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SubjectRe: [PATCH] gpio: introduce gpio_request_one() and friends
On Wed, Jan 13, 2010 at 4:29 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Wed, 13 Jan 2010 16:23:35 +0800 Eric Miao <eric.y.miao@gmail.com> wrote:
>
>> Attached is the patch against Documentation/gpio.txt
>
> Thanks.
>
> I was thinking kerneldoc in the .c file actually - most/all of the
> other interface functions in gpiolib.c seem to be done that way.
>

OK, updated as follows (I've also make this an attached patch in
case gmail wraps my line again):

commit db30b9c15be3ee3ddcd914aadecfc8815c1a0170
Author: Eric Miao <eric.y.miao@gmail.com>
Date: Fri Jan 8 12:16:28 2010 +0800

gpio: introduce gpio_request_one() and friends

gpio_request() without initial configuration of the GPIO is normally
useless, introduce gpio_request_one() together with GPIOF_ flags for
input/output direction and initial output level.

gpio_{request,free}_array() for multiple GPIOs.

Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>

diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index 1866c27..c2c6e9b 100644
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -253,6 +253,70 @@ pin setup (e.g. controlling which pin the GPIO
uses, pullup/pulldown).
Also note that it's your responsibility to have stopped using a GPIO
before you free it.

+Considering in most cases GPIOs are actually configured right after they
+are claimed, three additional calls are defined:
+
+ /* request a single GPIO, with initial configuration specified by
+ * 'flags', identical to gpio_request() wrt other arguments and
+ * return value
+ */
+ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
+
+ /* request multiple GPIOs in a single call
+ */
+ int gpio_request_array(struct gpio *array, size_t num);
+
+ /* release multiple GPIOs in a single call
+ */
+ void gpio_free_array(struct gpio *array, size_t num);
+
+where 'flags' is currently defined to specify the following properties:
+
+ * GPIOF_DIR_IN - to configure direction as input
+ * GPIOF_DIR_OUT - to configure direction as output
+
+ * GPIOF_INIT_LOW - as output, set initial level to LOW
+ * GPIOF_INIT_HIGH - as output, set initial level to HIGH
+
+since GPIOF_INIT_* are only valid when configured as output, so group valid
+combinations as:
+
+ * GPIOF_IN - configure as input
+ * GPIOF_OUT_INIT_LOW - configured as output, initial level LOW
+ * GPIOF_OUT_INIT_HIGH - configured as output, initial level HIGH
+
+In the future, these flags can be extended to support more properties such
+as open-drain status.
+
+Further more, to ease the claim/release of multiple GPIOs, 'struct gpio' is
+introduced to encapsulate all three fields as:
+
+ struct gpio {
+ unsigned gpio;
+ unsigned long flags;
+ const char *label;
+ };
+
+A typical example of usage:
+
+ static struct gpio leds_gpios[] = {
+ { 32, GPIOF_OUT_INIT_HIGH, "Power LED" }, /* default to ON */
+ { 33, GPIOF_OUT_INIT_LOW, "Green LED" }, /* default to OFF */
+ { 34, GPIOF_OUT_INIT_LOW, "Red LED" }, /* default to OFF */
+ { 35, GPIOF_OUT_INIT_LOW, "Blue LED" }, /* default to OFF */
+ { ... },
+ };
+
+ err = gpio_request_one(31, GPIOF_IN, "Reset Button");
+ if (err)
+ ...
+
+ err = gpio_request_array(leds_gpios, ARRAY_SIZE(leds_gpios));
+ if (err)
+ ...
+
+ gpio_free_array(leds_gpios, ARRAY_SIZE(leds_gpios));
+

GPIOs mapped to IRQs
--------------------
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index a25ad28..0a81a1e 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1239,6 +1239,64 @@ void gpio_free(unsigned gpio)
}
EXPORT_SYMBOL_GPL(gpio_free);

