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path: root/drivers/gpio/gpiolib-sysfs.c
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Diffstat (limited to 'drivers/gpio/gpiolib-sysfs.c')
-rw-r--r--drivers/gpio/gpiolib-sysfs.c150
1 files changed, 86 insertions, 64 deletions
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 6bf5332136..6853ecd98b 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/bitops.h>
+#include <linux/cleanup.h>
#include <linux/device.h>
#include <linux/idr.h>
#include <linux/init.h>
@@ -13,6 +14,7 @@
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
+#include <linux/srcu.h>
#include <linux/sysfs.h>
#include <linux/types.h>
@@ -170,6 +172,10 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
unsigned long irq_flags;
int ret;
+ CLASS(gpio_chip_guard, guard)(desc);
+ if (!guard.gc)
+ return -ENODEV;
+
data->irq = gpiod_to_irq(desc);
if (data->irq < 0)
return -EIO;
@@ -194,7 +200,7 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
* Remove this redundant call (along with the corresponding
* unlock) when those drivers have been fixed.
*/
- ret = gpiochip_lock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
+ ret = gpiochip_lock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
if (ret < 0)
goto err_put_kn;
@@ -208,7 +214,7 @@ static int gpio_sysfs_request_irq(struct device *dev, unsigned char flags)
return 0;
err_unlock:
- gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
+ gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
err_put_kn:
sysfs_put(data->value_kn);
@@ -224,9 +230,13 @@ static void gpio_sysfs_free_irq(struct device *dev)
struct gpiod_data *data = dev_get_drvdata(dev);
struct gpio_desc *desc = data->desc;
+ CLASS(gpio_chip_guard, guard)(desc);
+ if (!guard.gc)
+ return;
+
data->irq_flags = 0;
free_irq(data->irq, data);
- gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
+ gpiochip_unlock_as_irq(guard.gc, gpio_chip_hwgpio(desc));
sysfs_put(data->value_kn);
}
@@ -400,27 +410,27 @@ static const struct attribute_group *gpio_groups[] = {
static ssize_t base_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- const struct gpio_chip *chip = dev_get_drvdata(dev);
+ const struct gpio_device *gdev = dev_get_drvdata(dev);
- return sysfs_emit(buf, "%d\n", chip->base);
+ return sysfs_emit(buf, "%d\n", gdev->base);
}
static DEVICE_ATTR_RO(base);
static ssize_t label_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- const struct gpio_chip *chip = dev_get_drvdata(dev);
+ const struct gpio_device *gdev = dev_get_drvdata(dev);
- return sysfs_emit(buf, "%s\n", chip->label ?: "");
+ return sysfs_emit(buf, "%s\n", gdev->label);
}
static DEVICE_ATTR_RO(label);
static ssize_t ngpio_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- const struct gpio_chip *chip = dev_get_drvdata(dev);
+ const struct gpio_device *gdev = dev_get_drvdata(dev);
- return sysfs_emit(buf, "%u\n", chip->ngpio);
+ return sysfs_emit(buf, "%u\n", gdev->ngpio);
}
static DEVICE_ATTR_RO(ngpio);
@@ -443,13 +453,12 @@ static ssize_t export_store(const struct class *class,
const char *buf, size_t len)
{
struct gpio_desc *desc;
- struct gpio_chip *gc;
int status, offset;
long gpio;
status = kstrtol(buf, 0, &gpio);
- if (status < 0)
- goto done;
+ if (status)
+ return status;
desc = gpio_to_desc(gpio);
/* reject invalid GPIOs */
@@ -457,9 +466,13 @@ static ssize_t export_store(const struct class *class,
pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
return -EINVAL;
}
- gc = desc->gdev->chip;
+
+ CLASS(gpio_chip_guard, guard)(desc);
+ if (!guard.gc)
+ return -ENODEV;
+
offset = gpio_chip_hwgpio(desc);
- if (!gpiochip_line_is_valid(gc, offset)) {
+ if (!gpiochip_line_is_valid(guard.gc, offset)) {
pr_warn("%s: GPIO %ld masked\n", __func__, gpio);
return -EINVAL;
}
@@ -562,8 +575,6 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
const char *ioname = NULL;
struct gpio_device *gdev;
struct gpiod_data *data;
- struct gpio_chip *chip;
- unsigned long flags;
struct device *dev;
int status, offset;
@@ -578,29 +589,28 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
return -EINVAL;
}
+ CLASS(gpio_chip_guard, guard)(desc);
+ if (!guard.gc)
+ return -ENODEV;
+
+ if (test_and_set_bit(FLAG_EXPORT, &desc->flags))
+ return -EPERM;
+
gdev = desc->gdev;
- chip = gdev->chip;
mutex_lock(&sysfs_lock);
/* check if chip is being removed */
- if (!chip || !gdev->mockdev) {
+ if (!gdev->mockdev) {
status = -ENODEV;
goto err_unlock;
}
- spin_lock_irqsave(&gpio_lock, flags);
- if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
- test_bit(FLAG_EXPORT, &desc->flags)) {
- spin_unlock_irqrestore(&gpio_lock, flags);
- gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
- __func__,
