// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Watchdog for the 7101 PMU version found in the ALi M1535 chipsets
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/pci.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#define WATCHDOG_NAME "ALi_M1535"
#define WATCHDOG_TIMEOUT 60 /* 60 sec default timeout */
/* internal variables */
static unsigned long ali_is_open;
static char ali_expect_release;
static struct pci_dev *ali_pci;
static u32 ali_timeout_bits; /* stores the computed timeout */
static DEFINE_SPINLOCK(ali_lock); /* Guards the hardware */
/* module parameters */
static int timeout = WATCHDOG_TIMEOUT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
"Watchdog timeout in seconds. (0 < timeout < 18000, default="
__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
/*
* ali_start - start watchdog countdown
*
* Starts the timer running providing the timer has a counter
* configuration set.
*/
static void ali_start(void)
{
u32 val;
spin_lock(&ali_lock);
pci_read_config_dword(ali_pci, 0xCC, &val);
val &= ~0x3F; /* Mask count */
val |= (1 << 25) | ali_timeout_bits;
pci_write_config_dword(ali_pci, 0xCC, val);
spin_unlock(&ali_lock);
}
/*
* ali_stop - stop the timer countdown
*
* Stop the ALi watchdog countdown
*/
static void ali_stop(void)
{
u32 val;
spin_lock(&ali_lock);
pci_read_config_dword(ali_pci, 0xCC, &val);
val &= ~0x3F; /* Mask count to zero (disabled) */
val &= ~(1 << 25); /* and for safety mask the reset enable */
pci_write_config_dword(ali_pci, 0xCC, val);
spin_unlock(&ali_lock);
}
/*
* ali_keepalive - send a keepalive to the watchdog
*
* Send a keepalive to the timer (actually we restart the timer).
*/
static void ali_keepalive(void)
{
ali_start();
}
/*
* ali_settimer - compute the timer reload value
* @t: time in seconds
*
* Computes the timeout values needed
*/
static int ali_settimer(int t)
{
if (t < 0)
return -EINVAL;
else if (t < 60)
ali_timeout_bits = t|(1 << 6);
else if (t < 3600)
ali_timeout_bits = (t / 60)|(1 << 7);
else if (t < 18000)
ali_timeout_bits = (t / 300)|(1 << 6)|(1 << 7);
else
return -EINVAL;
timeout = t;
return 0;
}
/*
* /dev/watchdog handling
*/
/*
* ali_write - writes to ALi watchdog
* @file: file from VFS
* @data: user address of data
* @len: length of data
* @ppos: pointer to the file offset
*
* Handle a write to the ALi watchdog. Writing to the file pings
* the watchdog and resets it. Writing the magic 'V' sequence allows
* the next close to turn off the watchdog.
*/
static ssize_t ali_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
/* See if we got the magic character 'V' and reload the timer */
if (len) {
if (!nowayout) {
size_t i;
/* note: just in case someone wrote the
magic character five months ago... */
ali_expect_release = 0;
/* scan to see whether or not we got
the magic character */
for (i = 0; i != len; i++) {
char c;
if (get_user(c, data + i))
return -EFAULT;
if (c == 'V')
ali_expect_release = 42;
}
}
/* someone wrote to us, we should reload the timer */
ali_start();
}
return len;
}
/*
* ali_ioctl - handle watchdog ioctls
* @file: VFS file pointer
* @cmd: ioctl number
* @arg: arguments to the ioctl
*
* Handle the watchdog ioctls supported by the ALi driver. Really
* we want an extension to enable irq ack monitoring and the like
*/
static long ali_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
static const struct watchdog_info ident = {
.options = WDIOF_KEEPALIVEPING |
WDIOF_SETTIMEOUT |
WDIOF_MAGICCLOSE,
.firmware_version = 0,
.identity = "ALi M1535 WatchDog Timer",
};
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
case WDIOC_GETSTATUS:
case WDIOC_GETBOOTSTATUS:
return put_user(0, p);
case WDIOC_SETOPTIONS:
{
int new_options, retval = -EINVAL;
if (get_user(new_options, p))
return -EFAULT;
if (new_options & WDIOS_DISABLECARD) {
ali_stop();
retval = 0;
}
if (new_options & WDIOS_ENABLECARD) {
ali_start();
retval = 0;
}
return retval;
}
case WDIOC_KEEPALIVE:
ali_keepalive();
return 0;
case WDIOC_SETTIMEOUT:
{
int new_timeout;
if (get_user(new_timeout, p))
return -EFAULT;
if (ali_settimer(new_timeout))
return -EINVAL;
ali_keepalive();
}
fallthrough;
case WDIOC_GETTIMEOUT:
return put_user(timeout, p);
default:
return -ENOTTY;
}
}
/*
* ali_open - handle open of ali watchdog
* @inode: inode from VFS
* @file: file from VFS
*
* Open the ALi watchdog device. Ensure only one person opens it
* at a time. Also start the watchdog running.
