/*
* Octeon Watchdog driver
*
* Copyright (C) 2007, 2008, 2009, 2010 Cavium Networks
*
* Some parts derived from wdt.c
*
* (c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
* warranty for any of this software. This material is provided
* "AS-IS" and at no charge.
*
* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
*
* The OCTEON watchdog has a maximum timeout of 2^32 * io_clock.
* For most systems this is less than 10 seconds, so to allow for
* software to request longer watchdog heartbeats, we maintain software
* counters to count multiples of the base rate. If the system locks
* up in such a manner that we can not run the software counters, the
* only result is a watchdog reset sooner than was requested. But
* that is OK, because in this case userspace would likely not be able
* to do anything anyhow.
*
* The hardware watchdog interval we call the period. The OCTEON
* watchdog goes through several stages, after the first period an
* irq is asserted, then if it is not reset, after the next period NMI
* is asserted, then after an additional period a chip wide soft reset.
* So for the software counters, we reset watchdog after each period
* and decrement the counter. But for the last two periods we need to
* let the watchdog progress to the NMI stage so we disable the irq
* and let it proceed. Once in the NMI, we print the register state
* to the serial port and then wait for the reset.
*
* A watchdog is maintained for each CPU in the system, that way if
* one CPU suffers a lockup, we also get a register dump and reset.
* The userspace ping resets the watchdog on all CPUs.
*
* Before userspace opens the watchdog device, we still run the
* watchdogs to catch any lockups that may be kernel related.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/miscdevice.h>
#include <linux/interrupt.h>
#include <linux/watchdog.h>
#include <linux/cpumask.h>
#include <linux/bitops.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/fs.h>
#include <linux/irq.h>
#include <asm/mipsregs.h>
#include <asm/uasm.h>
#include <asm/octeon/octeon.h>
/* The count needed to achieve timeout_sec. */
static unsigned int timeout_cnt;
/* The maximum period supported. */
static unsigned int max_timeout_sec;
/* The current period. */
static unsigned int timeout_sec;
/* Set to non-zero when userspace countdown mode active */
static int do_coundown;
static unsigned int countdown_reset;
static unsigned int per_cpu_countdown[NR_CPUS];
static cpumask_t irq_enabled_cpus;
#define WD_TIMO 60 /* Default heartbeat = 60 seconds */
static int heartbeat = WD_TIMO;
module_param(heartbeat, int, S_IRUGO);
MODULE_PARM_DESC(heartbeat,
"Watchdog heartbeat in seconds. (0 < heartbeat, default="
__MODULE_STRING(WD_TIMO) ")");
static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, S_IRUGO);
MODULE_PARM_DESC(nowayout,
"Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
static unsigned long octeon_wdt_is_open;
static char expect_close;
static u32 __initdata nmi_stage1_insns[64];
/* We need one branch and therefore one relocation per target label. */
static struct uasm_label __initdata labels[5];
static struct uasm_reloc __initdata relocs[5];
enum lable_id {
label_enter_bootloader = 1
};
/* Some CP0 registers */
#define K0 26
#define C0_CVMMEMCTL 11, 7
#define C0_STATUS 12, 0
#define C0_EBASE 15, 1
#define C0_DESAVE 31, 0
void octeon_wdt_nmi_stage2(void);
static void __init octeon_wdt_build_stage1(void)
{
int i;
int len;
u32 *p = nmi_stage1_insns;
#ifdef CONFIG_HOTPLUG_CPU
struct uasm_label *l = labels;
struct uasm_reloc *r = relocs;
#endif
/*
* For the next few instructions running the debugger may
* cause corruption of k0 in the saved registers. Since we're
* about to crash, nobody probably cares.
*
* Save K0 into the debug scratch register
*/
uasm_i_dmtc0(&p, K0, C0_DESAVE);
uasm_i_mfc0(&p, K0, C0_STATUS);
#ifdef CONFIG_HOTPLUG_CPU
uasm_il_bbit0(&p, &r, K0, ilog2(ST0_NMI), label_enter_bootloader);
#endif
/* Force 64-bit addressing enabled */
uasm_i_ori(&p, K0, K0, ST0_UX | ST0_SX | ST0_KX);
uasm_i_mtc0(&p, K0, C0_STATUS);
#ifdef CONFIG_HOTPLUG_CPU
uasm_i_mfc0(&p, K0, C0_EBASE);
/* Coreid number in K0 */
uasm_i_andi(&p, K0, K0, 0xf);
/* 8 * coreid in bits 16-31 */
uasm_i_dsll_safe(&p, K0, K0, 3 + 16);
uasm_i_ori(&p, K0, K0, 0x8001);
uasm_i_dsll_safe(&p, K0, K0, 16);
uasm_i_ori(&p, K0, K0, 0x0700);
uasm_i_drotr_safe(&p, K0, K0, 32);
/*
* Should result in: 0x8001,0700,0000,8*coreid which is
* CVMX_CIU_WDOGX(coreid) - 0x0500
*
* Now ld K0, CVMX_CIU_WDOGX(coreid)
*/
uasm_i_ld(&p, K0, 0x500, K0);
/*
* If bit one set handle the NMI as a watchdog event.
