[PATCH 2/3 v3] of_spi: add generic binding support to specify ncs gpio
Jean-Christophe PLAGNIOL-VILLARD
plagnioj at jcrosoft.com
Sat Mar 3 14:45:26 EST 2012
On 19:32 Fri 02 Mar , Grant Likely wrote:
> On Fri, 2 Mar 2012 11:03:06 +0100, Jean-Christophe PLAGNIOL-VILLARD <plagnioj at 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 <plagnioj at jcrosoft.com>
> > Cc: devicetree-discuss at lists.ozlabs.org
> > Cc: spi-devel-general at lists.sourceforge.net
> > Cc: Grant Likely <grant.likely at 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?
for not chipslelect will remove
>
> > 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/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.
I want to have this transparent for the driver
I don't want it to manage this. The driver just need to known it's cs-gpio
and wich one
>
> > +
> > + spi->controller_data = (void*)master->chipselect_gpios[num];
>
> Controller_data cannot be used here since it is provided for use
> by the controller driver.
a new entry cs_gpio in the spi_device
>
> > + }
> > +
> > /* 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.
it's the case here it's just the management on the binding
>
> > +
> > + 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
ok
>
> > };
Best Regards,
J.
> >
> > static inline void *spi_master_get_devdata(struct spi_master *master)
> > --
> > 1.7.7
> >
>
> --
> email sent from notmuch.vim plugin
More information about the devicetree-discuss
mailing list