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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alim1535_wdt.c (9958B)


      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 *	Watchdog for the 7101 PMU version found in the ALi M1535 chipsets
      4 */
      5
      6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
      7
      8#include <linux/module.h>
      9#include <linux/moduleparam.h>
     10#include <linux/types.h>
     11#include <linux/miscdevice.h>
     12#include <linux/watchdog.h>
     13#include <linux/ioport.h>
     14#include <linux/notifier.h>
     15#include <linux/reboot.h>
     16#include <linux/init.h>
     17#include <linux/fs.h>
     18#include <linux/pci.h>
     19#include <linux/uaccess.h>
     20#include <linux/io.h>
     21
     22#define WATCHDOG_NAME "ALi_M1535"
     23#define WATCHDOG_TIMEOUT 60	/* 60 sec default timeout */
     24
     25/* internal variables */
     26static unsigned long ali_is_open;
     27static char ali_expect_release;
     28static struct pci_dev *ali_pci;
     29static u32 ali_timeout_bits;		/* stores the computed timeout */
     30static DEFINE_SPINLOCK(ali_lock);	/* Guards the hardware */
     31
     32/* module parameters */
     33static int timeout = WATCHDOG_TIMEOUT;
     34module_param(timeout, int, 0);
     35MODULE_PARM_DESC(timeout,
     36		"Watchdog timeout in seconds. (0 < timeout < 18000, default="
     37				__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
     38
     39static bool nowayout = WATCHDOG_NOWAYOUT;
     40module_param(nowayout, bool, 0);
     41MODULE_PARM_DESC(nowayout,
     42		"Watchdog cannot be stopped once started (default="
     43				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
     44
     45/*
     46 *	ali_start	-	start watchdog countdown
     47 *
     48 *	Starts the timer running providing the timer has a counter
     49 *	configuration set.
     50 */
     51
     52static void ali_start(void)
     53{
     54	u32 val;
     55
     56	spin_lock(&ali_lock);
     57
     58	pci_read_config_dword(ali_pci, 0xCC, &val);
     59	val &= ~0x3F;	/* Mask count */
     60	val |= (1 << 25) | ali_timeout_bits;
     61	pci_write_config_dword(ali_pci, 0xCC, val);
     62
     63	spin_unlock(&ali_lock);
     64}
     65
     66/*
     67 *	ali_stop	-	stop the timer countdown
     68 *
     69 *	Stop the ALi watchdog countdown
     70 */
     71
     72static void ali_stop(void)
     73{
     74	u32 val;
     75
     76	spin_lock(&ali_lock);
     77
     78	pci_read_config_dword(ali_pci, 0xCC, &val);
     79	val &= ~0x3F;		/* Mask count to zero (disabled) */
     80	val &= ~(1 << 25);	/* and for safety mask the reset enable */
     81	pci_write_config_dword(ali_pci, 0xCC, val);
     82
     83	spin_unlock(&ali_lock);
     84}
     85
     86/*
     87 *	ali_keepalive	-	send a keepalive to the watchdog
     88 *
     89 *	Send a keepalive to the timer (actually we restart the timer).
     90 */
     91
     92static void ali_keepalive(void)
     93{
     94	ali_start();
     95}
     96
     97/*
     98 *	ali_settimer	-	compute the timer reload value
     99 *	@t: time in seconds
    100 *
    101 *	Computes the timeout values needed
    102 */
    103
    104static int ali_settimer(int t)
    105{
    106	if (t < 0)
    107		return -EINVAL;
    108	else if (t < 60)
    109		ali_timeout_bits = t|(1 << 6);
    110	else if (t < 3600)
    111		ali_timeout_bits = (t / 60)|(1 << 7);
    112	else if (t < 18000)
    113		ali_timeout_bits = (t / 300)|(1 << 6)|(1 << 7);
    114	else
    115		return -EINVAL;
    116
    117	timeout = t;
    118	return 0;
    119}
    120
    121/*
    122 *	/dev/watchdog handling
    123 */
    124
    125/*
    126 *	ali_write	-	writes to ALi watchdog
    127 *	@file: file from VFS
    128 *	@data: user address of data
    129 *	@len: length of data
    130 *	@ppos: pointer to the file offset
    131 *
    132 *	Handle a write to the ALi watchdog. Writing to the file pings
    133 *	the watchdog and resets it. Writing the magic 'V' sequence allows
    134 *	the next close to turn off the watchdog.
