diff options
Diffstat (limited to 'drivers/gpio')
| -rw-r--r-- | drivers/gpio/gpiolib-sysfs.c | 52 |
1 files changed, 34 insertions, 18 deletions
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c index 682e4d34999c..1bb05aa33a84 100644 --- a/drivers/gpio/gpiolib-sysfs.c +++ b/drivers/gpio/gpiolib-sysfs.c @@ -12,12 +12,15 @@ struct gpiod_data { struct gpio_desc *desc; + + struct mutex mutex; struct kernfs_node *value_kn; int irq; }; -/* lock protects against unexport_gpio() being called while - * sysfs files are active. +/* + * Lock to serialise gpiod export and unexport, and prevent re-export of + * gpiod whose chip is being unregistered. */ static DEFINE_MUTEX(sysfs_lock); @@ -49,14 +52,15 @@ static ssize_t direction_show(struct device *dev, struct gpio_desc *desc = data->desc; ssize_t status; - mutex_lock(&sysfs_lock); + mutex_lock(&data->mutex); gpiod_get_direction(desc); status = sprintf(buf, "%s\n", test_bit(FLAG_IS_OUT, &desc->flags) ? "out" : "in"); - mutex_unlock(&sysfs_lock); + mutex_unlock(&data->mutex); + return status; } @@ -67,7 +71,7 @@ static ssize_t direction_store(struct device *dev, struct gpio_desc *desc = data->desc; ssize_t status; - mutex_lock(&sysfs_lock); + mutex_lock(&data->mutex); if (sysfs_streq(buf, "high")) status = gpiod_direction_output_raw(desc, 1); @@ -78,7 +82,8 @@ static ssize_t direction_store(struct device *dev, else status = -EINVAL; - mutex_unlock(&sysfs_lock); + mutex_unlock(&data->mutex); + return status ? : size; } static DEVICE_ATTR_RW(direction); @@ -90,11 +95,12 @@ static ssize_t value_show(struct device *dev, struct gpio_desc *desc = data->desc; ssize_t status; - mutex_lock(&sysfs_lock); + mutex_lock(&data->mutex); status = sprintf(buf, "%d\n", gpiod_get_value_cansleep(desc)); - mutex_unlock(&sysfs_lock); + mutex_unlock(&data->mutex); + return status; } @@ -105,7 +111,7 @@ static ssize_t value_store(struct device *dev, struct gpio_desc *desc = data->desc; ssize_t status; - mutex_lock(&sysfs_lock); + mutex_lock(&data->mutex); if (!test_bit(FLAG_IS_OUT, &desc->flags)) { status = -EPERM; @@ -119,7 +125,8 @@ static ssize_t value_store(struct device *dev, } } - mutex_unlock(&sysfs_lock); + mutex_unlock(&data->mutex); + return status; } static DEVICE_ATTR_RW(value); @@ -133,6 +140,7 @@ static irqreturn_t gpio_sysfs_irq(int irq, void *priv) return IRQ_HANDLED; } +/* Caller holds gpiod-data mutex. */ static int gpio_sysfs_request_irq(struct device *dev, unsigned long gpio_flags) { struct gpiod_data *data = dev_get_drvdata(dev); @@ -185,6 +193,10 @@ err_put_kn: return ret; } +/* + * Caller holds gpiod-data mutex (unless called after class-device + * deregistration). + */ static void gpio_sysfs_free_irq(struct device *dev) { struct gpiod_data *data = dev_get_drvdata(dev); @@ -215,7 +227,7 @@ static ssize_t edge_show(struct device *dev, ssize_t status = 0; int i; - mutex_lock(&sysfs_lock); + mutex_lock(&data->mutex); for (i = 0; i < ARRAY_SIZE(trigger_types); i++) { mask = desc->flags & GPIO_TRIGGER_MASK; @@ -225,7 +237,8 @@ static ssize_t edge_show(struct device *dev, } } - mutex_unlock(&sysfs_lock); + mutex_unlock(&data->mutex); + return status; } @@ -248,7 +261,7 @@ static ssize_t edge_store(struct device *dev, flags = trigger_types[i].flags; - mutex_lock(&sysfs_lock); + mutex_lock(&data->mutex); if ((desc->flags & GPIO_TRIGGER_MASK) == flags) { status = size; @@ -265,12 +278,13 @@ static ssize_t edge_store(struct device *dev, } out_unlock: - mutex_unlock(&sysfs_lock); + mutex_unlock(&data->mutex); return status; } static DEVICE_ATTR_RW(edge); +/* Caller holds gpiod-data mutex. */ static int sysfs_set_active_low(struct device *dev, int value) { struct gpiod_data *data = dev_get_drvdata(dev); @@ -304,12 +318,12 @@ static ssize_t active_low_show(struct device *dev, struct gpio_desc *desc = data->desc; ssize_t status; - mutex_lock(&sysfs_lock); + mutex_lock(&data->mutex); status = sprintf(buf, "%d\n", !!test_bit(FLAG_ACTIVE_LOW, &desc->flags)); - mutex_unlock(&sysfs_lock); + mutex_unlock(&data->mutex); return status; } @@ -317,16 +331,17 @@ static ssize_t active_low_show(struct device *dev, static ssize_t active_low_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t size) { + struct gpiod_data *data = dev_get_drvdata(dev); ssize_t status; long value; - mutex_lock(&sysfs_lock); + mutex_lock(&data->mutex); status = kstrtol(buf, 0, &value); if (status == 0) status = sysfs_set_active_low(dev, value != 0); - mutex_unlock(&sysfs_lock); + mutex_unlock(&data->mutex); return status ? : size; } @@ -583,6 +598,7 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change) } data->desc = desc; + mutex_init(&data->mutex); offset = gpio_chip_hwgpio(desc); if (chip->names && chip->names[offset]) |