gpio: tegra186: Fix chip_data type confusion

The tegra186 GPIO driver makes the assumption that the pointer
returned by irq_data_get_irq_chip_data() is a pointer to a
tegra_gpio structure. Unfortunately, it is actually a pointer
to the inner gpio_chip structure, as mandated by the gpiolib
infrastructure. Nice try.

The saving grace is that the gpio_chip is the first member of
tegra_gpio, so the bug has gone undetected since... forever.

Fix it by performing a container_of() on the pointer. This results
in no additional code, and makes it possible to understand how
the whole thing works.

Fixes: 5b2b135 ("gpio: Add Tegra186 support")
Signed-off-by: Marc Zyngier <[email protected]>
Cc: Thierry Reding <[email protected]>
Cc: Linus Walleij <[email protected]>
Cc: Bartosz Golaszewski <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Linus Walleij <[email protected]>

Author: Marc Zyngier

drivers/gpio/gpio-tegra186.c

@@ -343,9 +343,12 @@ static int tegra186_gpio_of_xlate(struct gpio_chip *chip,
 	return offset + pin;
 }
 
+#define to_tegra_gpio(x) container_of((x), struct tegra_gpio, gpio)
+
 static void tegra186_irq_ack(struct irq_data *data)
 {
-	struct tegra_gpio *gpio = irq_data_get_irq_chip_data(data);
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct tegra_gpio *gpio = to_tegra_gpio(gc);
 	void __iomem *base;
 
 	base = tegra186_gpio_get_base(gpio, data->hwirq);
@@ -357,7 +360,8 @@ static void tegra186_irq_ack(struct irq_data *data)
 
 static void tegra186_irq_mask(struct irq_data *data)
 {
-	struct tegra_gpio *gpio = irq_data_get_irq_chip_data(data);
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct tegra_gpio *gpio = to_tegra_gpio(gc);
 	void __iomem *base;
 	u32 value;
 
@@ -372,7 +376,8 @@ static void tegra186_irq_mask(struct irq_data *data)
 
 static void tegra186_irq_unmask(struct irq_data *data)
 {
-	struct tegra_gpio *gpio = irq_data_get_irq_chip_data(data);
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct tegra_gpio *gpio = to_tegra_gpio(gc);
 	void __iomem *base;
 	u32 value;
 
@@ -387,7 +392,8 @@ static void tegra186_irq_unmask(struct irq_data *data)
 
 static int tegra186_irq_set_type(struct irq_data *data, unsigned int type)
 {
-	struct tegra_gpio *gpio = irq_data_get_irq_chip_data(data);
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(data);
+	struct tegra_gpio *gpio = to_tegra_gpio(gc);
 	void __iomem *base;
 	u32 value;