2 * Octeon Watchdog driver
4 * Copyright (C) 2007, 2008, 2009, 2010 Cavium Networks
6 * Some parts derived from wdt.c
8 * (c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
16 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
17 * warranty for any of this software. This material is provided
18 * "AS-IS" and at no charge.
20 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
22 * This file is subject to the terms and conditions of the GNU General Public
23 * License. See the file "COPYING" in the main directory of this archive
27 * The OCTEON watchdog has a maximum timeout of 2^32 * io_clock.
28 * For most systems this is less than 10 seconds, so to allow for
29 * software to request longer watchdog heartbeats, we maintain software
30 * counters to count multiples of the base rate. If the system locks
31 * up in such a manner that we can not run the software counters, the
32 * only result is a watchdog reset sooner than was requested. But
33 * that is OK, because in this case userspace would likely not be able
34 * to do anything anyhow.
36 * The hardware watchdog interval we call the period. The OCTEON
37 * watchdog goes through several stages, after the first period an
38 * irq is asserted, then if it is not reset, after the next period NMI
39 * is asserted, then after an additional period a chip wide soft reset.
40 * So for the software counters, we reset watchdog after each period
41 * and decrement the counter. But for the last two periods we need to
42 * let the watchdog progress to the NMI stage so we disable the irq
43 * and let it proceed. Once in the NMI, we print the register state
44 * to the serial port and then wait for the reset.
46 * A watchdog is maintained for each CPU in the system, that way if
47 * one CPU suffers a lockup, we also get a register dump and reset.
48 * The userspace ping resets the watchdog on all CPUs.
50 * Before userspace opens the watchdog device, we still run the
51 * watchdogs to catch any lockups that may be kernel related.
55 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
57 #include <linux/miscdevice.h>
58 #include <linux/interrupt.h>
59 #include <linux/watchdog.h>
60 #include <linux/cpumask.h>
61 #include <linux/bitops.h>
62 #include <linux/kernel.h>
63 #include <linux/module.h>
64 #include <linux/string.h>
65 #include <linux/delay.h>
66 #include <linux/cpu.h>
67 #include <linux/smp.h>
69 #include <linux/irq.h>
71 #include <asm/mipsregs.h>
74 #include <asm/octeon/octeon.h>
76 /* The count needed to achieve timeout_sec. */
77 static unsigned int timeout_cnt
;
79 /* The maximum period supported. */
80 static unsigned int max_timeout_sec
;
82 /* The current period. */
83 static unsigned int timeout_sec
;
85 /* Set to non-zero when userspace countdown mode active */
86 static int do_coundown
;
87 static unsigned int countdown_reset
;
88 static unsigned int per_cpu_countdown
[NR_CPUS
];
90 static cpumask_t irq_enabled_cpus
;
92 #define WD_TIMO 60 /* Default heartbeat = 60 seconds */
94 static int heartbeat
= WD_TIMO
;
95 module_param(heartbeat
, int, S_IRUGO
);
96 MODULE_PARM_DESC(heartbeat
,
97 "Watchdog heartbeat in seconds. (0 < heartbeat, default="
98 __MODULE_STRING(WD_TIMO
) ")");
100 static bool nowayout
= WATCHDOG_NOWAYOUT
;
101 module_param(nowayout
, bool, S_IRUGO
);
102 MODULE_PARM_DESC(nowayout
,
103 "Watchdog cannot be stopped once started (default="
104 __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");
106 static unsigned long octeon_wdt_is_open
;
107 static char expect_close
;
109 static u32 __initdata nmi_stage1_insns
[64];
110 /* We need one branch and therefore one relocation per target label. */
111 static struct uasm_label __initdata labels
[5];
112 static struct uasm_reloc __initdata relocs
[5];
115 label_enter_bootloader
= 1
118 /* Some CP0 registers */
120 #define C0_CVMMEMCTL 11, 7
121 #define C0_STATUS 12, 0
122 #define C0_EBASE 15, 1
123 #define C0_DESAVE 31, 0
125 void octeon_wdt_nmi_stage2(void);
127 static void __init
octeon_wdt_build_stage1(void)
131 u32
*p
= nmi_stage1_insns
;
132 #ifdef CONFIG_HOTPLUG_CPU
133 struct uasm_label
*l
= labels
;
134 struct uasm_reloc
*r
= relocs
;
138 * For the next few instructions running the debugger may
139 * cause corruption of k0 in the saved registers. Since we're
140 * about to crash, nobody probably cares.