* otherwise transfer control to bootloader.
*/
uasm_il_bbit0(&p, &r, K0, 1, label_enter_bootloader);
uasm_i_nop(&p);
#endif
/* Clear Dcache so cvmseg works right. */
uasm_i_cache(&p, 1, 0, 0);
/* Use K0 to do a read/modify/write of CVMMEMCTL */
uasm_i_dmfc0(&p, K0, C0_CVMMEMCTL);
/* Clear out the size of CVMSEG */
uasm_i_dins(&p, K0, 0, 0, 6);
/* Set CVMSEG to its largest value */
uasm_i_ori(&p, K0, K0, 0x1c0 | 54);
/* Store the CVMMEMCTL value */
uasm_i_dmtc0(&p, K0, C0_CVMMEMCTL);
/* Load the address of the second stage handler */
UASM_i_LA(&p, K0, (long)octeon_wdt_nmi_stage2);
uasm_i_jr(&p, K0);
uasm_i_dmfc0(&p, K0, C0_DESAVE);
#ifdef CONFIG_HOTPLUG_CPU
uasm_build_label(&l, p, label_enter_bootloader);
/* Jump to the bootloader and restore K0 */
UASM_i_LA(&p, K0, (long)octeon_bootloader_entry_addr);
uasm_i_jr(&p, K0);
uasm_i_dmfc0(&p, K0, C0_DESAVE);
#endif
uasm_resolve_relocs(relocs, labels);
len = (int)(p - nmi_stage1_insns);
pr_debug("Synthesized NMI stage 1 handler (%d instructions)\n", len);
pr_debug("\t.set push\n");
pr_debug("\t.set noreorder\n");
for (i = 0; i < len; i++)
pr_debug("\t.word 0x%08x\n", nmi_stage1_insns[i]);
pr_debug("\t.set pop\n");
if (len > 32)
panic("NMI stage 1 handler exceeds 32 instructions, was %d\n", len);
}
static int cpu2core(int cpu)
{
#ifdef CONFIG_SMP
return cpu_logical_map(cpu);
#else
return cvmx_get_core_num();
#endif
}
static int core2cpu(int coreid)
{
#ifdef CONFIG_SMP
return cpu_number_map(coreid);
#else
return 0;
#endif
}
/**
* Poke the watchdog when an interrupt is received
*
* @cpl:
* @dev_id:
*
* Returns
*/
static irqreturn_t octeon_wdt_poke_irq(int cpl, void *dev_id)
{
unsigned int core = cvmx_get_core_num();
int cpu = core2cpu(core);
if (do_coundown) {
if (per_cpu_countdown[cpu] > 0) {
/* We're alive, poke the watchdog */
cvmx_write_csr(CVMX_CIU_PP_POKEX(core), 1);
per_cpu_countdown[cpu]--;
} else {
/* Bad news, you are about to reboot. */
disable_irq_nosync(cpl);
cpumask_clear_cpu(cpu, &irq_enabled_cpus);
}
} else {
/* Not open, just ping away... */
cvmx_write_csr(CVMX_CIU_PP_POKEX(core), 1);
}
return IRQ_HANDLED;
}
/* From setup.c */
extern int prom_putchar(char c);
/**
* Write a string to the uart
*
* @str: String to write
*/
static void octeon_wdt_write_string(const char *str)
{
/* Just loop writing one byte at a time */
while (*str)
prom_putchar(*str++);
}
/**
* Write a hex number out of the uart
*
* @value: Number to display
* @digits: Number of digits to print (1 to 16)
*/
static void octeon_wdt_write_hex(u64 value, int digits)
{
int d;
int v;
for (d = 0; d < digits; d++) {
v = (value >> ((digits - d - 1) * 4)) & 0xf;
if (v >= 10)
prom_putchar('a' + v - 10);
else
prom_putchar('0' + v);
}
}
const char *reg_name[] = {
"$0", "at", "v0", "v1", "a0", "a1", "a2", "a3",
"a4", "a5", "a6", "a7", "t0", "t1", "t2", "t3",
"s0", "s1", "s2", "s3", "s4", "s5", "s6", "s7",
"t8", "t9", "k0", "k1", "gp", "sp", "s8", "ra"
};
/**
* NMI stage 3 handler. NMIs are handled in the following manner:
* 1) The first NMI handler enables CVMSEG and transfers from
* the bootbus region into normal memory. It is careful to not
* destroy any registers.