+/**
+ * gpio_request_one - request a single GPIO with initial configuration
+ * @gpio: the GPIO number
+ * @flags: GPIO configuration as specified by GPIOF_*
+ * @label: a literal description string of this GPIO
+ */
+int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
+{
+ int err;
+
+ err = gpio_request(gpio, label);
+ if (err)
+ return err;
+
+ if (flags & GPIOF_DIR_IN)
+ err = gpio_direction_input(gpio);
+ else
+ err = gpio_direction_output(gpio,
+ (flags & GPIOF_INIT_HIGH) ? 1 : 0);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(gpio_request_one);
+
+/**
+ * gpio_request_array - request multiple GPIOs in a single call
+ * @array: array of the 'struct gpio'
+ * @num: how many GPIOs in the array
+ */
+int gpio_request_array(struct gpio *array, size_t num)
+{
+ int i, err;
+
+ for (i = 0; i < num; i++, array++) {
+ err = gpio_request_one(array->gpio, array->flags, array->label);
+ if (err)
+ goto err_free;
+ }
+ return 0;
+
+err_free:
+ while (i--)
+ gpio_free((--array)->gpio);
+ return err;
+}
+EXPORT_SYMBOL_GPL(gpio_request_array);
+
+/**
+ * gpio_free_array - release multiple GPIOs in a single call
+ * @array: array of the 'struct gpio'
+ * @num: how many GPIOs in the array
+ */
+void gpio_free_array(struct gpio *array, size_t num)
+{
+ while (num--)
+ gpio_free((array++)->gpio);
+}
+EXPORT_SYMBOL_GPL(gpio_free_array);

/**
* gpiochip_is_requested - return string iff signal was requested
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 485eeb6..979c6a5 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -136,6 +136,32 @@ extern int __gpio_cansleep(unsigned gpio);

extern int __gpio_to_irq(unsigned gpio);

+#define GPIOF_DIR_OUT (0 << 0)
+#define GPIOF_DIR_IN (1 << 0)
+
+#define GPIOF_INIT_LOW (0 << 1)
+#define GPIOF_INIT_HIGH (1 << 1)
+
+#define GPIOF_IN (GPIOF_DIR_IN)
+#define GPIOF_OUT_INIT_LOW (GPIOF_DIR_OUT | GPIOF_INIT_LOW)
+#define GPIOF_OUT_INIT_HIGH (GPIOF_DIR_OUT | GPIOF_INIT_HIGH)
+
+/**
+ * struct gpio - a structure describing a GPIO with configuration
+ * @gpio: the GPIO number
+ * @flags: GPIO configuration as specified by GPIOF_*
+ * @label: a literal description string of this GPIO
+ */
+struct gpio {
+ unsigned gpio;
+ unsigned long flags;
+ const char *label;
+};
+
+extern int gpio_request_one(unsigned gpio, unsigned long flags, const
char *label);
+extern int gpio_request_array(struct gpio *array, size_t num);
+extern void gpio_free_array(struct gpio *array, size_t num);
+
#ifdef CONFIG_GPIO_SYSFS

/*From db30b9c15be3ee3ddcd914aadecfc8815c1a0170 Mon Sep 17 00:00:00 2001
From: Eric Miao <eric.y.miao@gmail.com>
Date: Fri, 8 Jan 2010 12:16:28 +0800
Subject: [PATCH] gpio: introduce gpio_request_one() and friends

gpio_request() without initial configuration of the GPIO is normally
useless, introduce gpio_request_one() together with GPIOF_ flags for
input/output direction and initial output level.

gpio_{request,free}_array() for multiple GPIOs.

Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
---
Documentation/gpio.txt | 64 ++++++++++++++++++++++++++++++++++++++++++++
drivers/gpio/gpiolib.c | 58 +++++++++++++++++++++++++++++++++++++++
include/asm-generic/gpio.h | 26 ++++++++++++++++++
3 files changed, 148 insertions(+), 0 deletions(-)

diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index 1866c27..c2c6e9b 100644
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -253,6 +253,70 @@ pin setup (e.g. controlling which pin the GPIO uses, pullup/pulldown).
Also note that it's your responsibility to have stopped using a GPIO
before you free it.

