diff options
| -rw-r--r-- | drivers/gpio/gpiolib.c | 52 | ||||
| -rw-r--r-- | include/linux/gpio/driver.h | 25 |
2 files changed, 61 insertions, 16 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 72065532c1c7..1edc830a1b51 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1509,8 +1509,8 @@ EXPORT_SYMBOL_GPL(gpiod_direction_input); static int _gpiod_direction_output_raw(struct gpio_desc *desc, int value) { - struct gpio_chip *chip; - int status = -EINVAL; + struct gpio_chip *gc = desc->gdev->chip; + int ret; /* GPIOs used for IRQs shall not be set as output */ if (test_bit(FLAG_USED_AS_IRQ, &desc->flags)) { @@ -1520,28 +1520,50 @@ static int _gpiod_direction_output_raw(struct gpio_desc *desc, int value) return -EIO; } - /* Open drain pin should not be driven to 1 */ - if (value && test_bit(FLAG_OPEN_DRAIN, &desc->flags)) - return gpiod_direction_input(desc); - - /* Open source pin should not be driven to 0 */ - if (!value && test_bit(FLAG_OPEN_SOURCE, &desc->flags)) - return gpiod_direction_input(desc); + if (test_bit(FLAG_OPEN_DRAIN, &desc->flags)) { + /* First see if we can enable open drain in hardware */ + if (gc->set_single_ended) { + ret = gc->set_single_ended(gc, gpio_chip_hwgpio(desc), + LINE_MODE_OPEN_DRAIN); + if (!ret) + goto set_output_value; + } + /* Emulate open drain by not actively driving the line high */ + if (value) + return gpiod_direction_input(desc); + } + else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags)) { + if (gc->set_single_ended) { + ret = gc->set_single_ended(gc, gpio_chip_hwgpio(desc), + LINE_MODE_OPEN_SOURCE); + if (!ret) + goto set_output_value; + } + /* Emulate open source by not actively driving the line low */ + if (!value) + return gpiod_direction_input(desc); + } else { + /* Make sure to disable open drain/source hardware, if any */ + if (gc->set_single_ended) + gc->set_single_ended(gc, + gpio_chip_hwgpio(desc), + LINE_MODE_PUSH_PULL); + } - chip = desc->gdev->chip; - if (!chip->set || !chip->direction_output) { +set_output_value: + if (!gc->set || !gc->direction_output) { gpiod_warn(desc, "%s: missing set() or direction_output() operations\n", __func__); return -EIO; } - status = chip->direction_output(chip, gpio_chip_hwgpio(desc), value); - if (status == 0) + ret = gc->direction_output(gc, gpio_chip_hwgpio(desc), value); + if (!ret) 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); - return status; + trace_gpio_direction(desc_to_gpio(desc), 0, ret); + return ret; } /** diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index bee976f82788..50882e09289b 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -20,6 +20,18 @@ struct gpio_device; #ifdef CONFIG_GPIOLIB /** + * enum single_ended_mode - mode for single ended operation + * @LINE_MODE_PUSH_PULL: normal mode for a GPIO line, drive actively high/low + * @LINE_MODE_OPEN_DRAIN: set line to be open drain + * @LINE_MODE_OPEN_SOURCE: set line to be open source + */ +enum single_ended_mode { + LINE_MODE_PUSH_PULL, + LINE_MODE_OPEN_DRAIN, + LINE_MODE_OPEN_SOURCE, +}; + +/** * struct gpio_chip - abstract a GPIO controller * @label: a functional name for the GPIO device, such as a part * number or the name of the SoC IP-block implementing it. @@ -38,7 +50,15 @@ struct gpio_device; * @set: assigns output value for signal "offset" * @set_multiple: assigns output values for multiple signals defined by "mask" * @set_debounce: optional hook for setting debounce time for specified gpio in - * interrupt triggered gpio chips + * interrupt triggered gpio chips + * @set_single_ended: optional hook for setting a line as open drain, open + * source, or non-single ended (restore from open drain/source to normal + * push-pull mode) this should be implemented if the hardware supports + * open drain or open source settings. The GPIOlib will otherwise try + * to emulate open drain/source by not actively driving lines high/low + * if a consumer request this. The driver may return -ENOTSUPP if e.g. + * it supports just open drain but not open source and is called + * with LINE_MODE_OPEN_SOURCE as mode argument. * @to_irq: optional hook supporting non-static gpio_to_irq() mappings; * implementation may not sleep * @dbg_show: optional routine to show contents in debugfs; default code @@ -130,6 +150,9 @@ struct gpio_chip { int (*set_debounce)(struct gpio_chip *chip, unsigned offset, unsigned debounce); + int (*set_single_ended)(struct gpio_chip *chip, + unsigned offset, + enum single_ended_mode mode); int (*to_irq)(struct gpio_chip *chip, unsigned offset); |