* 2) The second stage handler uses CVMSEG to save the registers
* and create a stack for C code. It then calls the third level
* handler with one argument, a pointer to the register values.
* 3) The third, and final, level handler is the following C
* function that prints out some useful infomration.
*
* @reg: Pointer to register state before the NMI
*/
void octeon_wdt_nmi_stage3(u64 reg[32])
{
u64 i;
unsigned int coreid = cvmx_get_core_num();
/*
* Save status and cause early to get them before any changes
* might happen.
*/
u64 cp0_cause = read_c0_cause();
u64 cp0_status = read_c0_status();
u64 cp0_error_epc = read_c0_errorepc();
u64 cp0_epc = read_c0_epc();
/* Delay so output from all cores output is not jumbled together. */
__delay(100000000ull * coreid);
octeon_wdt_write_string("\r\n*** NMI Watchdog interrupt on Core 0x");
octeon_wdt_write_hex(coreid, 1);
octeon_wdt_write_string(" ***\r\n");
for (i = 0; i < 32; i++) {
octeon_wdt_write_string("\t");
octeon_wdt_write_string(reg_name[i]);
octeon_wdt_write_string("\t0x");
octeon_wdt_write_hex(reg[i], 16);
if (i & 1)
octeon_wdt_write_string("\r\n");
}
octeon_wdt_write_string("\terr_epc\t0x");
octeon_wdt_write_hex(cp0_error_epc, 16);
octeon_wdt_write_string("\tepc\t0x");
octeon_wdt_write_hex(cp0_epc, 16);
octeon_wdt_write_string("\r\n");
octeon_wdt_write_string("\tstatus\t0x");
octeon_wdt_write_hex(cp0_status, 16);
octeon_wdt_write_string("\tcause\t0x");
octeon_wdt_write_hex(cp0_cause, 16);
octeon_wdt_write_string("\r\n");
octeon_wdt_write_string("\tsum0\t0x");
octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU_INTX_SUM0(coreid * 2)), 16);
octeon_wdt_write_string("\ten0\t0x");
octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU_INTX_EN0(coreid * 2)), 16);
octeon_wdt_write_string("\r\n");
octeon_wdt_write_string("*** Chip soft reset soon ***\r\n");
}
static void octeon_wdt_disable_interrupt(int cpu)
{
unsigned int core;
unsigned int irq;
union cvmx_ciu_wdogx ciu_wdog;
core = cpu2core(cpu);
irq = OCTEON_IRQ_WDOG0 + core;
/* Poke the watchdog to clear out its state */
cvmx_write_csr(CVMX_CIU_PP_POKEX(core), 1);
/* Disable the hardware. */
ciu_wdog.u64 = 0;
cvmx_write_csr(CVMX_CIU_WDOGX(core), ciu_wdog.u64);
free_irq(irq, octeon_wdt_poke_irq);
}
static void octeon_wdt_setup_interrupt(int cpu)
{
unsigned int core;
unsigned int irq;
union cvmx_ciu_wdogx ciu_wdog;
core = cpu2core(cpu);
/* Disable it before doing anything with the interrupts. */
ciu_wdog.u64 = 0;
cvmx_write_csr(CVMX_CIU_WDOGX(core), ciu_wdog.u64);
per_cpu_countdown[cpu] = countdown_reset;
irq = OCTEON_IRQ_WDOG0 + core;
if (request_irq(irq, octeon_wdt_poke_irq,
IRQF_NO_THREAD, "octeon_wdt", octeon_wdt_poke_irq))
panic("octeon_wdt: Couldn't obtain irq %d", irq);
cpumask_set_cpu(cpu, &irq_enabled_cpus);
/* Poke the watchdog to clear out its state */
cvmx_write_csr(CVMX_CIU_PP_POKEX(core), 1);
/* Finally enable the watchdog now that all handlers are installed */
ciu_wdog.u64 = 0;
ciu_wdog.s.len = timeout_cnt;
ciu_wdog.s.mode = 3; /* 3 = Interrupt + NMI + Soft-Reset */
cvmx_write_csr(CVMX_CIU_WDOGX(core), ciu_wdog.u64);
}
static int octeon_wdt_cpu_callback(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
switch (action) {
