On Fri, 2 Mar 2012 11:03:06 +0100, Jean-Christophe PLAGNIOL-VILLARD
<plagn...@jcrosoft.com> 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 <plagn...@jcrosoft.com>
> Cc: devicetree-disc...@lists.ozlabs.org
> Cc: spi-devel-general@lists.sourceforge.net
> Cc: Grant Likely <grant.lik...@secretlab.ca>
> ---
> v3:
> use devm_kzalloc
>
> v2:
> specify the gpio array at controller level
>
> Best Regards,
> J.
> Documentation/devicetree/bindings/spi/spi-bus.txt | 6 +++
> drivers/spi/spi.c | 49 +++++++++++++++++++-
> include/linux/spi/spi.h | 5 ++
> 3 files changed, 57 insertions(+), 3 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.
ncs? What does the 'n' stand for?
> 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/spi/spi.c b/drivers/spi/spi.c
> index e2f4ca0..f3df51f 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;
I'd rather see an unconditional array of gpios; which only get used if a
valid gpio number is assigned.
> +
> + spi->controller_data = (void*)master->chipselect_gpios[num];
Controller_data cannot be used here since it is provided for use
by the controller driver.
> + }
> +
> /* 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 +571,36 @@ 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;
> +
> + cs = devm_kzalloc(&master->dev, sizeof(int) * nb, GFP_KERNEL);
> + master->chipselect_gpios = cs;
the chipselect gpios functionality should be available regardless
of whether or not DT is used. This should be moved out of the of-specific
register function.
> +
> + 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[i] = of_get_named_gpio(np, "ncs-gpios", i);
> +
> + return 0;
> +}
This function should be #ifdefed out when !OF
> +
> /**
> * spi_register_master - register SPI master controller
> * @master: initialized master, originally from spi_alloc_master()
> @@ -593,6 +632,10 @@ 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;
s/chipselect/cs/ would be quite a bit less verbose
> };
>
> static inline void *spi_master_get_devdata(struct spi_master *master)
> --
> 1.7.7
>
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