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Message-ID: <20091115175550.68964c72@taxman.wild-wind.fr.eu.org>
Date: Sun, 15 Nov 2009 17:55:50 +0100
From: Marc Zyngier <maz@...terjones.org>
To: lkml <linux-kernel@...r.kernel.org>
Cc: Linux Arm Kernel <linux-arm-kernel@...ts.infradead.org>,
Eric Miao <eric.y.miao@...il.com>
Subject: [RFC][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 a very basic way for the platform code to
be alerted when some input changes (both edge detection).
It can be seen as a poor man irq_chip.
Alternatively, this could be turned into a full-fledged irq_chip,
though I'm not sure it is worth the complexity.
The driver has been tested on an Arcom Zeus.
Signed-off-by: Marc Zyngier <maz@...terjones.org>
---
drivers/gpio/pca953x.c | 96 +++++++++++++++++++++++++++++++++++++------
include/linux/i2c/pca953x.h | 7 +++-
2 files changed, 89 insertions(+), 14 deletions(-)
diff --git a/drivers/gpio/pca953x.c b/drivers/gpio/pca953x.c
index 6a2fb3f..528b35f 100644
--- a/drivers/gpio/pca953x.c
+++ b/drivers/gpio/pca953x.c
@@ -14,6 +14,7 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/gpio.h>
+#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/i2c/pca953x.h>
#ifdef CONFIG_OF_GPIO
@@ -26,23 +27,27 @@
#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, },
+ { "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 +58,11 @@ struct pca953x_chip {
uint16_t reg_output;
uint16_t reg_direction;
+ uint16_t int_mask;
+ uint16_t int_prev_input;
+ void (*interrupt)(uint16_t, uint16_t, void *);
+ void *context;
+
struct i2c_client *client;
struct pca953x_platform_data *dyn_pdata;
struct gpio_chip gpio_chip;
@@ -202,6 +212,34 @@ static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
gc->names = chip->names;
}
+static irqreturn_t pca953x_irq_quick_handler(int irq, void *devid)
+{
+ /* Always happy to serve... */
+ return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t pca953x_irq_handler(int irq, void *devid)
+{
+ struct pca953x_chip *chip = devid;
+ uint16_t reg_val;
+ uint16_t mask;
+ int ret;
+
+ ret = pca953x_read_reg(chip, PCA953X_INPUT, ®_val);
+ if (ret)
+ return IRQ_HANDLED;
+
+ reg_val &= (chip->int_mask & chip->reg_direction);
+ mask = reg_val ^ chip->int_prev_input;
+
+ if (mask) {
+ chip->int_prev_input = reg_val;
+ chip->interrupt(reg_val, mask, chip->context);
+ }
+
+ return IRQ_HANDLED;
+}
+
/*
* Handlers for alternative sources of platform_data
*/
@@ -286,7 +324,7 @@ 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 +339,39 @@ static int __devinit pca953x_probe(struct i2c_client *client,
if (ret)
goto out_failed;
+ if (pdata->interrupt && (id->driver_data & PCA953X_INT)) {
+ ret = pca953x_read_reg(chip, PCA953X_INPUT,
+ &chip->int_prev_input);
+ if (ret)
+ goto out_failed;
+
+ chip->interrupt = pdata->interrupt;
+ chip->int_mask = pdata->mask;
+
+ /*
+ * There is no way to know which GPIO line generated the
+ * interrupt. We have to rely on the previous read for
+ * this purpose.
+ */
+ chip->int_prev_input &= chip->int_mask & chip->reg_direction;
+
+ ret = request_threaded_irq(client->irq,
+ pca953x_irq_quick_handler,
+ pca953x_irq_handler, 0,
+ dev_name(&client->dev), chip);
+ if (ret) {
+ dev_err(&client->dev, "failed to request irq %d\n",
+ client->irq);
+ goto out_failed;
+ }
+ }
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 +412,9 @@ static int pca953x_remove(struct i2c_client *client)
return ret;
}
+ if (chip->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..1e787c0 100644
--- a/include/linux/i2c/pca953x.h
+++ b/include/linux/i2c/pca953x.h
@@ -7,7 +7,10 @@ struct pca953x_platform_data {
/* initial polarity inversion setting */
uint16_t invert;
- void *context; /* param to setup/teardown */
+ /* input bitmask to trigger the interrupt callback */
+ uint16_t mask;
+
+ void *context; /* param to setup/teardown/interrupt */
int (*setup)(struct i2c_client *client,
unsigned gpio, unsigned ngpio,
@@ -15,5 +18,7 @@ struct pca953x_platform_data {
int (*teardown)(struct i2c_client *client,
unsigned gpio, unsigned ngpio,
void *context);
+ void (*interrupt)(uint16_t val, uint16_t mask,
+ void *context);
char **names;
};
--
1.6.0.4
--
I'm the slime oozin' out from your TV set...
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