Date:	Sat, 12 Jun 2010 11:59:15 -0700
From:	Gregory Bean <gbean@...eaurora.org>
To:	akpm@...ux-foundation.org
Cc:	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Gregory Bean <gbean@...eaurora.org>,
	David Brown <davidb@...eaurora.org>,
	Daniel Walker <dwalker@...eaurora.org>,
	Bryan Huntsman <bryanh@...eaurora.org>
Subject: [PATCH 2/2 v3] gpio: msm7200a: Add irq support to msm-gpiolib.

Signed-off-by: Gregory Bean <gbean@...eaurora.org>
---
 drivers/gpio/msm7200a-gpio.c  |  169 ++++++++++++++++++++++++++++++++++++++++-
 include/linux/msm7200a-gpio.h |   25 ++++++
 2 files changed, 193 insertions(+), 1 deletions(-)

diff --git a/drivers/gpio/msm7200a-gpio.c b/drivers/gpio/msm7200a-gpio.c
index 21de253..0e0d38d 100644
--- a/drivers/gpio/msm7200a-gpio.c
+++ b/drivers/gpio/msm7200a-gpio.c
@@ -23,6 +23,8 @@
 #include <linux/kernel.h>
 #include <linux/gpio.h>
 #include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
@@ -31,6 +33,9 @@
 struct msm_gpio_dev {
 	struct gpio_chip		gpio_chip;
 	spinlock_t			lock;
+	unsigned			irq_base;
+	unsigned			irq_summary;
+	bool				latch_level_irqs;
 	struct msm7200a_gpio_regs	regs;
 };
 
@@ -115,11 +120,131 @@ static void gpio_chip_set(struct gpio_chip *chip, unsigned offset, int value)
 	spin_unlock_irqrestore(&msm_gpio->lock, irq_flags);
 }
 
