[PATCH 1/2] gpio add interrupt support on pca953x

Marc Zyngier maz at misterjones.org
Tue Dec 22 14:59:47 EST 2009


On Tue, 22 Dec 2009 21:41:51 +0800
Eric Miao <eric.y.miao at gmail.com> wrote:

Eric, Haojian,

> Marc Zyngier was doing the similar thing, and submitted a patch to
> Andrew Morton already, but I prefer a full-functional IRQ chip based
> solution, so you may want to work with him together on this.
> 
> Marc,
> 
> Do you have the link to your patch?

Here's the current state of my tree, quickly rebased to 2.6.33-rc1.
To summarize, the main differences with Haojian's patch:
- uses threaded irqs/nested irqs
- setup is slightly more complicated (interrupt source mask and base
  interrupt number), but more correct (no dependency on gpio_to_irq()
  being a linear mapping, which is not always the case)

From d8dc00d1ebedcc889c41add70cceb8f15f106261 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz at misterjones.org>
Date: Tue, 22 Dec 2009 17:38:29 +0100
Subject: [PATCH] Add interrupt handling capability to pca953x.

Most of the GPIO expanders controlled by the pca953x driver are
able to report changes on the input pins through an *INT pin.

This patch implements the irq_chip functionality (edge detection
only).

The driver has been tested on an Arcom Zeus.

Signed-off-by: Marc Zyngier <maz at misterjones.org>
---
 drivers/gpio/pca953x.c      |  207 ++++++++++++++++++++++++++++++++++++++++---
 include/linux/i2c/pca953x.h |    5 +
 2 files changed, 199 insertions(+), 13 deletions(-)

diff --git a/drivers/gpio/pca953x.c b/drivers/gpio/pca953x.c
index 6a2fb3f..06c34a0 100644
--- a/drivers/gpio/pca953x.c
+++ b/drivers/gpio/pca953x.c
@@ -14,6 +14,8 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
 #include <linux/i2c.h>
 #include <linux/i2c/pca953x.h>
 #ifdef CONFIG_OF_GPIO
@@ -26,23 +28,28 @@
 #define PCA953X_INVERT         2
 #define PCA953X_DIRECTION      3
 
+#define PCA953X_GPIOS	       0x00FF
+#define PCA953X_INT	       0x0100
+
 static const struct i2c_device_id pca953x_id[] = {
-	{ "pca9534", 8, },
-	{ "pca9535", 16, },
+	{ "pca9534", 8  | PCA953X_INT, },
+	{ "pca9535", 16 | PCA953X_INT, },
 	{ "pca9536", 4, },
-	{ "pca9537", 4, },
-	{ "pca9538", 8, },
-	{ "pca9539", 16, },
-	{ "pca9554", 8, },
-	{ "pca9555", 16, },
+	{ "pca9537", 4  | PCA953X_INT, },
+	{ "pca9538", 8  | PCA953X_INT, },
+	{ "pca9539", 16 | PCA953X_INT, },
+	{ "pca9554", 8  | PCA953X_INT, },
+	{ "pca9555", 16 | PCA953X_INT, },
 	{ "pca9556", 8, },
 	{ "pca9557", 8, },
 
 	{ "max7310", 8, },
-	{ "max7315", 8, },
-	{ "pca6107", 8, },
-	{ "tca6408", 8, },
-	{ "tca6416", 16, },
+	{ "max7312", 16 | PCA953X_INT, },
+	{ "max7313", 16 | PCA953X_INT, },
+	{ "max7315", 8  | PCA953X_INT, },
+	{ "pca6107", 8  | PCA953X_INT, },
+	{ "tca6408", 8  | PCA953X_INT, },
+	{ "tca6416", 16 | PCA953X_INT, },
 	/* NYET:  { "tca6424", 24, }, */
 	{ }
 };
@@ -53,6 +60,15 @@ struct pca953x_chip {
 	uint16_t reg_output;
 	uint16_t reg_direction;
 
