[ARM] Orion edge GPIO IRQ support

This patch adds support for Orion edge sensitive GPIO IRQs.

Signed-off-by: Tzachi Perelstein <tzachi@marvell.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>
CC: Thomas Gleixner <tglx@linutronix.de>

arch/arm/mach-orion/gpio.c

@@ -93,7 +93,7 @@ int gpio_get_value(unsigned pin)
 	int val, mask = 1 << pin;
 
 	if (orion_read(GPIO_IO_CONF) & mask)
-		val = orion_read(GPIO_DATA_IN);
+		val = orion_read(GPIO_DATA_IN) ^ orion_read(GPIO_IN_POL);
 	else
 		val = orion_read(GPIO_OUT);
 

arch/arm/mach-orion/irq.c

@@ -19,22 +19,66 @@
 
 /*****************************************************************************
  * Orion GPIO IRQ
+ *
+ * GPIO_IN_POL register controlls whether GPIO_DATA_IN will hold the same
+ * value of the line or the opposite value.
+ *
+ * Level IRQ handlers: DATA_IN is used directly as cause register.
+ *                     Interrupt are masked by LEVEL_MASK registers.
+ * Edge IRQ handlers:  Change in DATA_IN are latched in EDGE_CAUSE.
+ *                     Interrupt are masked by EDGE_MASK registers.
+ * Both-edge handlers: Similar to regular Edge handlers, but also swaps
+ *                     the polarity to catch the next line transaction.
+ *                     This is a race condition that might not perfectly
+ *                     work on some use cases.
+ *
+ * Every eight GPIO lines are grouped (OR'ed) before going up to main
+ * cause register.
+ *
+ *                    EDGE  cause    mask
+ *        data-in   /--------| |-----| |----\
+ *     -----| |-----                         ---- to main cause reg
+ *           X      \----------------| |----/
+ *        polarity    LEVEL          mask
+ *
  ****************************************************************************/
+static void orion_gpio_irq_ack(u32 irq)
+{
+	int pin = irq_to_gpio(irq);
+	if (irq_desc[irq].status & IRQ_LEVEL)
+		/*
+		 * Mask bit for level interrupt
+		 */
+		orion_clrbits(GPIO_LEVEL_MASK, 1 << pin);
+	else
+		/*
+		 * Clear casue bit for egde interrupt
+		 */
+		orion_clrbits(GPIO_EDGE_CAUSE, 1 << pin);
+}
+
 static void orion_gpio_irq_mask(u32 irq)
 {
 	int pin = irq_to_gpio(irq);
-	orion_clrbits(GPIO_LEVEL_MASK, 1 << pin);
+	if (irq_desc[irq].status & IRQ_LEVEL)
+		orion_clrbits(GPIO_LEVEL_MASK, 1 << pin);
+	else
+		orion_clrbits(GPIO_EDGE_MASK, 1 << pin);
 }
 
 static void orion_gpio_irq_unmask(u32 irq)
 {
 	int pin = irq_to_gpio(irq);
-	orion_setbits(GPIO_LEVEL_MASK, 1 << pin);
+	if (irq_desc[irq].status & IRQ_LEVEL)
+		orion_setbits(GPIO_LEVEL_MASK, 1 << pin);
+	else
+		orion_setbits(GPIO_EDGE_MASK, 1 << pin);
 }
 
 static int orion_gpio_set_irq_type(u32 irq, u32 type)
 {
 	int pin = irq_to_gpio(irq);
+	struct irq_desc *desc;
 
 	if ((orion_read(GPIO_IO_CONF) & (1 << pin)) == 0) {
 		printk(KERN_ERR "orion_gpio_set_irq_type failed "
@@ -42,24 +86,56 @@ static int orion_gpio_set_irq_type(u32 irq, u32 type)
 		return -EINVAL;
 	}
 
