[RFC PATCH 2/5] gpio: gpiolib: Add OF support for maintaining GPIO values on reset

Andrew Jeffery
2017-10-20T03:37:24Z

Add flags and the associated flag mappings between interfaces to enable
GPIO reset tolerance to be specified via devicetree.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
---
drivers/gpio/gpiolib-of.c | 2 ++
drivers/gpio/gpiolib.c | 5 +++++
include/dt-bindings/gpio/gpio.h | 4 ++++
include/linux/of_gpio.h | 1 +
4 files changed, 12 insertions(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index e0d59e61b52f..4a268ba52998 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -155,6 +155,8 @@ struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,

if (of_flags & OF_GPIO_SLEEP_MAY_LOSE_VALUE)
*flags |= GPIO_SLEEP_MAY_LOSE_VALUE;
+ if (of_flags & OF_GPIO_RESET_TOLERANT)
+ *flags |= GPIO_RESET_TOLERANT;

return desc;
}
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d9dc7e588699..6b4c5df10e84 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -3434,6 +3434,7 @@ struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
bool active_low = false;
bool single_ended = false;
bool open_drain = false;
+ bool reset_tolerant = false;
int ret;

if (!fwnode)
@@ -3448,6 +3449,7 @@ struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
active_low = flags & OF_GPIO_ACTIVE_LOW;
single_ended = flags & OF_GPIO_SINGLE_ENDED;
open_drain = flags & OF_GPIO_OPEN_DRAIN;
+ reset_tolerant = flags & OF_GPIO_RESET_TOLERANT;
}
} else if (is_acpi_node(fwnode)) {
struct acpi_gpio_info info;
@@ -3478,6 +3480,9 @@ struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
lflags |= GPIO_OPEN_SOURCE;
}

+ if (reset_tolerant)
+ lflags |= GPIO_RESET_TOLERANT;
+
ret = gpiod_configure_flags(desc, propname, lflags, dflags);
if (ret < 0) {
gpiod_put(desc);
diff --git a/include/dt-bindings/gpio/gpio.h b/include/dt-bindings/gpio/gpio.h
index 70de5b7a6c9b..01c75d9e308e 100644
--- a/include/dt-bindings/gpio/gpio.h
+++ b/include/dt-bindings/gpio/gpio.h
@@ -32,4 +32,8 @@
#define GPIO_SLEEP_MAINTAIN_VALUE 0
#define GPIO_SLEEP_MAY_LOSE_VALUE 8

+/* Bit 4 express GPIO persistence on reset */
+#define GPIO_RESET_INTOLERANT 0
+#define GPIO_RESET_TOLERANT 16
+
#endif
diff --git a/include/linux/of_gpio.h b/include/linux/of_gpio.h
index 1fe205582111..9b34737706a7 100644
--- a/include/linux/of_gpio.h
+++ b/include/linux/of_gpio.h
@@ -32,6 +32,7 @@ enum of_gpio_flags {
OF_GPIO_SINGLE_ENDED = 0x2,
OF_GPIO_OPEN_DRAIN = 0x4,
OF_GPIO_SLEEP_MAY_LOSE_VALUE = 0x8,
+ OF_GPIO_RESET_TOLERANT = 0x16,
};

#ifdef CONFIG_OF_GPIO
--
2.11.0