On 11:54 Mon 30 Jan , Grant Likely wrote:
> On Mon, Jan 30, 2012 at 04:27:49PM +0100, 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-gpio, the gpio number will be passed via the
> > controller_data
> > and the number of chip select will automatically increased.
> >
> > When a spi master have only gpio chip select and is probe via dt check the
> > number of chip select only when adding slave.
> >
> > Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagn...@jcrosoft.com>
> > Cc: devicetree-disc...@lists.ozlabs.org
> > Cc: spi-devel-general@lists.sourceforge.net
> > ---
> > Documentation/devicetree/bindings/spi/spi-bus.txt | 9 ++++++-
> > drivers/of/of_spi.c | 27
> > ++++++++++++++------
> > drivers/spi/spi.c | 2 +-
> > 3 files changed, 28 insertions(+), 10 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt
> > b/Documentation/devicetree/bindings/spi/spi-bus.txt
> > index e782add..1dccf35 100644
> > --- a/Documentation/devicetree/bindings/spi/spi-bus.txt
> > +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt
> > @@ -21,9 +21,16 @@ 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 a gpio a specified to the SPI slave and no hardware chip select is
> > present
> > +the reg property #address-cells and #size-cells are not needed.
> > +
> > +When use the ncs-gpio the gpio number will be passed via the
> > controller_data
> > +and 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.
> > +- reg - (required if no ncs-gpio) chip select address of
> > device.
> > +- ncs-gpio - (required if no reg) chip select gpio of device.
>
> There is already precedence for using gpios for chip selects. The slave
> device
> nodes remain as they are and it is the responsibility of the spi bus node
> to have a gpios property with a list of SS gpios. The order of the gpios
> property should match the 'reg' address numbering of the child node.
>
> I don't like the idea of having multiple bindings for the slave address of
> the spi device (reg or ncs-gpio)
>
> What I want to see is generic SS helper code that spi bus drivers
> default to and correctly implement parsing of chip select gpios.
>
> I'm not going to apply this patch.
I do not want to see any of managment in the driver, I want a generic way to
specify only gpio cs and hw and gpio cs
spi1: spi@fffcc000 {
ncs-gpios = <&pioB 3 0>;
status = "okay";
mmc-slot@0 {
reg = <0>;
compatible = "mmc-spi-slot";
gpios = <&pioC 4 0 /* CD */
>;
voltage-ranges = <3200 3400>;
spi-max-frequency = <20000000>;
};
};
as on atmel spi we have no HW spi the cs is 0
if there is 3 hw cs the reg will be 3
we have 4 hw chipselect 3 enabled and one gpio chipselect
spi1: spi@fffcc000 {
ncs-hw = < 0 1 1 1>;
ncs-gpios = <&pioB 3 0>;
status = "okay";
mmc-slot@0 {
reg = <3>;
compatible = "mmc-spi-slot";
gpios = <&pioC 4 0 /* CD */
>;
voltage-ranges = <3200 3400>;
spi-max-frequency = <20000000>;
};
};
the idea is to pass the ncs_pin in the spi_device so the driver just have
to check if the chipselect is hw or gpio and then use it the right way
Best Regards,
J.
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