142 * Save K0 into the debug scratch register
144 uasm_i_dmtc0(&p
, K0
, C0_DESAVE
);
146 uasm_i_mfc0(&p
, K0
, C0_STATUS
);
147 #ifdef CONFIG_HOTPLUG_CPU
148 if (octeon_bootloader_entry_addr
)
149 uasm_il_bbit0(&p
, &r
, K0
, ilog2(ST0_NMI
),
150 label_enter_bootloader
);
152 /* Force 64-bit addressing enabled */
153 uasm_i_ori(&p
, K0
, K0
, ST0_UX
| ST0_SX
| ST0_KX
);
154 uasm_i_mtc0(&p
, K0
, C0_STATUS
);
156 #ifdef CONFIG_HOTPLUG_CPU
157 if (octeon_bootloader_entry_addr
) {
158 uasm_i_mfc0(&p
, K0
, C0_EBASE
);
159 /* Coreid number in K0 */
160 uasm_i_andi(&p
, K0
, K0
, 0xf);
161 /* 8 * coreid in bits 16-31 */
162 uasm_i_dsll_safe(&p
, K0
, K0
, 3 + 16);
163 uasm_i_ori(&p
, K0
, K0
, 0x8001);
164 uasm_i_dsll_safe(&p
, K0
, K0
, 16);
165 uasm_i_ori(&p
, K0
, K0
, 0x0700);
166 uasm_i_drotr_safe(&p
, K0
, K0
, 32);
168 * Should result in: 0x8001,0700,0000,8*coreid which is
169 * CVMX_CIU_WDOGX(coreid) - 0x0500
171 * Now ld K0, CVMX_CIU_WDOGX(coreid)
173 uasm_i_ld(&p
, K0
, 0x500, K0
);
175 * If bit one set handle the NMI as a watchdog event.
176 * otherwise transfer control to bootloader.
178 uasm_il_bbit0(&p
, &r
, K0
, 1, label_enter_bootloader
);
183 /* Clear Dcache so cvmseg works right. */
184 uasm_i_cache(&p
, 1, 0, 0);
186 /* Use K0 to do a read/modify/write of CVMMEMCTL */
187 uasm_i_dmfc0(&p
, K0
, C0_CVMMEMCTL
);
188 /* Clear out the size of CVMSEG */
189 uasm_i_dins(&p
, K0
, 0, 0, 6);
190 /* Set CVMSEG to its largest value */
191 uasm_i_ori(&p
, K0
, K0
, 0x1c0 | 54);
192 /* Store the CVMMEMCTL value */
193 uasm_i_dmtc0(&p
, K0
, C0_CVMMEMCTL
);
195 /* Load the address of the second stage handler */
196 UASM_i_LA(&p
, K0
, (long)octeon_wdt_nmi_stage2
);
198 uasm_i_dmfc0(&p
, K0
, C0_DESAVE
);
200 #ifdef CONFIG_HOTPLUG_CPU
201 if (octeon_bootloader_entry_addr
) {
202 uasm_build_label(&l
, p
, label_enter_bootloader
);
203 /* Jump to the bootloader and restore K0 */
204 UASM_i_LA(&p
, K0
, (long)octeon_bootloader_entry_addr
);
206 uasm_i_dmfc0(&p
, K0
, C0_DESAVE
);
209 uasm_resolve_relocs(relocs
, labels
);
211 len
= (int)(p
- nmi_stage1_insns
);
212 pr_debug("Synthesized NMI stage 1 handler (%d instructions)\n", len
);
214 pr_debug("\t.set push\n");
215 pr_debug("\t.set noreorder\n");
216 for (i
= 0; i
< len
