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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 <[email protected]>
Cc: Harry Wei <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Johan Hovold <[email protected]>
Reviewed-by: Alexandre Courbot <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>
This commit is contained in:
Johan Hovold 2015-05-04 17:10:33 +02:00 • committed by Linus Walleij
commit 166a85e442
7 changed files with 2 additions and 89 deletions
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9
Documentation/gpio/gpio-legacy.txt
View file

@ -751,9 +751,6 @@ requested using gpio_request():
int gpio_export_link(struct device *dev, const char *name,
unsigned gpio)
/* change the polarity of a GPIO node in sysfs */
int gpio_sysfs_set_active_low(unsigned gpio, int value);
After a kernel driver requests a GPIO, it may only be made available in
the sysfs interface by gpio_export(). The driver can control whether the
signal direction may change. This helps drivers prevent userspace code
@ -767,9 +764,3 @@ After the GPIO has been exported, gpio_export_link() allows creating
symlinks from elsewhere in sysfs to the GPIO sysfs node. Drivers can
use this to provide the interface under their own device in sysfs with
a descriptive name.
Drivers can use gpio_sysfs_set_active_low() to hide GPIO line polarity
differences between boards from user space. This only affects the
sysfs interface. Polarity change can be done both before and after
gpio_export(), and previously enabled poll(2) support for either
rising or falling edge will be reconfigured to follow this setting.

8
Documentation/gpio/sysfs.txt
View file

@ -132,9 +132,6 @@ requested using gpio_request():
int gpiod_export_link(struct device *dev, const char *name,
struct gpio_desc *desc);
/* change the polarity of a GPIO node in sysfs */
int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value);
After a kernel driver requests a GPIO, it may only be made available in
the sysfs interface by gpiod_export(). The driver can control whether the
signal direction may change. This helps drivers prevent userspace code
@ -148,8 +145,3 @@ After the GPIO has been exported, gpiod_export_link() allows creating
symlinks from elsewhere in sysfs to the GPIO sysfs node. Drivers can
use this to provide the interface under their own device in sysfs with
a descriptive name.
Drivers can use gpiod_sysfs_set_active_low() to hide GPIO line polarity
differences between boards from user space. Polarity change can be done both
before and after gpiod_export(), and previously enabled poll(2) support for
either rising or falling edge will be reconfigured to follow this setting.