    135 */
    136
    137static ssize_t ali_write(struct file *file, const char __user *data,
    138						size_t len, loff_t *ppos)
    139{
    140	/* See if we got the magic character 'V' and reload the timer */
    141	if (len) {
    142		if (!nowayout) {
    143			size_t i;
    144
    145			/* note: just in case someone wrote the
    146			   magic character five months ago... */
    147			ali_expect_release = 0;
    148
    149			/* scan to see whether or not we got
    150			   the magic character */
    151			for (i = 0; i != len; i++) {
    152				char c;
    153				if (get_user(c, data + i))
    154					return -EFAULT;
    155				if (c == 'V')
    156					ali_expect_release = 42;
    157			}
    158		}
    159
    160		/* someone wrote to us, we should reload the timer */
    161		ali_start();
    162	}
    163	return len;
    164}
    165
    166/*
    167 *	ali_ioctl	-	handle watchdog ioctls
    168 *	@file: VFS file pointer
    169 *	@cmd: ioctl number
    170 *	@arg: arguments to the ioctl
    171 *
    172 *	Handle the watchdog ioctls supported by the ALi driver. Really
    173 *	we want an extension to enable irq ack monitoring and the like
    174 */
    175
    176static long ali_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
    177{
    178	void __user *argp = (void __user *)arg;
    179	int __user *p = argp;
    180	static const struct watchdog_info ident = {
    181		.options =		WDIOF_KEEPALIVEPING |
    182					WDIOF_SETTIMEOUT |
    183					WDIOF_MAGICCLOSE,
    184		.firmware_version =	0,
    185		.identity =		"ALi M1535 WatchDog Timer",
    186	};
    187
    188	switch (cmd) {
    189	case WDIOC_GETSUPPORT:
    190		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
    191
    192	case WDIOC_GETSTATUS:
    193	case WDIOC_GETBOOTSTATUS:
    194		return put_user(0, p);
    195	case WDIOC_SETOPTIONS:
    196	{
    197		int new_options, retval = -EINVAL;
    198
    199		if (get_user(new_options, p))
    200			return -EFAULT;
    201		if (new_options & WDIOS_DISABLECARD) {
    202			ali_stop();
    203			retval = 0;
    204		}
    205		if (new_options & WDIOS_ENABLECARD) {
    206			ali_start();
    207			retval = 0;
    208		}
    209		return retval;
    210	}
    211	case WDIOC_KEEPALIVE:
    212		ali_keepalive();
    213		return 0;
    214	case WDIOC_SETTIMEOUT:
    215	{
    216		int new_timeout;
    217		if (get_user(new_timeout, p))
    218			return -EFAULT;
    219		if (ali_settimer(new_timeout))
    220			return -EINVAL;
    221		ali_keepalive();
    222	}
    223		fallthrough;
    224	case WDIOC_GETTIMEOUT:
    225		return put_user(timeout, p);
    226	default:
    227		return -ENOTTY;
    228	}
    229}
    230
    231/*
    232 *	ali_open	-	handle open of ali watchdog
    233 *	@inode: inode from VFS
    234 *	@file: file from VFS
    235 *
    236 *	Open the ALi watchdog device. Ensure only one person opens it
    237 *	at a time. Also start the watchdog running.
    238 */
    239
    240static int ali_open(struct inode *inode, struct file *file)
    241{
    242	/* /dev/watchdog can only be opened once */
    243	if (test_and_set_bit(0, &ali_is_open))
    244		return -EBUSY;
    245
    246	/* Activate */
    247	ali_start();
    248	return stream_open(inode, file);
    249}
    250
    251/*
    252 *	ali_release	-	close an ALi watchdog
    253 *	@inode: inode from VFS
    254 *	@file: file from VFS
    255 *
    256 *	Close the ALi watchdog device. Actual shutdown of the timer
    257 *	only occurs if the magic sequence has been set.
    258 */
    259
    260static int ali_release(struct inode *inode, struct file *file)
    261{
    262	/*
    263	 *      Shut off the timer.
    264	 */
    265	if (ali_expect_release == 42)
    266		ali_stop();
    267	else {
    268		pr_crit("Unexpected close, not stopping watchdog!\n");
    269		ali_keepalive();
    270	}
    271	clear_bit(0, &ali_is_open);
    272	ali_expect_release = 0;
    273	return 0;
    274}
    275
    276/*
    277 *	ali_notify_sys	-	System down notifier
    278 *
    279 *	Notifier for system down
    280 */
    281
    282
    283static int ali_notify_sys(struct notifier_block *this,
    284					unsigned long code, void *unused)
    285{
    286	if (code == SYS_DOWN || code == SYS_HALT)
    287		ali_stop();		/* Turn the WDT off */
    288	return NOTIFY_DONE;
    289}
    290
    291/*
    292 *	Data for PCI driver interface
    293 *
    294 *	This data only exists for exporting the supported
    295 *	PCI ids via MODULE_DEVICE_TABLE.  We do not actually
    296 *	register a pci_driver, because someone else might one day
    297 *	want to register another driver on the same PCI id.