; i
++)
217 pr_debug("\t.word 0x%08x\n", nmi_stage1_insns
[i
]);
218 pr_debug("\t.set pop\n");
221 panic("NMI stage 1 handler exceeds 32 instructions, was %d\n", len
);
224 static int cpu2core(int cpu
)
227 return cpu_logical_map(cpu
);
229 return cvmx_get_core_num();
233 static int core2cpu(int coreid
)
236 return cpu_number_map(coreid
);
243 * Poke the watchdog when an interrupt is received
250 static irqreturn_t
octeon_wdt_poke_irq(int cpl
, void *dev_id
)
252 unsigned int core
= cvmx_get_core_num();
253 int cpu
= core2cpu(core
);
256 if (per_cpu_countdown
[cpu
] > 0) {
257 /* We're alive, poke the watchdog */
258 cvmx_write_csr(CVMX_CIU_PP_POKEX(core
), 1);
259 per_cpu_countdown
[cpu
]--;
261 /* Bad news, you are about to reboot. */
262 disable_irq_nosync(cpl
);
263 cpumask_clear_cpu(cpu
, &irq_enabled_cpus
);
266 /* Not open, just ping away... */
267 cvmx_write_csr(CVMX_CIU_PP_POKEX(core
), 1);
273 extern int prom_putchar(char c
);
276 * Write a string to the uart
278 * @str: String to write
280 static void octeon_wdt_write_string(const char *str
)
282 /* Just loop writing one byte at a time */
284 prom_putchar(*str
++);
288 * Write a hex number out of the uart
290 * @value: Number to display
291 * @digits: Number of digits to print (1 to 16)
293 static void octeon_wdt_write_hex(u64 value
, int digits
)
297 for (d
= 0; d
< digits
; d
++) {
298 v
= (value
>> ((digits
- d
- 1) * 4)) & 0xf;
300 prom_putchar('a' + v
- 10);
302 prom_putchar('0' + v
);
306 const char *reg_name
[] = {
307 "$0", "at", "v0", "v1", "a0", "a1", "a2", "a3",
308 "a4", "a5", "a6", "a7", "t0", "t1", "t2", "t3",
309 "s0", "s1", "s2", "s3", "s4", "s5", "s6", "s7",
310 "t8", "t9", "k0", "k1", "gp", "sp", "s8", "ra"
314 * NMI stage 3 handler. NMIs are handled in the following manner:
315 * 1) The first NMI handler enables CVMSEG and transfers from
316 * the bootbus region into normal memory. It is careful to not
317 * destroy any registers.
318 * 2) The second stage handler uses CVMSEG to save the registers
319 * and create a stack for C code. It then calls the third level
320 * handler with one argument, a pointer to the register values.
321 * 3) The third, and final, level handler is the following C
322 * function that prints out some useful infomration.
