target/linux/brcm2708/patches-4.4/0012-spi-bcm2835-Support-pin-groups-other-than-7-11.patch

   1 From bc9d2c297e886dfcc340414a61de970942ad7319 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.org>
   3 Date: Wed, 24 Jun 2015 14:10:44 +0100
   4 Subject: [PATCH 012/127] spi-bcm2835: Support pin groups other than 7-11
   5
   6 The spi-bcm2835 driver automatically uses GPIO chip-selects due to
   7 some unreliability of the native ones. In doing so it chooses the
   8 same pins as the native chip-selects would use, but the existing
   9 code always uses pins 7 and 8, wherever the SPI function is mapped.
  10
  11 Search the pinctrl group assigned to the driver for pins that
  12 correspond to native chip-selects, and use those for GPIO chip-
  13 selects.
  14
  15 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  16 ---
  17  drivers/spi/spi-bcm2835.c | 45 +++++++++++++++++++++++++++++++++++++--------
  18  1 file changed, 37 insertions(+), 8 deletions(-)
  19
  20 --- a/drivers/spi/spi-bcm2835.c
  21 +++ b/drivers/spi/spi-bcm2835.c
  22 @@ -688,6 +688,8 @@ static int bcm2835_spi_setup(struct spi_
  23  {
  24         int err;
  25         struct gpio_chip *chip;
  26 +       struct device_node *pins;
  27 +       u32 pingroup_index;
  28         /*
  29          * sanity checking the native-chipselects
  30          */
  31 @@ -704,15 +706,42 @@ static int bcm2835_spi_setup(struct spi_
  32                         "setup: only two native chip-selects are supported\n");
  33                 return -EINVAL;
  34         }
  35 -       /* now translate native cs to GPIO */
  36
  37 -       /* get the gpio chip for the base */
  38 -       chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
  39 -       if (!chip)
  40 -               return 0;
  41 +       /* now translate native cs to GPIO */
  42 +       /* first look for chip select pins in the devices pin groups */
  43 +       for (pingroup_index = 0;
  44 +            (pins = of_parse_phandle(spi->master->dev.of_node,
  45 +                                    "pinctrl-0",
  46 +                                     pingroup_index)) != 0;
  47 +            pingroup_index++) {
  48 +               u32 pin;
  49 +               u32 pin_index;
  50 +               for (pin_index = 0;
  51 +                    of_property_read_u32_index(pins,
  52 +                                               "brcm,pins",
  53 +                                               pin_index,
  54 +                                               &pin) == 0;
  55 +                    pin_index++) {
  56 +                       if (((spi->chip_select == 0) &&
  57 +                            ((pin == 8) || (pin == 36) || (pin == 46))) ||
  58 +                           ((spi->chip_select == 1) &&
  59 +                            ((pin == 7) || (pin == 35)))) {
  60 +                               spi->cs_gpio = pin;
  61 +                               break;
  62 +                       }
  63 +               }
  64 +               of_node_put(pins);
  65 +       }
  66 +       /* if that fails, assume GPIOs 7-11 are used */
  67 +       if (!gpio_is_valid(spi->cs_gpio) ) {
  68 +               /* get the gpio chip for the base */
  69 +               chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
  70 +               if (!chip)
  71 +                       return 0;
  72
  73 -       /* and calculate the real CS */
  74 -       spi->cs_gpio = chip->base + 8 - spi->chip_select;
  75 +               /* and calculate the real CS */
  76 +               spi->cs_gpio = chip->base + 8 - spi->chip_select;
  77 +       }
  78
  79         /* and set up the "mode" and level */
  80         dev_info(&spi->dev, "setting up native-CS%i as GPIO %i\n",