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Date: Wed, 5 Dec 2012 22:32:47 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: linux-kernel@...r.kernel.org
Cc: Grant Likely <grant.likely@...retlab.ca>,
Linus Walleij <linus.walleij@...aro.org>,
Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH] gpio: export 'debounce' attribute if supported by the gpio chip
Create a 'debounce' attribute if debounce is supported by the gpio
chip and a gpio pin is exported.
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
drivers/gpio/gpiolib.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 59 insertions(+), 0 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index a971e3d..13ee9a7 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -67,6 +67,7 @@ struct gpio_desc {
#ifdef CONFIG_DEBUG_FS
const char *label;
#endif
+ unsigned debounce;
};
static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
@@ -215,6 +216,10 @@ static DEFINE_MUTEX(sysfs_lock);
* * is read/write as zero/nonzero
* * also affects existing and subsequent "falling" and "rising"
* /edge configuration
+ * /debounce
+ * * configures debounce time in uS
+ * * available only if debounce is supported by the chip
+ * * is read/write; 0 to disable or debounce time
*/
static ssize_t gpio_direction_show(struct device *dev,
@@ -320,6 +325,55 @@ static ssize_t gpio_value_store(struct device *dev,
static const DEVICE_ATTR(value, 0644,
gpio_value_show, gpio_value_store);
+static ssize_t gpio_debounce_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ const struct gpio_desc *desc = dev_get_drvdata(dev);
+ ssize_t status;
+
+ mutex_lock(&sysfs_lock);
+
+ if (!test_bit(FLAG_EXPORT, &desc->flags))
+ status = -EIO;
+ else
+ status = sprintf(buf, "%u\n", desc->debounce);
+
+ mutex_unlock(&sysfs_lock);
+ return status;
+}
+
+static ssize_t gpio_debounce_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ const struct gpio_desc *desc = dev_get_drvdata(dev);
+ unsigned gpio = desc - gpio_desc;
+ ssize_t status;
+
+ mutex_lock(&sysfs_lock);
+
+ if (!test_bit(FLAG_EXPORT, &desc->flags))
+ status = -EIO;
+ else if (test_bit(FLAG_IS_OUT, &desc->flags))
+ status = -EPERM;
+ else {
+ long value;
+
+ status = kstrtoul(buf, 0, &value);
+ if (status == 0) {
+ status = gpio_set_debounce(gpio, value);
+ if (status == 0)
+ status = size;
+ }
+ }
+
+ mutex_unlock(&sysfs_lock);
+ return status;
+}
+
+static const DEVICE_ATTR(debounce, 0644,
+ gpio_debounce_show, gpio_debounce_store);
+
static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
{
struct sysfs_dirent *value_sd = priv;
@@ -741,6 +795,10 @@ int gpio_export(unsigned gpio, bool direction_may_change)
status = device_create_file(dev,
&dev_attr_direction);
+ if (!status && desc->chip->set_debounce)
+ status = device_create_file(dev,
+ &dev_attr_debounce);
+
if (!status && gpio_to_irq(gpio) >= 0
&& (direction_may_change
|| !test_bit(FLAG_IS_OUT,
@@ -1507,6 +1565,7 @@ int gpio_set_debounce(unsigned gpio, unsigned debounce)
might_sleep_if(chip->can_sleep);
+ desc->debounce = debounce;
return chip->set_debounce(chip, gpio, debounce);
fail:
--
1.7.5.4
--
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