    298 */
    299
    300static const struct pci_device_id ali_pci_tbl[] __used = {
    301	{ PCI_VENDOR_ID_AL, 0x1533, PCI_ANY_ID, PCI_ANY_ID,},
    302	{ PCI_VENDOR_ID_AL, 0x1535, PCI_ANY_ID, PCI_ANY_ID,},
    303	{ 0, },
    304};
    305MODULE_DEVICE_TABLE(pci, ali_pci_tbl);
    306
    307/*
    308 *	ali_find_watchdog	-	find a 1535 and 7101
    309 *
    310 *	Scans the PCI hardware for a 1535 series bridge and matching 7101
    311 *	watchdog device. This may be overtight but it is better to be safe
    312 */
    313
    314static int __init ali_find_watchdog(void)
    315{
    316	struct pci_dev *pdev;
    317	u32 wdog;
    318
    319	/* Check for a 1533/1535 series bridge */
    320	pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1535, NULL);
    321	if (pdev == NULL)
    322		pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1533, NULL);
    323	if (pdev == NULL)
    324		return -ENODEV;
    325	pci_dev_put(pdev);
    326
    327	/* Check for the a 7101 PMU */
    328	pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x7101, NULL);
    329	if (pdev == NULL)
    330		return -ENODEV;
    331
    332	if (pci_enable_device(pdev)) {
    333		pci_dev_put(pdev);
    334		return -EIO;
    335	}
    336
    337	ali_pci = pdev;
    338
    339	/*
    340	 *	Initialize the timer bits
    341	 */
    342	pci_read_config_dword(pdev, 0xCC, &wdog);
    343
    344	/* Timer bits */
    345	wdog &= ~0x3F;
    346	/* Issued events */
    347	wdog &= ~((1 << 27)|(1 << 26)|(1 << 25)|(1 << 24));
    348	/* No monitor bits */
    349	wdog &= ~((1 << 16)|(1 << 13)|(1 << 12)|(1 << 11)|(1 << 10)|(1 << 9));
    350
    351	pci_write_config_dword(pdev, 0xCC, wdog);
    352
    353	return 0;
    354}
    355
    356/*
    357 *	Kernel Interfaces
    358 */
    359
    360static const struct file_operations ali_fops = {
    361	.owner		=	THIS_MODULE,
    362	.llseek		=	no_llseek,
    363	.write		=	ali_write,
    364	.unlocked_ioctl =	ali_ioctl,
    365	.compat_ioctl	= 	compat_ptr_ioctl,
    366	.open		=	ali_open,
    367	.release	=	ali_release,
    368};
    369
    370static struct miscdevice ali_miscdev = {
    371	.minor =	WATCHDOG_MINOR,
    372	.name =		"watchdog",
    373	.fops =		&ali_fops,
    374};
    375
    376static struct notifier_block ali_notifier = {
    377	.notifier_call =	ali_notify_sys,
    378};
    379
    380/*
    381 *	watchdog_init	-	module initialiser
    382 *
    383 *	Scan for a suitable watchdog and if so initialize it. Return an error
    384 *	if we cannot, the error causes the module to unload
    385 */
    386
    387static int __init watchdog_init(void)
    388{
    389	int ret;
    390
    391	/* Check whether or not the hardware watchdog is there */
    392	if (ali_find_watchdog() != 0)
    393		return -ENODEV;
    394
    395	/* Check that the timeout value is within it's range;
    396	   if not reset to the default */
    397	if (timeout < 1 || timeout >= 18000) {
    398		timeout = WATCHDOG_TIMEOUT;
    399		pr_info("timeout value must be 0 < timeout < 18000, using %d\n",
    400			timeout);
    401	}
    402
    403	/* Calculate the watchdog's timeout */
    404	ali_settimer(timeout);
    405
    406	ret = register_reboot_notifier(&ali_notifier);
    407	if (ret != 0) {
    408		pr_err("cannot register reboot notifier (err=%d)\n", ret);
    409		goto out;
    410	}
    411
    412	ret = misc_register(&ali_miscdev);
    413	if (ret != 0) {
    414		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
    415		       WATCHDOG_MINOR, ret);
    416		goto unreg_reboot;
    417	}
    418
    419	pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
    420		timeout, nowayout);
    421
    422out:
    423	return ret;
    424unreg_reboot:
    425	unregister_reboot_notifier(&ali_notifier);
    426	goto out;
    427}
    428
    429/*
    430 *	watchdog_exit	-	module de-initialiser
    431 *
    432 *	Called while unloading a successfully installed watchdog module.
    433 */
    434
    435static void __exit watchdog_exit(void)
    436{
    437	/* Stop the timer before we leave */
    438	ali_stop();
    439
    440	/* Deregister */
    441	misc_deregister(&ali_miscdev);
    442	unregister_reboot_notifier(&ali_notifier);
    443	pci_dev_put(ali_pci);
    444}
    445
    446module_init(watchdog_init);
    447module_exit(watchdog_exit);
    448
    449MODULE_AUTHOR("Alan Cox");
    450MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
    451MODULE_LICENSE("GPL");