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authorRyan Mallon <rmallon@gmail.com>2012-10-22 11:39:12 +1100
committerLinus Walleij <linus.walleij@linaro.org>2012-10-23 00:13:36 +0200
commitfc4e2514995d9cd7f3e1a67098ce65d72acf8ec7 (patch)
tree05cb8ff2fbf178fd5282e970173cac05f6e6c132 /drivers/gpio/gpiolib.c
parent67a0d4993d85ee2f42c9909127794553df69dd59 (diff)
downloadop-kernel-dev-fc4e2514995d9cd7f3e1a67098ce65d72acf8ec7.zip
op-kernel-dev-fc4e2514995d9cd7f3e1a67098ce65d72acf8ec7.tar.gz
gpiolib: Refactor gpio_export
The gpio_export function uses nested if statements and the status variable to handle the failure cases. This makes the function logic difficult to follow. Refactor the code to abort immediately on failure using goto. This makes the code slightly longer, but significantly reduces the nesting and number of split lines and makes the code easier to read. Signed-off-by: Ryan Mallon <rmallon@gmail.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'drivers/gpio/gpiolib.c')
-rw-r--r--drivers/gpio/gpiolib.c85
1 files changed, 46 insertions, 39 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 5d6c71e..d5f9742 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -702,8 +702,9 @@ int gpio_export(unsigned gpio, bool direction_may_change)
{
unsigned long flags;
struct gpio_desc *desc;
- int status = -EINVAL;
+ int status;
const char *ioname = NULL;
+ struct device *dev;
/* can't export until sysfs is available ... */
if (!gpio_class.p) {
@@ -711,59 +712,65 @@ int gpio_export(unsigned gpio, bool direction_may_change)
return -ENOENT;
}
- if (!gpio_is_valid(gpio))
- goto done;
+ if (!gpio_is_valid(gpio)) {
+ pr_debug("%s: gpio %d is not valid\n", __func__, gpio);
+ return -EINVAL;
+ }
mutex_lock(&sysfs_lock);
spin_lock_irqsave(&gpio_lock, flags);
desc = &gpio_desc[gpio];
- if (test_bit(FLAG_REQUESTED, &desc->flags)
- && !test_bit(FLAG_EXPORT, &desc->flags)) {
- status = 0;
- if (!desc->chip->direction_input
- || !desc->chip->direction_output)
- direction_may_change = false;
+ if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
+ test_bit(FLAG_EXPORT, &desc->flags)) {
+ spin_unlock_irqrestore(&gpio_lock, flags);
+ pr_debug("%s: gpio %d unavailable (requested=%d, exported=%d)\n",
+ __func__, gpio,
+ test_bit(FLAG_REQUESTED, &desc->flags),
+ test_bit(FLAG_EXPORT, &desc->flags));
+ return -EPERM;
}
+
+ if (!desc->chip->direction_input || !desc->chip->direction_output)
+ direction_may_change = false;
spin_unlock_irqrestore(&gpio_lock, flags);
if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
ioname = desc->chip->names[gpio - desc->chip->base];
- if (status == 0) {
- struct device *dev;
-
- dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
- desc, ioname ? ioname : "gpio%u", gpio);
- if (!IS_ERR(dev)) {
- status = sysfs_create_group(&dev->kobj,
- &gpio_attr_group);
-
- if (!status && direction_may_change)
- status = device_create_file(dev,
- &dev_attr_direction);
-
- if (!status && gpio_to_irq(gpio) >= 0
- && (direction_may_change
- || !test_bit(FLAG_IS_OUT,
- &desc->flags)))
- status = device_create_file(dev,
- &dev_attr_edge);
-
- if (status != 0)
- device_unregister(dev);
- } else
- status = PTR_ERR(dev);
- if (status == 0)
- set_bit(FLAG_EXPORT, &desc->flags);
+ dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
+ desc, ioname ? ioname : "gpio%u", gpio);
+ if (IS_ERR(dev)) {
+ status = PTR_ERR(dev);
+ goto fail_unlock;
}
- mutex_unlock(&sysfs_lock);
-
-done:
+ status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
if (status)
- pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
+ goto fail_unregister_device;
+
+ if (direction_may_change) {
+ status = device_create_file(dev, &dev_attr_direction);
+ if (status)
+ goto fail_unregister_device;
+ }
+ if (gpio_to_irq(gpio) >= 0 && (direction_may_change ||
+ !test_bit(FLAG_IS_OUT, &desc->flags))) {
+ status = device_create_file(dev, &dev_attr_edge);
+ if (status)
+ goto fail_unregister_device;
+ }
+
+ set_bit(FLAG_EXPORT, &desc->flags);
+ mutex_unlock(&sysfs_lock);
+ return 0;
+
+fail_unregister_device:
+ device_unregister(dev);
+fail_unlock:
+ mutex_unlock(&sysfs_lock);
+ pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
return status;
}
EXPORT_SYMBOL_GPL(gpio_export);
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