target/linux/bcm27xx/patches-6.1/950-1236-spi-bcm2835-Support-spi0-0cs-and-SPI_NO_CS-mode.patch

   1 From 5d9075ed7e73dc6ccebf78710c78f39ddc2dd78e Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.com>
   3 Date: Mon, 8 Jan 2024 11:42:57 +0000
   4 Subject: [PATCH] spi: bcm2835: Support spi0-0cs and SPI_NO_CS mode
   5
   6 The forced conversion of native CS lines into software CS lines is done
   7 whether or not the controller has been given any CS lines to use. This
   8 breaks the use of the spi0-0cs overlay to prevent SPI from claiming any
   9 CS lines, particularly with spidev which doesn't pass in the SPI_NO_CS
  10 flag at creation.
  11
  12 Use the presence of an empty cs-gpios property as an indication that no
  13 CS lines should be used, bypassing the native CS conversion code.
  14
  15 See: https://github.com/raspberrypi/linux/issues/5835
  16
  17 Signed-off-by: Phil Elwell <phil@raspberrypi.com>
  18 ---
  19  drivers/spi/spi-bcm2835.c | 5 +++++
  20  1 file changed, 5 insertions(+)
  21
  22 --- a/drivers/spi/spi-bcm2835.c
  23 +++ b/drivers/spi/spi-bcm2835.c
  24 @@ -1222,6 +1222,7 @@ static int bcm2835_spi_setup(struct spi_
  25         struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
  26         struct bcm2835_spidev *slv = spi_get_ctldata(spi);
  27         struct gpio_chip *chip;
  28 +       int len;
  29         int ret;
  30         u32 cs;
  31
  32 @@ -1287,6 +1288,10 @@ static int bcm2835_spi_setup(struct spi_
  33                 goto err_cleanup;
  34         }
  35
  36 +       /* Skip forced CS conversion if controller has an empty cs-gpios property */
  37 +       if (of_find_property(ctlr->dev.of_node, "cs-gpios", &len) && len == 0)
  38 +               return 0;
  39 +
  40         /*
  41          * Translate native CS to GPIO
  42          *