pinctrl: sh-pfc: Rollback to mux if required when the gpio is freed

Some drivers require switching between function and gpio at run-time.
Allow to roll back from gpio to mux when the gpio is freed.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

drivers/pinctrl/sh-pfc/pinctrl.c

@@ -26,6 +26,7 @@
 #include "../pinconf.h"
 
 struct sh_pfc_pin_config {
+	unsigned int mux_mark;
 	bool mux_set;
 	bool gpio_enabled;
 };
@@ -353,6 +354,16 @@ static int sh_pfc_func_set_mux(struct pinctrl_dev *pctldev, unsigned selector,
 	spin_lock_irqsave(&pfc->lock, flags);
 
 	for (i = 0; i < grp->nr_pins; ++i) {
+		int idx = sh_pfc_get_pin_index(pfc, grp->pins[i]);
+		struct sh_pfc_pin_config *cfg = &pmx->configs[idx];
+
+		/*
+		 * This driver cannot manage both gpio and mux when the gpio
+		 * pin is already enabled. So, this function fails.
+		 */
+		if (cfg->gpio_enabled)
+			return -EBUSY;
+
 		ret = sh_pfc_config_mux(pfc, grp->mux[i], PINMUX_TYPE_FUNCTION);
 		if (ret < 0)
 			goto done;
@@ -364,6 +375,7 @@ static int sh_pfc_func_set_mux(struct pinctrl_dev *pctldev, unsigned selector,
 		struct sh_pfc_pin_config *cfg = &pmx->configs[idx];
 
 		cfg->mux_set = true;
+		cfg->mux_mark = grp->mux[i];
 	}
 
 done:
@@ -417,6 +429,9 @@ static void sh_pfc_gpio_disable_free(struct pinctrl_dev *pctldev,
 
 	spin_lock_irqsave(&pfc->lock, flags);
 	cfg->gpio_enabled = false;
+	/* If mux is already set, this configures it here */
+	if (cfg->mux_set)
+		sh_pfc_config_mux(pfc, cfg->mux_mark, PINMUX_TYPE_FUNCTION);
 	spin_unlock_irqrestore(&pfc->lock, flags);
 }