[PATCH 2/2] gpio/omap: auto-setup a GPIO when used as an IRQ

[Javier Martinez Canillas]

The OMAP GPIO controller HW requires a pin to be configured in GPIO
input mode in order to operate as an interrupt input. Since drivers
should not be aware of whether an interrupt pin is also a GPIO or not,
the HW should be fully configured/enabled as an IRQ if a driver solely
uses IRQ APIs such as request_irq(), and never calls any GPIO-related
APIs. As such, add the missing HW setup to the OMAP GPIO controller's
irq_chip driver.

Since this bypasses the GPIO subsystem we have to ensure that another
driver won't be able to request the same GPIO pin that is used as an
IRQ and set its direction as output. Requesting the GPIO and setting
its direction as input is allowed though.

This fixes smsc911x ethernet support for tobi and igep OMAP3 boards
and OMAP4 SDP SPI based ethernet that use a GPIO as an interrupt line.

Signed-off-by: Javier Martinez Canillas <javier.martinez@xxxxxxxxxxxxxxx>
---
 drivers/gpio/gpio-omap.c | 129 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 83 insertions(+), 46 deletions(-)

diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
index a4fe038..89675f8 100644
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -424,6 +424,52 @@ static int _set_gpio_triggering(struct gpio_bank *bank, int gpio,
 	return 0;
 }
 
+static void _enable_gpio_module(struct gpio_bank *bank, unsigned offset)
+{
+	if (bank->regs->pinctrl) {
+		void __iomem *reg = bank->base + bank->regs->pinctrl;
+
+		/* Claim the pin for MPU */
+		__raw_writel(__raw_readl(reg) | (1 << offset), reg);
+	}
+
+	if (bank->regs->ctrl && !BANK_USED(bank)) {
+		void __iomem *reg = bank->base + bank->regs->ctrl;
+		u32 ctrl;
+
+		ctrl = __raw_readl(reg);
+		/* Module is enabled, clocks are not gated */
+		ctrl &= ~GPIO_MOD_CTRL_BIT;
+		__raw_writel(ctrl, reg);
+		bank->context.ctrl = ctrl;
+	}
+}
+
+static void _disable_gpio_module(struct gpio_bank *bank, unsigned offset)
+{
+	void __iomem *base = bank->base;
+
+	if (bank->regs->wkup_en &&
+	    !LINE_USED(bank->mod_usage, offset) &&
+	    !LINE_USED(bank->irq_usage, offset)) {
+		/* Disable wake-up during idle for dynamic tick */
+		_gpio_rmw(base, bank->regs->wkup_en, 1 << offset, 0);
+		bank->context.wake_en =
+			__raw_readl(bank->base + bank->regs->wkup_en);
+	}
+
+	if (bank->regs->ctrl && !BANK_USED(bank)) {
+		void __iomem *reg = bank->base + bank->regs->ctrl;
+		u32 ctrl;
+
+		ctrl = __raw_readl(reg);
+		/* Module is disabled, clocks are gated */
+		ctrl |= GPIO_MOD_CTRL_BIT;
+		__raw_writel(ctrl, reg);
+		bank->context.ctrl = ctrl;
+	}
+}
+
 static int gpio_is_input(struct gpio_bank *bank, int mask)
 {
 	void __iomem *reg = bank->base + bank->regs->direction;
@@ -437,9 +483,10 @@ static int gpio_irq_type(struct irq_data *d, unsigned type)
 	unsigned gpio = 0;
 	int retval;
 	unsigned long flags;
+	unsigned offset;
 
-	if (WARN_ON(!BANK_USED(bank)))
-		return -EINVAL;
+	if (!BANK_USED(bank))
+		pm_runtime_get_sync(bank->dev);
 
 #ifdef CONFIG_ARCH_OMAP1
 	if (d->irq > IH_MPUIO_BASE)
@@ -457,7 +504,16 @@ static int gpio_irq_type(struct irq_data *d, unsigned type)
 		return -EINVAL;
 
 	spin_lock_irqsave(&bank->lock, flags);
-	retval = _set_gpio_triggering(bank, GPIO_INDEX(bank, gpio), type);
+	offset = GPIO_INDEX(bank, gpio);
+	retval = _set_gpio_triggering(bank, offset, type);
+	if (!LINE_USED(bank->mod_usage, offset)) {
+		_enable_gpio_module(bank, offset);
+		_set_gpio_direction(bank, offset, 1);
+	} else if (!gpio_is_input(bank, 1 << offset)) {
+		spin_unlock_irqrestore(&bank->lock, flags);
+		return -EINVAL;
+	}
+
 	bank->irq_usage |= 1 << GPIO_INDEX(bank, gpio);
 	spin_unlock_irqrestore(&bank->lock, flags);
 