+static int gpio_chip_to_irq(struct gpio_chip *chip, unsigned offset)
+{
+	struct msm_gpio_dev *msm_gpio = to_msm_gpio_dev(chip);
+	return msm_gpio->irq_base + offset;
+}
+
+static void forget_level_irq(struct msm_gpio_dev *msm_gpio, unsigned offset)
+{
+	if (!msm_gpio->latch_level_irqs) {
+		unsigned v = readl(msm_gpio->regs.int_edge);
+		unsigned b = bit(offset);
+
+		if (!(v & b))
+			writel(b, msm_gpio->regs.int_clear);
+	}
+}
+
+static void msm_gpio_irq_mask(unsigned int irq)
+{
+	unsigned long irq_flags;
+	struct msm_gpio_dev *msm_gpio = get_irq_chip_data(irq);
+	unsigned offset = irq - msm_gpio->irq_base;
+
+	spin_lock_irqsave(&msm_gpio->lock, irq_flags);
+	forget_level_irq(msm_gpio, offset);
+	clr_gpio_bit(offset, msm_gpio->regs.int_en);
+	spin_unlock_irqrestore(&msm_gpio->lock, irq_flags);
+}
+
+static void msm_gpio_irq_unmask(unsigned int irq)
+{
+	unsigned long irq_flags;
+	struct msm_gpio_dev *msm_gpio = get_irq_chip_data(irq);
+	unsigned offset = irq - msm_gpio->irq_base;
+
+	spin_lock_irqsave(&msm_gpio->lock, irq_flags);
+	forget_level_irq(msm_gpio, offset);
+	set_gpio_bit(offset, msm_gpio->regs.int_en);
+	spin_unlock_irqrestore(&msm_gpio->lock, irq_flags);
+}
+
+static int msm_gpio_irq_set_type(unsigned int irq, unsigned int flow_type)
+{
+	unsigned long irq_flags;
+	struct msm_gpio_dev *msm_gpio = get_irq_chip_data(irq);
+	unsigned offset = irq - msm_gpio->irq_base;
+
+	if ((flow_type & IRQ_TYPE_EDGE_BOTH) ==	IRQ_TYPE_EDGE_BOTH)
+		return -ENOTSUPP;
+
+	if ((flow_type & (IRQF_TRIGGER_HIGH | IRQF_TRIGGER_LOW)) ==
+		(IRQF_TRIGGER_HIGH | IRQF_TRIGGER_LOW))
+		return -ENOTSUPP;
+
+	spin_lock_irqsave(&msm_gpio->lock, irq_flags);
+
+	if (flow_type & IRQ_TYPE_EDGE_BOTH) {
+		set_gpio_bit(offset, msm_gpio->regs.int_edge);
+		irq_desc[irq].handle_irq = handle_edge_irq;
+	} else {
+		clr_gpio_bit(offset, msm_gpio->regs.int_edge);
+		irq_desc[irq].handle_irq = handle_level_irq;
+	}
+
+	if (flow_type & (IRQF_TRIGGER_HIGH | IRQF_TRIGGER_RISING))
+		set_gpio_bit(offset, msm_gpio->regs.int_pos);
+	else
+		clr_gpio_bit(offset, msm_gpio->regs.int_pos);
+
+	spin_unlock_irqrestore(&msm_gpio->lock, irq_flags);
+
+	return 0;
+}
+
+static void msm_gpio_irq_mask_ack(unsigned int irq)
+{
+	msm_gpio_irq_mask(irq);
+}
+
+static irqreturn_t msm_gpio_irq_handler(int irq, void *dev)
+{
+	struct msm_gpio_dev *msm_gpio = dev;
+	unsigned long irq_flags;
+	unsigned e, s, triggered_irqs;
+	int b;
+
+	/*
+	 * The int_status register latches trigger events whether or not
+	 * the gpio line is enabled as an interrupt source.  Therefore,
+	 * the set of pins which defines the interrupts which need to fire
+	 * is the intersection of int_status and int_en - int_status
+	 * alone provides an incomplete picture.
+	 */
+	spin_lock_irqsave(&msm_gpio->lock, irq_flags);
+	s = readl(msm_gpio->regs.int_status);
+	e = readl(msm_gpio->regs.int_en);
+	triggered_irqs = s & e;
+	if (triggered_irqs)
+		writel(triggered_irqs, msm_gpio->regs.int_clear);
+	spin_unlock_irqrestore(&msm_gpio->lock, irq_flags);
+
+	if (!triggered_irqs)
+		return IRQ_NONE;
+
+	while (triggered_irqs) {
+		b = ffs(triggered_irqs) - 1;
+		triggered_irqs &= ~bit(b);
+		generic_handle_irq(msm_gpio->irq_base + b);
+	}
+	return IRQ_HANDLED;
+}
+
+static struct irq_chip msm_gpio_irq_chip = {
+	.name			= "msm_gpio",
+	.mask			= msm_gpio_irq_mask,
+	.mask_ack		= msm_gpio_irq_mask_ack,
+	.unmask			= msm_gpio_irq_unmask,
+	.set_type		= msm_gpio_irq_set_type,
+};
+
 static int msm_gpio_probe(struct platform_device *dev)
 {
 	struct msm_gpio_dev *msm_gpio;
 	struct msm7200a_gpio_platform_data *pdata = dev->dev.platform_data;
-	int ret;
+	int i, irq, ret;
 
 	if (!pdata)
 		return -EINVAL;
@@ -139,12 +264,53 @@ static int msm_gpio_probe(struct platform_device *dev)
 	msm_gpio->gpio_chip.direction_output = gpio_chip_direction_output;
 	msm_gpio->gpio_chip.get              = gpio_chip_get;
 	msm_gpio->gpio_chip.set              = gpio_chip_set;
+	msm_gpio->gpio_chip.to_irq           = gpio_chip_to_irq;
+	msm_gpio->irq_base                   = pdata->irq_base;
+	msm_gpio->irq_summary                = pdata->irq_summary;
+	msm_gpio->latch_level_irqs           = pdata->latch_level_irqs;
 
 	ret = gpiochip_add(&msm_gpio->gpio_chip);
 	if (ret < 0)
 		goto err_post_malloc;
 
