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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mtx-1_wdt.c (5954B)

      1// SPDX-License-Identifier: GPL-2.0+
      2/*
      3 *      Driver for the MTX-1 Watchdog.
      4 *
      5 *      (C) Copyright 2005 4G Systems <info@4g-systems.biz>,
      6 *							All Rights Reserved.
      7 *                              http://www.4g-systems.biz
      8 *
      9 *	(C) Copyright 2007 OpenWrt.org, Florian Fainelli <florian@openwrt.org>
     10 *      (c) Copyright 2005    4G Systems <info@4g-systems.biz>
     11 *
     12 *      Release 0.01.
     13 *      Author: Michael Stickel  michael.stickel@4g-systems.biz
     14 *
     15 *      Release 0.02.
     16 *	Author: Florian Fainelli florian@openwrt.org
     17 *		use the Linux watchdog/timer APIs
     18 *
     19 *      The Watchdog is configured to reset the MTX-1
     20 *      if it is not triggered for 100 seconds.
     21 *      It should not be triggered more often than 1.6 seconds.
     22 *
     23 *      A timer triggers the watchdog every 5 seconds, until
     24 *      it is opened for the first time. After the first open
     25 *      it MUST be triggered every 2..95 seconds.
     26 */
     27
     28#include <linux/module.h>
     29#include <linux/moduleparam.h>
     30#include <linux/types.h>
     31#include <linux/errno.h>
     32#include <linux/miscdevice.h>
     33#include <linux/fs.h>
     34#include <linux/ioport.h>
     35#include <linux/timer.h>
     36#include <linux/completion.h>
     37#include <linux/jiffies.h>
     38#include <linux/watchdog.h>
     39#include <linux/platform_device.h>
     40#include <linux/io.h>
     41#include <linux/uaccess.h>
     42#include <linux/gpio/consumer.h>
     43
     44#define MTX1_WDT_INTERVAL	(5 * HZ)
     45
     46static int ticks = 100 * HZ;
     47
     48static struct {
     49	struct completion stop;
     50	spinlock_t lock;
     51	int running;
     52	struct timer_list timer;
     53	int queue;
     54	int default_ticks;
     55	unsigned long inuse;
     56	struct gpio_desc *gpiod;
     57	unsigned int gstate;
     58} mtx1_wdt_device;
     59
     60static void mtx1_wdt_trigger(struct timer_list *unused)
     61{
     62	spin_lock(&mtx1_wdt_device.lock);
     63	if (mtx1_wdt_device.running)
     64		ticks--;
     65
     66	/* toggle wdt gpio */
     67	mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate;
     68	gpiod_set_value(mtx1_wdt_device.gpiod, mtx1_wdt_device.gstate);
     69
     70	if (mtx1_wdt_device.queue && ticks)
     71		mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
     72	else
     73		complete(&mtx1_wdt_device.stop);
     74	spin_unlock(&mtx1_wdt_device.lock);
     75}
     76
     77static void mtx1_wdt_reset(void)
     78{
     79	ticks = mtx1_wdt_device.default_ticks;
     80}
     81
     82
     83static void mtx1_wdt_start(void)
     84{
     85	unsigned long flags;
     86
     87	spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
     88	if (!mtx1_wdt_device.queue) {
     89		mtx1_wdt_device.queue = 1;
     90		mtx1_wdt_device.gstate = 1;
     91		gpiod_set_value(mtx1_wdt_device.gpiod, 1);
     92		mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
     93	}
     94	mtx1_wdt_device.running++;
     95	spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
     96}
     97
     98static int mtx1_wdt_stop(void)
     99{
    100	unsigned long flags;
    101
    102	spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
    103	if (mtx1_wdt_device.queue) {
    104		mtx1_wdt_device.queue = 0;
    105		mtx1_wdt_device.gstate = 0;
    106		gpiod_set_value(mtx1_wdt_device.gpiod, 0);
    107	}
    108	ticks = mtx1_wdt_device.default_ticks;
    109	spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
    110	return 0;
    111}
    112
    113/* Filesystem functions */
    114
    115static int mtx1_wdt_open(struct inode *inode, struct file *file)
