYMBOL_GPL(spi_alloc_master); +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, "ncs-gpios"); + + if (nb < 1) + return 0; + + master->chipselect_gpios = kzalloc(sizeof(int) * nb, GFP_KERNEL); + + if (!master->chipselect_gpios) + return -ENOMEM; + + master->first_gpio_chipselect = master->num_chipselect; + master->num_chipselect += nb; + master->num_gpio_chipselect = nb; + + for (i = 0; i < nb; i++) { + cs = &master->chipselect_gpios[i]; + + *cs = of_get_named_gpio(np, "ncs-gpios", i); + } + + return 0; +} + /** * spi_register_master - register SPI master controller * @master: initialized master, originally from spi_alloc_master() @@ -593,6 +634,10 @@ 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..d21c267 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -318,6 +318,11 @@ struct spi_master { /* called on release() to free memory provided by spi_master */ void (*cleanup)(struct spi_device *spi); + + /* gpio chip select */ + int *chipselect_gpios; + int first_gpio_chipselect; + int num_gpio_chipselect; }; static inline void *spi_master_get_devdata(struct spi_master *master) -- 1.7.7 _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
