gpio: tegra: Dynamically allocate IRQ base, and support DT

Enhance the driver to dynamically allocate the base IRQ number, and
create an IRQ domain for itself. The use of an IRQ domain ensures that
any device tree node interrupts properties are correctly parsed.

Describe interrupt-related properties in the device tree binding docs,
and the contents of "child" node interrupts property.

Update tegra*.dtsi to specify the required interrupt-related properties.

Finally, remove the definition of TEGRA_GPIO_TO_IRQ; this macro no longer
gives correct results since the IRQ numbers for GPIOs are dynamically
allocated.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Olof Johansson <olof@lixom.net>

Documentation/devicetree/bindings/gpio/gpio_nvidia.txt

@@ -8,6 +8,16 @@ Required properties:
   second cell is used to specify optional parameters:
   - bit 0 specifies polarity (0 for normal, 1 for inverted)
 - gpio-controller : Marks the device node as a GPIO controller.
+- #interrupt-cells : Should be 2.
+  The first cell is the GPIO number.
+  The second cell is used to specify flags:
+    bits[3:0] trigger type and level flags:
+      1 = low-to-high edge triggered.
+      2 = high-to-low edge triggered.
+      4 = active high level-sensitive.
+      8 = active low level-sensitive.
+      Valid combinations are 1, 2, 3, 4, 8.
+- interrupt-controller : Marks the device node as an interrupt controller.
 
 Example:
 
@@ -23,4 +33,6 @@ gpio: gpio@6000d000 {
 		       0 89 0x04 >;
 	#gpio-cells = <2>;
 	gpio-controller;
+	#interrupt-cells = <2>;
+	interrupt-controller;
 };

arch/arm/boot/dts/tegra20.dtsi

@@ -101,6 +101,8 @@ gpio: gpio@6000d000 {
 			       0 89 0x04 >;
 		#gpio-cells = <2>;
 		gpio-controller;
+		#interrupt-cells = <2>;
+		interrupt-controller;
 	};
 
 	pinmux: pinmux@70000000 {

arch/arm/boot/dts/tegra30.dtsi

@@ -107,6 +107,8 @@ gpio: gpio@6000d000 {
 			       0 125 0x04 >;
 		#gpio-cells = <2>;
 		gpio-controller;
+		#interrupt-cells = <2>;
+		interrupt-controller;
 	};
 
 	serial@70006000 {

arch/arm/mach-tegra/include/mach/gpio-tegra.h

@@ -25,8 +25,6 @@
 
 #define TEGRA_NR_GPIOS		INT_GPIO_NR
 
-#define TEGRA_GPIO_TO_IRQ(gpio) (INT_GPIO_BASE + (gpio))
-
 struct tegra_gpio_table {
 	int	gpio;	/* GPIO number */
 	bool	enable;	/* Enable for GPIO at init? */

drivers/gpio/gpio-tegra.c

@@ -25,6 +25,7 @@
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/module.h>
+#include <linux/irqdomain.h>
 
 #include <asm/mach/irq.h>
 
@@ -74,7 +75,7 @@ struct tegra_gpio_bank {
 #endif
 };
 
-
+static struct irq_domain irq_domain;
 static void __iomem *regs;
 static struct tegra_gpio_bank tegra_gpio_banks[7];
 
@@ -139,7 +140,7 @@ static int tegra_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
 
 static int tegra_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
 {
-	return TEGRA_GPIO_TO_IRQ(offset);
+	return irq_domain_to_irq(&irq_domain, offset);
 }
 
 static struct gpio_chip tegra_gpio_chip = {
@@ -155,28 +156,28 @@ static struct gpio_chip tegra_gpio_chip = {
 
 static void tegra_gpio_irq_ack(struct irq_data *d)
 {
-	int gpio = d->irq - INT_GPIO_BASE;
+	int gpio = d->hwirq;
 
 	tegra_gpio_writel(1 << GPIO_BIT(gpio), GPIO_INT_CLR(gpio));
 }
 
 static void tegra_gpio_irq_mask(struct irq_data *d)
 {
-	int gpio = d->irq - INT_GPIO_BASE;
+	int gpio = d->hwirq;
 
 	tegra_gpio_mask_write(GPIO_MSK_INT_ENB(gpio), gpio, 0);
 }
 
 static void tegra_gpio_irq_unmask(struct irq_data *d)
 {
-	int gpio = d->irq - INT_GPIO_BASE;
+	int gpio = d->hwirq;
 
 	tegra_gpio_mask_write(GPIO_MSK_INT_ENB(gpio), gpio, 1);
 }
 
 static int tegra_gpio_irq_set_type(struct irq_data *d, unsigned int type)
 {
-	int gpio = d->irq - INT_GPIO_BASE;
+	int gpio = d->hwirq;
 	struct tegra_gpio_bank *bank = irq_data_get_irq_chip_data(d);
 	int port = GPIO_PORT(gpio);
 	int lvl_type;
@@ -343,6 +344,16 @@ static int __devinit tegra_gpio_probe(struct platform_device *pdev)
 	int i;
 	int j;
 
+	irq_domain.irq_base = irq_alloc_descs(-1, 0, TEGRA_NR_GPIOS, 0);
+	if (irq_domain.irq_base < 0) {
+		dev_err(&pdev->dev, "Couldn't allocate IRQ numbers\n");
+		return -ENODEV;
+	}
+	irq_domain.nr_irq = TEGRA_NR_GPIOS;
+	irq_domain.ops = &irq_domain_simple_ops;
+	irq_domain.of_node = pdev->dev.of_node;
+	irq_domain_add(&irq_domain);
+
 	for (i = 0; i < ARRAY_SIZE(tegra_gpio_banks); i++) {
 		res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
 		if (!res) {
@@ -381,7 +392,7 @@ static int __devinit tegra_gpio_probe(struct platform_device *pdev)
 	gpiochip_add(&tegra_gpio_chip);
 
 	for (gpio = 0; gpio < TEGRA_NR_GPIOS; gpio++) {
-		int irq = TEGRA_GPIO_TO_IRQ(gpio);
+		int irq = irq_domain_to_irq(&irq_domain, gpio);
 		/* No validity check; all Tegra GPIOs are valid IRQs */
 
 		bank = &tegra_gpio_banks[GPIO_BANK(gpio)];