- test_bit(FLAG_REQUESTED, &desc->flags),
- test_bit(FLAG_EXPORT, &desc->flags));
+ if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
+ gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
status = -EPERM;
goto err_unlock;
}
- spin_unlock_irqrestore(&gpio_lock, flags);
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data) {
@@ -610,14 +620,14 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
data->desc = desc;
mutex_init(&data->mutex);
- if (chip->direction_input && chip->direction_output)
+ if (guard.gc->direction_input && guard.gc->direction_output)
data->direction_can_change = direction_may_change;
else
data->direction_can_change = false;
offset = gpio_chip_hwgpio(desc);
- if (chip->names && chip->names[offset])
- ioname = chip->names[offset];
+ if (guard.gc->names && guard.gc->names[offset])
+ ioname = guard.gc->names[offset];
dev = device_create_with_groups(&gpio_class, &gdev->dev,
MKDEV(0, 0), data, gpio_groups,
@@ -628,7 +638,6 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
goto err_free_data;
}
- set_bit(FLAG_EXPORT, &desc->flags);
mutex_unlock(&sysfs_lock);
return 0;
@@ -636,6 +645,7 @@ err_free_data:
kfree(data);
err_unlock:
mutex_unlock(&sysfs_lock);
+ clear_bit(FLAG_EXPORT, &desc->flags);
gpiod_dbg(desc, "%s: status %d\n", __func__, status);
return status;
}
@@ -732,7 +742,7 @@ EXPORT_SYMBOL_GPL(gpiod_unexport);
int gpiochip_sysfs_register(struct gpio_device *gdev)
{
- struct gpio_chip *chip = gdev->chip;
+ struct gpio_chip *chip;
struct device *parent;
struct device *dev;
@@ -745,6 +755,12 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
if (!class_is_registered(&gpio_class))
return 0;
+ guard(srcu)(&gdev->srcu);
+
+ chip = srcu_dereference(gdev->chip, &gdev->srcu);
+ if (!chip)
+ return -ENODEV;
+
/*
* For sysfs backward compatibility we need to preserve this
* preferred parenting to the gpio_chip parent field, if set.
@@ -755,7 +771,7 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
parent = &gdev->dev;
/* use chip->base for the ID; it's already known to be unique */
- dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), chip,
+ dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), gdev,
gpiochip_groups, GPIOCHIP_NAME "%d",
chip->base);
if (IS_ERR(dev))
@@ -771,17 +787,23 @@ int gpiochip_sysfs_register(struct gpio_device *gdev)
void gpiochip_sysfs_unregister(struct gpio_device *gdev)
{
struct gpio_desc *desc;
- struct gpio_chip *chip = gdev->chip;
+ struct gpio_chip *chip;
- if (!gdev->mockdev)
- return;
+ scoped_guard(mutex, &sysfs_lock) {
+ if (!gdev->mockdev)
+ return;
- device_unregister(gdev->mockdev);
+ device_unregister(gdev->mockdev);
- /* prevent further gpiod exports */
- mutex_lock(&sysfs_lock);
- gdev->mockdev = NULL;
- mutex_unlock(&sysfs_lock);
+ /* prevent further gpiod exports */
+ gdev->mockdev = NULL;
+ }
+
+ guard(srcu)(&gdev->srcu);
+
+ chip = srcu_dereference(gdev->chip, &gdev->srcu);
+ if (!chip)
+ return;
/* unregister gpiod class devices owned by sysfs */
for_each_gpio_desc_with_flag(chip, desc, FLAG_SYSFS) {
@@ -790,11 +812,29 @@ void gpiochip_sysfs_unregister(struct gpio_device *gdev)
}
}
+/*
+ * We're not really looking for a device - we just want to iterate over the
+ * list and call this callback for each GPIO device. This is why this function
+ * always returns 0.
+ */
+static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data)
+{
+ struct gpio_device *gdev = gc->gpiodev;
+ int ret;
+
+ if (gdev->mockdev)
+ return 0;
+
+ ret = gpiochip_sysfs_register(gdev);
+ if (ret)
+ chip_err(gc, "failed to register the sysfs entry: %d\n", ret);
+
+ return 0;
+}
+
static int __init gpiolib_sysfs_init(void)
{
- int status;
- unsigned long flags;
- struct gpio_device *gdev;
+ int status;
status = class_register(&gpio_class);
if (status < 0)
@@ -806,26 +846,8 @@ static int __init gpiolib_sysfs_init(void)
* We run before arch_initcall() so chip->dev nodes can have
* registered, and so arch_initcall() can always gpiod_export().
*/
- spin_lock_irqsave(&gpio_lock, flags);
- list_for_each_entry(gdev, &gpio_devices, list) {
- if (gdev->mockdev)
- continue;
-
- /*
- * TODO we yield gpio_lock here because
- * gpiochip_sysfs_register() acquires a mutex. This is unsafe
- * and needs to be fixed.
- *
- * Also it would be nice to use gpio_device_find() here so we
- * can keep gpio_chips local to gpiolib.c, but the yield of
- * gpio_lock prevents us from doing this.
- */
- spin_unlock_irqrestore(&gpio_lock, flags);
- status = gpiochip_sysfs_register(gdev);
- spin_lock_irqsave(&gpio_lock, flags);
- }
- spin_unlock_irqrestore(&gpio_lock, flags);
+ (void)gpio_device_find(NULL, gpiofind_sysfs_register);
- return status;
+ return 0;
}
postcore_initcall(gpiolib_sysfs_init);