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path: root/drivers/gpio/gpiolib.c
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Diffstat (limited to 'drivers/gpio/gpiolib.c')
-rw-r--r--drivers/gpio/gpiolib.c272
1 files changed, 134 insertions, 138 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 95d2a7b2ea3e..4c93cf73a826 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -2,6 +2,7 @@
#include <linux/acpi.h>
#include <linux/bitmap.h>
+#include <linux/cleanup.h>
#include <linux/compat.h>
#include <linux/debugfs.h>
#include <linux/device.h>
@@ -15,6 +16,7 @@
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/pinctrl/consumer.h>
#include <linux/seq_file.h>
@@ -45,19 +47,6 @@
* GPIOs can sometimes cost only an instruction or two per bit.
*/
-
-/* When debugging, extend minimal trust to callers and platform code.
- * Also emit diagnostic messages that may help initial bringup, when
- * board setup or driver bugs are most common.
- *
- * Otherwise, minimize overhead in what may be bitbanging codepaths.
- */
-#ifdef DEBUG
-#define extra_checks 1
-#else
-#define extra_checks 0
-#endif
-
/* Device and char device-related information */
static DEFINE_IDA(gpio_ida);
static dev_t gpio_devt;
@@ -94,7 +83,9 @@ DEFINE_SPINLOCK(gpio_lock);
static DEFINE_MUTEX(gpio_lookup_lock);
static LIST_HEAD(gpio_lookup_list);
+
LIST_HEAD(gpio_devices);
+DECLARE_RWSEM(gpio_devices_sem);
static DEFINE_MUTEX(gpio_machine_hogs_mutex);
static LIST_HEAD(gpio_machine_hogs);
@@ -126,20 +117,15 @@ static inline void desc_set_label(struct gpio_desc *d, const char *label)
struct gpio_desc *gpio_to_desc(unsigned gpio)
{
struct gpio_device *gdev;
- unsigned long flags;
-
- spin_lock_irqsave(&gpio_lock, flags);
- list_for_each_entry(gdev, &gpio_devices, list) {
- if (gdev->base <= gpio &&
- gdev->base + gdev->ngpio > gpio) {
- spin_unlock_irqrestore(&gpio_lock, flags);
- return &gdev->descs[gpio - gdev->base];
+ scoped_guard(rwsem_read, &gpio_devices_sem) {
+ list_for_each_entry(gdev, &gpio_devices, list) {
+ if (gdev->base <= gpio &&
+ gdev->base + gdev->ngpio > gpio)
+ return &gdev->descs[gpio - gdev->base];
}
}
- spin_unlock_irqrestore(&gpio_lock, flags);
-
if (!gpio_is_valid(gpio))
pr_warn("invalid GPIO %d\n", gpio);
@@ -255,6 +241,20 @@ int gpio_device_get_base(struct gpio_device *gdev)
EXPORT_SYMBOL_GPL(gpio_device_get_base);
/**
+ * gpio_device_get_label() - Get the label of this GPIO device
+ * @gdev: GPIO device
+ *
+ * Returns:
+ * Pointer to the string containing the GPIO device label. The string's
+ * lifetime is tied to that of the underlying GPIO device.
+ */
+const char *gpio_device_get_label(struct gpio_device *gdev)
+{
+ return gdev->label;
+}
+EXPORT_SYMBOL(gpio_device_get_label);
+
+/**
* gpio_device_get_chip() - Get the gpio_chip implementation of this GPIO device
* @gdev: GPIO device
*
@@ -276,7 +276,7 @@ struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev)
EXPORT_SYMBOL_GPL(gpio_device_get_chip);
/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
-static int gpiochip_find_base(int ngpio)
+static int gpiochip_find_base_unlocked(int ngpio)
{
struct gpio_device *gdev;
int base = GPIO_DYNAMIC_BASE;
@@ -349,7 +349,7 @@ EXPORT_SYMBOL_GPL(gpiod_get_direction);
* Return -EBUSY if the new chip overlaps with some other chip's integer
* space.
