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gpio: move gpio_ensure_requested() into legacy C file
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gpio_ensure_requested() only makes sense when using the integer-based
GPIO API, so make sure it is called from there instead of the gpiod
API which we know cannot be called with a non-requested GPIO anyway.

The uses of gpio_ensure_requested() in the gpiod API were kind of
out-of-place anyway, so putting them in gpio-legacy.c helps clearing the
code.

Actually, considering the time this ensure_requested mechanism has been
around, maybe we should just turn this patch into "remove
gpio_ensure_requested()" if we know for sure that no user depend on it
anymore?

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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Alexandre Courbot authored and Linus Walleij committed Jul 23, 2014
1 parent d74be6d commit d82da79
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Showing 3 changed files with 113 additions and 137 deletions.
106 changes: 106 additions & 0 deletions drivers/gpio/gpiolib-legacy.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,64 @@

#include "gpiolib.h"

/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
* when setting direction, and otherwise illegal. Until board setup code
* and drivers use explicit requests everywhere (which won't happen when
* those calls have no teeth) we can't avoid autorequesting. This nag
* message should motivate switching to explicit requests... so should
* the weaker cleanup after faults, compared to gpio_request().
*
* NOTE: the autorequest mechanism is going away; at this point it's
* only "legal" in the sense that (old) code using it won't break yet,
* but instead only triggers a WARN() stack dump.
*/
static int gpio_ensure_requested(struct gpio_desc *desc)
{
struct gpio_chip *chip = desc->chip;
unsigned long flags;
bool request = false;
int err = 0;

spin_lock_irqsave(&gpio_lock, flags);

if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
"autorequest GPIO-%d\n", desc_to_gpio(desc))) {
if (!try_module_get(chip->owner)) {
gpiod_err(desc, "%s: module can't be gotten\n",
__func__);
clear_bit(FLAG_REQUESTED, &desc->flags);
/* lose */
err = -EIO;
goto end;
}
desc->label = "[auto]";
/* caller must chip->request() w/o spinlock */
if (chip->request)
request = true;
}

end:
spin_unlock_irqrestore(&gpio_lock, flags);

if (request) {
might_sleep_if(chip->can_sleep);
err = chip->request(chip, gpio_chip_hwgpio(desc));

if (err < 0) {
gpiod_dbg(desc, "%s: chip request fail, %d\n",
__func__, err);
spin_lock_irqsave(&gpio_lock, flags);

desc->label = NULL;
clear_bit(FLAG_REQUESTED, &desc->flags);

spin_unlock_irqrestore(&gpio_lock, flags);
}
}

return err;
}

void gpio_free(unsigned gpio)
{
gpiod_free(gpio_to_desc(gpio));
Expand Down Expand Up @@ -100,3 +158,51 @@ void gpio_free_array(const struct gpio *array, size_t num)
gpio_free((array++)->gpio);
}
EXPORT_SYMBOL_GPL(gpio_free_array);

int gpio_direction_input(unsigned gpio)
{
struct gpio_desc *desc = gpio_to_desc(gpio);
int err;

if (!desc)
return -EINVAL;

err = gpio_ensure_requested(desc);
if (err < 0)
return err;

return gpiod_direction_input(desc);
}
EXPORT_SYMBOL_GPL(gpio_direction_input);

int gpio_direction_output(unsigned gpio, int value)
{
struct gpio_desc *desc = gpio_to_desc(gpio);
int err;

if (!desc)
return -EINVAL;

err = gpio_ensure_requested(desc);
if (err < 0)
return err;

return gpiod_direction_output_raw(desc, value);
}
EXPORT_SYMBOL_GPL(gpio_direction_output);

int gpio_set_debounce(unsigned gpio, unsigned debounce)
{
struct gpio_desc *desc = gpio_to_desc(gpio);
int err;

if (!desc)
return -EINVAL;

err = gpio_ensure_requested(desc);
if (err < 0)
return err;

return gpiod_set_debounce(desc, debounce);
}
EXPORT_SYMBOL_GPL(gpio_set_debounce);
129 changes: 4 additions & 125 deletions drivers/gpio/gpiolib.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -95,39 +95,6 @@ int desc_to_gpio(const struct gpio_desc *desc)
EXPORT_SYMBOL_GPL(desc_to_gpio);


/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
* when setting direction, and otherwise illegal. Until board setup code
* and drivers use explicit requests everywhere (which won't happen when
* those calls have no teeth) we can't avoid autorequesting. This nag
* message should motivate switching to explicit requests... so should
* the weaker cleanup after faults, compared to gpio_request().
*
* NOTE: the autorequest mechanism is going away; at this point it's
* only "legal" in the sense that (old) code using it won't break yet,
* but instead only triggers a WARN() stack dump.
*/
static int gpio_ensure_requested(struct gpio_desc *desc)
{
const struct gpio_chip *chip = desc->chip;
const int gpio = desc_to_gpio(desc);

if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
"autorequest GPIO-%d\n", gpio)) {
if (!try_module_get(chip->owner)) {
gpiod_err(desc, "%s: module can't be gotten\n",
__func__);
clear_bit(FLAG_REQUESTED, &desc->flags);
/* lose */
return -EIO;
}
desc_set_label(desc, "[auto]");
/* caller must chip->request() w/o spinlock */
if (chip->request)
return 1;
}
return 0;
}

