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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>
hifive-unleashed-5.1
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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.

8
Documentation/zh_CN/gpio.txt
View File

@ -638,9 +638,6 @@ GPIO 控制器的路径类似 /sys/class/gpio/gpiochip42/ (对于从#42 GPIO
int gpio_export_link(struct device *dev, const char *name,
unsigned gpio)
/* 改变 sysfs 中的一个 GPIO 节点的极性 */
int gpio_sysfs_set_active_low(unsigned gpio, int value);
在一个内核驱动申请一个 GPIO 之后，它可以通过 gpio_export()使其在 sysfs
接口中可见。该驱动可以控制信号方向是否可修改。这有助于防止用户空间代码无意间
破坏重要的系统状态。
@ -651,8 +648,3 @@ GPIO 控制器的路径类似 /sys/class/gpio/gpiochip42/ (对于从#42 GPIO
在 GPIO 被导出之后，gpio_export_link()允许在 sysfs 文件系统的任何地方
创建一个到这个 GPIO sysfs 节点的符号链接。这样驱动就可以通过一个描述性的
名字，在 sysfs 中他们所拥有的设备下提供一个(到这个 GPIO sysfs 节点的)接口。
驱动可以使用 gpio_sysfs_set_active_low() 来在用户空间隐藏电路板之间
GPIO 线的极性差异。这个仅对 sysfs 接口起作用。极性的改变可以在 gpio_export()
前后进行,且之前使能的轮询操作(poll(2))支持(上升或下降沿)将会被重新配置来遵循
这个设置。

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

5
include/asm-generic/gpio.h
View File

@ -128,11 +128,6 @@ static inline int gpio_export_link(struct device *dev, const char *name,
return gpiod_export_link(dev, name, gpio_to_desc(gpio));
}
static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
{
return gpiod_sysfs_set_active_low(gpio_to_desc(gpio), value);
}
static inline void gpio_unexport(unsigned gpio)
{
gpiod_unexport(gpio_to_desc(gpio));

7
include/linux/gpio.h
View File

@ -196,13 +196,6 @@ static inline int gpio_export_link(struct device *dev, const char *name,
return -EINVAL;
}
static inline int gpio_sysfs_set_active_low(unsigned gpio, int value)
{
/* GPIO can never have been requested */
WARN_ON(1);
return -EINVAL;
}
static inline void gpio_unexport(unsigned gpio)
{
/* GPIO can never have been exported */

6
include/linux/gpio/consumer.h
View File

@ -449,7 +449,6 @@ static inline int desc_to_gpio(const struct gpio_desc *desc)
int gpiod_export(struct gpio_desc *desc, bool direction_may_change);
int gpiod_export_link(struct device *dev, const char *name,
struct gpio_desc *desc);
int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value);
void gpiod_unexport(struct gpio_desc *desc);
#else /* CONFIG_GPIOLIB && CONFIG_GPIO_SYSFS */
@ -466,11 +465,6 @@ static inline int gpiod_export_link(struct device *dev, const char *name,
return -ENOSYS;
}
static inline int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
{
return -ENOSYS;
}
static inline void gpiod_unexport(struct gpio_desc *desc)
{
}