gpio: crystalcove: Do not write regular gpio registers for virtual GPIOs

The Crystal Cove PMIC has 16 real GPIOs but the ACPI code for devices
with this PMIC may address up to 95 GPIOs, these extra GPIOs are
called virtual GPIOs and are used by the ACPI code as a method of
accessing various non GPIO bits of PMIC.

Commit dcdc3018d635 ("gpio: crystalcove: support virtual GPIO") added
dummy support for these to avoid a bunch of ACPI errors, but instead of
ignoring writes / reads to them by doing:

if (gpio >= CRYSTALCOVE_GPIO_NUM)
	return 0;

It accidentally introduced the following wrong check:

if (gpio > CRYSTALCOVE_VGPIO_NUM)
	return 0;

Which means that attempts by the ACPI code to access these gpios
causes some arbitrary gpio to get touched through for example
GPIO1P0CTLO + gpionr % 8.

Since we do support input/output (but not interrupts) on the 0x5e
virtual GPIO, this commit makes to_reg return -ENOTSUPP for unsupported
virtual GPIOs so as to not have to check for (gpio >= CRYSTALCOVE_GPIO_NUM
&& gpio != 0x5e) everywhere and to make it easier to add support for more
virtual GPIOs in the future.

It then adds a check for to_reg returning an error to all callers where
this may happen fixing the ACPI code accessing virtual GPIOs accidentally
causing changes to real GPIOs.

Fixes: dcdc3018d635 ("gpio: crystalcove: support virtual GPIO")
Cc: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-crystalcove.c

@@ -90,8 +90,18 @@ static inline int to_reg(int gpio, enum ctrl_register reg_type)
 {
 	int reg;
 
-	if (gpio == 94)
-		return GPIOPANELCTL;
+	if (gpio >= CRYSTALCOVE_GPIO_NUM) {
+		/*
+		 * Virtual GPIO called from ACPI, for now we only support
+		 * the panel ctl.
+		 */
+		switch (gpio) {
+		case 0x5e:
+			return GPIOPANELCTL;
+		default:
+			return -EOPNOTSUPP;
+		}
+	}
 
 	if (reg_type == CTRL_IN) {
 		if (gpio < 8)
@@ -130,36 +140,36 @@ static void crystalcove_update_irq_ctrl(struct crystalcove_gpio *cg, int gpio)
 static int crystalcove_gpio_dir_in(struct gpio_chip *chip, unsigned gpio)
 {
 	struct crystalcove_gpio *cg = gpiochip_get_data(chip);
+	int reg = to_reg(gpio, CTRL_OUT);
 
-	if (gpio > CRYSTALCOVE_VGPIO_NUM)
+	if (reg < 0)
 		return 0;
 
-	return regmap_write(cg->regmap, to_reg(gpio, CTRL_OUT),
-			    CTLO_INPUT_SET);
+	return regmap_write(cg->regmap, reg, CTLO_INPUT_SET);
 }
 
 static int crystalcove_gpio_dir_out(struct gpio_chip *chip, unsigned gpio,
 				    int value)
 {
 	struct crystalcove_gpio *cg = gpiochip_get_data(chip);
+	int reg = to_reg(gpio, CTRL_OUT);
 
-	if (gpio > CRYSTALCOVE_VGPIO_NUM)
+	if (reg < 0)
 		return 0;
 
-	return regmap_write(cg->regmap, to_reg(gpio, CTRL_OUT),
-			    CTLO_OUTPUT_SET | value);
+	return regmap_write(cg->regmap, reg, CTLO_OUTPUT_SET | value);
 }
 
 static int crystalcove_gpio_get(struct gpio_chip *chip, unsigned gpio)
 {
 	struct crystalcove_gpio *cg = gpiochip_get_data(chip);
-	int ret;
 	unsigned int val;
+	int ret, reg = to_reg(gpio, CTRL_IN);
 
-	if (gpio > CRYSTALCOVE_VGPIO_NUM)
+	if (reg < 0)
 		return 0;
 
-	ret = regmap_read(cg->regmap, to_reg(gpio, CTRL_IN), &val);
+	ret = regmap_read(cg->regmap, reg, &val);
 	if (ret)
 		return ret;
 
@@ -170,14 +180,15 @@ static void crystalcove_gpio_set(struct gpio_chip *chip,
 				 unsigned gpio, int value)
 {
 	struct crystalcove_gpio *cg = gpiochip_get_data(chip);
+	int reg = to_reg(gpio, CTRL_OUT);
 
-	if (gpio > CRYSTALCOVE_VGPIO_NUM)
+	if (reg < 0)
 		return;
 
 	if (value)
-		regmap_update_bits(cg->regmap, to_reg(gpio, CTRL_OUT), 1, 1);
+		regmap_update_bits(cg->regmap, reg, 1, 1);
 	else
-		regmap_update_bits(cg->regmap, to_reg(gpio, CTRL_OUT), 1, 0);
+		regmap_update_bits(cg->regmap, reg, 1, 0);
 }
 
 static int crystalcove_irq_type(struct irq_data *data, unsigned type)
@@ -185,6 +196,9 @@ static int crystalcove_irq_type(struct irq_data *data, unsigned type)
 	struct crystalcove_gpio *cg =
 		gpiochip_get_data(irq_data_get_irq_chip_data(data));
 
+	if (data->hwirq >= CRYSTALCOVE_GPIO_NUM)
+		return 0;
+
 	switch (type) {
 	case IRQ_TYPE_NONE:
 		cg->intcnt_value = CTLI_INTCNT_DIS;
@@ -235,8 +249,10 @@ static void crystalcove_irq_unmask(struct irq_data *data)
 	struct crystalcove_gpio *cg =
 		gpiochip_get_data(irq_data_get_irq_chip_data(data));
 
-	cg->set_irq_mask = false;
-	cg->update |= UPDATE_IRQ_MASK;
+	if (data->hwirq < CRYSTALCOVE_GPIO_NUM) {
+		cg->set_irq_mask = false;
+		cg->update |= UPDATE_IRQ_MASK;
+	}
 }
 
 static void crystalcove_irq_mask(struct irq_data *data)
@@ -244,8 +260,10 @@ static void crystalcove_irq_mask(struct irq_data *data)
 	struct crystalcove_gpio *cg =
 		gpiochip_get_data(irq_data_get_irq_chip_data(data));
 
-	cg->set_irq_mask = true;
-	cg->update |= UPDATE_IRQ_MASK;
+	if (data->hwirq < CRYSTALCOVE_GPIO_NUM) {
+		cg->set_irq_mask = true;
+		cg->update |= UPDATE_IRQ_MASK;
+	}
 }
 
 static struct irq_chip crystalcove_irqchip = {