From c979072887ef70aab2ab6e71544853df71017925 Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Wed, 12 Jan 2022 08:23:28 +0000 Subject: [PATCH] spi: gpio: Add sck-idle-input property The sck-idle-input property indicates that the spi-gpio driver should return the SCK line to an input when the chip select signals are inactive. Signed-off-by: Phil Elwell --- drivers/spi/spi-gpio.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) --- a/drivers/spi/spi-gpio.c +++ b/drivers/spi/spi-gpio.c @@ -35,6 +35,7 @@ struct spi_gpio { struct gpio_desc *sck; struct gpio_desc *miso; struct gpio_desc *mosi; + bool sck_idle_input; struct gpio_desc **cs_gpios; }; @@ -201,8 +202,12 @@ static void spi_gpio_chipselect(struct s struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi); /* set initial clock line level */ - if (is_active) - gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL); + if (is_active) { + if (spi_gpio->sck_idle_input) + gpiod_direction_output(spi_gpio->sck, spi->mode & SPI_CPOL); + else + gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL); + } /* Drive chip select line, if we have one */ if (spi_gpio->cs_gpios) { @@ -211,6 +216,9 @@ static void spi_gpio_chipselect(struct s /* SPI chip selects are normally active-low */ gpiod_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active); } + + if (spi_gpio->sck_idle_input && !is_active) + gpiod_direction_input(spi_gpio->sck); } static int spi_gpio_setup(struct spi_device *spi) @@ -299,6 +307,7 @@ static int spi_gpio_request(struct devic if (IS_ERR(spi_gpio->miso)) return PTR_ERR(spi_gpio->miso); + spi_gpio->sck_idle_input = device_property_read_bool(dev, "sck-idle-input"); spi_gpio->sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW); return PTR_ERR_OR_ZERO(spi_gpio->sck); }