1 // SPDX-License-Identifier: GPL-2.0-only
3 * Intel_SCU 0.2: An Intel SCU IOH Based Watchdog Device
7 * Copyright (C) 2009-2010 Intel Corporation. All rights reserved.
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 #include <linux/compiler.h>
13 #include <linux/kernel.h>
14 #include <linux/moduleparam.h>
15 #include <linux/types.h>
16 #include <linux/miscdevice.h>
17 #include <linux/watchdog.h>
19 #include <linux/notifier.h>
20 #include <linux/reboot.h>
21 #include <linux/init.h>
22 #include <linux/jiffies.h>
23 #include <linux/uaccess.h>
24 #include <linux/slab.h>
26 #include <linux/interrupt.h>
27 #include <linux/delay.h>
28 #include <linux/sched.h>
29 #include <linux/signal.h>
30 #include <linux/sfi.h>
32 #include <linux/atomic.h>
33 #include <asm/intel_scu_ipc.h>
34 #include <asm/apb_timer.h>
35 #include <asm/intel-mid.h>
37 #include "intel_scu_watchdog.h"
39 /* Bounds number of times we will retry loading time count */
40 /* This retry is a work around for a silicon bug. */
43 #define IPC_SET_WATCHDOG_TIMER 0xF8
45 static int timer_margin = DEFAULT_SOFT_TO_HARD_MARGIN;
46 module_param(timer_margin, int, 0);
47 MODULE_PARM_DESC(timer_margin,
48 "Watchdog timer margin"
49 "Time between interrupt and resetting the system"
50 "The range is from 1 to 160"
51 "This is the time for all keep alives to arrive");
53 static int timer_set = DEFAULT_TIME;
54 module_param(timer_set, int, 0);
55 MODULE_PARM_DESC(timer_set,
56 "Default Watchdog timer setting"
58 "The range is from 1 to 170"
59 "This is the time for all keep alives to arrive");
61 /* After watchdog device is closed, check force_boot. If:
62 * force_boot == 0, then force boot on next watchdog interrupt after close,
63 * force_boot == 1, then force boot immediately when device is closed.
65 static int force_boot;
66 module_param(force_boot, int, 0);
67 MODULE_PARM_DESC(force_boot,
68 "A value of 1 means that the driver will reboot"
69 "the system immediately if the /dev/watchdog device is closed"
70 "A value of 0 means that when /dev/watchdog device is closed"
71 "the watchdog timer will be refreshed for one more interval"
72 "of length: timer_set. At the end of this interval, the"
73 "watchdog timer will reset the system."
76 /* there is only one device in the system now; this can be made into
77 * an array in the future if we have more than one device */
79 static struct intel_scu_watchdog_dev watchdog_device;
81 /* Forces restart, if force_reboot is set */
82 static void watchdog_fire(void)
85 pr_crit("Initiating system reboot\n");
87 pr_crit("Reboot didn't ?????\n");
91 pr_crit("Immediate Reboot Disabled\n");
92 pr_crit("System will reset when watchdog timer times out!\n");
96 static int check_timer_margin(int new_margin)
98 if ((new_margin < MIN_TIME_CYCLE) ||
99 (new_margin > MAX_TIME - timer_set)) {
100 pr_debug("value of new_margin %d is out of the range %d to %d\n",
101 new_margin, MIN_TIME_CYCLE, MAX_TIME - timer_set);
110 static int watchdog_set_ipc(int soft_threshold, int threshold)
113 u8 cbuf[16] = { '\0' };
116 ipc_wbuf = (u32 *)&cbuf;
117 ipc_wbuf[0] = soft_threshold;
118 ipc_wbuf[1] = threshold;
120 ipc_ret = intel_scu_ipc_command(
121 IPC_SET_WATCHDOG_TIMER,
129 pr_err("Error setting SCU watchdog timer: %x\n", ipc_ret);
135 * Intel_SCU operations
138 /* timer interrupt handler */
139 static irqreturn_t watchdog_timer_interrupt(int irq, void *dev_id)
142 int_status = ioread32(watchdog_device.timer_interrupt_status_addr);
144 pr_debug("irq, int_status: %x\n", int_status);
149 /* has the timer been started? If not, then this is spurious */
150 if (watchdog_device.timer_started == 0) {
151 pr_debug("spurious interrupt received\n");
155 /* temporarily disable the timer */
156 iowrite32(0x00000002, watchdog_device.timer_control_addr);
158 /* set the timer to the threshold */
