#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/gpio.h>
#include <linux/idr.h>
/* Optional implementation infrastructure for GPIO interfaces.
*
* Platforms may want to use this if they tend to use very many GPIOs
* that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
*
* When kernel footprint or instruction count is an issue, simpler
* implementations may be preferred. The GPIO programming interface
* allows for inlining speed-critical get/set operations for common
* cases, so that access to SOC-integrated 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
/* gpio_lock prevents conflicts during gpio_desc[] table updates.
* While any GPIO is requested, its gpio_chip is not removable;
* each GPIO's "requested" flag serves as a lock and refcount.
*/
static DEFINE_SPINLOCK(gpio_lock);
struct gpio_desc {
struct gpio_chip *chip;
unsigned long flags;
/* flag symbols are bit numbers */
#define FLAG_REQUESTED 0
#define FLAG_IS_OUT 1
#define FLAG_RESERVED 2
#define FLAG_EXPORT 3 /* protected by sysfs_lock */
#define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */
#define FLAG_TRIG_FALL 5 /* trigger on falling edge */
#define FLAG_TRIG_RISE 6 /* trigger on rising edge */
#define FLAG_ACTIVE_LOW 7 /* sysfs value has active low */
#define PDESC_ID_SHIFT 16 /* add new flags before this one */
#define GPIO_FLAGS_MASK ((1 << PDESC_ID_SHIFT) - 1)
#define GPIO_TRIGGER_MASK (BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
#ifdef CONFIG_DEBUG_FS
const char *label;
#endif
};
static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
#ifdef CONFIG_GPIO_SYSFS
struct poll_desc {
struct work_struct work;
struct sysfs_dirent *value_sd;
};
static struct idr pdesc_idr;
#endif
static inline void desc_set_label(struct gpio_desc *d, const char *label)
{
#ifdef CONFIG_DEBUG_FS
d->label = label;
#endif
}
/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
* when setting direction, and otherwise illegal. Until board setup code
* and drivers use explicit requests everywhere (which won't happen when
* those calls have no teeth) we can't avoid autorequesting. This nag
* message should motivate switching to explicit requests... so should
* the weaker cleanup after faults, compared to gpio_request().
*
* NOTE: the autorequest mechanism is going away; at this point it's
* only "legal" in the sense that (old) code using it won't break yet,
* but instead only triggers a WARN() stack dump.
*/
static int gpio_ensure_requested(struct gpio_desc *desc, unsigned offset)
{
const struct gpio_chip *chip = desc->chip;
const int gpio = chip->base + offset;
if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
"autorequest GPIO-%d\n", gpio)) {
if (!try_module_get(chip->owner)) {
pr_err("GPIO-%d: module can't be gotten \n", gpio);
clear_bit(FLAG_REQUESTED, &desc->flags);
/* lose */
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