pinctrl: bcm2835: Add strict_gpiod module parameter

Setting strict_gpiod to Y makes libgpiod and the gpiod utilities behave
as documented, i.e. pins are returned to being GPIO inputs when they are
released.

Signed-off-by: Phil Elwell <[email protected]>

Author: pelwell

drivers/pinctrl/pinctrl-rp1.c

@@ -573,6 +573,10 @@ static const char * const irq_type_names[] = {
 	[IRQ_TYPE_LEVEL_LOW] = "level-low",
 };
 
+static bool strict_gpiod = false;
+module_param(strict_gpiod, bool, 0644);
+MODULE_PARM_DESC(strict_gpiod, "unless true, outputs remain outputs when freed");
+
 static int rp1_pinconf_set(struct pinctrl_dev *pctldev,
 			   unsigned int offset, unsigned long *configs,
 			   unsigned int num_configs);
@@ -1201,8 +1205,9 @@ static int rp1_pmx_free(struct pinctrl_dev *pctldev, unsigned offset)
 	struct rp1_pin_info *pin = rp1_get_pin_pctl(pctldev, offset);
 	u32 fsel = rp1_get_fsel(pin);
 
-	/* Return non-GPIOs to GPIO_IN */
-	if (fsel != RP1_FSEL_GPIO) {
+	/* Return non-GPIOs to GPIO_IN, unless strict_gpiod is set */
+	pr_err("%s(%d) - strict_gpiod %d\n", __func__, offset, strict_gpiod);
+	if (strict_gpiod || fsel != RP1_FSEL_GPIO) {
 		rp1_set_dir(pin, RP1_DIR_INPUT);
 		rp1_set_fsel(pin, RP1_FSEL_GPIO);
 	}