*/
-static int gpiodev_add_to_list(struct gpio_device *gdev)
+static int gpiodev_add_to_list_unlocked(struct gpio_device *gdev)
{
struct gpio_device *prev, *next;
@@ -398,26 +398,21 @@ static int gpiodev_add_to_list(struct gpio_device *gdev)
static struct gpio_desc *gpio_name_to_desc(const char * const name)
{
struct gpio_device *gdev;
- unsigned long flags;
if (!name)
return NULL;
- spin_lock_irqsave(&gpio_lock, flags);
+ guard(rwsem_read)(&gpio_devices_sem);
list_for_each_entry(gdev, &gpio_devices, list) {
struct gpio_desc *desc;
for_each_gpio_desc(gdev->chip, desc) {
- if (desc->name && !strcmp(desc->name, name)) {
- spin_unlock_irqrestore(&gpio_lock, flags);
+ if (desc->name && !strcmp(desc->name, name))
return desc;
- }
}
}
- spin_unlock_irqrestore(&gpio_lock, flags);
-
return NULL;
}
@@ -655,11 +650,6 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
static void gpiodev_release(struct device *dev)
{
struct gpio_device *gdev = to_gpio_device(dev);
- unsigned long flags;
-
- spin_lock_irqsave(&gpio_lock, flags);
- list_del(&gdev->list);
- spin_unlock_irqrestore(&gpio_lock, flags);
ida_free(&gpio_ida, gdev->id);
kfree_const(gdev->label);
@@ -817,7 +807,6 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
struct lock_class_key *request_key)
{
struct gpio_device *gdev;
- unsigned long flags;
unsigned int i;
int base = 0;
int ret = 0;
@@ -882,49 +871,46 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
gdev->ngpio = gc->ngpio;
- spin_lock_irqsave(&gpio_lock, flags);
+ scoped_guard(rwsem_write, &gpio_devices_sem) {
+ /*
+ * TODO: this allocates a Linux GPIO number base in the global
+ * GPIO numberspace for this chip. In the long run we want to
+ * get *rid* of this numberspace and use only descriptors, but
+ * it may be a pipe dream. It will not happen before we get rid
+ * of the sysfs interface anyways.
+ */
+ base = gc->base;
- /*
- * TODO: this allocates a Linux GPIO number base in the global
- * GPIO numberspace for this chip. In the long run we want to
- * get *rid* of this numberspace and use only descriptors, but
- * it may be a pipe dream. It will not happen before we get rid
- * of the sysfs interface anyways.
- */
- base = gc->base;
- if (base < 0) {
- base = gpiochip_find_base(gc->ngpio);
if (base < 0) {
- spin_unlock_irqrestore(&gpio_lock, flags);
- ret = base;
- base = 0;
+ base = gpiochip_find_base_unlocked(gc->ngpio);
+ if (base < 0) {
+ ret = base;
+ base = 0;
+ goto err_free_label;
+ }
+ /*
+ * TODO: it should not be necessary to reflect the assigned
+ * base outside of the GPIO subsystem. Go over drivers and
+ * see if anyone makes use of this, else drop this and assign
+ * a poison instead.
+ */
+ gc->base = base;
+ } else {
+ dev_warn(&gdev->dev,
+ "Static allocation of GPIO base is deprecated, use dynamic allocation.\n");
+ }
+ gdev->base = base;
+
+ ret = gpiodev_add_to_list_unlocked(gdev);
+ if (ret) {
+ chip_err(gc, "GPIO integer space overlap, cannot add chip\n");
goto err_free_label;
}
- /*
- * TODO: it should not be necessary to reflect the assigned
- * base outside of the GPIO subsystem. Go over drivers and
- * see if anyone makes use of this, else drop this and assign
- * a poison instead.
