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gpio: Hide valid_mask from direct assignments

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The valid_mask member of the struct gpio_chip is unconditionally written
by the GPIO core at driver registration. Current documentation does not
mention this but just says the valid_mask is used if it's not NULL. This
lured me to try populating it directly in the GPIO driver probe instead
of using the init_valid_mask() callback. It took some retries with
different bitmaps and eventually a bit of code-reading to understand why
the valid_mask was not obeyed. I could've avoided this trial and error if
the valid_mask was hidden in the struct gpio_device instead of being a
visible member of the struct gpio_chip.

Help the next developer who decides to directly populate the valid_mask
in struct gpio_chip by hiding the valid_mask in struct gpio_device and
keep it internal to the GPIO core.

Suggested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/4547ca90d910d60cab3d56d864d59ddde47a5e93.1741180097.git.mazziesaccount@gmail.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
This commit is contained in:
Matti Vaittinen 2025-03-05 15:13:25 +02:00 • committed by Bartosz Golaszewski
parent 43b665c961
commit 8015443e24
3 changed files with 11 additions and 16 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

16
drivers/gpio/gpiolib.c
View file

@ -672,7 +672,7 @@ static int gpiochip_apply_reserved_ranges(struct gpio_chip *gc)
if (start >= gc->ngpio || start + count > gc->ngpio)
continue;
bitmap_clear(gc->valid_mask, start, count);
bitmap_clear(gc->gpiodev->valid_mask, start, count);
}
kfree(ranges);
@ -686,8 +686,8 @@ static int gpiochip_init_valid_mask(struct gpio_chip *gc)
if (!(gpiochip_count_reserved_ranges(gc) || gc->init_valid_mask))
return 0;
gc->valid_mask = gpiochip_allocate_mask(gc);
if (!gc->valid_mask)
gc->gpiodev->valid_mask = gpiochip_allocate_mask(gc);
if (!gc->gpiodev->valid_mask)
return -ENOMEM;
ret = gpiochip_apply_reserved_ranges(gc);
@ -696,7 +696,7 @@ static int gpiochip_init_valid_mask(struct gpio_chip *gc)
if (gc->init_valid_mask)
return gc->init_valid_mask(gc,
gc->valid_mask,
gc->gpiodev->valid_mask,
gc->ngpio);
return 0;
@ -704,7 +704,7 @@ static int gpiochip_init_valid_mask(struct gpio_chip *gc)
static void gpiochip_free_valid_mask(struct gpio_chip *gc)
{
gpiochip_free_mask(&gc->valid_mask);
gpiochip_free_mask(&gc->gpiodev->valid_mask);
}
static int gpiochip_add_pin_ranges(struct gpio_chip *gc)
@ -735,7 +735,7 @@ static int gpiochip_add_pin_ranges(struct gpio_chip *gc)
*/
const unsigned long *gpiochip_query_valid_mask(const struct gpio_chip *gc)
{
return gc->valid_mask;
return gc->gpiodev->valid_mask;
}
EXPORT_SYMBOL_GPL(gpiochip_query_valid_mask);
@ -743,9 +743,9 @@ bool gpiochip_line_is_valid(const struct gpio_chip *gc,
unsigned int offset)
{
/* No mask means all valid */
if (likely(!gc->valid_mask))
if (likely(!gc->gpiodev->valid_mask))
return true;
return test_bit(offset, gc->valid_mask);
return test_bit(offset, gc->gpiodev->valid_mask);
}
EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);

3
drivers/gpio/gpiolib.h
View file

@ -32,6 +32,8 @@
* @chip: pointer to the corresponding gpiochip, holding static
* data for this device
* @descs: array of ngpio descriptors.
* @valid_mask: If not %NULL, holds bitmask of GPIOs which are valid to be
* used from the chip.
* @desc_srcu: ensures consistent state of GPIO descriptors exposed to users
* @ngpio: the number of GPIO lines on this GPIO device, equal to the size
* of the @descs array.
@ -65,6 +67,7 @@ struct gpio_device {
struct module *owner;
struct gpio_chip __rcu *chip;
struct gpio_desc *descs;
unsigned long *valid_mask;
struct srcu_struct desc_srcu;
unsigned int base;
u16 ngpio;

8
include/linux/gpio/driver.h
View file

@ -514,14 +514,6 @@ struct gpio_chip {
struct gpio_irq_chip irq;
#endif /* CONFIG_GPIOLIB_IRQCHIP */
/**
* @valid_mask:
*
* If not %NULL, holds bitmask of GPIOs which are valid to be used
* from the chip.
*/
unsigned long *valid_mask;
#if defined(CONFIG_OF_GPIO)
/*
* If CONFIG_OF_GPIO is enabled, then all GPIO controllers described in