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Subject[PATCH 23/23] gpio: sysfs: move irq trigger flags to class-device data
Date
Move irq trigger flags, which as sysfs-interface specific, to the class
device data.

This avoids accessing the gpio-descriptor flags field using non-atomic
operations without any locking, and allows for a more clear separation
of the sysfs interface from gpiolib core.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/gpio/gpiolib-sysfs.c | 48 ++++++++++++++++++++++----------------------
drivers/gpio/gpiolib.h | 4 ----
2 files changed, 24 insertions(+), 28 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 27a8c84fc241..8786b8b79ce6 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -10,12 +10,18 @@

#include "gpiolib.h"

+#define GPIO_IRQF_TRIGGER_FALLING BIT(0)
+#define GPIO_IRQF_TRIGGER_RISING BIT(1)
+#define GPIO_IRQF_TRIGGER_BOTH (GPIO_IRQF_TRIGGER_FALLING | \
+ GPIO_IRQF_TRIGGER_RISING)
+
struct gpiod_data {
struct gpio_desc *desc;

struct mutex mutex;
struct kernfs_node *value_kn;
int irq;
+ unsigned char irq_flags;

bool direction_can_change;
};
@@ -143,7 +149,7 @@ static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
}

/* Caller holds gpiod-data mutex. */
-static int gpio_sysfs_request_irq(struct device *dev, unsigned long gpio_flags)
+static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
{
struct gpiod_data *data = dev_get_drvdata(dev);
struct gpio_desc *desc = data->desc;
@@ -159,10 +165,10 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned long gpio_flags)
return -ENODEV;

irq_flags = IRQF_SHARED;
- if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
+ if (flags & GPIO_IRQF_TRIGGER_FALLING)
irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
- if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
+ if (flags & GPIO_IRQF_TRIGGER_RISING)
irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;

@@ -171,7 +177,7 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned long gpio_flags)
if (ret < 0)
goto err_put_kn;

- desc->flags |= gpio_flags;
+ data->irq_flags = flags;

return 0;

@@ -188,37 +194,33 @@ err_put_kn:
static void gpio_sysfs_free_irq(struct device *dev)
{
struct gpiod_data *data = dev_get_drvdata(dev);
- struct gpio_desc *desc = data->desc;

- desc->flags &= ~GPIO_TRIGGER_MASK;
+ data->irq_flags = 0;
free_irq(data->irq, data);
sysfs_put(data->value_kn);
}

static const struct {
const char *name;
- unsigned long flags;
+ unsigned char flags;
} trigger_types[] = {
{ "none", 0 },
- { "falling", BIT(FLAG_TRIG_FALL) },
- { "rising", BIT(FLAG_TRIG_RISE) },
- { "both", BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) },
+ { "falling", GPIO_IRQF_TRIGGER_FALLING },
+ { "rising", GPIO_IRQF_TRIGGER_RISING },
+ { "both", GPIO_IRQF_TRIGGER_BOTH },
};

static ssize_t edge_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gpiod_data *data = dev_get_drvdata(dev);
- struct gpio_desc *desc = data->desc;
- unsigned long mask;
ssize_t status = 0;
int i;

mutex_lock(&data->mutex);

for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
- mask = desc->flags & GPIO_TRIGGER_MASK;
- if (mask == trigger_types[i].flags) {
+ if (data->irq_flags == trigger_types[i].flags) {
status = sprintf(buf, "%s\n", trigger_types[i].name);
break;
}
@@ -233,8 +235,7 @@ static ssize_t edge_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
struct gpiod_data *data = dev_get_drvdata(dev);
- struct gpio_desc *desc = data->desc;
- unsigned long flags;
+ unsigned char flags;
ssize_t status = size;
int i;

@@ -250,12 +251,12 @@ static ssize_t edge_store(struct device *dev,

mutex_lock(&data->mutex);

- if ((desc->flags & GPIO_TRIGGER_MASK) == flags) {
+ if (flags == data->irq_flags) {
status = size;
goto out_unlock;
}

- if (desc->flags & GPIO_TRIGGER_MASK)
+ if (data->irq_flags)
gpio_sysfs_free_irq(dev);

if (flags) {
@@ -277,6 +278,7 @@ static int gpio_sysfs_set_active_low(struct device *dev, int value)
struct gpiod_data *data = dev_get_drvdata(dev);
struct gpio_desc *desc = data->desc;
int status = 0;
+ unsigned int flags = data->irq_flags;

if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
return 0;
@@ -287,12 +289,10 @@ static int gpio_sysfs_set_active_low(struct device *dev, int value)
clear_bit(FLAG_ACTIVE_LOW, &desc->flags);

/* reconfigure poll(2) support if enabled on one edge only */
- if (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
- !!test_bit(FLAG_TRIG_FALL, &desc->flags)) {
- unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;
-
+ if (flags == GPIO_IRQF_TRIGGER_FALLING ||
+ flags == GPIO_IRQF_TRIGGER_RISING) {
gpio_sysfs_free_irq(dev);
- status = gpio_sysfs_request_irq(dev, trigger_flags);
+ status = gpio_sysfs_request_irq(dev, flags);
}

return status;
@@ -685,7 +685,7 @@ void gpiod_unexport(struct gpio_desc *desc)
/*
* Release irq after deregistration to prevent race with edge_store.
*/
- if (desc->flags & GPIO_TRIGGER_MASK)
+ if (data->irq_flags)
gpio_sysfs_free_irq(dev);

mutex_unlock(&sysfs_lock);
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 591257a4359a..e048be7d1f5e 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -81,16 +81,12 @@ struct gpio_desc {
#define FLAG_IS_OUT 1
#define FLAG_EXPORT 2 /* protected by sysfs_lock */
#define FLAG_SYSFS 3 /* exported via /sys/class/gpio/control */
-#define FLAG_TRIG_FALL 4 /* trigger on falling edge */
-#define FLAG_TRIG_RISE 5 /* trigger on rising edge */
#define FLAG_ACTIVE_LOW 6 /* value has active low */
#define FLAG_OPEN_DRAIN 7 /* Gpio is open drain type */
#define FLAG_OPEN_SOURCE 8 /* Gpio is open source type */
#define FLAG_USED_AS_IRQ 9 /* GPIO is connected to an IRQ */
#define FLAG_IS_HOGGED 11 /* GPIO is hogged */

-#define GPIO_TRIGGER_MASK (BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
-
const char *label;
};

--
2.0.5


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