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watchdog: Remove AMD Elan SC520 processor watchdog driver

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AMD Elan support was removed from the upstream kernel with commit
8b793a92d8 ("x86/cpu: Remove M486/M486SX/ELAN support"). Its
watchdog driver can no longer be enabled except for test builds.
Remove it.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Guenter Roeck 2026-05-05 09:23:43 -07:00
parent 3394e89488
commit 550c3bcdda
4 changed files with 0 additions and 453 deletions
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9
Documentation/watchdog/watchdog-parameters.rst
View File

@ -522,15 +522,6 @@ sc1200wdt:
-------------------------------------------------
sc520_wdt:
timeout:
Watchdog timeout in seconds. (1 <= timeout <= 3600, default=30)
nowayout:
Watchdog cannot be stopped once started
(default=kernel config parameter)
-------------------------------------------------
sch311x_wdt:
force_id:
Override the detected device ID

13
drivers/watchdog/Kconfig
View File

@ -1270,19 +1270,6 @@ config GEODE_WDT
You can compile this driver directly into the kernel, or use
it as a module. The module will be called geodewdt.
config SC520_WDT
tristate "AMD Elan SC520 processor Watchdog"
depends on MELAN || COMPILE_TEST
help
This is the driver for the hardware watchdog built in to the
AMD "Elan" SC520 microcomputer commonly used in embedded systems.
This watchdog simply watches your kernel to make sure it doesn't
freeze, and if it does, it reboots your computer after a certain
amount of time.
You can compile this driver directly into the kernel, or use
it as a module. The module will be called sc520_wdt.
config SBC_FITPC2_WATCHDOG
tristate "Compulab SBC-FITPC2 watchdog"
depends on (X86 || COMPILE_TEST) && HAS_IOPORT

1
drivers/watchdog/Makefile
View File

@ -117,7 +117,6 @@ obj-$(CONFIG_EXAR_WDT) += exar_wdt.o
obj-$(CONFIG_F71808E_WDT) += f71808e_wdt.o
obj-$(CONFIG_SP5100_TCO) += sp5100_tco.o
obj-$(CONFIG_GEODE_WDT) += geodewdt.o
obj-$(CONFIG_SC520_WDT) += sc520_wdt.o
obj-$(CONFIG_SBC_FITPC2_WATCHDOG) += sbc_fitpc2_wdt.o
obj-$(CONFIG_EUROTECH_WDT) += eurotechwdt.o
obj-$(CONFIG_IB700_WDT) += ib700wdt.o