159 iowrite32(watchdog_device.threshold,
160 watchdog_device.timer_load_count_addr);
162 /* allow the timer to run */
163 iowrite32(0x00000003, watchdog_device.timer_control_addr);
168 static int intel_scu_keepalive(void)
171 /* read eoi register - clears interrupt */
172 ioread32(watchdog_device.timer_clear_interrupt_addr);
174 /* temporarily disable the timer */
175 iowrite32(0x00000002, watchdog_device.timer_control_addr);
177 /* set the timer to the soft_threshold */
178 iowrite32(watchdog_device.soft_threshold,
179 watchdog_device.timer_load_count_addr);
181 /* allow the timer to run */
182 iowrite32(0x00000003, watchdog_device.timer_control_addr);
187 static int intel_scu_stop(void)
189 iowrite32(0, watchdog_device.timer_control_addr);
193 static int intel_scu_set_heartbeat(u32 t)
200 watchdog_device.timer_set = t;
201 watchdog_device.threshold =
202 timer_margin * watchdog_device.timer_tbl_ptr->freq_hz;
203 watchdog_device.soft_threshold =
204 (watchdog_device.timer_set - timer_margin)
205 * watchdog_device.timer_tbl_ptr->freq_hz;
207 pr_debug("set_heartbeat: timer freq is %d\n",
208 watchdog_device.timer_tbl_ptr->freq_hz);
209 pr_debug("set_heartbeat: timer_set is %x (hex)\n",
210 watchdog_device.timer_set);
211 pr_debug("set_heartbeat: timer_margin is %x (hex)\n", timer_margin);
212 pr_debug("set_heartbeat: threshold is %x (hex)\n",
213 watchdog_device.threshold);
214 pr_debug("set_heartbeat: soft_threshold is %x (hex)\n",
215 watchdog_device.soft_threshold);
217 /* Adjust thresholds by FREQ_ADJUSTMENT factor, to make the */
218 /* watchdog timing come out right. */
219 watchdog_device.threshold =
220 watchdog_device.threshold / FREQ_ADJUSTMENT;
221 watchdog_device.soft_threshold =
222 watchdog_device.soft_threshold / FREQ_ADJUSTMENT;
224 /* temporarily disable the timer */
225 iowrite32(0x00000002, watchdog_device.timer_control_addr);
227 /* send the threshold and soft_threshold via IPC to the processor */
228 ipc_ret = watchdog_set_ipc(watchdog_device.soft_threshold,
229 watchdog_device.threshold);
232 /* Make sure the watchdog timer is stopped */
237 /* Soft Threshold set loop. Early versions of silicon did */
238 /* not always set this count correctly. This loop checks */
239 /* the value and retries if it was not set correctly. */
242 soft_value = watchdog_device.soft_threshold & 0xFFFF0000;
245 /* Make sure timer is stopped */
248 if (MAX_RETRY < retry_count++) {
249 /* Unable to set timer value */
250 pr_err("Unable to set timer\n");
254 /* set the timer to the soft threshold */
255 iowrite32(watchdog_device.soft_threshold,
256 watchdog_device.timer_load_count_addr);
258 /* read count value before starting timer */
259 ioread32(watchdog_device.timer_load_count_addr);
261 /* Start the timer */
262 iowrite32(0x00000003, watchdog_device.timer_control_addr);
264 /* read the value the time loaded into its count reg */
265 hw_value = ioread32(watchdog_device.timer_load_count_addr);
266 hw_value = hw_value & 0xFFFF0000;
269 } while (soft_value != hw_value);
271 watchdog_device.timer_started = 1;
277 * /dev/watchdog handling
280 static int intel_scu_open(struct inode *inode, struct file *file)
283 /* Set flag to indicate that watchdog device is open */
284 if (test_and_set_bit(0, &watchdog_device.driver_open))
287 /* Check for reopen of driver. Reopens are not allowed */
288 if (watchdog_device.driver_closed)
291 return stream_open(inode, file);
294 static int intel_scu_release(struct inode *inode, struct file *file)
297 * This watchdog should not be closed, after the timer
298 * is started with the WDIPC_SETTIMEOUT ioctl
299 * If force_boot is set watchdog_fire() will cause an
300 * immediate reset. If force_boot is not set, the watchdog
301 * timer is refreshed for one more interval. At the end
302 * of that interval, the watchdog timer will reset the system.