+	desc = irq_desc + irq;
+
 	switch (type) {
 	case IRQT_HIGH:
+		desc->handle_irq = handle_level_irq;
+		desc->status |= IRQ_LEVEL;
 		orion_clrbits(GPIO_IN_POL, (1 << pin));
 		break;
 	case IRQT_LOW:
+		desc->handle_irq = handle_level_irq;
+		desc->status |= IRQ_LEVEL;
+		orion_setbits(GPIO_IN_POL, (1 << pin));
+		break;
+	case IRQT_RISING:
+		desc->handle_irq = handle_edge_irq;
+		desc->status &= ~IRQ_LEVEL;
+		orion_clrbits(GPIO_IN_POL, (1 << pin));
+		break;
+	case IRQT_FALLING:
+		desc->handle_irq = handle_edge_irq;
+		desc->status &= ~IRQ_LEVEL;
 		orion_setbits(GPIO_IN_POL, (1 << pin));
+		break;
+	case IRQT_BOTHEDGE:
+		desc->handle_irq = handle_edge_irq;
+		desc->status &= ~IRQ_LEVEL;
+		/*
+		 * set initial polarity based on current input level
+		 */
+		if ((orion_read(GPIO_IN_POL) ^ orion_read(GPIO_DATA_IN))
+		    & (1 << pin))
+			orion_setbits(GPIO_IN_POL, (1 << pin)); /* falling */
+		else
+			orion_clrbits(GPIO_IN_POL, (1 << pin)); /* rising */
+
 		break;
 	default:
 		printk(KERN_ERR "failed to set irq=%d (type=%d)\n", irq, type);
 		return -EINVAL;
 	}
 
+	desc->status &= ~IRQ_TYPE_SENSE_MASK;
+	desc->status |= type & IRQ_TYPE_SENSE_MASK;
+
 	return 0;
 }
 
 static struct irq_chip orion_gpio_irq_chip = {
 	.name		= "Orion-IRQ-GPIO",
-	.ack		= orion_gpio_irq_mask,
+	.ack		= orion_gpio_irq_ack,
 	.mask		= orion_gpio_irq_mask,
 	.unmask		= orion_gpio_irq_unmask,
 	.set_type	= orion_gpio_set_irq_type,
@@ -67,24 +143,24 @@ static struct irq_chip orion_gpio_irq_chip = {
 
 static void orion_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
 {
-	int i;
-	u32 cause, shift;
+	u32 cause, offs, pin;
 
 	BUG_ON(irq < IRQ_ORION_GPIO_0_7 || irq > IRQ_ORION_GPIO_24_31);
-	shift = (irq - IRQ_ORION_GPIO_0_7) * 8;
-	cause = orion_read(GPIO_EDGE_CAUSE) & orion_read(GPIO_LEVEL_MASK);
-	cause &= (0xff << shift);
-
-	for (i = shift; i < shift + 8; i++) {
-		if (cause & (1 << i)) {
-			int gpio_irq = i + IRQ_ORION_GPIO_START;
-			if (gpio_irq > 0) {
-				desc = irq_desc + gpio_irq;
-				desc_handle_irq(gpio_irq, desc);
-			} else {
-				printk(KERN_ERR "orion_gpio_irq_handler error, "
-						"invalid irq %d\n", gpio_irq);
+	offs = (irq - IRQ_ORION_GPIO_0_7) * 8;
+	cause = (orion_read(GPIO_DATA_IN) & orion_read(GPIO_LEVEL_MASK)) |
+		(orion_read(GPIO_EDGE_CAUSE) & orion_read(GPIO_EDGE_MASK));
+
+	for (pin = offs; pin < offs + 8; pin++) {
+		if (cause & (1 << pin)) {
+			irq = gpio_to_irq(pin);
+			desc = irq_desc + irq;
+			if ((desc->status & IRQ_TYPE_SENSE_MASK) == IRQT_BOTHEDGE) {
+				/* Swap polarity (race with GPIO line) */
+				u32 polarity = orion_read(GPIO_IN_POL);
+				polarity ^= 1 << pin;
+				orion_write(GPIO_IN_POL, polarity);
 			}
+			desc_handle_irq(irq, desc);
 		}
 	}
 }
@@ -92,19 +168,24 @@ static void orion_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
 static void __init orion_init_gpio_irq(void)
 {
 	int i;
+	struct irq_desc *desc;
 
 	/*
 	 * Mask and clear GPIO IRQ interrupts
 	 */
 	orion_write(GPIO_LEVEL_MASK, 0x0);
+	orion_write(GPIO_EDGE_MASK, 0x0);
 	orion_write(GPIO_EDGE_CAUSE, 0x0);
 
 	/*
-	 * Register chained level handlers for GPIO IRQs
+	 * Register chained level handlers for GPIO IRQs by default.
+	 * User can use set_type() if he wants to use edge types handlers.
 	 */
 	for (i = IRQ_ORION_GPIO_START; i < NR_IRQS; i++) {
 		set_irq_chip(i, &orion_gpio_irq_chip);
 		set_irq_handler(i, handle_level_irq);
+		desc = irq_desc + i;
+		desc->status |= IRQ_LEVEL;
 		set_irq_flags(i, IRQF_VALID);
 	}
 	set_irq_chained_handler(IRQ_ORION_GPIO_0_7, orion_gpio_irq_handler);