*/
static int ali_open(struct inode *inode, struct file *file)
{
/* /dev/watchdog can only be opened once */
if (test_and_set_bit(0, &ali_is_open))
return -EBUSY;
/* Activate */
ali_start();
return stream_open(inode, file);
}
/*
* ali_release - close an ALi watchdog
* @inode: inode from VFS
* @file: file from VFS
*
* Close the ALi watchdog device. Actual shutdown of the timer
* only occurs if the magic sequence has been set.
*/
static int ali_release(struct inode *inode, struct file *file)
{
/*
* Shut off the timer.
*/
if (ali_expect_release == 42)
ali_stop();
else {
pr_crit("Unexpected close, not stopping watchdog!\n");
ali_keepalive();
}
clear_bit(0, &ali_is_open);
ali_expect_release = 0;
return 0;
}
/*
* ali_notify_sys - System down notifier
*
* Notifier for system down
*/
static int ali_notify_sys(struct notifier_block *this,
unsigned long code, void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT)
ali_stop(); /* Turn the WDT off */
return NOTIFY_DONE;
}
/*
* Data for PCI driver interface
*
* This data only exists for exporting the supported
* PCI ids via MODULE_DEVICE_TABLE. We do not actually
* register a pci_driver, because someone else might one day
* want to register another driver on the same PCI id.
*/
static const struct pci_device_id ali_pci_tbl[] __used = {
{ PCI_VENDOR_ID_AL, 0x1533, PCI_ANY_ID, PCI_ANY_ID,},
{ PCI_VENDOR_ID_AL, 0x1535, PCI_ANY_ID, PCI_ANY_ID,},
{ 0, },
};
MODULE_DEVICE_TABLE(pci, ali_pci_tbl);
/*
* ali_find_watchdog - find a 1535 and 7101
*
* Scans the PCI hardware for a 1535 series bridge and matching 7101
* watchdog device. This may be overtight but it is better to be safe
*/
static int __init ali_find_watchdog(void)
{
struct pci_dev *pdev;
u32 wdog;
/* Check for a 1533/1535 series bridge */
pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1535, NULL);
if (pdev == NULL)
pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x1533, NULL);
if (pdev == NULL)
return -ENODEV;
pci_dev_put(pdev);
/* Check for the a 7101 PMU */
pdev = pci_get_device(PCI_VENDOR_ID_AL, 0x7101, NULL);
if (pdev == NULL)
return -ENODEV;
if (pci_enable_device(pdev)) {
pci_dev_put(pdev);
return -EIO;
}
ali_pci = pdev;
/*
* Initialize the timer bits
*/
pci_read_config_dword(pdev, 0xCC, &wdog);
/* Timer bits */
wdog &= ~0x3F;
/* Issued events */
wdog &= ~((1 << 27)|(1 << 26)|(1 << 25)|(1 << 24));
/* No monitor bits */
wdog &= ~((1 << 16)|(1 << 13)|(1 << 12)|(1 << 11)|(1 << 10)|(1 << 9));
pci_write_config_dword(pdev, 0xCC, wdog);
return 0;
}
/*
* Kernel Interfaces
*/
static const struct file_operations ali_fops = {
.owner = THIS_MODULE,
.write = ali_write,
.unlocked_ioctl = ali_ioctl,
.compat_ioctl = compat_ptr_ioctl,
.open = ali_open,
.release = ali_release,
};
static struct miscdevice ali_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &ali_fops,
};
static struct notifier_block ali_notifier = {
.notifier_call = ali_notify_sys,
};
/*
* watchdog_init - module initialiser
*
* Scan for a suitable watchdog and if so initialize it. Return an error
* if we cannot, the error causes the module to unload
*/
static int __init watchdog_init(void)
{
int ret;
/* Check whether or not the hardware watchdog is there */
if (ali_find_watchdog() != 0)
return -ENODEV;
/* Check that the timeout value is within it's range;
if not reset to the default */
if (timeout < 1 || timeout >= 18000) {
timeout = WATCHDOG_TIMEOUT;
pr_info("timeout value must be 0 < timeout < 18000, using %d\n",
timeout);
}
/* Calculate the watchdog's timeout */
ali_settimer(timeout);
ret = register_reboot_notifier(&ali_notifier);
if (ret != 0) {
pr_err("cannot register reboot notifier (err=%d)\n", ret);
goto out;
}
ret = misc_register(&ali_miscdev);
if (ret != 0) {
pr_err("cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, ret);
goto unreg_reboot;
}
pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
timeout, nowayout);
out:
return ret;
unreg_reboot:
unregister_reboot_notifier(&ali_notifier);
goto out;
}
/*
* watchdog_exit - module de-initialiser
*
* Called while unloading a successfully installed watchdog module.
*/
static void __exit watchdog_exit(void)
{
/* Stop the timer before we leave */
ali_stop();
/* Deregister */
misc_deregister(&ali_miscdev);
unregister_reboot_notifier(&ali_notifier);
pci_dev_put(ali_pci);
}
module_init(watchdog_init);
module_exit(watchdog_exit);
MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("ALi M1535 PMU Watchdog Timer driver");
MODULE_LICENSE("GPL");
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