target/linux/bcm27xx/patches-5.4/950-0789-Revert-spi-spi-bcm2835-Disable-forced-software-CS.patch

   1 From 1d78f72cb5a387922870e2a54228be25f84f95f6 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.com>
   3 Date: Tue, 16 Jun 2020 10:23:29 +0100
   4 Subject: [PATCH] Revert "spi: spi-bcm2835: Disable forced software
   5  CS"
   6
   7 This reverts commit 2697f0186db346176832b8eb79adaf5c874681e8.
   8
   9 See: https://github.com/raspberrypi/linux/pull/3687
  10 ---
  11  drivers/spi/spi-bcm2835.c | 37 +++++++++++++++++++++++++++++++++++++
  12  1 file changed, 37 insertions(+)
  13
  14 --- a/drivers/spi/spi-bcm2835.c
  15 +++ b/drivers/spi/spi-bcm2835.c
  16 @@ -1241,6 +1241,43 @@ static int bcm2835_spi_setup(struct spi_
  17                 return -EINVAL;
  18         }
  19
  20 +       /*
  21 +        * Translate native CS to GPIO
  22 +        *
  23 +        * FIXME: poking around in the gpiolib internals like this is
  24 +        * not very good practice. Find a way to locate the real problem
  25 +        * and fix it. Why is the GPIO descriptor in spi->cs_gpiod
  26 +        * sometimes not assigned correctly? Erroneous device trees?
  27 +        */
  28 +
  29 +       /* get the gpio chip for the base */
  30 +       chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
  31 +       if (!chip)
  32 +               return 0;
  33 +
  34 +       /*
  35 +        * Retrieve the corresponding GPIO line used for CS.
  36 +        * The inversion semantics will be handled by the GPIO core
  37 +        * code, so we pass GPIOS_OUT_LOW for "unasserted" and
  38 +        * the correct flag for inversion semantics. The SPI_CS_HIGH
  39 +        * on spi->mode cannot be checked for polarity in this case
  40 +        * as the flag use_gpio_descriptors enforces SPI_CS_HIGH.
  41 +        */
  42 +       if (of_property_read_bool(spi->dev.of_node, "spi-cs-high"))
  43 +               lflags = GPIO_ACTIVE_HIGH;
  44 +       else
  45 +               lflags = GPIO_ACTIVE_LOW;
  46 +       spi->cs_gpiod = gpiochip_request_own_desc(chip, 8 - spi->chip_select,
  47 +                                                 DRV_NAME,
  48 +                                                 lflags,
  49 +                                                 GPIOD_OUT_LOW);
  50 +       if (IS_ERR(spi->cs_gpiod))
  51 +               return PTR_ERR(spi->cs_gpiod);
  52 +
  53 +       /* and set up the "mode" and level */
  54 +       dev_info(&spi->dev, "setting up native-CS%i to use GPIO\n",
  55 +                spi->chip_select);
  56 +
  57         return 0;
  58  }
  59