gpiolib: don't allow setting values on input lines

Some drivers as well as the character device and sysfs code check
whether the line actually is in output mode before allowing the user to
set a value.

However, GPIO value setters now return integer values and can indicate
failures. This allows us to move these checks into the core code.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250311-gpio-set-check-output-v1-1-d971bca9e6fa@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 107d75558b5a80db138c361d2a56bcebed5cd20a..e6a289fa0f8fd5edb3b180ef668ac8777e3dac86 100644 (file)
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1366,9 +1366,6 @@ static long linereq_set_values(struct linereq *lr, void __user *ip)
        /* scan requested lines to determine the subset to be set */
        for (num_set = 0, i = 0; i < lr->num_lines; i++) {
                if (lv.mask & BIT_ULL(i)) {
-                       /* setting inputs is not allowed */
-                       if (!test_bit(FLAG_IS_OUT, &lr->lines[i].desc->flags))
-                               return -EPERM;
                        /* add to compacted values */
                        if (lv.bits & BIT_ULL(i))
                                __set_bit(num_set, vals);

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 1acfa43bf1ab02e82b1bc1cfe7f49606651e1907..4a3aa09dad9d54dc77f28d596723fd5546cb3ae8 100644 (file)
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -134,17 +134,15 @@ static ssize_t value_store(struct device *dev,
        long value;
 
        status = kstrtol(buf, 0, &value);
+       if (status)
+               return status;
 
        guard(mutex)(&data->mutex);
 
-       if (!test_bit(FLAG_IS_OUT, &desc->flags))
-               return -EPERM;
-
+       status = gpiod_set_value_cansleep(desc, value);
        if (status)
                return status;
 
-       gpiod_set_value_cansleep(desc, value);
-
        return size;
 }
 static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index b8197502a5ac598ce3c88c1e9a1d6c0b74516aac..8252a671d7208105a315bdc914acb092d5f95e79 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -3593,6 +3593,9 @@ static int gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value)
 
 static int gpiod_set_raw_value_commit(struct gpio_desc *desc, bool value)
 {
+       if (unlikely(!test_bit(FLAG_IS_OUT, &desc->flags)))
+               return -EPERM;
+
        CLASS(gpio_chip_guard, guard)(desc);
        if (!guard.gc)
                return -ENODEV;
@@ -3664,6 +3667,12 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
                if (!can_sleep)
                        WARN_ON(array_info->gdev->can_sleep);
 
+               for (i = 0; i < array_size; i++) {
+                       if (unlikely(!test_bit(FLAG_IS_OUT,
+                                              &desc_array[i]->flags)))
+                               return -EPERM;
+               }
+
                guard(srcu)(&array_info->gdev->srcu);
                gc = srcu_dereference(array_info->gdev->chip,
                                      &array_info->gdev->srcu);
@@ -3723,6 +3732,9 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
                        int hwgpio = gpio_chip_hwgpio(desc);
                        int value = test_bit(i, value_bitmap);
 
+                       if (unlikely(!test_bit(FLAG_IS_OUT, &desc->flags)))
+                               return -EPERM;
+
                        /*
                         * Pins applicable for fast input but not for
                         * fast output processing may have been already