On Tue, May 23, 2017 at 7:03 AM, Chris Packham <[email protected]> wrote: > By using a gpio_desc and gpiod_set_value() instead of a numeric gpio and > gpio_set_value() the gpio flags are taken into account. This is useful > when using a gpio chip-select to supplement a controllers native > chip-select.
I think would be better to move everything in SPI core to GPIO descriptors. > > Signed-off-by: Chris Packham <[email protected]> > --- > > Notes: > My specific use-case is I have a board that uses the spi-orion driver but > only has one CS pin available. In order to access two spi slave devices > the > board has a 1-of-2 decoder/demultiplexer which is driven via a gpio. > > The problem is that for one of the 2 slave devices the gpio level required > is opposite to the chip-select so I can't simply specify "spi-cs-high". > With this change I can flag the gpio as active low and the gpio subsystem > takes care of the additional inversion required. > > drivers/spi/spi.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index 6f87fec409b5..b39c0f9956dd 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -725,7 +725,10 @@ static void spi_set_cs(struct spi_device *spi, bool > enable) > enable = !enable; > > if (gpio_is_valid(spi->cs_gpio)) { > - gpio_set_value(spi->cs_gpio, !enable); > + struct gpio_desc *gpio = gpio_to_desc(spi->cs_gpio); > + > + if (gpio) > + gpiod_set_value(gpio, !enable); > /* Some SPI masters need both GPIO CS & slave_select */ > if ((spi->master->flags & SPI_MASTER_GPIO_SS) && > spi->master->set_cs) > -- > 2.13.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-spi" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- With Best Regards, Andy Shevchenko