430
drivers/watchdog/sc520_wdt.c
View File

@ -1,430 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* AMD Elan SC520 processor Watchdog Timer driver
*
* Based on acquirewdt.c by Alan Cox,
* and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
*
* The authors do NOT admit liability nor provide warranty for
* any of this software. This material is provided "AS-IS" in
* the hope that it may be useful for others.
*
* (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>
* 9/27 - 2001 [Initial release]
*
* Additional fixes Alan Cox
* - Fixed formatting
* - Removed debug printks
* - Fixed SMP built kernel deadlock
* - Switched to private locks not lock_kernel
* - Used ioremap/writew/readw
* - Added NOWAYOUT support
* 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
* - Change comments
* - Eliminate fop_llseek
* - Change CONFIG_WATCHDOG_NOWAYOUT semantics
* - Add KERN_* tags to printks
* - fix possible wdt_is_open race
* - Report proper capabilities in watchdog_info
* - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
* GETTIMEOUT, SETOPTIONS} ioctls
* 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
* - cleanup of trailing spaces
* - added extra printk's for startup problems
* - use module_param
* - made timeout (the emulated heartbeat) a module_param
* - made the keepalive ping an internal subroutine
* 3/27 - 2004 Changes by Sean Young <sean@mess.org>
* - set MMCR_BASE to 0xfffef000
* - CBAR does not need to be read
* - removed debugging printks
*
* This WDT driver is different from most other Linux WDT
* drivers in that the driver will ping the watchdog by itself,
* because this particular WDT has a very short timeout (1.6
* seconds) and it would be insane to count on any userspace
* daemon always getting scheduled within that time frame.
*
* This driver uses memory mapped IO, and spinlock.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/io.h>
#include <linux/uaccess.h>
/*
* The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
*
* 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
* 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
*
* We will program the SC520 watchdog for a timeout of 2.01s.
* If we reset the watchdog every ~250ms we should be safe.
*/
#define WDT_INTERVAL (HZ/4+1)
/*
* We must not require too good response from the userspace daemon.
* Here we require the userspace daemon to send us a heartbeat
* char to /dev/watchdog every 30 seconds.
*/
#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
static int timeout = WATCHDOG_TIMEOUT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
"Watchdog timeout in seconds. (1 <= timeout <= 3600, 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) ")");
/*
* AMD Elan SC520 - Watchdog Timer Registers
*/
#define MMCR_BASE 0xfffef000 /* The default base address */
#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
/* WDT Control Register bit definitions */
#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
static __u16 __iomem *wdtmrctl;
static void wdt_timer_ping(struct timer_list *);
static DEFINE_TIMER(timer, wdt_timer_ping);
static unsigned long next_heartbeat;
static unsigned long wdt_is_open;
static char wdt_expect_close;
static DEFINE_SPINLOCK(wdt_spinlock);
/*
* Whack the dog
*/
static void wdt_timer_ping(struct timer_list *unused)
{
/* If we got a heartbeat pulse within the WDT_US_INTERVAL
* we agree to ping the WDT
*/
if (time_before(jiffies, next_heartbeat)) {
/* Ping the WDT */
spin_lock(&wdt_spinlock);
writew(0xAAAA, wdtmrctl);
writew(0x5555, wdtmrctl);
spin_unlock(&wdt_spinlock);
/* Re-set the timer interval */
mod_timer(&timer, jiffies + WDT_INTERVAL);
} else
pr_warn("Heartbeat lost! Will not ping the watchdog\n");
}
/*
* Utility routines
*/
static void wdt_config(int writeval)
{
unsigned long flags;
/* buy some time (ping) */
spin_lock_irqsave(&wdt_spinlock, flags);
readw(wdtmrctl); /* ensure write synchronization */
writew(0xAAAA, wdtmrctl);
writew(0x5555, wdtmrctl);
/* unlock WDT = make WDT configuration register writable one time */
writew(0x3333, wdtmrctl);
writew(0xCCCC, wdtmrctl);
/* write WDT configuration register */
writew(writeval, wdtmrctl);
spin_unlock_irqrestore(&wdt_spinlock, flags);
}
static int wdt_startup(void)
{
next_heartbeat = jiffies + (timeout * HZ);
/* Start the timer */
mod_timer(&timer, jiffies + WDT_INTERVAL);
/* Start the watchdog */
wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04);
pr_info("Watchdog timer is now enabled\n");
return 0;
}
static int wdt_turnoff(void)
{
/* Stop the timer */
timer_delete_sync(&timer);
/* Stop the watchdog */
wdt_config(0);
pr_info("Watchdog timer is now disabled...\n");
return 0;
}
static int wdt_keepalive(void)
{
/* user land ping */
next_heartbeat = jiffies + (timeout * HZ);
return 0;
}
static int wdt_set_heartbeat(int t)
{
if ((t < 1) || (t > 3600)) /* arbitrary upper limit */
return -EINVAL;
timeout = t;
return 0;
}
/*
* /dev/watchdog handling
*/
static ssize_t fop_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
/* See if we got the magic character 'V' and reload the timer */
if (count) {
if (!nowayout) {
size_t ofs;
/* note: just in case someone wrote the magic character
* five months ago... */
wdt_expect_close = 0;
/* now scan */
for (ofs = 0; ofs != count; ofs++) {
char c;
if (get_user(c, buf + ofs))
return -EFAULT;
if (c == 'V')
wdt_expect_close = 42;
}
}
/* Well, anyhow someone wrote to us, we should
return that favour */
wdt_keepalive();
}
return count;
}
static int fop_open(struct inode *inode, struct file *file)
{
/* Just in case we're already talking to someone... */
if (test_and_set_bit(0, &wdt_is_open))
return -EBUSY;
if (nowayout)
__module_get(THIS_MODULE);
/* Good, fire up the show */
wdt_startup();
return stream_open(inode, file);
}
static int fop_close(struct inode *inode, struct file *file)
{
if (wdt_expect_close == 42)
wdt_turnoff();
else {
pr_crit("Unexpected close, not stopping watchdog!\n");
wdt_keepalive();
}
clear_bit(0, &wdt_is_open);
wdt_expect_close = 0;
return 0;
}
static long fop_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 = 1,
.identity = "SC520",
};
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) {
wdt_turnoff();
retval = 0;
}
if (new_options & WDIOS_ENABLECARD) {
wdt_startup();
retval = 0;
}
return retval;
}
case WDIOC_KEEPALIVE:
wdt_keepalive();
return 0;
case WDIOC_SETTIMEOUT:
{
int new_timeout;
if (get_user(new_timeout, p))
return -EFAULT;
if (wdt_set_heartbeat(new_timeout))
return -EINVAL;
wdt_keepalive();
}
fallthrough;
case WDIOC_GETTIMEOUT:
return put_user(timeout, p);
default:
return -ENOTTY;
}
}
static const struct file_operations wdt_fops = {
.owner = THIS_MODULE,
.write = fop_write,
.open = fop_open,
.release = fop_close,
.unlocked_ioctl = fop_ioctl,
.compat_ioctl = compat_ptr_ioctl,
};
static struct miscdevice wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &wdt_fops,
};
/*
* Notifier for system down
*/
static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
void *unused)
{
if (code == SYS_DOWN || code == SYS_HALT)
wdt_turnoff();
return NOTIFY_DONE;
}
/*
* The WDT needs to learn about soft shutdowns in order to
* turn the timebomb registers off.
*/
static struct notifier_block wdt_notifier = {
.notifier_call = wdt_notify_sys,
};
static void __exit sc520_wdt_unload(void)
{
if (!nowayout)
wdt_turnoff();
/* Deregister */
misc_deregister(&wdt_miscdev);
unregister_reboot_notifier(&wdt_notifier);
iounmap(wdtmrctl);
}
static int __init sc520_wdt_init(void)
{
int rc = -EBUSY;
/* Check that the timeout value is within it's range ;
if not reset to the default */
if (wdt_set_heartbeat(timeout)) {
wdt_set_heartbeat(WATCHDOG_TIMEOUT);
pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n",
WATCHDOG_TIMEOUT);
}
wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2);
if (!wdtmrctl) {
pr_err("Unable to remap memory\n");
rc = -ENOMEM;
goto err_out_region2;
}
rc = register_reboot_notifier(&wdt_notifier);
if (rc) {
pr_err("cannot register reboot notifier (err=%d)\n", rc);
goto err_out_ioremap;
}
rc = misc_register(&wdt_miscdev);
if (rc) {
pr_err("cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, rc);
goto err_out_notifier;
}
pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
timeout, nowayout);
return 0;
err_out_notifier:
unregister_reboot_notifier(&wdt_notifier);
err_out_ioremap:
iounmap(wdtmrctl);
err_out_region2:
return rc;
}
module_init(sc520_wdt_init);
module_exit(sc520_wdt_unload);
MODULE_AUTHOR("Scott and Bill Jennings");
MODULE_DESCRIPTION(
"Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
MODULE_LICENSE("GPL");