324 * @reg: Pointer to register state before the NMI
326 void octeon_wdt_nmi_stage3(u64 reg
[32])
330 unsigned int coreid
= cvmx_get_core_num();
332 * Save status and cause early to get them before any changes
335 u64 cp0_cause
= read_c0_cause();
336 u64 cp0_status
= read_c0_status();
337 u64 cp0_error_epc
= read_c0_errorepc();
338 u64 cp0_epc
= read_c0_epc();
340 /* Delay so output from all cores output is not jumbled together. */
341 __delay(100000000ull * coreid
);
343 octeon_wdt_write_string("\r\n*** NMI Watchdog interrupt on Core 0x");
344 octeon_wdt_write_hex(coreid
, 1);
345 octeon_wdt_write_string(" ***\r\n");
346 for (i
= 0; i
< 32; i
++) {
347 octeon_wdt_write_string("\t");
348 octeon_wdt_write_string(reg_name
[i
]);
349 octeon_wdt_write_string("\t0x");
350 octeon_wdt_write_hex(reg
[i
], 16);
352 octeon_wdt_write_string("\r\n");
354 octeon_wdt_write_string("\terr_epc\t0x");
355 octeon_wdt_write_hex(cp0_error_epc
, 16);
357 octeon_wdt_write_string("\tepc\t0x");
358 octeon_wdt_write_hex(cp0_epc
, 16);
359 octeon_wdt_write_string("\r\n");
361 octeon_wdt_write_string("\tstatus\t0x");
362 octeon_wdt_write_hex(cp0_status
, 16);
363 octeon_wdt_write_string("\tcause\t0x");
364 octeon_wdt_write_hex(cp0_cause
, 16);
365 octeon_wdt_write_string("\r\n");
367 octeon_wdt_write_string("\tsum0\t0x");
368 octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU_INTX_SUM0(coreid
* 2)), 16);
369 octeon_wdt_write_string("\ten0\t0x");
370 octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU_INTX_EN0(coreid
* 2)), 16);
371 octeon_wdt_write_string("\r\n");
373 octeon_wdt_write_string("*** Chip soft reset soon ***\r\n");
376 static void octeon_wdt_disable_interrupt(int cpu
)
380 union cvmx_ciu_wdogx ciu_wdog
;
382 core
= cpu2core(cpu
);
384 irq
= OCTEON_IRQ_WDOG0
+ core
;
386 /* Poke the watchdog to clear out its state */
387 cvmx_write_csr(CVMX_CIU_PP_POKEX(core
), 1);
389 /* Disable the hardware. */
391 cvmx_write_csr(CVMX_CIU_WDOGX(core
), ciu_wdog
.u64
);
393 free_irq(irq
, octeon_wdt_poke_irq
);
396 static void octeon_wdt_setup_interrupt(int cpu
)
400 union cvmx_ciu_wdogx ciu_wdog
;
402 core
= cpu2core(cpu
);
404 /* Disable it before doing anything with the interrupts. */
406 cvmx_write_csr(CVMX_CIU_WDOGX(core
), ciu_wdog
.u64
);
408 per_cpu_countdown
[cpu
] = countdown_reset
;
410 irq
= OCTEON_IRQ_WDOG0
+ core
;
412 if (request_irq(irq
, octeon_wdt_poke_irq
,
413 IRQF_NO_THREAD
, "octeon_wdt", octeon_wdt_poke_irq
))
414 panic("octeon_wdt: Couldn't obtain irq %d", irq
);
416 cpumask_set_cpu(cpu
, &irq_enabled_cpus
);
418 /* Poke the watchdog to clear out its state */
419 cvmx_write_csr(CVMX_CIU_PP_POKEX(core
), 1);
421 /* Finally enable the watchdog now that all handlers are installed */
423 ciu_wdog
.s
.len
= timeout_cnt
;
424 ciu_wdog
.s
.mode
= 3; /* 3 = Interrupt + NMI + Soft-Reset */
425 cvmx_write_csr(CVMX_CIU_WDOGX(core
), ciu_wdog
.u64
);
428 static int octeon_wdt_cpu_callback(struct notifier_block
*nfb
,
429 unsigned long action
, void *hcpu
)
431 unsigned int cpu
= (unsigned long)hcpu
;
434 case CPU_DOWN_PREPARE
:
435 octeon_wdt_disable_interrupt(cpu
);
438 case CPU_DOWN_FAILED
:
439 octeon_wdt_setup_interrupt(cpu
);
447 static void octeon_wdt_ping(void)
452 for_each_online_cpu(cpu
) {
453 coreid
= cpu2core(cpu
);
454 cvmx_write_csr(CVMX_CIU_PP_POKEX(coreid
), 1);
455 per_cpu_countdown
[cpu
] = countdown_reset
;
456 if ((countdown_reset
|| !do_coundown
) &&
457 !cpumask_test_cpu(cpu
, &irq_enabled_cpus
)) {
458 /* We have to enable the irq */
459 int irq
= OCTEON_IRQ_WDOG0
+ coreid
;
461 cpumask_set_cpu(cpu
, &irq_enabled_cpus
);
466 static void octeon_wdt_calc_parameters(int t
)
468 unsigned int periods
;
470 timeout_sec
= max_timeout_sec
;
474 * Find the largest interrupt period, that can evenly divide
475 * the requested heartbeat time.
