* [PATCH v4 1/2] dt-bindings: GPIO: Add gpio-initval
2015-12-04 13:06 [PATCH v4 0/2] gpiolib: Initializing GPIOs using DT property gpio-initval Markus Pargmann
@ 2015-12-04 13:06 ` Markus Pargmann
2015-12-04 16:39 ` Philipp Zabel
2015-12-04 13:06 ` [PATCH v4 2/2] gpiolib: Add GPIO initialization Markus Pargmann
1 sibling, 1 reply; 4+ messages in thread
From: Markus Pargmann @ 2015-12-04 13:06 UTC (permalink / raw)
To: Linus Walleij
Cc: Alexandre Courbot, devicetree, linux-gpio, kernel,
Markus Pargmann
Add a binding for GPIO initialization.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
---
Documentation/devicetree/bindings/gpio/gpio.txt | 34 ++++++++++++++++---------
1 file changed, 22 insertions(+), 12 deletions(-)
diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
index 069cdf6f9dac..d11abfa13add 100644
--- a/Documentation/devicetree/bindings/gpio/gpio.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio.txt
@@ -155,29 +155,39 @@ gpio-controller@00000000 {
ngpios = <18>;
}
-The GPIO chip may contain GPIO hog definitions. GPIO hogging is a mechanism
-providing automatic GPIO request and configuration as part of the
-gpio-controller's driver probe function.
+The GPIO chip may contain GPIO definitions. These define properties for single
+GPIOs of this controller.
-Each GPIO hog definition is represented as a child node of the GPIO controller.
+There are two types of GPIO definitions:
+
+- GPIO hogging is a mechanism providing automatic GPIO request and
+ configuration as part of the gpio-controller driver's probe function. The
+ GPIO is held until the gpio-controller is removed.
+- GPIO initialization provides an automatic initialization to known save
+ values. The GPIO can be used normally afterwards.
+
+Each GPIO definition is represented as a child node of the GPIO controller.
Required properties:
-- gpio-hog: A property specifying that this child node represent a GPIO hog.
- gpios: Store the GPIO information (id, flags, ...). Shall contain the
number of cells specified in its parent node (GPIO controller
node).
-Only one of the following properties scanned in the order shown below.
-This means that when multiple properties are present they will be searched
-in the order presented below and the first match is taken as the intended
-configuration.
+
+Optional properties:
+- line-name: The GPIO label name. If not present the node name is used.
+
+ The following two options are mutually exclusive. One of them should be
+ specified, but not both:
+- gpio-hog: A property specifying that this child node represent a GPIO hog.
+- gpio-initval: This GPIO should be initialized to the specified configuration.
+
+ The following three options are mutually exclusive. They change the setting of
+ the GPIO pin. One of them should be specified:
- input: A property specifying to set the GPIO direction as input.
- output-low A property specifying to set the GPIO direction as output with
the value low.
- output-high A property specifying to set the GPIO direction as output with
the value high.
-Optional properties:
-- line-name: The GPIO label name. If not present the node name is used.
-
Example of two SOC GPIO banks defined as gpio-controller nodes:
qe_pio_a: gpio-controller@1400 {
--
2.6.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v4 2/2] gpiolib: Add GPIO initialization
2015-12-04 13:06 [PATCH v4 0/2] gpiolib: Initializing GPIOs using DT property gpio-initval Markus Pargmann
2015-12-04 13:06 ` [PATCH v4 1/2] dt-bindings: GPIO: Add gpio-initval Markus Pargmann
@ 2015-12-04 13:06 ` Markus Pargmann
1 sibling, 0 replies; 4+ messages in thread
From: Markus Pargmann @ 2015-12-04 13:06 UTC (permalink / raw)
To: Linus Walleij
Cc: Alexandre Courbot, devicetree, linux-gpio, kernel,
Markus Pargmann
This functions adds a way to initialize a GPIO without hogging it.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
---
drivers/gpio/gpiolib-of.c | 13 ++++++++-----
drivers/gpio/gpiolib.c | 26 ++++++++++++++++++++++++++
drivers/gpio/gpiolib.h | 2 ++
3 files changed, 36 insertions(+), 5 deletions(-)
diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 5fe34a9df3e6..48cdc22eabf2 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -211,15 +211,18 @@ static void of_gpiochip_scan_gpios(struct gpio_chip *chip)
enum gpiod_flags dflags;
for_each_child_of_node(chip->of_node, np) {
- if (!of_property_read_bool(np, "gpio-hog"))
- continue;
desc = of_parse_own_gpio(np, &name, &lflags, &dflags);
- if (IS_ERR(desc))
+ if (IS_ERR(desc) || !dflags)
continue;
- if (gpiod_hog(desc, name, lflags, dflags))
- continue;
+ if (of_property_read_bool(np, "gpio-hog"))
+ gpiod_hog(desc, name, lflags, dflags);
+ else if (of_property_read_bool(np, "gpio-initval"))
+ gpiod_initialize(desc, lflags, dflags);
+ else
+ dev_dbg(chip->dev, "GPIO line %d (%s): neither gpio-hog nor gpio-initval found.\n",
+ desc_to_gpio(desc), np->name);
}
}
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index a18f00fc1bb8..10e16b3f0667 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2329,6 +2329,32 @@ static void gpiochip_free_hogs(struct gpio_chip *chip)
}
/**
+ * gpiod_initialize - Initialize a GPIO with a given value
+ * @desc: gpio whose value will be assigned
+ * @lflags: gpio_lookup_flags - returned from of_find_gpio() or
+ * of_get_gpio_hog()
+ * @dflags: gpiod_flags - optional GPIO initialization flags
+ *
+ * This is used to initialize GPIOs that were defined in DT
+ */
+int gpiod_initialize(struct gpio_desc *desc, unsigned long lflags,
+ enum gpiod_flags dflags)
+{
+ int status;
+
+ gpiod_parse_flags(desc, lflags);
+
+ status = gpiod_configure_flags(desc, NULL, dflags);
+ if (status < 0) {
+ pr_err("initial setup of GPIO (chip %s, offset %d) failed\n",
+ gpiod_to_chip(desc)->label, gpio_chip_hwgpio(desc));
+ return status;
+ }
+
+ return 0;
+}
+
+/**
* gpiod_get_array - obtain multiple GPIOs from a multi-index GPIO function
* @dev: GPIO consumer, can be NULL for system-global GPIOs
* @con_id: function within the GPIO consumer
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 98ab08c0aa2d..4abf53a5e651 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -107,6 +107,8 @@ int gpiod_request(struct gpio_desc *desc, const char *label);
void gpiod_free(struct gpio_desc *desc);
int gpiod_hog(struct gpio_desc *desc, const char *name,
unsigned long lflags, enum gpiod_flags dflags);
+int gpiod_initialize(struct gpio_desc *desc, unsigned long lflags,
+ enum gpiod_flags dflags);
/*
* Return the GPIO number of the passed descriptor relative to its chip
--
2.6.2
^ permalink raw reply related [flat|nested] 4+ messages in thread