+Considering in most cases GPIOs are actually configured right after they
+are claimed, three additional calls are defined:
+
+ /* request a single GPIO, with initial configuration specified by
+ * 'flags', identical to gpio_request() wrt other arguments and
+ * return value
+ */
+ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
+
+ /* request multiple GPIOs in a single call
+ */
+ int gpio_request_array(struct gpio *array, size_t num);
+
+ /* release multiple GPIOs in a single call
+ */
+ void gpio_free_array(struct gpio *array, size_t num);
+
+where 'flags' is currently defined to specify the following properties:
+
+ * GPIOF_DIR_IN - to configure direction as input
+ * GPIOF_DIR_OUT - to configure direction as output
+
+ * GPIOF_INIT_LOW - as output, set initial level to LOW
+ * GPIOF_INIT_HIGH - as output, set initial level to HIGH
+
+since GPIOF_INIT_* are only valid when configured as output, so group valid
+combinations as:
+
+ * GPIOF_IN - configure as input
+ * GPIOF_OUT_INIT_LOW - configured as output, initial level LOW
+ * GPIOF_OUT_INIT_HIGH - configured as output, initial level HIGH
+
+In the future, these flags can be extended to support more properties such
+as open-drain status.
+
+Further more, to ease the claim/release of multiple GPIOs, 'struct gpio' is
+introduced to encapsulate all three fields as:
+
+ struct gpio {
+ unsigned gpio;
+ unsigned long flags;
+ const char *label;
+ };
+
+A typical example of usage:
+
+ static struct gpio leds_gpios[] = {
+ { 32, GPIOF_OUT_INIT_HIGH, "Power LED" }, /* default to ON */
+ { 33, GPIOF_OUT_INIT_LOW, "Green LED" }, /* default to OFF */
+ { 34, GPIOF_OUT_INIT_LOW, "Red LED" }, /* default to OFF */
+ { 35, GPIOF_OUT_INIT_LOW, "Blue LED" }, /* default to OFF */
+ { ... },
+ };
+
+ err = gpio_request_one(31, GPIOF_IN, "Reset Button");
+ if (err)
+ ...
+
+ err = gpio_request_array(leds_gpios, ARRAY_SIZE(leds_gpios));
+ if (err)
+ ...
+
+ gpio_free_array(leds_gpios, ARRAY_SIZE(leds_gpios));
+

GPIOs mapped to IRQs
--------------------
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index a25ad28..0a81a1e 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1239,6 +1239,64 @@ void gpio_free(unsigned gpio)
}
EXPORT_SYMBOL_GPL(gpio_free);

+/**
+ * gpio_request_one - request a single GPIO with initial configuration
+ * @gpio: the GPIO number
+ * @flags: GPIO configuration as specified by GPIOF_*
+ * @label: a literal description string of this GPIO
+ */
+int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
+{
+ int err;
+
+ err = gpio_request(gpio, label);
+ if (err)
+ return err;
+
+ if (flags & GPIOF_DIR_IN)
+ err = gpio_direction_input(gpio);
+ else
+ err = gpio_direction_output(gpio,
+ (flags & GPIOF_INIT_HIGH) ? 1 : 0);
+
+ return err;
+}
+EXPORT_SYMBOL_GPL(gpio_request_one);
+
+/**
+ * gpio_request_array - request multiple GPIOs in a single call
+ * @array: array of the 'struct gpio'
+ * @num: how many GPIOs in the array
+ */
+int gpio_request_array(struct gpio *array, size_t num)
+{
+ int i, err;
+
+ for (i = 0; i < num; i++, array++) {
+ err = gpio_request_one(array->gpio, array->flags, array->label);
+ if (err)
+ goto err_free;
+ }
+ return 0;
+
+err_free:
+ while (i--)
+ gpio_free((--array)->gpio);
+ return err;
+}
+EXPORT_SYMBOL_GPL(gpio_request_array);
+
+/**
+ * gpio_free_array - release multiple GPIOs in a single call
+ * @array: array of the 'struct gpio'
+ * @num: how many GPIOs in the array
+ */
+void gpio_free_array(struct gpio *array, size_t num)
+{
+ while (num--)
+ gpio_free((array++)->gpio);
+}
+EXPORT_SYMBOL_GPL(gpio_free_array);

/**
* gpiochip_is_requested - return string iff signal was requested
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 485eeb6..979c6a5 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -136,6 +136,32 @@ extern int __gpio_cansleep(unsigned gpio);

extern int __gpio_to_irq(unsigned gpio);

+#define GPIOF_DIR_OUT (0 << 0)
+#define GPIOF_DIR_IN (1 << 0)
+
+#define GPIOF_INIT_LOW (0 << 1)
+#define GPIOF_INIT_HIGH (1 << 1)
+
+#define GPIOF_IN (GPIOF_DIR_IN)
+#define GPIOF_OUT_INIT_LOW (GPIOF_DIR_OUT | GPIOF_INIT_LOW)
+#define GPIOF_OUT_INIT_HIGH (GPIOF_DIR_OUT | GPIOF_INIT_HIGH)
+
+/**
+ * struct gpio - a structure describing a GPIO with configuration
+ * @gpio: the GPIO number
+ * @flags: GPIO configuration as specified by GPIOF_*
+ * @label: a literal description string of this GPIO
+ */
+struct gpio {
+ unsigned gpio;
+ unsigned long flags;
+ const char *label;
+};
+
+extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);
+extern int gpio_request_array(struct gpio *array, size_t num);
+extern void gpio_free_array(struct gpio *array, size_t num);
+
#ifdef CONFIG_GPIO_SYSFS

/*
--
1.6.3.3
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