+	for (i = 0; i < msm_gpio->gpio_chip.ngpio; ++i) {
+		irq = msm_gpio->irq_base + i;
+		set_irq_chip_data(irq, msm_gpio);
+		set_irq_chip(irq, &msm_gpio_irq_chip);
+		set_irq_handler(irq, handle_level_irq);
+		set_irq_flags(irq, IRQF_VALID);
+	}
+
+	/*
+	 * We use a level-triggered interrupt because of the nature
+	 * of the shared GPIO-group interrupt.
+	 *
+	 * Many GPIO chips may be sharing the same group IRQ line, and
+	 * it is possible for GPIO interrupt to re-occur while the system
+	 * is still servicing the group interrupt associated with it.
+	 * The group IRQ line would not de-assert and re-assert, and
+	 * we'd get no second edge to cause the group IRQ to be handled again.
+	 *
+	 * Using a level interrupt guarantees that the group IRQ handlers
+	 * will continue to be called as long as any GPIO chip in the group
+	 * is asserting, even if the condition began while the group
+	 * handler was in mid-pass.
+	 */
+	ret = request_irq(msm_gpio->irq_summary,
+			  msm_gpio_irq_handler,
+			  IRQF_SHARED | IRQF_TRIGGER_HIGH,
+			  dev_name(&dev->dev),
+			  msm_gpio);
+	if (ret < 0)
+		goto err_post_gpiochip_add;
+
 	return ret;
+err_post_gpiochip_add:
+	/*
+	 * Under no circumstances should a line be held on a gpiochip
+	 * which hasn't finished probing.
+	 */
+	BUG_ON(gpiochip_remove(&msm_gpio->gpio_chip) < 0);
 err_post_malloc:
 	kfree(msm_gpio);
 	return ret;
@@ -158,6 +324,7 @@ static int msm_gpio_remove(struct platform_device *dev)
 	if (ret < 0)
 		return ret;
 
+	free_irq(msm_gpio->irq_summary, msm_gpio);
 	kfree(msm_gpio);
 
 	return 0;
diff --git a/include/linux/msm7200a-gpio.h b/include/linux/msm7200a-gpio.h
index c44d16b..317c1fd 100644
--- a/include/linux/msm7200a-gpio.h
+++ b/include/linux/msm7200a-gpio.h
@@ -34,6 +34,11 @@
  * @in:		GPIO_IN_n
  * @out:	GPIO_OUT_n
  * @oe:		GPIO_OE_n
+ * @int_status:	GPIO_INT_STATUS_n
+ * @int_clear:	GPIO_INT_CLEAR_n
+ * @int_en:	GPIO_INT_EN_n
+ * @int_edge:	GPIO_INT_EDGE_n
+ * @int_pos:	GPIO_INT_POS_n
  *
  * Registers are not guaranteed to be packed in memory, or even
  * located in a predictable pattern.
@@ -42,6 +47,11 @@ struct msm7200a_gpio_regs {
 	void __iomem *in;
 	void __iomem *out;
 	void __iomem *oe;
+	void __iomem *int_status;
+	void __iomem *int_clear;
+	void __iomem *int_en;
+	void __iomem *int_edge;
+	void __iomem *int_pos;
 };
 
 /**
@@ -50,12 +60,27 @@ struct msm7200a_gpio_regs {
  *		directly to gpio_chip.base.
  * @ngpio:	The number of gpio lines to be managed by the device.
  *		Must be <= 32.  Corresponds directly to gpio_chip.ngpio.
+ * @irq_base:	The first irq to be assigned to the device.  The gpio
+ *		at 'gpio_base' will be assigned irq 'irq_base',
+ *		gpio 'gpio_base + 1' will receive irq 'irq_base + 1',
+ *		and so on.
+ * @irq_summary:	The summary irq line which will be used by the device
+ *			to notify the kernel when an interrupt occurs on
+ *			any of its gpio lines.  Most MSM SoCs have more
+ *			than one gpio device sharing each of these.
+ * @latch_level_irqs:	The MSM gpio hardware latches level interrupts,
+ *			which is atypical.  Setting this flag to false
+ *			makes the driver compensate for this and produce
+ *			the traditional unlatched behavior for level irqs.
  * @regs:	Addresses of the registers which control the gpios
  *		to be managed by the device.
  */
 struct msm7200a_gpio_platform_data {
 	unsigned gpio_base;
 	unsigned ngpio;
+	unsigned irq_base;
+	unsigned irq_summary;
+	bool latch_level_irqs;
 	struct msm7200a_gpio_regs regs;
 };
 
-- 
1.7.0.4

--
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
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