- */
- gc->base = base;
- } else {
- dev_warn(&gdev->dev,
- "Static allocation of GPIO base is deprecated, use dynamic allocation.\n");
- }
- gdev->base = base;
- ret = gpiodev_add_to_list(gdev);
- if (ret) {
- spin_unlock_irqrestore(&gpio_lock, flags);
- chip_err(gc, "GPIO integer space overlap, cannot add chip\n");
- goto err_free_label;
+ for (i = 0; i < gc->ngpio; i++)
+ gdev->descs[i].gdev = gdev;
}
- for (i = 0; i < gc->ngpio; i++)
- gdev->descs[i].gdev = gdev;
-
- spin_unlock_irqrestore(&gpio_lock, flags);
-
BLOCKING_INIT_NOTIFIER_HEAD(&gdev->line_state_notifier);
BLOCKING_INIT_NOTIFIER_HEAD(&gdev->device_notifier);
init_rwsem(&gdev->sem);
@@ -1015,9 +1001,8 @@ err_free_gpiochip_mask:
goto err_print_message;
}
err_remove_from_list:
- spin_lock_irqsave(&gpio_lock, flags);
- list_del(&gdev->list);
- spin_unlock_irqrestore(&gpio_lock, flags);
+ scoped_guard(rwsem_write, &gpio_devices_sem)
+ list_del(&gdev->list);
err_free_label:
kfree_const(gdev->label);
err_free_descs:
@@ -1048,8 +1033,8 @@ EXPORT_SYMBOL_GPL(gpiochip_add_data_with_key);
void gpiochip_remove(struct gpio_chip *gc)
{
struct gpio_device *gdev = gc->gpiodev;
- unsigned long flags;
- unsigned int i;
+ unsigned long flags;
+ unsigned int i;
down_write(&gdev->sem);
@@ -1071,7 +1056,7 @@ void gpiochip_remove(struct gpio_chip *gc)
spin_lock_irqsave(&gpio_lock, flags);
for (i = 0; i < gdev->ngpio; i++) {
- if (gpiochip_is_requested(gc, i))
+ if (test_bit(FLAG_REQUESTED, &gdev->descs[i].flags))
break;
}
spin_unlock_irqrestore(&gpio_lock, flags);
@@ -1080,6 +1065,9 @@ void gpiochip_remove(struct gpio_chip *gc)
dev_crit(&gdev->dev,
"REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED\n");
+ scoped_guard(rwsem_write, &gpio_devices_sem)
+ list_del(&gdev->list);
+
/*
* The gpiochip side puts its use of the device to rest here:
* if there are no userspace clients, the chardev and device will
@@ -1126,7 +1114,7 @@ struct gpio_device *gpio_device_find(void *data,
*/
might_sleep();
- guard(spinlock_irqsave)(&gpio_lock);
+ guard(rwsem_read)(&gpio_devices_sem);
list_for_each_entry(gdev, &gpio_devices, list) {
if (gdev->chip && match(gdev->chip, data))
@@ -2185,10 +2173,10 @@ EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);
*/
static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
{
- struct gpio_chip *gc = desc->gdev->chip;
- int ret;
- unsigned long flags;
- unsigned offset;
+ struct gpio_chip *gc = desc->gdev->chip;
+ unsigned long flags;
+ unsigned int offset;
+ int ret;
if (label) {
label = kstrdup_const(label, GFP_KERNEL);
@@ -2300,9 +2288,9 @@ int gpiod_request(struct gpio_desc *desc, const char *label)
static bool gpiod_free_commit(struct gpio_desc *desc)
{
- bool ret = false;
- unsigned long flags;
- struct gpio_chip *gc;
+ struct gpio_chip *gc;
+ unsigned long flags;
+ bool ret = false;
might_sleep();
@@ -2331,9 +2319,6 @@ static bool gpiod_free_commit(struct gpio_desc *desc)
#ifdef CONFIG_OF_DYNAMIC
desc->hog = NULL;
#endif
-#ifdef CONFIG_GPIO_CDEV
- WRITE_ONCE(desc->debounce_period_us, 0);
-#endif
ret = true;
}
@@ -2353,38 +2338,53 @@ void gpiod_free(struct gpio_desc *desc)
return;
if (!gpiod_free_commit(desc))
- WARN_ON(extra_checks);
+ WARN_ON(1);
module_put(desc->gdev->owner);
gpio_device_put(desc->gdev);
}
/**
- * gpiochip_is_requested - return string iff signal was requested
- * @gc: controller managing the signal
- * @offset: of signal within controller's 0..(ngpio - 1) range
+ * gpiochip_dup_line_label - Get a copy of the consumer label.