@@ -620,30 +676,14 @@ static int omap_gpio_request(struct gpio_chip *chip, unsigned offset)
 
 	spin_lock_irqsave(&bank->lock, flags);
 	/* Set trigger to none. You need to enable the desired trigger with
-	 * request_irq() or set_irq_type().
+	 * request_irq() or set_irq_type(). Only do this if the IRQ line has
+	 * not already been requested.
 	 */
-	_set_gpio_triggering(bank, offset, IRQ_TYPE_NONE);
-
-	if (bank->regs->pinctrl) {
-		void __iomem *reg = bank->base + bank->regs->pinctrl;
-
-		/* Claim the pin for MPU */
-		__raw_writel(__raw_readl(reg) | (1 << offset), reg);
+	if (!LINE_USED(bank->irq_usage, offset)) {
+		_set_gpio_triggering(bank, offset, IRQ_TYPE_NONE);
+		_enable_gpio_module(bank, offset);
 	}
-
-	if (bank->regs->ctrl && !BANK_USED(bank)) {
-		void __iomem *reg = bank->base + bank->regs->ctrl;
-		u32 ctrl;
-
-		ctrl = __raw_readl(reg);
-		/* Module is enabled, clocks are not gated */
-		ctrl &= ~GPIO_MOD_CTRL_BIT;
-		__raw_writel(ctrl, reg);
-		bank->context.ctrl = ctrl;
-	}
-
 	bank->mod_usage |= 1 << offset;
-
 	spin_unlock_irqrestore(&bank->lock, flags);
 
 	return 0;
@@ -652,31 +692,11 @@ static int omap_gpio_request(struct gpio_chip *chip, unsigned offset)
 static void omap_gpio_free(struct gpio_chip *chip, unsigned offset)
 {
 	struct gpio_bank *bank = container_of(chip, struct gpio_bank, chip);
-	void __iomem *base = bank->base;
 	unsigned long flags;
 
 	spin_lock_irqsave(&bank->lock, flags);
-
-	if (bank->regs->wkup_en) {
-		/* Disable wake-up during idle for dynamic tick */
-		_gpio_rmw(base, bank->regs->wkup_en, 1 << offset, 0);
-		bank->context.wake_en =
-			__raw_readl(bank->base + bank->regs->wkup_en);
-	}
-
 	bank->mod_usage &= ~(1 << offset);
-
-	if (bank->regs->ctrl && !BANK_USED(bank)) {
-		void __iomem *reg = bank->base + bank->regs->ctrl;
-		u32 ctrl;
-
-		ctrl = __raw_readl(reg);
-		/* Module is disabled, clocks are gated */
-		ctrl |= GPIO_MOD_CTRL_BIT;
-		__raw_writel(ctrl, reg);
-		bank->context.ctrl = ctrl;
-	}
-
+	_disable_gpio_module(bank, offset);
 	_reset_gpio(bank, bank->chip.base + offset);
 	spin_unlock_irqrestore(&bank->lock, flags);
 
@@ -778,8 +798,16 @@ static void gpio_irq_shutdown(struct irq_data *d)
 
 	spin_lock_irqsave(&bank->lock, flags);
 	bank->irq_usage &= ~(1 << offset);
+	_disable_gpio_module(bank, offset);
 	_reset_gpio(bank, gpio);
 	spin_unlock_irqrestore(&bank->lock, flags);
+
+	/*
+	 * If this is the last IRQ to be freed in the bank,
+	 * disable the bank module.
+	 */
+	if (!BANK_USED(bank))
+		pm_runtime_put(bank->dev);
 }
 
 static void gpio_ack_irq(struct irq_data *d)
@@ -929,13 +957,22 @@ static int gpio_output(struct gpio_chip *chip, unsigned offset, int value)
 {
 	struct gpio_bank *bank;
 	unsigned long flags;
+	int retval = 0;
 
 	bank = container_of(chip, struct gpio_bank, chip);
 	spin_lock_irqsave(&bank->lock, flags);
+
+	if (LINE_USED(bank->irq_usage, offset)) {
+			retval = -EINVAL;
+			goto exit;
+	}
+
 	bank->set_dataout(bank, offset, value);
 	_set_gpio_direction(bank, offset, 0);
+
+exit:
 	spin_unlock_irqrestore(&bank->lock, flags);
-	return 0;
+	return retval;
 }
 
 static int gpio_debounce(struct gpio_chip *chip, unsigned offset,
-- 
1.8.4.rc3

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