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gpio: remove gpiod_sysfs_set_active_low

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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>
This commit is contained in:
Johan Hovold
2015-05-04 17:10:33 +02:00
committed by Linus Walleij
parent 426577bd88
commit 166a85e442
7 changed files with 2 additions and 89 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
drivers/gpio/gpiolib-sysfs.c
View File

@@ -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);
@@ -680,50 +680,6 @@ 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