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.
drivers/pinctrl/bcm/pinctrl-bcm2835.c
Signed-off-by: Phil Elwell <phil@raspberrypi.com>

Author: pelwell

drivers/pinctrl/bcm/pinctrl-bcm2835.c

@@ -244,6 +244,10 @@ static const char * const irq_type_names[] = {
 	[IRQ_TYPE_LEVEL_LOW] = "level-low",
 };
 
+static bool strict_gpiod;
+module_param(strict_gpiod, bool, 0644);
+MODULE_PARM_DESC(strict_gpiod, "unless true, outputs remain outputs when freed");
+
 static inline u32 bcm2835_gpio_rd(struct bcm2835_pinctrl *pc, unsigned reg)
 {
 	return readl(pc->base + reg);
@@ -941,8 +945,8 @@ static int bcm2835_pmx_free(struct pinctrl_dev *pctldev,
 	struct bcm2835_pinctrl *pc = pinctrl_dev_get_drvdata(pctldev);
 	enum bcm2835_fsel fsel = bcm2835_pinctrl_fsel_get(pc, offset);
 
-	/* Return non-GPIOs to GPIO_IN */
-	if (fsel != BCM2835_FSEL_GPIO_IN && fsel != BCM2835_FSEL_GPIO_OUT)
+	/* Return non-GPIOs to GPIO_IN, unless strict_gpiod is set */
+	if (strict_gpiod || (fsel != BCM2835_FSEL_GPIO_IN && fsel != BCM2835_FSEL_GPIO_OUT))
 		bcm2835_pinctrl_fsel_set(pc, offset, BCM2835_FSEL_GPIO_IN);
 
 	return 0;