diff options
| -rw-r--r-- | Documentation/devicetree/bindings/spi/spi-bus.txt | 20 | ||||
| -rw-r--r-- | drivers/spi/spi.c | 54 | ||||
| -rw-r--r-- | include/linux/spi/spi.h | 3 |
3 files changed, 74 insertions, 3 deletions
diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt index d2c33d0f533e..77a8b0d39b54 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 @@ -24,6 +25,22 @@ support describing the chip select layout. Optional property: - num-cs : total number of chipselects +If cs-gpios is used the number of chip select will automatically increased +with max(cs-gpios > hw cs) + +So if for example the controller has 2 CS lines, and the cs-gpios +property looks like this: + +cs-gpios = <&gpio1 0 0> <0> <&gpio1 1 0> <&gpio1 2 0>; + +Then it should be configured so that num_chipselect = 4 with the +following mapping: + +cs0 : &gpio1 0 0 +cs1 : native +cs2 : &gpio1 1 0 +cs3 : &gpio1 2 0 + SPI slave nodes must be children of the SPI master node and can contain the following properties. - reg - (required) chip select address of device. @@ -37,6 +54,9 @@ 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 cs_gpio + 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 84c2861d6f4d..1587a4a5ff41 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -30,6 +30,7 @@ #include <linux/slab.h> #include <linux/mod_devicetable.h> #include <linux/spi/spi.h> +#include <linux/of_gpio.h> #include <linux/pm_runtime.h> #include <linux/export.h> #include <linux/sched.h> @@ -327,6 +328,7 @@ 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; } @@ -344,15 +346,16 @@ 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; } @@ -376,6 +379,9 @@ int spi_add_device(struct spi_device *spi) goto done; } + if (master->cs_gpios) + spi->cs_gpio = master->cs_gpios[spi->chip_select]; + /* 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... @@ -946,6 +952,44 @@ 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) +{ + u16 nb; + int i, *cs; + struct device_node *np = master->dev.of_node; + + if (!np) + return 0; + + nb = of_gpio_named_count(np, "cs-gpios"); + master->num_chipselect = max(nb, master->num_chipselect); + + if (nb < 1) + return 0; + + cs = devm_kzalloc(&master->dev, + sizeof(int) * master->num_chipselect, + GFP_KERNEL); + master->cs_gpios = cs; + + if (!master->cs_gpios) + return -ENOMEM; + + memset(cs, -EINVAL, master->num_chipselect); + + 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() @@ -977,6 +1021,10 @@ 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 fa702aeb5038..f62918946d86 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -90,6 +90,7 @@ 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 @@ -362,6 +363,8 @@ struct spi_master { int (*transfer_one_message)(struct spi_master *master, struct spi_message *mesg); int (*unprepare_transfer_hardware)(struct spi_master *master); + /* gpio chip select */ + int *cs_gpios; }; static inline void *spi_master_get_devdata(struct spi_master *master) |