305 if (!test_and_clear_bit(0, &watchdog_device.driver_open)) {
306 pr_debug("intel_scu_release, without open\n");
310 if (!watchdog_device.timer_started) {
311 /* Just close, since timer has not been started */
312 pr_debug("closed, without starting timer\n");
316 pr_crit("Unexpected close of /dev/watchdog!\n");
318 /* Since the timer was started, prevent future reopens */
319 watchdog_device.driver_closed = 1;
321 /* Refresh the timer for one more interval */
322 intel_scu_keepalive();
324 /* Reboot system (if force_boot is set) */
327 /* We should only reach this point if force_boot is not set */
331 static ssize_t intel_scu_write(struct file *file,
337 if (watchdog_device.timer_started)
338 /* Watchdog already started, keep it alive */
339 intel_scu_keepalive();
341 /* Start watchdog with timer value set by init */
342 intel_scu_set_heartbeat(watchdog_device.timer_set);
347 static long intel_scu_ioctl(struct file *file,
351 void __user *argp = (void __user *)arg;
352 u32 __user *p = argp;
356 static const struct watchdog_info ident = {
357 .options = WDIOF_SETTIMEOUT
358 | WDIOF_KEEPALIVEPING,
359 .firmware_version = 0, /* @todo Get from SCU via
360 ipc_get_scu_fw_version()? */
361 .identity = "Intel_SCU IOH Watchdog" /* len < 32 */
365 case WDIOC_GETSUPPORT:
366 return copy_to_user(argp,
368 sizeof(ident)) ? -EFAULT : 0;
369 case WDIOC_GETSTATUS:
370 case WDIOC_GETBOOTSTATUS:
371 return put_user(0, p);
372 case WDIOC_KEEPALIVE:
373 intel_scu_keepalive();
376 case WDIOC_SETTIMEOUT:
377 if (get_user(new_margin, p))
380 if (check_timer_margin(new_margin))
383 if (intel_scu_set_heartbeat(new_margin))
386 case WDIOC_GETTIMEOUT:
387 return put_user(watchdog_device.soft_threshold, p);
395 * Notifier for system down
397 static int intel_scu_notify_sys(struct notifier_block *this,
399 void *another_unused)
401 if (code == SYS_DOWN || code == SYS_HALT)
402 /* Turn off the watchdog timer. */
410 static const struct file_operations intel_scu_fops = {
411 .owner = THIS_MODULE,
413 .write = intel_scu_write,
414 .unlocked_ioctl = intel_scu_ioctl,
415 .open = intel_scu_open,
416 .release = intel_scu_release,
419 static int __init intel_scu_watchdog_init(void)
422 u32 __iomem *tmp_addr;
425 * We don't really need to check this as the SFI timer get will fail
426 * but if we do so we can exit with a clearer reason and no noise.
428 * If it isn't an intel MID device then it doesn't have this watchdog
430 if (!intel_mid_identify_cpu())
433 /* Check boot parameters to verify that their initial values */
435 /* Check value of timer_set boot parameter */
436 if ((timer_set < MIN_TIME_CYCLE) ||
437 (timer_set > MAX_TIME - MIN_TIME_CYCLE)) {
438 pr_err("value of timer_set %x (hex) is out of range from %x to %x (hex)\n",
439 timer_set, MIN_TIME_CYCLE, MAX_TIME - MIN_TIME_CYCLE);
443 /* Check value of timer_margin boot parameter */
444 if (check_timer_margin(timer_margin))
447 watchdog_device.timer_tbl_ptr = sfi_get_mtmr(sfi_mtimer_num-1);
449 if (watchdog_device.timer_tbl_ptr == NULL) {
450 pr_debug("timer is not available\n");
453 /* make sure the timer exists */
454 if (watchdog_device.timer_tbl_ptr->phys_addr == 0) {
455 pr_debug("timer %d does not have valid physical memory\n",
460 if (watchdog_device.timer_tbl_ptr->irq == 0) {
461 pr_debug("timer %d invalid irq\n", sfi_mtimer_num);
465 tmp_addr = ioremap_nocache(watchdog_device.timer_tbl_ptr->phys_addr,
468 if (tmp_addr == NULL) {
469 pr_debug("timer unable to ioremap\n");
473 watchdog_device.timer_load_count_addr = tmp_addr++;
474 watchdog_device.timer_current_value_addr = tmp_addr++;
475 watchdog_device.timer_control_addr = tmp_addr++;
476 watchdog_device.timer_clear_interrupt_addr = tmp_addr++;
477 watchdog_device.timer_interrupt_status_addr = tmp_addr++;
479 /* Set the default time values in device structure */
481 watchdog_device.timer_set = timer_set;
482 watchdog_device.threshold =
483 timer_margin * watchdog_device.timer_tbl_ptr->freq_hz;
484 watchdog_device.soft_threshold =
485 (watchdog_device.timer_set - timer_margin)
486 * watchdog_device.timer_tbl_ptr->freq_hz;
489 watchdog_device.intel_scu_notifier.notifier_call =
490 intel_scu_notify_sys;
492 ret = register_reboot_notifier(&watchdog_device.intel_scu_notifier);
494 pr_err("cannot register notifier %d)\n", ret);
495 goto register_reboot_error;
498 watchdog_device.miscdev.minor = WATCHDOG_MINOR;
499 watchdog_device.miscdev.name = "watchdog";
500 watchdog_device.miscdev.fops = &intel_scu_fops;
502 ret = misc_register(&watchdog_device.miscdev);
504 pr_err("cannot register miscdev %d err =%d\n",
505 WATCHDOG_MINOR, ret);
506 goto misc_register_error;
509 ret = request_irq((unsigned int)watchdog_device.timer_tbl_ptr->irq,
510 watchdog_timer_interrupt,
511 IRQF_SHARED, "watchdog",
512 &watchdog_device.timer_load_count_addr);
514 pr_err("error requesting irq %d\n", ret);
515 goto request_irq_error;
517 /* Make sure timer is disabled before returning */
524 misc_deregister(&watchdog_device.miscdev);
526 unregister_reboot_notifier(&watchdog_device.intel_scu_notifier);
527 register_reboot_error:
529 iounmap(watchdog_device.timer_load_count_addr);
532 late_initcall(intel_scu_watchdog_init);