git.openwrt.org Git - openwrt/staging/linusw.git/blob

   1 From 78ced8c841ba08b41eacd064e7c7a9b3fe7556ad 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 0553/1085] spi: gpio: 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 | 76 +++++++++++++++++++++++++++++-------------
  15  1 file changed, 52 insertions(+), 24 deletions(-)
  16
  17 --- a/drivers/spi/spi-gpio.c
  18 +++ b/drivers/spi/spi-gpio.c
  19 @@ -34,8 +34,9 @@ struct spi_gpio {
  20         struct gpio_desc                *sck;
  21         struct gpio_desc                *miso;
  22         struct gpio_desc                *mosi;
  23 -       bool                            sck_idle_input;
  24         struct gpio_desc                **cs_gpios;
  25 +       bool                            sck_idle_input;
  26 +       bool                            cs_dont_invert;
  27  };
  28
  29  /*----------------------------------------------------------------------*/
  30 @@ -232,12 +233,18 @@ static void spi_gpio_chipselect(struct s
  31                         gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
  32         }
  33
  34 -       /* Drive chip select line, if we have one */
  35 +       /*
  36 +        * Drive chip select line, if we have one.
  37 +        * SPI chip selects are normally active-low, but when
  38 +        * cs_dont_invert is set, we assume their polarity is
  39 +        * controlled by the GPIO, and write '1' to assert.
  40 +        */
  41         if (spi_gpio->cs_gpios) {
  42                 struct gpio_desc *cs = spi_gpio->cs_gpios[spi_get_chipselect(spi, 0)];
  43 +               int val = ((spi->mode & SPI_CS_HIGH) || spi_gpio->cs_dont_invert) ?
  44 +                       is_active : !is_active;
  45
  46 -               /* SPI chip selects are normally active-low */
  47 -               gpiod_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
  48 +               gpiod_set_value_cansleep(cs, val);
  49         }
  50
  51         if (spi_gpio->sck_idle_input && !is_active)
  52 @@ -253,12 +260,14 @@ static int spi_gpio_setup(struct spi_dev
  53         /*
  54          * The CS GPIOs have already been
  55          * initialized from the descriptor lookup.
  56 +        * Here we set them to the non-asserted state.
  57          */
  58         if (spi_gpio->cs_gpios) {
  59                 cs = spi_gpio->cs_gpios[spi_get_chipselect(spi, 0)];
  60                 if (!spi->controller_state && cs)
  61                         status = gpiod_direction_output(cs,
  62 -                                                 !(spi->mode & SPI_CS_HIGH));
  63 +                                                       !((spi->mode & SPI_CS_HIGH) ||
  64 +                                                          spi_gpio->cs_dont_invert));
  65         }
  66
  67         if (!status)
  68 @@ -335,6 +344,38 @@ static int spi_gpio_request(struct devic
  69         return PTR_ERR_OR_ZERO(spi_gpio->sck);
  70  }
  71
  72 +/*
  73 + * In order to implement "sck-idle-input" (which requires SCK
  74 + * direction and CS level to be switched in a particular order),
  75 + * we need to control GPIO chip selects from within this driver.
  76 + */
  77 +
  78 +static int spi_gpio_probe_get_cs_gpios(struct device *dev,
  79 +                                      struct spi_master *master,
  80 +                                      bool gpio_defines_polarity)
  81 +{
  82 +       int i;
  83 +       struct spi_gpio *spi_gpio = spi_master_get_devdata(master);
  84 +
  85 +       spi_gpio->cs_dont_invert = gpio_defines_polarity;
  86 +       spi_gpio->cs_gpios = devm_kcalloc(dev, master->num_chipselect,
  87 +                                         sizeof(*spi_gpio->cs_gpios),
  88 +                                         GFP_KERNEL);
  89 +       if (!spi_gpio->cs_gpios)
  90 +               return -ENOMEM;
  91 +
  92 +       for (i = 0; i < master->num_chipselect; i++) {
  93 +               spi_gpio->cs_gpios[i] =
  94 +                       devm_gpiod_get_index(dev, "cs", i,
  95 +                                            gpio_defines_polarity ?
  96 +                                               GPIOD_OUT_LOW : GPIOD_OUT_HIGH);
  97 +               if (IS_ERR(spi_gpio->cs_gpios[i]))
  98 +                       return PTR_ERR(spi_gpio->cs_gpios[i]);
  99 +       }
 100 +
 101 +       return 0;
 102 +}
 103 +
 104  #ifdef CONFIG_OF
 105  static const struct of_device_id spi_gpio_dt_ids[] = {
 106         { .compatible = "spi-gpio" },
 107 @@ -345,10 +386,12 @@ MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids)
 108  static int spi_gpio_probe_dt(struct platform_device *pdev,
 109                              struct spi_controller *host)
 110  {
 111 -       host->dev.of_node = pdev->dev.of_node;
 112 -       host->use_gpio_descriptors = true;
 113 +       struct device *dev = &pdev->dev;
 114
 115 -       return 0;
 116 +       host->dev.of_node = dev->of_node;
 117 +       host->num_chipselect = gpiod_count(dev, "cs");
 118 +
 119 +       return spi_gpio_probe_get_cs_gpios(dev, host, true);
 120  }
 121  #else
 122  static inline int spi_gpio_probe_dt(struct platform_device *pdev,
 123 @@ -363,8 +406,6 @@ static int spi_gpio_probe_pdata(struct p
 124  {
 125         struct device *dev = &pdev->dev;
 126         struct spi_gpio_platform_data *pdata = dev_get_platdata(dev);
 127 -       struct spi_gpio *spi_gpio = spi_controller_get_devdata(host);
 128 -       int i;
 129
 130  #ifdef GENERIC_BITBANG
 131         if (!pdata || !pdata->num_chipselect)
 132 @@ -376,20 +417,7 @@ static int spi_gpio_probe_pdata(struct p
 133          */
 134         host->num_chipselect = pdata->num_chipselect ?: 1;
 135
 136 -       spi_gpio->cs_gpios = devm_kcalloc(dev, host->num_chipselect,
 137 -                                         sizeof(*spi_gpio->cs_gpios),
 138 -                                         GFP_KERNEL);
 139 -       if (!spi_gpio->cs_gpios)
 140 -               return -ENOMEM;
 141 -
 142 -       for (i = 0; i < host->num_chipselect; i++) {
 143 -               spi_gpio->cs_gpios[i] = devm_gpiod_get_index(dev, "cs", i,
 144 -                                                            GPIOD_OUT_HIGH);
 145 -               if (IS_ERR(spi_gpio->cs_gpios[i]))
 146 -                       return PTR_ERR(spi_gpio->cs_gpios[i]);
 147 -       }
 148 -
 149 -       return 0;
 150 +       return spi_gpio_probe_get_cs_gpios(dev, host, false);
 151  }
 152
 153  static int spi_gpio_probe(struct platform_device *pdev)