[PATCH] gpio: pca953x: add irq_chip for irq demuxing

[Alek Du]

This patch is required when using this gpio driver with gpio_keys driver

Signed-off-by: Alek Du <alek.du@xxxxxxxxx>
CC: David Brownell <david-b@xxxxxxxxxxx>
---
 drivers/gpio/pca953x.c      |   54 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/i2c/pca953x.h |    3 ++
 2 files changed, 57 insertions(+), 0 deletions(-)

diff --git a/drivers/gpio/pca953x.c b/drivers/gpio/pca953x.c
index 8ab1308..47c1d99 100644
--- a/drivers/gpio/pca953x.c
+++ b/drivers/gpio/pca953x.c
@@ -13,6 +13,7 @@
 
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/interrupt.h>
 #include <linux/i2c.h>
 #include <linux/i2c/pca953x.h>
 #ifdef CONFIG_OF_GPIO
@@ -51,6 +52,7 @@ MODULE_DEVICE_TABLE(i2c, pca953x_id);
 
 struct pca953x_chip {
 	unsigned gpio_start;
+	unsigned irq_base;
 	uint16_t reg_output;
 	uint16_t reg_direction;
 
@@ -183,6 +185,13 @@ static void pca953x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
 	chip->reg_output = reg_val;
 }
 
+static int pca953x_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
+{
+	struct pca953x_chip *chip = container_of(gc, struct pca953x_chip,
+								gpio_chip);
+	return chip->irq_base + offset;
+}
+
 static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
 {
 	struct gpio_chip *gc;
@@ -193,6 +202,7 @@ static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
 	gc->direction_output = pca953x_gpio_direction_output;
 	gc->get = pca953x_gpio_get_value;
 	gc->set = pca953x_gpio_set_value;
+	gc->to_irq = pca953x_gpio_to_irq;
 	gc->can_sleep = 1;
 
 	gc->base = chip->gpio_start;
@@ -251,6 +261,34 @@ pca953x_get_alt_pdata(struct i2c_client *client)
 }
 #endif
 
+/* the irq_chip at least needs one handler */
+static void pca953x_irq_unmask(unsigned irq)
+{
+}
+
+static struct irq_chip pca953x_irqchip = {
+	.name		= "pca953x_irqchip",
+	.unmask		= pca953x_irq_unmask,
+};
+
+static void pca953x_irq_handler(unsigned irq, struct irq_desc *desc)
+{
+	struct pca953x_chip *chip = (struct pca953x_chip *)get_irq_data(irq);
+	int i;
+
+	if (desc->chip->ack)
+		desc->chip->ack(irq);
+	/* we must call all sub-irqs, since there is no way to read
+	 * I2C gpio expander's status in irq context. The driver itself
+	 * would be reponsible to check if the irq is for him.
+	 */
+	for (i = 0; i < chip->gpio_chip.ngpio; i++)
+		generic_handle_irq(chip->irq_base + i);
+
+	if (desc->chip->unmask)
+		desc->chip->unmask(irq);
+}
+
 static int __devinit pca953x_probe(struct i2c_client *client,
 				   const struct i2c_device_id *id)
 {
@@ -284,6 +322,8 @@ static int __devinit pca953x_probe(struct i2c_client *client,
 
 	chip->names = pdata->names;
 
+	chip->irq_base = pdata->irq_base;
+
 	/* initialize cached registers from their original values.
 	 * we can't share this chip with another i2c master.
 	 */
@@ -315,6 +355,20 @@ static int __devinit pca953x_probe(struct i2c_client *client,
 	}
 
 	i2c_set_clientdata(client, chip);
+
+	if (chip->irq_base) {
+		int i;
+
+		set_irq_type(client->irq,
+				IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING);
+		set_irq_chained_handler(client->irq, pca953x_irq_handler);
+		set_irq_data(client->irq, chip);
+		for (i = 0; i < chip->gpio_chip.ngpio; i++) {
+			set_irq_chip_and_handler_name(i + chip->irq_base,
+				&pca953x_irqchip, handle_simple_irq, "demux");
+			set_irq_chip_data(i + chip->irq_base, chip);
+		}
+	}
 	return 0;
 
 out_failed:
diff --git a/include/linux/i2c/pca953x.h b/include/linux/i2c/pca953x.h
index 81736d6..bf7c0a3 100644
--- a/include/linux/i2c/pca953x.h
+++ b/include/linux/i2c/pca953x.h
@@ -4,6 +4,9 @@ struct pca953x_platform_data {
 	/* number of the first GPIO */
 	unsigned	gpio_base;
 
+	/* number of the first IRQ */
+	unsigned	irq_base;
+
 	/* initial polarity inversion setting */
 	uint16_t	invert;
 
-- 
1.6.0.4
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