/**
* gpiod_to_chip - Return the GPIO chip to which a GPIO descriptor belongs
* @desc: descriptor to return the chip of
Expand Down Expand Up @@ -964,10 +931,8 @@ void gpiochip_free_own_desc(struct gpio_desc *desc)
*/
int gpiod_direction_input(struct gpio_desc *desc)
{
unsigned long flags;
struct gpio_chip *chip;
int status = -EINVAL;
int offset;

if (!desc || !desc->chip) {
pr_warn("%s: invalid GPIO\n", __func__);
Expand All @@ -982,52 +947,20 @@ int gpiod_direction_input(struct gpio_desc *desc)
return -EIO;
}

spin_lock_irqsave(&gpio_lock, flags);

status = gpio_ensure_requested(desc);
if (status < 0)
goto fail;

/* now we know the gpio is valid and chip won't vanish */

spin_unlock_irqrestore(&gpio_lock, flags);

might_sleep_if(chip->can_sleep);

offset = gpio_chip_hwgpio(desc);
if (status) {
status = chip->request(chip, offset);
if (status < 0) {
gpiod_dbg(desc, "%s: chip request fail, %d\n",
__func__, status);
/* and it's not available to anyone else ...
* gpio_request() is the fully clean solution.
*/
goto lose;
}
}

status = chip->direction_input(chip, offset);
status = chip->direction_input(chip, gpio_chip_hwgpio(desc));
if (status == 0)
clear_bit(FLAG_IS_OUT, &desc->flags);

trace_gpio_direction(desc_to_gpio(desc), 1, status);
lose:
return status;
fail:
spin_unlock_irqrestore(&gpio_lock, flags);
if (status)
gpiod_dbg(desc, "%s: status %d\n", __func__, status);

return status;
}
EXPORT_SYMBOL_GPL(gpiod_direction_input);

static int _gpiod_direction_output_raw(struct gpio_desc *desc, int value)
{
unsigned long flags;
struct gpio_chip *chip;
int status = -EINVAL;
int offset;

/* GPIOs used for IRQs shall not be set as output */
if (test_bit(FLAG_USED_AS_IRQ, &desc->flags)) {
Expand All @@ -1053,42 +986,11 @@ static int _gpiod_direction_output_raw(struct gpio_desc *desc, int value)
return -EIO;
}

spin_lock_irqsave(&gpio_lock, flags);

status = gpio_ensure_requested(desc);
if (status < 0)
goto fail;

/* now we know the gpio is valid and chip won't vanish */

spin_unlock_irqrestore(&gpio_lock, flags);

might_sleep_if(chip->can_sleep);

offset = gpio_chip_hwgpio(desc);
if (status) {
status = chip->request(chip, offset);
if (status < 0) {
gpiod_dbg(desc, "%s: chip request fail, %d\n",
__func__, status);
/* and it's not available to anyone else ...
* gpio_request() is the fully clean solution.
*/
goto lose;
}
}

status = chip->direction_output(chip, offset, value);
status = chip->direction_output(chip, gpio_chip_hwgpio(desc), value);
if (status == 0)
set_bit(FLAG_IS_OUT, &desc->flags);
trace_gpio_value(desc_to_gpio(desc), 0, value);
trace_gpio_direction(desc_to_gpio(desc), 0, status);
lose:
return status;
fail:
spin_unlock_irqrestore(&gpio_lock, flags);
if (status)
gpiod_dbg(desc, "%s: gpio status %d\n", __func__, status);
return status;
}

Expand Down Expand Up @@ -1147,10 +1049,7 @@ EXPORT_SYMBOL_GPL(gpiod_direction_output);
*/
int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
{
unsigned long flags;
struct gpio_chip *chip;
int status = -EINVAL;
int offset;

if (!desc || !desc->chip) {
pr_warn("%s: invalid GPIO\n", __func__);
Expand All @@ -1165,27 +1064,7 @@ int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
return -ENOTSUPP;
}

spin_lock_irqsave(&gpio_lock, flags);

status = gpio_ensure_requested(desc);
if (status < 0)
goto fail;

/* now we know the gpio is valid and chip won't vanish */

spin_unlock_irqrestore(&gpio_lock, flags);

might_sleep_if(chip->can_sleep);

offset = gpio_chip_hwgpio(desc);
return chip->set_debounce(chip, offset, debounce);

fail:
spin_unlock_irqrestore(&gpio_lock, flags);
if (status)
gpiod_dbg(desc, "%s: status %d\n", __func__, status);

return status;
return chip->set_debounce(chip, gpio_chip_hwgpio(desc), debounce);
}
EXPORT_SYMBOL_GPL(gpiod_set_debounce);

Expand Down
15 changes: 3 additions & 12 deletions include/asm-generic/gpio.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -63,19 +63,10 @@ static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
extern int gpio_request(unsigned gpio, const char *label);
extern void gpio_free(unsigned gpio);

static inline int gpio_direction_input(unsigned gpio)
{
return gpiod_direction_input(gpio_to_desc(gpio));
}
static inline int gpio_direction_output(unsigned gpio, int value)
{
return gpiod_direction_output_raw(gpio_to_desc(gpio), value);
}
extern int gpio_direction_input(unsigned gpio);
extern int gpio_direction_output(unsigned gpio, int value);

static inline int gpio_set_debounce(unsigned gpio, unsigned debounce)
{
return gpiod_set_debounce(gpio_to_desc(gpio), debounce);
}
extern int gpio_set_debounce(unsigned gpio, unsigned debounce);

static inline int gpio_get_value_cansleep(unsigned gpio)
{
Expand Down

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