gpio: sysfs: move irq trigger flags to class-device data

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>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 9047b2d..b57ed8e 100644 (file)
--- 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;
 
@@ -183,7 +189,7 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned long gpio_flags)
        if (ret < 0)
                goto err_unlock;
 
-       desc->flags |= gpio_flags;
+       data->irq_flags = flags;
 
        return 0;
 
@@ -204,7 +210,7 @@ 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);
        gpiochip_unlock_as_irq(desc->chip, gpio_chip_hwgpio(desc));
        sysfs_put(data->value_kn);
@@ -212,28 +218,25 @@ static void gpio_sysfs_free_irq(struct device *dev)
 
 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;
                }
@@ -248,8 +251,7 @@ 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;
 
@@ -265,12 +267,12 @@ 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) {
@@ -292,6 +294,7 @@ 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;
@@ -302,12 +305,10 @@ 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;
@@ -700,7 +701,7 @@ 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 479041f..bf34300 100644 (file)
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -83,16 +83,12 @@ 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;
 };