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Subject[RESEND RFC PATCH 1/2] gpio: Add isr property of gpio pins
Date
From: Peter Rosin <peda@axentia.se>

Adds the possibility to read the interrupt status register bit for the
gpio pin. Expose the bit as an isr file in sysfs.

Signed-off-by: Peter Rosin <peda@axentia.se>
---
Documentation/gpio/sysfs.txt | 12 ++++++++++++
drivers/gpio/gpiolib-sysfs.c | 30 ++++++++++++++++++++++++++++++
drivers/gpio/gpiolib.c | 15 +++++++++++++++
include/linux/gpio/consumer.h | 1 +
include/linux/gpio/driver.h | 2 ++
5 files changed, 60 insertions(+)

diff --git a/Documentation/gpio/sysfs.txt b/Documentation/gpio/sysfs.txt
index 535b6a8a7a7c..ded7ef9d01be 100644
--- a/Documentation/gpio/sysfs.txt
+++ b/Documentation/gpio/sysfs.txt
@@ -97,6 +97,18 @@ and have the following read/write attributes:
for "rising" and "falling" edges will follow this
setting.

+ "isr" ... reads as either 0 (false) or 1 (true). Reading the
+ file will clear the value, so that reading a 1 means
+ that there has been an interrupt-triggering action
+ on the pin since the file was last read.
+
+ This file exists only if the gpio chip supports reading
+ the interrupt status register bit for the pin.
+
+ Note that if reading the isr register for this pin
+ interferes with active interrupts, the read will fail
+ with an error.
+
GPIO controllers have paths like /sys/class/gpio/gpiochip42/ (for the
controller implementing GPIOs starting at #42) and have the following
read-only attributes:
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index b57ed8e55ab5..f6fe68fab191 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -139,6 +139,28 @@ static ssize_t value_store(struct device *dev,
}
static DEVICE_ATTR_RW(value);

+static ssize_t isr_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+ ssize_t status;
+ int isr;
+
+ mutex_lock(&data->mutex);
+
+ isr = gpiod_get_isr_cansleep(desc);
+ if (isr < 0)
+ status = isr;
+ else
+ status = sprintf(buf, "%d\n", isr);
+
+ mutex_unlock(&data->mutex);
+
+ return status;
+}
+static DEVICE_ATTR_RO(isr);
+
static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
{
struct gpiod_data *data = priv;
@@ -367,6 +389,13 @@ static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
mode = 0;
if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
mode = 0;
+ } else if (attr == &dev_attr_isr.attr) {
+ if (!desc->chip->get_isr)
+ mode = 0;
+ if (gpiod_to_irq(desc) < 0)
+ mode = 0;
+ if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
+ mode = 0;
}

return mode;
@@ -377,6 +406,7 @@ static struct attribute *gpio_attrs[] = {
&dev_attr_edge.attr,
&dev_attr_value.attr,
&dev_attr_active_low.attr,
+ &dev_attr_isr.attr,
NULL,
};

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index bf4bd1d120c3..b45e70b2713e 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1572,6 +1572,21 @@ int gpiod_get_value_cansleep(const struct gpio_desc *desc)
}
EXPORT_SYMBOL_GPL(gpiod_get_value_cansleep);

+int gpiod_get_isr_cansleep(const struct gpio_desc *desc)
+{
+ struct gpio_chip *chip;
+ int offset;
+
+ might_sleep_if(extra_checks);
+ if (!desc)
+ return -EINVAL;
+
+ chip = desc->chip;
+ offset = gpio_chip_hwgpio(desc);
+ return chip->get_isr ? chip->get_isr(chip, offset) : -ENXIO;
+}
+EXPORT_SYMBOL_GPL(gpiod_get_isr_cansleep);
+
/**
* gpiod_set_raw_value_cansleep() - assign a gpio's raw value
* @desc: gpio whose value will be assigned
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index adac255aee86..d0290c14dc84 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -119,6 +119,7 @@ void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value);
void gpiod_set_raw_array_value_cansleep(unsigned int array_size,
struct gpio_desc **desc_array,
int *value_array);
+int gpiod_get_isr_cansleep(const struct gpio_desc *desc);

int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce);

diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index c8393cd4d44f..dccfb12f9112 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -96,6 +96,8 @@ struct gpio_chip {
unsigned offset);
void (*set)(struct gpio_chip *chip,
unsigned offset, int value);
+ int (*get_isr)(struct gpio_chip *chip,
+ unsigned offset);
void (*set_multiple)(struct gpio_chip *chip,
unsigned long *mask,
unsigned long *bits);
--
1.7.10.4


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