+	struct mutex irq_lock;
+	uint16_t irq_interrupt;
+	uint16_t irq_mask;
+	uint16_t irq_stat;
+	uint16_t irq_trig_raise;
+	uint16_t irq_trig_fall;
+
+	int	 irq_base;
+
 	struct i2c_client *client;
 	struct pca953x_platform_data *dyn_pdata;
 	struct gpio_chip gpio_chip;
@@ -202,6 +218,121 @@ static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
 	gc->names = chip->names;
 }
 
+static int pca953x_gpio_to_irq(struct gpio_chip *gc, unsigned off)
+{
+	struct pca953x_chip *chip;
+
+	chip = container_of(gc, struct pca953x_chip, gpio_chip);
+	if (chip->irq_interrupt & (1 << off))
+		return chip->irq_base + off;
+
+	return -ENXIO;
+}
+
+static void pca953x_irq_mask(unsigned int irq)
+{
+	struct pca953x_chip *chip = get_irq_chip_data(irq);
+
+	chip->irq_mask &= ~(1 << (irq - chip->irq_base));
+}
+
+static void pca953x_irq_unmask(unsigned int irq)
+{
+	struct pca953x_chip *chip = get_irq_chip_data(irq);
+
+	chip->irq_mask |= 1 << (irq - chip->irq_base);
+}
+
+static void pca953x_irq_bus_lock(unsigned int irq)
+{
+	struct pca953x_chip *chip = get_irq_chip_data(irq);
+
+	mutex_lock(&chip->irq_lock);
+}
+
+static void pca953x_irq_bus_sync_unlock(unsigned int irq)
+{
+	struct pca953x_chip *chip = get_irq_chip_data(irq);
+
+	mutex_unlock(&chip->irq_lock);
+}
+
+static int pca953x_irq_set_type(unsigned int irq, unsigned int type)
+{
+	struct pca953x_chip *chip = get_irq_chip_data(irq);
+	uint16_t mask = 1 << (irq - chip->irq_base);
+
+	if (!(type & IRQ_TYPE_EDGE_BOTH)) {
+		dev_err(&chip->client->dev, "unsupported irq type %d\n", type);
+		return -EINVAL;
+	}
+
+	if (type & IRQ_TYPE_EDGE_FALLING)
+		chip->irq_trig_fall |= mask;
+	else
+		chip->irq_trig_fall &= ~mask;
+
+	if (type & IRQ_TYPE_EDGE_RISING)
+		chip->irq_trig_raise |= mask;
+	else
+		chip->irq_trig_raise &= ~mask;
+
+	return 0;
+}
+
+static struct irq_chip pca953x_irq_chip = {
+	.name			= "pca953x",
+	.mask			= pca953x_irq_mask,
+	.unmask			= pca953x_irq_unmask,
+	.bus_lock		= pca953x_irq_bus_lock,
+	.bus_sync_unlock	= pca953x_irq_bus_sync_unlock,
+	.set_type		= pca953x_irq_set_type,
+};
+
+static irqreturn_t pca953x_irq_handler(int irq, void *devid)
+{
+	struct pca953x_chip *chip = devid;
+	uint16_t cur_stat;
+	uint16_t old_stat;
+	uint16_t pending;
+	int ret;
+
+	ret = pca953x_read_reg(chip, PCA953X_INPUT, &cur_stat);
+	if (ret)
+		return IRQ_HANDLED;
+
+	cur_stat &= (chip->irq_interrupt & chip->reg_direction);
+	old_stat = chip->irq_stat;
+	pending = (cur_stat ^ old_stat) & chip->irq_mask;
+
+	if (!pending)
+		return IRQ_HANDLED;
+
+	chip->irq_stat = cur_stat;
+
+	do {
+		uint16_t level;
+		uint16_t level_mask;
+		int trigger = 0;
+
+		level = __ffs(pending);
+		level_mask = 1 << level;
+
+		if (old_stat & level_mask & chip->irq_trig_fall)
+			trigger = 1;
+
+		if (cur_stat & level_mask & chip->irq_trig_raise)
+			trigger = 1;
+
+		if (trigger)
+			handle_nested_irq(level + chip->irq_base);
+
+		pending &= ~level_mask;
+	} while (pending);
+
+	return IRQ_HANDLED;
+}
+
 /*
  * Handlers for alternative sources of platform_data
  */
@@ -286,7 +417,7 @@ static int __devinit pca953x_probe(struct i2c_client *client,
 	/* initialize cached registers from their original values.
 	 * we can't share this chip with another i2c master.
 	 */
-	pca953x_setup_gpio(chip, id->driver_data);
+	pca953x_setup_gpio(chip, id->driver_data & PCA953X_GPIOS);
 
