[PATCH 2/3] of_spi: add generic binding support to specify ncs gpio
Jean-Christophe PLAGNIOL-VILLARD
plagnioj at jcrosoft.com
Mon Feb 13 23:24:19 EST 2012
Hi Grant,
ping
Best Regards,
J.
On 17:14 Thu 09 Feb , Jean-Christophe PLAGNIOL-VILLARD wrote:
> 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 <plagnioj at jcrosoft.com>
> Cc: devicetree-discuss at lists.ozlabs.org
> Cc: spi-devel-general at lists.sourceforge.net
> ---
> 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 at 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
More information about the linux-arm-kernel
mailing list