Re: [PATCH 2/3] of_spi: add generic binding support to specify ncs gpio

[Jean-Christophe PLAGNIOL-VILLARD <plagnioj-sclMFOaUSTBWk0Htik3J/w@public.gmane.org>]

Hi Grant,

	can I have a feedback

	the Atmel SPI depend on it

Best Regards,
J.
On 05:24 Tue 14 Feb     , Jean-Christophe PLAGNIOL-VILLARD wrote:
> 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-sclMFOaUSTBWk0Htik3J/w@public.gmane.org>
> > Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
> > Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> > ---
> >  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
> 
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