target/linux/bcm27xx/patches-5.15/950-0696-spi-gpio-Add-sck-idle-input-property.patch

   1 From c979072887ef70aab2ab6e71544853df71017925 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.com>
   3 Date: Wed, 12 Jan 2022 08:23:28 +0000
   4 Subject: [PATCH] spi: gpio: Add sck-idle-input property
   5
   6 The sck-idle-input property indicates that the spi-gpio driver should
   7 return the SCK line to an input when the chip select signals are
   8 inactive.
   9
  10 Signed-off-by: Phil Elwell <phil@raspberrypi.com>
  11 ---
  12  drivers/spi/spi-gpio.c | 13 +++++++++++--
  13  1 file changed, 11 insertions(+), 2 deletions(-)
  14
  15 --- a/drivers/spi/spi-gpio.c
  16 +++ b/drivers/spi/spi-gpio.c
  17 @@ -35,6 +35,7 @@ struct spi_gpio {
  18         struct gpio_desc                *sck;
  19         struct gpio_desc                *miso;
  20         struct gpio_desc                *mosi;
  21 +       bool                            sck_idle_input;
  22         struct gpio_desc                **cs_gpios;
  23  };
  24
  25 @@ -201,8 +202,12 @@ static void spi_gpio_chipselect(struct s
  26         struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
  27
  28         /* set initial clock line level */
  29 -       if (is_active)
  30 -               gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
  31 +       if (is_active) {
  32 +               if (spi_gpio->sck_idle_input)
  33 +                       gpiod_direction_output(spi_gpio->sck, spi->mode & SPI_CPOL);
  34 +               else
  35 +                       gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
  36 +       }
  37
  38         /* Drive chip select line, if we have one */
  39         if (spi_gpio->cs_gpios) {
  40 @@ -211,6 +216,9 @@ static void spi_gpio_chipselect(struct s
  41                 /* SPI chip selects are normally active-low */
  42                 gpiod_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
  43         }
  44 +
  45 +       if (spi_gpio->sck_idle_input && !is_active)
  46 +               gpiod_direction_input(spi_gpio->sck);
  47  }
  48
  49  static int spi_gpio_setup(struct spi_device *spi)
  50 @@ -289,6 +297,7 @@ static int spi_gpio_request(struct devic
  51         if (IS_ERR(spi_gpio->miso))
  52                 return PTR_ERR(spi_gpio->miso);
  53
  54 +       spi_gpio->sck_idle_input = device_property_read_bool(dev, "sck-idle-input");
  55         spi_gpio->sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW);
  56         return PTR_ERR_OR_ZERO(spi_gpio->sck);
  57  }