+ * @gc: GPIO chip controlling this line.
+ * @offset: Hardware offset of the line.
*
- * Returns NULL if the GPIO is not currently requested, else a string.
- * The string returned is the label passed to gpio_request(); if none has been
- * passed it is a meaningless, non-NULL constant.
+ * Returns:
+ * Pointer to a copy of the consumer label if the line is requested or NULL
+ * if it's not. If a valid pointer was returned, it must be freed using
+ * kfree(). In case of a memory allocation error, the function returns %ENOMEM.
*
- * This function is for use by GPIO controller drivers. The label can
- * help with diagnostics, and knowing that the signal is used as a GPIO
- * can help avoid accidentally multiplexing it to another controller.
+ * Must not be called from atomic context.
*/
-const char *gpiochip_is_requested(struct gpio_chip *gc, unsigned int offset)
+char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset)
{
struct gpio_desc *desc;
+ char *label;
desc = gpiochip_get_desc(gc, offset);
if (IS_ERR(desc))
return NULL;
- if (test_bit(FLAG_REQUESTED, &desc->flags) == 0)
+ guard(spinlock_irqsave)(&gpio_lock);
+
+ if (!test_bit(FLAG_REQUESTED, &desc->flags))
return NULL;
- return desc->label;
+
+ /*
+ * FIXME: Once we mark gpiod_direction_input/output() and
+ * gpiod_get_direction() with might_sleep(), we'll be able to protect
+ * the GPIO descriptors with mutex (while value setting operations will
+ * become lockless).
+ *
+ * Until this happens, this allocation needs to be atomic.
+ */
+ label = kstrdup(desc->label, GFP_ATOMIC);
+ if (!label)
+ return ERR_PTR(-ENOMEM);
+
+ return label;
}
-EXPORT_SYMBOL_GPL(gpiochip_is_requested);
+EXPORT_SYMBOL_GPL(gpiochip_dup_line_label);
/**
* gpiochip_request_own_desc - Allow GPIO chip to request its own descriptor
@@ -2564,8 +2564,8 @@ int gpio_set_debounce_timeout(struct gpio_desc *desc, unsigned int debounce)
*/
int gpiod_direction_input(struct gpio_desc *desc)
{
- struct gpio_chip *gc;
- int ret = 0;
+ struct gpio_chip *gc;
+ int ret = 0;
VALIDATE_DESC(desc);
gc = desc->gdev->chip;
@@ -2914,7 +2914,7 @@ static int gpio_chip_get_value(struct gpio_chip *gc, const struct gpio_desc *des
static int gpiod_get_raw_value_commit(const struct gpio_desc *desc)
{
- struct gpio_chip *gc;
+ struct gpio_chip *gc;
int value;
gc = desc->gdev->chip;
@@ -3209,7 +3209,7 @@ static void gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value
static void gpiod_set_raw_value_commit(struct gpio_desc *desc, bool value)
{
- struct gpio_chip *gc;
+ struct gpio_chip *gc;
gc = desc->gdev->chip;
trace_gpio_value(desc_to_gpio(desc), 0, value);
@@ -3716,7 +3716,7 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_persistent);
*/
int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc)
{
- might_sleep_if(extra_checks);
+ might_sleep();
VALIDATE_DESC(desc);
return gpiod_get_raw_value_commit(desc);
}
@@ -3735,7 +3735,7 @@ int gpiod_get_value_cansleep(const struct gpio_desc *desc)
{
int value;
- might_sleep_if(extra_checks);
+ might_sleep();
VALIDATE_DESC(desc);
value = gpiod_get_raw_value_commit(desc);
if (value < 0)
@@ -3766,7 +3766,7 @@ int gpiod_get_raw_array_value_cansleep(unsigned int array_size,
struct gpio_array *array_info,
unsigned long *value_bitmap)
{