477 while ((t
% timeout_sec
) != 0)
480 periods
= t
/ timeout_sec
;
483 * The last two periods are after the irq is disabled, and
484 * then to the nmi, so we subtract them off.
487 countdown_reset
= periods
> 2 ? periods
- 2 : 0;
489 timeout_cnt
= ((octeon_get_io_clock_rate() >> 8) * timeout_sec
) >> 8;
492 static int octeon_wdt_set_heartbeat(int t
)
496 union cvmx_ciu_wdogx ciu_wdog
;
501 octeon_wdt_calc_parameters(t
);
503 for_each_online_cpu(cpu
) {
504 coreid
= cpu2core(cpu
);
505 cvmx_write_csr(CVMX_CIU_PP_POKEX(coreid
), 1);
507 ciu_wdog
.s
.len
= timeout_cnt
;
508 ciu_wdog
.s
.mode
= 3; /* 3 = Interrupt + NMI + Soft-Reset */
509 cvmx_write_csr(CVMX_CIU_WDOGX(coreid
), ciu_wdog
.u64
);
510 cvmx_write_csr(CVMX_CIU_PP_POKEX(coreid
), 1);
512 octeon_wdt_ping(); /* Get the irqs back on. */
518 * @file: file handle to the watchdog
519 * @buf: buffer to write (unused as data does not matter here
520 * @count: count of bytes
521 * @ppos: pointer to the position to write. No seeks allowed
523 * A write to a watchdog device is defined as a keepalive signal. Any
524 * write of data will do, as we we don't define content meaning.
527 static ssize_t
octeon_wdt_write(struct file
*file
, const char __user
*buf
,
528 size_t count
, loff_t
*ppos
)
534 /* In case it was set long ago */
537 for (i
= 0; i
!= count
; i
++) {
539 if (get_user(c
, buf
+ i
))
552 * @file: file handle to the device
553 * @cmd: watchdog command
554 * @arg: argument pointer
556 * The watchdog API defines a common set of functions for all
557 * watchdogs according to their available features. We only
558 * actually usefully support querying capabilities and setting
562 static long octeon_wdt_ioctl(struct file
*file
, unsigned int cmd
,
565 void __user
*argp
= (void __user
*)arg
;
566 int __user
*p
= argp
;
569 static struct watchdog_info ident
= {
570 .options
= WDIOF_SETTIMEOUT
|
573 .firmware_version
= 1,
574 .identity
= "OCTEON",
578 case WDIOC_GETSUPPORT
:
579 return copy_to_user(argp
, &ident
, sizeof(ident
)) ? -EFAULT
: 0;
580 case WDIOC_GETSTATUS
:
581 case WDIOC_GETBOOTSTATUS
:
582 return put_user(0, p
);
583 case WDIOC_KEEPALIVE
:
586 case WDIOC_SETTIMEOUT
:
587 if (get_user(new_heartbeat
, p
))
589 if (octeon_wdt_set_heartbeat(new_heartbeat
))
592 case WDIOC_GETTIMEOUT
:
593 return put_user(heartbeat
, p
);
601 * @inode: inode of device
602 * @file: file handle to device
604 * The watchdog device has been opened. The watchdog device is single
605 * open and on opening we do a ping to reset the counters.
608 static int octeon_wdt_open(struct inode
*inode
, struct file
*file
)
610 if (test_and_set_bit(0, &octeon_wdt_is_open
))
617 return nonseekable_open(inode
, file
);
621 * octeon_wdt_release:
622 * @inode: inode to board
623 * @file: file handle to board
625 * The watchdog has a configurable API. There is a religious dispute
626 * between people who want their watchdog to be able to shut down and
627 * those who want to be sure if the watchdog manager dies the machine
628 * reboots. In the former case we disable the counters, in the latter
629 * case you have to open it again very soon.
