Hi Masahiro,
On 4 July 2015 at 22:55, Masahiro Yamada yamada.masahiro@socionext.com wrote:
Hi Simon,
2015-07-03 9:15 GMT+09:00 Simon Glass sjg@chromium.org:
At present the driver model GPIO API does not support pull-up/pull-down on input GPIOs. This is required in some cases.
Add this feature to the API with two new methods that drivers can optionally implement.
Signed-off-by: Simon Glass sjg@chromium.org
drivers/gpio/gpio-uclass.c | 31 +++++++++++++++++++++++++++++++ include/asm-generic/gpio.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 77 insertions(+)
diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c index 4efda31..c4ba580 100644 --- a/drivers/gpio/gpio-uclass.c +++ b/drivers/gpio/gpio-uclass.c @@ -374,6 +374,37 @@ int dm_gpio_set_dir(struct gpio_desc *desc) return dm_gpio_set_dir_flags(desc, desc->flags); }
+int dm_gpio_set_pull(struct gpio_desc *desc, enum gpio_pull pull) +{
struct dm_gpio_ops *ops = gpio_get_ops(desc->dev);int ret;ret = check_reserved(desc, "set_pull");if (ret)return ret;if (!ops->set_pull)return -ENOSYS;return ops->set_pull(desc->dev, desc->offset, pull);+}
+int dm_gpio_get_pull(struct gpio_desc *desc, unsigned offset) +{
struct dm_gpio_ops *ops = gpio_get_ops(desc->dev);int ret;ret = check_reserved(desc, "get_pull");if (ret)return ret;if (!ops->get_pull)return -ENOSYS;return ops->get_pull(desc->dev, desc->offset);+}
/**
- gpio_get_value() - [COMPAT] Sample GPIO pin and return it's value
- gpio: GPIO number
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index 0af599f..db5504f 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -126,6 +126,13 @@ struct gpio_desc { */ };
+/* GPIO pull directions (used for input lines) */ +enum gpio_pull {
GPIO_PULL_NONE,GPIO_PULL_DOWN,GPIO_PULL_UP,+};
/**
- dm_gpio_is_valid() - Check if a GPIO is valid
@@ -276,6 +283,26 @@ struct dm_gpio_ops { */ int (*xlate)(struct udevice *dev, struct gpio_desc *desc, struct fdtdec_phandle_args *args);
/*** set_pull() - set pull direction** @dev: Device to adjust* @offset: GPIO offset within device* @pull: New pull direction* @return 0 if OK, -ve on error*/int (*set_pull)(struct udevice *dev, unsigned offset,enum gpio_pull pull);/*** get_pull() - get pull direction** @dev: Device to check* @offset: GPIO offset within device* @return current pull direction or -ve on error*/int (*get_pull)(struct udevice *dev, unsigned offset);};
Do you want to control pull-up/down only for GPIOs? Pin-biasing makes sense for dedicated functions as well as GPIOs. At least, I am inclined to enable pull-up registers for SCL/SDA (I2C) pins on my boards.
As far as I know, in Linux, such stuff is handled in pinctrl drivers. I see no .set_pull() callback in struct gpio_chip in Linux.
As far as I see your pinctrl implementation, (http://patchwork.ozlabs.org/patch/487801/) it looks like "pinctrl = pinmuxing" in U-Boot, whereas "pinctrl = pinmuxing + pin-configuration" in Linux.
That's true, but still it is useful to be able to set pull direction for GPIOs. I did sent a pinctrl uclass patch recently. Perhaps we could add a new function there. But how would we identify which pin to change? The GPIO pin name is convenient but may not be available in the pinctrl driver, since this adds a lot of size to the device tree.
Regards, Simon