- might_sleep_if(extra_checks);
+ might_sleep();
if (!desc_array)
return -EINVAL;
return gpiod_get_array_value_complex(true, true, array_size,
@@ -3792,7 +3792,7 @@ int gpiod_get_array_value_cansleep(unsigned int array_size,
struct gpio_array *array_info,
unsigned long *value_bitmap)
{
- might_sleep_if(extra_checks);
+ might_sleep();
if (!desc_array)
return -EINVAL;
return gpiod_get_array_value_complex(false, true, array_size,
@@ -3813,7 +3813,7 @@ EXPORT_SYMBOL_GPL(gpiod_get_array_value_cansleep);
*/
void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value)
{
- might_sleep_if(extra_checks);
+ might_sleep();
VALIDATE_DESC_VOID(desc);
gpiod_set_raw_value_commit(desc, value);
}
@@ -3831,7 +3831,7 @@ EXPORT_SYMBOL_GPL(gpiod_set_raw_value_cansleep);
*/
void gpiod_set_value_cansleep(struct gpio_desc *desc, int value)
{
- might_sleep_if(extra_checks);
+ might_sleep();
VALIDATE_DESC_VOID(desc);
gpiod_set_value_nocheck(desc, value);
}
@@ -3854,7 +3854,7 @@ int gpiod_set_raw_array_value_cansleep(unsigned int array_size,
struct gpio_array *array_info,
unsigned long *value_bitmap)
{
- might_sleep_if(extra_checks);
+ might_sleep();
if (!desc_array)
return -EINVAL;
return gpiod_set_array_value_complex(true, true, array_size, desc_array,
@@ -3896,7 +3896,7 @@ int gpiod_set_array_value_cansleep(unsigned int array_size,
struct gpio_array *array_info,
unsigned long *value_bitmap)
{
- might_sleep_if(extra_checks);
+ might_sleep();
if (!desc_array)
return -EINVAL;
return gpiod_set_array_value_complex(false, true, array_size,
@@ -4696,13 +4696,11 @@ core_initcall(gpiolib_dev_init);
static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev)
{
- struct gpio_chip *gc = gdev->chip;
- struct gpio_desc *desc;
- unsigned gpio = gdev->base;
- int value;
- bool is_out;
- bool is_irq;
- bool active_low;
+ struct gpio_chip *gc = gdev->chip;
+ bool active_low, is_irq, is_out;
+ unsigned int gpio = gdev->base;
+ struct gpio_desc *desc;
+ int value;
for_each_gpio_desc(gc, desc) {
if (test_bit(FLAG_REQUESTED, &desc->flags)) {
@@ -4727,35 +4725,33 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev)
static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
{
- unsigned long flags;
struct gpio_device *gdev = NULL;
loff_t index = *pos;
s->private = "";
- spin_lock_irqsave(&gpio_lock, flags);
- list_for_each_entry(gdev, &gpio_devices, list)
- if (index-- == 0) {
- spin_unlock_irqrestore(&gpio_lock, flags);
+ guard(rwsem_read)(&gpio_devices_sem);
+
+ list_for_each_entry(gdev, &gpio_devices, list) {
+ if (index-- == 0)
return gdev;
- }
- spin_unlock_irqrestore(&gpio_lock, flags);
+ }
return NULL;
}
static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
- unsigned long flags;
struct gpio_device *gdev = v;
void *ret = NULL;
- spin_lock_irqsave(&gpio_lock, flags);
- if (list_is_last(&gdev->list, &gpio_devices))
- ret = NULL;
- else
- ret = list_first_entry(&gdev->list, struct gpio_device, list);
- spin_unlock_irqrestore(&gpio_lock, flags);
+ scoped_guard(rwsem_read, &gpio_devices_sem) {
+ if (list_is_last(&gdev->list, &gpio_devices))
+ ret = NULL;
+ else
+ ret = list_first_entry(&gdev->list, struct gpio_device,
+ list);
+ }
s->private = "\n";
++*pos;
generated by cgit v1.2.3 (git 2.39.0) at 2024-08-04 02:26:05 +0300