path: root/drivers/input/keyboard/gpio_keys.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for keys on GPIO lines capable of generating interrupts.
 *
 * Copyright 2005 Phil Blundell
 * Copyright 2010, 2011 David Jander <david@protonic.nl>
 */

#include <linux/module.h>

#include <linux/hrtimer.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/sched.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/gpio_keys.h>
#include <linux/workqueue.h>
#include <linux/gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/spinlock.h>
#include <dt-bindings/input/gpio-keys.h>

struct gpio_button_data {
	const struct gpio_keys_button *button;
	struct input_dev *input;
	struct gpio_desc *gpiod;

	unsigned short *code;

	struct hrtimer release_timer;
	unsigned int release_delay;	/* in msecs, for IRQ-only buttons */

	struct delayed_work work;
	struct hrtimer debounce_timer;
	unsigned int software_debounce;	/* in msecs, for GPIO-driven buttons */

	unsigned int irq;
	unsigned int wakeirq;
	unsigned int wakeup_trigger_type;

	spinlock_t lock;
	bool disabled;
	bool key_pressed;
	bool suspended;
	bool debounce_use_hrtimer;
};

struct gpio_keys_drvdata {
	const struct gpio_keys_platform_data *pdata;
	struct input_dev *input;
	struct mutex disable_lock;
	unsigned short *keymap;
	struct gpio_button_data data[];
};

/*
 * SYSFS interface for enabling/disabling keys and switches:
 *
 * There are 4 attributes under /sys/devices/platform/gpio-keys/
 *	keys [ro]              - bitmap of keys (EV_KEY) which can be
 *	                         disabled
 *	switches [ro]          - bitmap of switches (EV_SW) which can be
 *	                         disabled
 *	disabled_keys [rw]     - bitmap of keys currently disabled
 *	disabled_switches [rw] - bitmap of switches currently disabled
 *
 * Userland can change these values and hence disable event generation
 * for each key (or switch). Disabling a key means its interrupt line
 * is disabled.
 *
 * For example, if we have following switches set up as gpio-keys:
 *	SW_DOCK = 5
 *	SW_CAMERA_LENS_COVER = 9
 *	SW_KEYPAD_SLIDE = 10
 *	SW_FRONT_PROXIMITY = 11
 * This is read from switches:
 *	11-9,5
 * Next we want to disable proximity (11) and dock (5), we write:
 *	11,5
 * to file disabled_switches. Now proximity and dock IRQs are disabled.
 * This can be verified by reading the file disabled_switches:
 *	11,5
 * If we now want to enable proximity (11) switch we write:
 *	5
 * to disabled_switches.
 *
 * We can disable only those keys which don't allow sharing the irq.
 */

/**
 * get_n_events_by_type() - returns maximum number of events per @type
 * @type: type of button (%EV_KEY, %EV_SW)
 *
 * Return value of this function can be used to allocate bitmap
 * large enough to hold all bits for given type.
 */
static int get_n_events_by_type(int type)
{
	BUG_ON(type != EV_SW && type != EV_KEY);

	return (type == EV_KEY) ? KEY_CNT : SW_CNT;
}

/**
 * get_bm_events_by_type() - returns bitmap of supported events per @type
 * @dev: input device from which bitmap is retrieved
 * @type: type of button (%EV_KEY, %EV_SW)
 *
 * Return value of this function can be used to allocate bitmap
 * large enough to hold all bits for given type.
 */
static const unsigned long *get_bm_events_by_type(struct input_dev *dev,
						  int type)
{
	BUG_ON(type != EV_SW && type != EV_KEY);

	return (type == EV_KEY) ? dev->keybit : dev->swbit;
}

static void gpio_keys_quiesce_key(void *data)
{
	struct gpio_button_data *bdata = data;

	if (!bdata->gpiod)
		hrtimer_cancel(&bdata->release_timer);
	else if (bdata->debounce_use_hrtimer)
		hrtimer_cancel(&bdata->debounce_timer);
	else
		cancel_delayed_work_sync(&bdata->work);
}

/**
 * gpio_keys_disable_button() - disables given GPIO button
 * @bdata: button data for button to be disabled
 *
 * Disables button pointed by @bdata. This is done by masking
 * IRQ line. After this function is called, button won't generate
 * input events anymore. Note that one can only disable buttons
 * that don't share IRQs.
 *
 * Make sure that @bdata->disable_lock is locked when entering
 * this function to avoid races when concurrent threads are
 * disabling buttons at the same time.
 */
static void gpio_keys_disable_button(struct gpio_button_data *bdata)
{
	if (!bdata->disabled) {
		/*
		 * Disable IRQ and associated timer/work structure.
		 */
		disable_irq(bdata->irq);
		gpio_keys_quiesce_key(bdata);
		bdata->disabled = true;
	}
}

/**
 * gpio_keys_enable_button() - enables given GPIO button
 * @bdata: button data for button to be disabled
 *
 * Enables given button pointed by @bdata.
 *
 * Make sure that @bdata->disable_lock is locked when entering
 * this function to avoid races with concurrent threads trying
 * to enable the same button at the same time.
 */
static void gpio_keys_enable_button(struct gpio_button_data *bdata)
{
	if (bdata->disabled) {
		enable_irq(bdata->irq);
		bdata->disabled = false;
	}
}

/**
 * gpio_keys_attr_show_helper() - fill in stringified bitmap of buttons
 * @ddata: pointer to drvdata
 * @buf: buffer where stringified bitmap is written
 * @type: button type (%EV_KEY, %EV_SW)
 * @only_disabled: does caller want only those buttons that are
 *                 currently disabled or all buttons that can be
 *                 disabled
 *
 * This function writes buttons that can be disabled to @buf. If
 * @only_disabled is true, then @buf contains only those buttons
 * that are currently disabled. Returns 0 on success or negative
 * errno on failure.
 */
static ssize_t gpio_keys_attr_show_helper(struct gpio_keys_drvdata *ddata,
					  char *buf, unsigned int type,
					  bool only_disabled)
{
	int n_events = get_n_events_by_type(type);
	unsigned long *bits;
	ssize_t ret;
	int i;

	bits =