cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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extcon-gpio.c (4503B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * extcon_gpio.c - Single-state GPIO extcon driver based on extcon class
      4 *
      5 * Copyright (C) 2008 Google, Inc.
      6 * Author: Mike Lockwood <lockwood@android.com>
      7 *
      8 * Modified by MyungJoo Ham <myungjoo.ham@samsung.com> to support extcon
      9 * (originally switch class is supported)
     10 */
     11
     12#include <linux/devm-helpers.h>
     13#include <linux/extcon-provider.h>
     14#include <linux/gpio/consumer.h>
     15#include <linux/init.h>
     16#include <linux/interrupt.h>
     17#include <linux/kernel.h>
     18#include <linux/module.h>
     19#include <linux/platform_device.h>
     20#include <linux/slab.h>
     21#include <linux/workqueue.h>
     22
     23/**
     24 * struct gpio_extcon_data - A simple GPIO-controlled extcon device state container.
     25 * @edev:		Extcon device.
     26 * @work:		Work fired by the interrupt.
     27 * @debounce_jiffies:	Number of jiffies to wait for the GPIO to stabilize, from the debounce
     28 *			value.
     29 * @gpiod:		GPIO descriptor for this external connector.
     30 * @extcon_id:		The unique id of specific external connector.
     31 * @debounce:		Debounce time for GPIO IRQ in ms.
     32 * @check_on_resume:	Boolean describing whether to check the state of gpio
     33 *			while resuming from sleep.
     34 */
     35struct gpio_extcon_data {
     36	struct extcon_dev *edev;
     37	struct delayed_work work;
     38	unsigned long debounce_jiffies;
     39	struct gpio_desc *gpiod;
     40	unsigned int extcon_id;
     41	unsigned long debounce;
     42	bool check_on_resume;
     43};
     44
     45static void gpio_extcon_work(struct work_struct *work)
     46{
     47	int state;
     48	struct gpio_extcon_data	*data =
     49		container_of(to_delayed_work(work), struct gpio_extcon_data,
     50			     work);
     51
     52	state = gpiod_get_value_cansleep(data->gpiod);
     53	extcon_set_state_sync(data->edev, data->extcon_id, state);
     54}
     55
     56static irqreturn_t gpio_irq_handler(int irq, void *dev_id)
     57{
     58	struct gpio_extcon_data *data = dev_id;
     59
     60	queue_delayed_work(system_power_efficient_wq, &data->work,
     61			      data->debounce_jiffies);
     62	return IRQ_HANDLED;
     63}
     64
     65static int gpio_extcon_probe(struct platform_device *pdev)
     66{
     67	struct gpio_extcon_data *data;
     68	struct device *dev = &pdev->dev;
     69	unsigned long irq_flags;
     70	int irq;
     71	int ret;
     72
     73	data = devm_kzalloc(dev, sizeof(struct gpio_extcon_data), GFP_KERNEL);
     74	if (!data)
     75		return -ENOMEM;
     76
     77	/*
     78	 * FIXME: extcon_id represents the unique identifier of external
     79	 * connectors such as EXTCON_USB, EXTCON_DISP_HDMI and so on. extcon_id
     80	 * is necessary to register the extcon device. But, it's not yet
     81	 * developed to get the extcon id from device-tree or others.
     82	 * On later, it have to be solved.
     83	 */
     84	if (data->extcon_id > EXTCON_NONE)
     85		return -EINVAL;
     86
     87	data->gpiod = devm_gpiod_get(dev, "extcon", GPIOD_IN);
     88	if (IS_ERR(data->gpiod))
     89		return PTR_ERR(data->gpiod);
     90	irq = gpiod_to_irq(data->gpiod);
     91	if (irq <= 0)
     92		return irq;
     93
     94	/*
     95	 * It is unlikely that this is an acknowledged interrupt that goes
     96	 * away after handling, what we are looking for are falling edges
     97	 * if the signal is active low, and rising edges if the signal is
     98	 * active high.
     99	 */
    100	if (gpiod_is_active_low(data->gpiod))
    101		irq_flags = IRQF_TRIGGER_FALLING;
    102	else
    103		irq_flags = IRQF_TRIGGER_RISING;
    104
    105	/* Allocate the memory of extcon devie and register extcon device */
    106	data->edev = devm_extcon_dev_allocate(dev, &data->extcon_id);
    107	if (IS_ERR(data->edev)) {
    108		dev_err(dev, "failed to allocate extcon device\n");
    109		return -ENOMEM;
    110	}
    111
    112	ret = devm_extcon_dev_register(dev, data->edev);
    113	if (ret < 0)
    114		return ret;
    115
    116	ret = devm_delayed_work_autocancel(dev, &data->work, gpio_extcon_work);
    117	if (ret)
    118		return ret;
    119
    120	/*
    121	 * Request the interrupt of gpio to detect whether external connector
    122	 * is attached or detached.
    123	 */
    124	ret = devm_request_any_context_irq(dev, irq,
    125					gpio_irq_handler, irq_flags,
    126					pdev->name, data);
    127	if (ret < 0)
    128		return ret;
    129
    130	platform_set_drvdata(pdev, data);
    131	/* Perform initial detection */
    132	gpio_extcon_work(&data->work.work);
    133
    134	return 0;
    135}
    136
    137#ifdef CONFIG_PM_SLEEP
    138static int gpio_extcon_resume(struct device *dev)
    139{
    140	struct gpio_extcon_data *data;
    141
    142	data = dev_get_drvdata(dev);
    143	if (data->check_on_resume)
    144		queue_delayed_work(system_power_efficient_wq,
    145			&data->work, data->debounce_jiffies);
    146
    147	return 0;
    148}
    149#endif
    150
    151static SIMPLE_DEV_PM_OPS(gpio_extcon_pm_ops, NULL, gpio_extcon_resume);
    152
    153static struct platform_driver gpio_extcon_driver = {
    154	.probe		= gpio_extcon_probe,
    155	.driver		= {
    156		.name	= "extcon-gpio",
    157		.pm	= &gpio_extcon_pm_ops,
    158	},
    159};
    160
    161module_platform_driver(gpio_extcon_driver);
    162
    163MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
    164MODULE_DESCRIPTION("GPIO extcon driver");
    165MODULE_LICENSE("GPL");