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gpio: expose pull-up/pull-down line flags to userspace

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Add pull-up/pull-down flags to the gpio line get and
set ioctl() calls.  Use cases include a push button
that does not have an external resistor.

Addition use cases described by Limor Fried (ladyada) of
Adafruit in this PR for Adafruit_Blinka Python lib:
https://github.com/adafruit/Adafruit_Blinka/pull/59

Signed-off-by: Drew Fustini <drew@pdp7.com>
[Kent: added BIAS to GPIO flag names and restrict application to input
lines]
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
This commit is contained in:
Drew Fustini 2019-11-05 10:04:23 +08:00 committed by Bartosz Golaszewski
parent f932a68695
commit 9225d5169d
2 changed files with 22 additions and 0 deletions
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18
drivers/gpio/gpiolib.c
View File

@ -422,6 +422,8 @@ struct linehandle_state {
(GPIOHANDLE_REQUEST_INPUT | \
GPIOHANDLE_REQUEST_OUTPUT | \
GPIOHANDLE_REQUEST_ACTIVE_LOW | \
GPIOHANDLE_REQUEST_BIAS_PULL_UP | \
GPIOHANDLE_REQUEST_BIAS_PULL_DOWN | \
GPIOHANDLE_REQUEST_OPEN_DRAIN | \
GPIOHANDLE_REQUEST_OPEN_SOURCE)
@ -553,6 +555,12 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
(lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)))
return -EINVAL;
/* PULL_UP and PULL_DOWN flags only make sense for input mode. */
if (!(lflags & GPIOHANDLE_REQUEST_INPUT) &&
((lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP) ||
(lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN)))
return -EINVAL;
lh = kzalloc(sizeof(*lh), GFP_KERNEL);
if (!lh)
return -ENOMEM;
@ -593,6 +601,10 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
set_bit(FLAG_OPEN_DRAIN, &desc->flags);
if (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)
set_bit(FLAG_OPEN_SOURCE, &desc->flags);
if (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN)
set_bit(FLAG_PULL_DOWN, &desc->flags);
if (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)
set_bit(FLAG_PULL_UP, &desc->flags);
ret = gpiod_set_transitory(desc, false);
if (ret < 0)
@ -1092,6 +1104,10 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
lineinfo.flags |= (GPIOLINE_FLAG_OPEN_SOURCE |
GPIOLINE_FLAG_IS_OUT);
if (test_bit(FLAG_PULL_DOWN, &desc->flags))
lineinfo.flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
if (test_bit(FLAG_PULL_UP, &desc->flags))
lineinfo.flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
return -EFAULT;
@ -2785,6 +2801,8 @@ static bool gpiod_free_commit(struct gpio_desc *desc)
clear_bit(FLAG_REQUESTED, &desc->flags);
clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
clear_bit(FLAG_PULL_UP, &desc->flags);
clear_bit(FLAG_PULL_DOWN, &desc->flags);
clear_bit(FLAG_IS_HOGGED, &desc->flags);
ret = true;
}

4
include/uapi/linux/gpio.h
View File

@ -33,6 +33,8 @@ struct gpiochip_info {
#define GPIOLINE_FLAG_ACTIVE_LOW (1UL << 2)
#define GPIOLINE_FLAG_OPEN_DRAIN (1UL << 3)
#define GPIOLINE_FLAG_OPEN_SOURCE (1UL << 4)
#define GPIOLINE_FLAG_BIAS_PULL_UP (1UL << 5)
#define GPIOLINE_FLAG_BIAS_PULL_DOWN (1UL << 6)
/**
* struct gpioline_info - Information about a certain GPIO line
@ -62,6 +64,8 @@ struct gpioline_info {
#define GPIOHANDLE_REQUEST_ACTIVE_LOW (1UL << 2)
#define GPIOHANDLE_REQUEST_OPEN_DRAIN (1UL << 3)
#define GPIOHANDLE_REQUEST_OPEN_SOURCE (1UL << 4)
#define GPIOHANDLE_REQUEST_BIAS_PULL_UP (1UL << 5)
#define GPIOHANDLE_REQUEST_BIAS_PULL_DOWN (1UL << 6)
/**
* struct gpiohandle_request - Information about a GPIO handle request