diff options
Diffstat (limited to 'include/linux/gpio')
| -rw-r--r-- | include/linux/gpio/driver.h | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index d8dcd0e44cab..f6b95734073f 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -178,9 +178,13 @@ static inline struct gpio_irq_chip *to_gpio_irq_chip(struct irq_chip *chip) * @free: optional hook for chip-specific deactivation, such as * disabling module power and clock; may sleep * @get_direction: returns direction for signal "offset", 0=out, 1=in, - * (same as GPIOF_DIR_XXX), or negative error + * (same as GPIOF_DIR_XXX), or negative error. + * It is recommended to always implement this function, even on + * input-only or output-only gpio chips. * @direction_input: configures signal "offset" as input, or returns error + * This can be omitted on input-only or output-only gpio chips. * @direction_output: configures signal "offset" as output, or returns error + * This can be omitted on input-only or output-only gpio chips. * @get: returns value for signal "offset", 0=low, 1=high, or negative error * @get_multiple: reads values for multiple signals defined by "mask" and * stores them in "bits", returns 0 on success or negative error |