gpio: remove gpiod_sysfs_set_active_low

Remove gpiod_sysfs_set_active_low (and gpio_sysfs_set_active_low) which
allowed code to change the polarity of a gpio line even after it had
been exported through sysfs.

Drivers should not care, and generally does not know, about gpio-line
polarity which is a hardware feature that needs to be described by
firmware.

It is currently possible to define gpio-line polarity in device-tree and
acpi firmware or using platform data. Userspace can also change the
polarity through sysfs.

Note that drivers using the legacy gpio interface could still use
GPIOF_ACTIVE_LOW to change the polarity before exporting the gpio.

There are no in-kernel users of this interface.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Harry Wei <harryxiyou@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@zh-kernel.org
Cc: linux-arch@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 2 insertions, 46 deletions

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index aeb73ef2955e..9dcd346a20fb 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -308,8 +308,8 @@ static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
                 clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
 
         /* reconfigure poll(2) support if enabled on one edge only */
-        if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
-                                !!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
+        if (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
+                                !!test_bit(FLAG_TRIG_FALL, &desc->flags)) {
                 unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;
 
                 gpio_setup_irq(desc, dev, 0);
@@ -681,50 +681,6 @@ int gpiod_export_link(struct device *dev, const char *name,
 EXPORT_SYMBOL_GPL(gpiod_export_link);
 
 /**
- * gpiod_sysfs_set_active_low - set the polarity of gpio sysfs value
- * @gpio: gpio to change
- * @value: non-zero to use active low, i.e. inverted values
- *
- * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
- * The GPIO does not have to be exported yet.  If poll(2) support has
- * been enabled for either rising or falling edge, it will be
- * reconfigured to follow the new polarity.
- *
- * Returns zero on success, else an error.
- */
-int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
-{
-        struct device           *dev = NULL;
-        int                     status = -EINVAL;
-
-        if (!desc) {
-                pr_warn("%s: invalid GPIO\n", __func__);
-                return -EINVAL;
-        }
-
-        mutex_lock(&sysfs_lock);
-
-        if (test_bit(FLAG_EXPORT, &desc->flags)) {
-                dev = class_find_device(&gpio_class, NULL, desc, match_export);
-                if (dev == NULL) {
-                        status = -ENODEV;
-                        goto unlock;
-                }
-        }
-
-        status = sysfs_set_active_low(desc, dev, value);
-        put_device(dev);
-unlock:
-        mutex_unlock(&sysfs_lock);
-
-        if (status)
-                gpiod_dbg(desc, "%s: status %d\n", __func__, status);
-
-        return status;
-}
-EXPORT_SYMBOL_GPL(gpiod_sysfs_set_active_low);
-
-/**
  * gpiod_unexport - reverse effect of gpio_export()
  * @gpio: gpio to make unavailable
  *