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gpio: pca953x.c: add interrupt handling capability
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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.

[akpm@linux-foundation.org: the compiler does inlining for us nowadays]
Signed-off-by: Marc Zyngier <maz@misterjones.org>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Haojian Zhuang <haojian.zhuang@gmail.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Nate Case <ncase@xes-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Marc Zyngier authored and Linus Torvalds committed Mar 6, 2010
1 parent 8c35c89 commit 89ea8bb
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Showing 3 changed files with 247 additions and 12 deletions.
7 changes: 7 additions & 0 deletions drivers/gpio/Kconfig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,13 @@ config GPIO_PCA953X
This driver can also be built as a module. If so, the module
will be called pca953x.

config GPIO_PCA953X_IRQ
bool "Interrupt controller support for PCA953x"
depends on GPIO_PCA953X=y
help
Say yes here to enable the pca953x to be used as an interrupt
controller. It requires the driver to be built in the kernel.

config GPIO_PCF857X
tristate "PCF857x, PCA{85,96}7x, and MAX732[89] I2C GPIO expanders"
depends on I2C
Expand Down
249 changes: 237 additions & 12 deletions drivers/gpio/pca953x.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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, }, */
{ }
};
Expand All @@ -53,6 +60,15 @@ struct pca953x_chip {
uint16_t reg_output;
uint16_t reg_direction;

#ifdef CONFIG_GPIO_PCA953X_IRQ
struct mutex irq_lock;
uint16_t irq_mask;
uint16_t irq_stat;
uint16_t irq_trig_raise;
uint16_t irq_trig_fall;
int irq_base;
#endif

struct i2c_client *client;
struct pca953x_platform_data *dyn_pdata;
struct gpio_chip gpio_chip;
Expand Down Expand Up @@ -202,6 +218,210 @@ static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
gc->names = chip->names;
}

#ifdef CONFIG_GPIO_PCA953X_IRQ
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);
return chip->irq_base + off;
}

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 level = irq - chip->irq_base;
uint16_t mask = 1 << level;

if (!(type & IRQ_TYPE_EDGE_BOTH)) {
dev_err(&chip->client->dev, "irq %d: unsupported type %d\n",
irq, 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 pca953x_gpio_direction_input(&chip->gpio_chip, level);
}

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 uint16_t pca953x_irq_pending(struct pca953x_chip *chip)
{
uint16_t cur_stat;
uint16_t old_stat;
uint16_t pending;
uint16_t trigger;
int ret;

ret = pca953x_read_reg(chip, PCA953X_INPUT, &cur_stat);
if (ret)
return 0;

/* Remove output pins from the equation */
cur_stat &= chip->reg_direction;

old_stat = chip->irq_stat;
trigger = (cur_stat ^ old_stat) & chip->irq_mask;

if (!trigger)
return 0;

chip->irq_stat = cur_stat;

pending = (old_stat & chip->irq_trig_fall) |
(cur_stat & chip->irq_trig_raise);
pending &= trigger;

return pending;
}

static irqreturn_t pca953x_irq_handler(int irq, void *devid)
{
struct pca953x_chip *chip = devid;
uint16_t pending;
uint16_t level;

pending = pca953x_irq_pending(chip);

if (!pending)
return IRQ_HANDLED;

do {
level = __ffs(pending);
handle_nested_irq(level + chip->irq_base);

pending &= ~(1 << level);
} while (pending);

return IRQ_HANDLED;
}

static int pca953x_irq_setup(struct pca953x_chip *chip,
const struct i2c_device_id *id)
{
struct i2c_client *client = chip->client;
struct pca953x_platform_data *pdata = client->dev.platform_data;
int ret;

if (pdata->irq_base && (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->reg_direction;
chip->irq_base = pdata->irq_base;
mutex_init(&chip->irq_lock);

for (lvl = 0; lvl < chip->gpio_chip.ngpio; 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);
#ifdef CONFIG_ARM
set_irq_flags(irq, IRQF_VALID);
#else
set_irq_noprobe(irq);
#endif
}

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;
}

return 0;

out_failed:
chip->irq_base = 0;
return ret;
}

static void pca953x_irq_teardown(struct pca953x_chip *chip)
{
if (chip->irq_base)
free_irq(chip->client->irq, chip);
}
#else /* CONFIG_GPIO_PCA953X_IRQ */
static int pca953x_irq_setup(struct pca953x_chip *chip,
const struct i2c_device_id *id)
{
struct i2c_client *client = chip->client;
struct pca953x_platform_data *pdata = client->dev.platform_data;

if (pdata->irq_base && (id->driver_data & PCA953X_INT))
dev_warn(&client->dev, "interrupt support not compiled in\n");

return 0;
}

static void pca953x_irq_teardown(struct pca953x_chip *chip)
{
}
#endif

/*
* Handlers for alternative sources of platform_data
*/
Expand Down Expand Up @@ -286,7 +506,7 @@ 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)
Expand All @@ -301,6 +521,9 @@ static int __devinit pca953x_probe(struct i2c_client *client,
if (ret)
goto out_failed;

ret = pca953x_irq_setup(chip, id);
if (ret)
goto out_failed;

ret = gpiochip_add(&chip->gpio_chip);
if (ret)
Expand All @@ -317,6 +540,7 @@ static int __devinit pca953x_probe(struct i2c_client *client,
return 0;

out_failed:
pca953x_irq_teardown(chip);
kfree(chip->dyn_pdata);
kfree(chip);
return ret;
Expand Down Expand Up @@ -345,6 +569,7 @@ static int pca953x_remove(struct i2c_client *client)
return ret;
}

pca953x_irq_teardown(chip);
kfree(chip->dyn_pdata);
kfree(chip);
return 0;
Expand Down
3 changes: 3 additions & 0 deletions include/linux/i2c/pca953x.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,9 @@ struct pca953x_platform_data {
/* initial polarity inversion setting */
uint16_t invert;

/* interrupt base */
int irq_base;

void *context; /* param to setup/teardown */

int (*setup)(struct i2c_client *client,
Expand Down

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