    116{
    117	if (test_and_set_bit(0, &mtx1_wdt_device.inuse))
    118		return -EBUSY;
    119	return stream_open(inode, file);
    120}
    121
    122
    123static int mtx1_wdt_release(struct inode *inode, struct file *file)
    124{
    125	clear_bit(0, &mtx1_wdt_device.inuse);
    126	return 0;
    127}
    128
    129static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd,
    130							unsigned long arg)
    131{
    132	void __user *argp = (void __user *)arg;
    133	int __user *p = (int __user *)argp;
    134	unsigned int value;
    135	static const struct watchdog_info ident = {
    136		.options = WDIOF_CARDRESET,
    137		.identity = "MTX-1 WDT",
    138	};
    139
    140	switch (cmd) {
    141	case WDIOC_GETSUPPORT:
    142		if (copy_to_user(argp, &ident, sizeof(ident)))
    143			return -EFAULT;
    144		break;
    145	case WDIOC_GETSTATUS:
    146	case WDIOC_GETBOOTSTATUS:
    147		put_user(0, p);
    148		break;
    149	case WDIOC_SETOPTIONS:
    150		if (get_user(value, p))
    151			return -EFAULT;
    152		if (value & WDIOS_ENABLECARD)
    153			mtx1_wdt_start();
    154		else if (value & WDIOS_DISABLECARD)
    155			mtx1_wdt_stop();
    156		else
    157			return -EINVAL;
    158		return 0;
    159	case WDIOC_KEEPALIVE:
    160		mtx1_wdt_reset();
    161		break;
    162	default:
    163		return -ENOTTY;
    164	}
    165	return 0;
    166}
    167
    168
    169static ssize_t mtx1_wdt_write(struct file *file, const char *buf,
    170						size_t count, loff_t *ppos)
    171{
    172	if (!count)
    173		return -EIO;
    174	mtx1_wdt_reset();
    175	return count;
    176}
    177
    178static const struct file_operations mtx1_wdt_fops = {
    179	.owner		= THIS_MODULE,
    180	.llseek		= no_llseek,
    181	.unlocked_ioctl	= mtx1_wdt_ioctl,
    182	.compat_ioctl	= compat_ptr_ioctl,
    183	.open		= mtx1_wdt_open,
    184	.write		= mtx1_wdt_write,
    185	.release	= mtx1_wdt_release,
    186};
    187
    188
    189static struct miscdevice mtx1_wdt_misc = {
    190	.minor	= WATCHDOG_MINOR,
    191	.name	= "watchdog",
    192	.fops	= &mtx1_wdt_fops,
    193};
    194
    195
    196static int mtx1_wdt_probe(struct platform_device *pdev)
    197{
    198	int ret;
    199
    200	mtx1_wdt_device.gpiod = devm_gpiod_get(&pdev->dev,
    201					       NULL, GPIOD_OUT_HIGH);
    202	if (IS_ERR(mtx1_wdt_device.gpiod)) {
    203		dev_err(&pdev->dev, "failed to request gpio");
    204		return PTR_ERR(mtx1_wdt_device.gpiod);
    205	}
    206
    207	spin_lock_init(&mtx1_wdt_device.lock);
    208	init_completion(&mtx1_wdt_device.stop);
    209	mtx1_wdt_device.queue = 0;
    210	clear_bit(0, &mtx1_wdt_device.inuse);
    211	timer_setup(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0);
    212	mtx1_wdt_device.default_ticks = ticks;
    213
    214	ret = misc_register(&mtx1_wdt_misc);
    215	if (ret < 0) {
    216		dev_err(&pdev->dev, "failed to register\n");
    217		return ret;
    218	}
    219	mtx1_wdt_start();
    220	dev_info(&pdev->dev, "MTX-1 Watchdog driver\n");
    221	return 0;
    222}
    223
    224static int mtx1_wdt_remove(struct platform_device *pdev)
    225{
    226	/* FIXME: do we need to lock this test ? */
    227	if (mtx1_wdt_device.queue) {
    228		mtx1_wdt_device.queue = 0;
    229		wait_for_completion(&mtx1_wdt_device.stop);
    230	}
    231
    232	misc_deregister(&mtx1_wdt_misc);
    233	return 0;
    234}
    235
    236static struct platform_driver mtx1_wdt_driver = {
    237	.probe = mtx1_wdt_probe,
    238	.remove = mtx1_wdt_remove,
    239	.driver.name = "mtx1-wdt",
    240	.driver.owner = THIS_MODULE,
    241};
    242
    243module_platform_driver(mtx1_wdt_driver);
    244
    245MODULE_AUTHOR("Michael Stickel, Florian Fainelli");
    246MODULE_DESCRIPTION("Driver for the MTX-1 watchdog");
    247MODULE_LICENSE("GPL");
    248MODULE_ALIAS("platform:mtx1-wdt");