632 static int octeon_wdt_release(struct inode
*inode
, struct file
*file
)
638 pr_crit("WDT device closed unexpectedly. WDT will not stop!\n");
640 clear_bit(0, &octeon_wdt_is_open
);
645 static const struct file_operations octeon_wdt_fops
= {
646 .owner
= THIS_MODULE
,
648 .write
= octeon_wdt_write
,
649 .unlocked_ioctl
= octeon_wdt_ioctl
,
650 .open
= octeon_wdt_open
,
651 .release
= octeon_wdt_release
,
654 static struct miscdevice octeon_wdt_miscdev
= {
655 .minor
= WATCHDOG_MINOR
,
657 .fops
= &octeon_wdt_fops
,
660 static struct notifier_block octeon_wdt_cpu_notifier
= {
661 .notifier_call
= octeon_wdt_cpu_callback
,
666 * Module/ driver initialization.
668 * Returns Zero on success
670 static int __init
octeon_wdt_init(void)
678 * Watchdog time expiration length = The 16 bits of LEN
679 * represent the most significant bits of a 24 bit decrementer
680 * that decrements every 256 cycles.
682 * Try for a timeout of 5 sec, if that fails a smaller number
688 timeout_cnt
= ((octeon_get_io_clock_rate() >> 8) * max_timeout_sec
) >> 8;
689 } while (timeout_cnt
> 65535);
691 BUG_ON(timeout_cnt
== 0);
693 octeon_wdt_calc_parameters(heartbeat
);
695 pr_info("Initial granularity %d Sec\n", timeout_sec
);
697 ret
= misc_register(&octeon_wdt_miscdev
);
699 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
700 WATCHDOG_MINOR
, ret
);
704 /* Build the NMI handler ... */
705 octeon_wdt_build_stage1();
707 /* ... and install it. */
708 ptr
= (u64
*) nmi_stage1_insns
;
709 for (i
= 0; i
< 16; i
++) {
710 cvmx_write_csr(CVMX_MIO_BOOT_LOC_ADR
, i
* 8);
711 cvmx_write_csr(CVMX_MIO_BOOT_LOC_DAT
, ptr
[i
]);
713 cvmx_write_csr(CVMX_MIO_BOOT_LOC_CFGX(0), 0x81fc0000);
715 cpumask_clear(&irq_enabled_cpus
);
717 cpu_notifier_register_begin();
718 for_each_online_cpu(cpu
)
719 octeon_wdt_setup_interrupt(cpu
);
721 __register_hotcpu_notifier(&octeon_wdt_cpu_notifier
);
722 cpu_notifier_register_done();
729 * Module / driver shutdown
731 static void __exit
octeon_wdt_cleanup(void)
735 misc_deregister(&octeon_wdt_miscdev
);
737 cpu_notifier_register_begin();
738 __unregister_hotcpu_notifier(&octeon_wdt_cpu_notifier
);
740 for_each_online_cpu(cpu
) {
741 int core
= cpu2core(cpu
);
742 /* Disable the watchdog */
743 cvmx_write_csr(CVMX_CIU_WDOGX(core
), 0);
744 /* Free the interrupt handler */
745 free_irq(OCTEON_IRQ_WDOG0
+ core
, octeon_wdt_poke_irq
);
748 cpu_notifier_register_done();
751 * Disable the boot-bus memory, the code it points to is soon
754 cvmx_write_csr(CVMX_MIO_BOOT_LOC_CFGX(0), 0);
757 MODULE_LICENSE("GPL");
758 MODULE_AUTHOR("Cavium Networks <support@caviumnetworks.com>");
759 MODULE_DESCRIPTION("Cavium Networks Octeon Watchdog driver.");
760 module_init(octeon_wdt_init
);
761 module_exit(octeon_wdt_cleanup
);