target/linux/bcm27xx/patches-6.1/950-0900-drivers-spi-Fix-spi-gpio-to-correctly-implement-sck-.patch

   1 From 380c336af070edf85826abbb0057bf92a03ec466 Mon Sep 17 00:00:00 2001
   2 From: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>
   3 Date: Wed, 1 Mar 2023 17:57:11 +0000
   4 Subject: [PATCH] drivers: spi: Fix spi-gpio to correctly implement
   5  sck-idle-input
   6
   7 Formerly, if configured using DT, CS GPIOs were driven from spi.c
   8 and it was possible for CS to be asserted (low) *before* starting
   9 to drive SCK. CS GPIOs have been brought under control of this
  10 driver in both ACPI and DT cases, with a fixup for GPIO polarity.
  11
  12 Signed-off-by: Nick Hollinghurst <nick.hollinghurst@raspberrypi.com>
  13 ---
  14  drivers/spi/spi-gpio.c | 74 +++++++++++++++++++++++++++++-------------
  15  1 file changed, 51 insertions(+), 23 deletions(-)
  16
  17 --- a/drivers/spi/spi-gpio.c
  18 +++ b/drivers/spi/spi-gpio.c
  19 @@ -37,6 +37,7 @@ struct spi_gpio {
  20         struct gpio_desc                *mosi;
  21         bool                            sck_idle_input;
  22         struct gpio_desc                **cs_gpios;
  23 +       bool                            cs_dont_invert;
  24  };
  25
  26  /*----------------------------------------------------------------------*/
  27 @@ -233,12 +234,18 @@ static void spi_gpio_chipselect(struct s
  28                         gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
  29         }
  30
  31 -       /* Drive chip select line, if we have one */
  32 +       /*
  33 +        * Drive chip select line, if we have one.
  34 +        * SPI chip selects are normally active-low, but when
  35 +        * cs_dont_invert is set, we assume their polarity is
  36 +        * controlled by the GPIO, and write '1' to assert.
  37 +        */
  38         if (spi_gpio->cs_gpios) {
  39                 struct gpio_desc *cs = spi_gpio->cs_gpios[spi->chip_select];
  40 +               int val = ((spi->mode & SPI_CS_HIGH) || spi_gpio->cs_dont_invert) ?
  41 +                       is_active : !is_active;
  42
  43 -               /* SPI chip selects are normally active-low */
  44 -               gpiod_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
  45 +               gpiod_set_value_cansleep(cs, val);
  46         }
  47
  48         if (spi_gpio->sck_idle_input && !is_active)
  49 @@ -254,12 +261,14 @@ static int spi_gpio_setup(struct spi_dev
  50         /*
  51          * The CS GPIOs have already been
  52          * initialized from the descriptor lookup.
  53 +        * Here we set them to the non-asserted state.
  54          */
  55         if (spi_gpio->cs_gpios) {
  56                 cs = spi_gpio->cs_gpios[spi->chip_select];
  57                 if (!spi->controller_state && cs)
  58                         status = gpiod_direction_output(cs,
  59 -                                                 !(spi->mode & SPI_CS_HIGH));
  60 +                                                       !((spi->mode & SPI_CS_HIGH) ||
  61 +                                                          spi_gpio->cs_dont_invert));
  62         }
  63
  64         if (!status)
  65 @@ -336,6 +345,38 @@ static int spi_gpio_request(struct devic
  66         return PTR_ERR_OR_ZERO(spi_gpio->sck);
  67  }
  68
  69 +/*
  70 + * In order to implement "sck-idle-input" (which requires SCK
  71 + * direction and CS level to be switched in a particular order),
  72 + * we need to control GPIO chip selects from within this driver.
  73 + */
  74 +
  75 +static int spi_gpio_probe_get_cs_gpios(struct device *dev,
  76 +                                      struct spi_master *master,
  77 +                                      bool gpio_defines_polarity)
  78 +{
  79 +       int i;
  80 +       struct spi_gpio *spi_gpio = spi_master_get_devdata(master);
  81 +
  82 +       spi_gpio->cs_dont_invert = gpio_defines_polarity;
  83 +       spi_gpio->cs_gpios = devm_kcalloc(dev, master->num_chipselect,
  84 +                                         sizeof(*spi_gpio->cs_gpios),
  85 +                                         GFP_KERNEL);
  86 +       if (!spi_gpio->cs_gpios)
  87 +               return -ENOMEM;
  88 +
  89 +       for (i = 0; i < master->num_chipselect; i++) {
  90 +               spi_gpio->cs_gpios[i] =
  91 +                       devm_gpiod_get_index(dev, "cs", i,
  92 +                                            gpio_defines_polarity ?
  93 +                                               GPIOD_OUT_LOW : GPIOD_OUT_HIGH);
  94 +               if (IS_ERR(spi_gpio->cs_gpios[i]))
  95 +                       return PTR_ERR(spi_gpio->cs_gpios[i]);
  96 +       }
  97 +
  98 +       return 0;
  99 +}
 100 +
 101  #ifdef CONFIG_OF
 102  static const struct of_device_id spi_gpio_dt_ids[] = {
 103         { .compatible = "spi-gpio" },
 104 @@ -346,10 +387,12 @@ MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids)
 105  static int spi_gpio_probe_dt(struct platform_device *pdev,
 106                              struct spi_master *master)
 107  {
 108 -       master->dev.of_node = pdev->dev.of_node;
 109 -       master->use_gpio_descriptors = true;
 110 +       struct device *dev = &pdev->dev;
 111
 112 -       return 0;
 113 +       master->dev.of_node = dev->of_node;
 114 +       master->num_chipselect = gpiod_count(dev, "cs");
 115 +
 116 +       return spi_gpio_probe_get_cs_gpios(dev, master, true);
 117  }
 118  #else
 119  static inline int spi_gpio_probe_dt(struct platform_device *pdev,
 120 @@ -364,8 +407,6 @@ static int spi_gpio_probe_pdata(struct p
 121  {
 122         struct device *dev = &pdev->dev;
 123         struct spi_gpio_platform_data *pdata = dev_get_platdata(dev);
 124 -       struct spi_gpio *spi_gpio = spi_master_get_devdata(master);
 125 -       int i;
 126
 127  #ifdef GENERIC_BITBANG
 128         if (!pdata || !pdata->num_chipselect)
 129 @@ -377,20 +418,7 @@ static int spi_gpio_probe_pdata(struct p
 130          */
 131         master->num_chipselect = pdata->num_chipselect ?: 1;
 132
 133 -       spi_gpio->cs_gpios = devm_kcalloc(dev, master->num_chipselect,
 134 -                                         sizeof(*spi_gpio->cs_gpios),
 135 -                                         GFP_KERNEL);
 136 -       if (!spi_gpio->cs_gpios)
 137 -               return -ENOMEM;
 138 -
 139 -       for (i = 0; i < master->num_chipselect; i++) {
 140 -               spi_gpio->cs_gpios[i] = devm_gpiod_get_index(dev, "cs", i,
 141 -                                                            GPIOD_OUT_HIGH);
 142 -               if (IS_ERR(spi_gpio->cs_gpios[i]))
 143 -                       return PTR_ERR(spi_gpio->cs_gpios[i]);
 144 -       }
 145 -
 146 -       return 0;
 147 +       return spi_gpio_probe_get_cs_gpios(dev, master, false);
 148  }
 149
 150  static int spi_gpio_probe(struct platform_device *pdev)