 	ret = pca953x_read_reg(chip, PCA953X_OUTPUT, &chip->reg_output);
 	if (ret)
@@ -301,10 +432,57 @@ static int __devinit pca953x_probe(struct i2c_client *client,
 	if (ret)
 		goto out_failed;
 
+	if (pdata->interrupt && (id->driver_data & PCA953X_INT)) {
+		int lvl;
+
+		ret = pca953x_read_reg(chip, PCA953X_INPUT,
+				       &chip->irq_stat);
+		if (ret)
+			goto out_failed;
+
+		/*
+		 * There is no way to know which GPIO line generated the
+		 * interrupt.  We have to rely on the previous read for
+		 * this purpose.
+		 */
+		chip->irq_stat &= chip->irq_interrupt & chip->reg_direction;
+		chip->irq_interrupt = pdata->interrupt;
+		chip->irq_base = pdata->irq_base;
+		mutex_init(&chip->irq_lock);
+
+		/* FIXME: Error handling? */
+		for (lvl = 0; lvl < chip->gpio_chip.ngpio; lvl++) {
+			if (chip->irq_interrupt & (1 << lvl)) {
+				int irq = lvl + chip->irq_base;
+
+				set_irq_chip_data(irq, chip);
+				set_irq_chip_and_handler(irq, &pca953x_irq_chip,
+							 handle_edge_irq);
+				set_irq_nested_thread(irq, 1);
+				set_irq_flags(irq, IRQF_VALID);
+			}
+		}
+
+		ret = request_threaded_irq(client->irq,
+					   NULL,
+					   pca953x_irq_handler,
+					   IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					   dev_name(&client->dev), chip);
+		if (ret) {
+			dev_err(&client->dev, "failed to request irq %d\n",
+				client->irq);
+			goto out_failed;
+		}
+
+		chip->gpio_chip.to_irq = pca953x_gpio_to_irq;
+	}
 
 	ret = gpiochip_add(&chip->gpio_chip);
-	if (ret)
+	if (ret) {
+		if (pdata->interrupt)
+			free_irq(client->irq, chip);
 		goto out_failed;
+	}
 
 	if (pdata->setup) {
 		ret = pdata->setup(client, chip->gpio_chip.base,
@@ -345,6 +523,9 @@ static int pca953x_remove(struct i2c_client *client)
 		return ret;
 	}
 
+	if (chip->irq_interrupt)
+		free_irq(client->irq, chip);
+
 	kfree(chip->dyn_pdata);
 	kfree(chip);
 	return 0;
diff --git a/include/linux/i2c/pca953x.h b/include/linux/i2c/pca953x.h
index 81736d6..6a2c8a6 100644
--- a/include/linux/i2c/pca953x.h
+++ b/include/linux/i2c/pca953x.h
@@ -7,6 +7,11 @@ struct pca953x_platform_data {
 	/* initial polarity inversion setting */
 	uint16_t	invert;
 
+	/* input bitmask to trigger the interrupt */
+	uint16_t	interrupt;
+
+	int		irq_base;
+
 	void		*context;	/* param to setup/teardown */
 
 	int		(*setup)(struct i2c_client *client,
-- 
1.6.0.4


-- 
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