spi: bcm2835: Restore native CS probing when pinctrl-bcm2835 is absent

The lookup table forces the use of the "pinctrl-bcm2835" GPIO chip
provider and essentially assumes that there is going to be such a
provider, and if not, we will fail to set-up the SPI device.

While this is true on Raspberry Pi based systems (2835/36/37, 2711,
2712), this is not true on 7712/77122 Broadcom STB systems which use the
SPI driver, but not the GPIO driver.

There used to be an early check:

       chip = gpiochip_find("pinctrl-bcm2835", chip_match_name);
       if (!chip)
               return 0;

which would accomplish that nicely, bring something similar back by
checking for the compatible strings matched by the pinctrl-bcm2835.c
driver, if there is no Device Tree node matching those compatible
strings, then we won't find any GPIO provider registered by the
"pinctrl-bcm2835" driver.

Fixes: 21f252cd29f0 ("spi: bcm2835: reduce the abuse of the GPIO API")
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20250401233603.2938955-1-florian.fainelli@broadcom.com
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 06a81727d74ddd53ac111e235d0f1c4f30b15419..77de5a07639afbf64f287a1e5b700c849415ae24 100644 (file)
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -1226,7 +1226,12 @@ static int bcm2835_spi_setup(struct spi_device *spi)
        struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
        struct bcm2835_spidev *target = spi_get_ctldata(spi);
        struct gpiod_lookup_table *lookup __free(kfree) = NULL;
-       int ret;
+       const char *pinctrl_compats[] = {
+               "brcm,bcm2835-gpio",
+               "brcm,bcm2711-gpio",
+               "brcm,bcm7211-gpio",
+       };
+       int ret, i;
        u32 cs;
 
        if (!target) {
@@ -1291,6 +1296,14 @@ static int bcm2835_spi_setup(struct spi_device *spi)
                goto err_cleanup;
        }
 
+       for (i = 0; i < ARRAY_SIZE(pinctrl_compats); i++) {
+               if (of_find_compatible_node(NULL, NULL, pinctrl_compats[i]))
+                       break;
+       }
+
+       if (i == ARRAY_SIZE(pinctrl_compats))
+               return 0;
+
        /*
         * TODO: The code below is a slightly better alternative to the utter
         * abuse of the GPIO API that I found here before. It creates a