case CPU_DOWN_PREPARE:
octeon_wdt_disable_interrupt(cpu);
break;
case CPU_ONLINE:
case CPU_DOWN_FAILED:
octeon_wdt_setup_interrupt(cpu);
break;
default:
break;
}
return NOTIFY_OK;
}
static void octeon_wdt_ping(void)
{
int cpu;
int coreid;
for_each_online_cpu(cpu) {
coreid = cpu2core(cpu);
cvmx_write_csr(CVMX_CIU_PP_POKEX(coreid), 1);
per_cpu_countdown[cpu] = countdown_reset;
if ((countdown_reset || !do_coundown) &&
!cpumask_test_cpu(cpu, &irq_enabled_cpus)) {
/* We have to enable the irq */
int irq = OCTEON_IRQ_WDOG0 + coreid;
enable_irq(irq);
cpumask_set_cpu(cpu, &irq_enabled_cpus);
}
}
}
static void octeon_wdt_calc_parameters(int t)
{
unsigned int periods;
timeout_sec = max_timeout_sec;
/*
* Find the largest interrupt period, that can evenly divide
* the requested heartbeat time.
*/
while ((t % timeout_sec) != 0)
timeout_sec--;
periods = t / timeout_sec;
/*
* The last two periods are after the irq is disabled, and
* then to the nmi, so we subtract them off.
*/
countdown_reset = periods > 2 ? periods - 2 : 0;
heartbeat = t;
timeout_cnt = ((octeon_get_io_clock_rate() >> 8) * timeout_sec) >> 8;
}
static int octeon_wdt_set_heartbeat(int t)
{
int cpu;
int coreid;
union cvmx_ciu_wdogx ciu_wdog;
if (t <= 0)
return -1;
octeon_wdt_calc_parameters(t);
for_each_online_cpu(cpu) {
coreid = cpu2core(cpu);
cvmx_write_csr(CVMX_CIU_PP_POKEX(coreid), 1);
ciu_wdog.u64 = 0;
ciu_wdog.s.len = timeout_cnt;
ciu_wdog.s.mode = 3; /* 3 = Interrupt + NMI + Soft-Reset */
cvmx_write_csr(CVMX_CIU_WDOGX(coreid), ciu_wdog.u64);
cvmx_write_csr(CVMX_CIU_PP_POKEX(coreid), 1);
}
octeon_wdt_ping(); /* Get the irqs back on. */
return 0;
}
/**
* octeon_wdt_write:
* @file: file handle to the watchdog
* @buf: buffer to write (unused as data does not matter here
* @count: count of bytes
* @ppos: pointer to the position to write. No seeks allowed
*
* A write to a watchdog device is defined as a keepalive signal. Any
* write of data will do, as we we don't define content meaning.
*/
static ssize_t octeon_wdt_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
if (count) {
if (!nowayout) {
size_t i;
/* In case it was set long ago */
expect_close = 0;
for (i = 0; i != count; i++) {
char c;
if (get_user(c, buf + i))
return -EFAULT;
if (c == 'V')
expect_close = 1;
}
}
octeon_wdt_ping();
}
return count;
}
/**
* octeon_wdt_ioctl:
* @file: file handle to the device
* @cmd: watchdog command
* @arg: argument pointer
*
* The watchdog API defines a common set of functions for all
* watchdogs according to their available features. We only
* actually usefully support querying capabilities and setting
* the timeout.
*/
static long octeon_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
void __user *argp = (void __user *)arg;
int __user *p = argp;
int new_heartbeat;
static struct watchdog_info ident = {
.options = WDIOF_SETTIMEOUT|
WDIOF_MAGICCLOSE|
WDIOF_KEEPALIVEPING,
.firmware_version = 1,
.identity = "OCTEON",
};
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_KEEPALIVE:
octeon_wdt_ping();
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_heartbeat, p))
return -EFAULT;
if (octeon_wdt_set_heartbeat(new_heartbeat))
return -EINVAL;
/* Fall through. */
case WDIOC_GETTIMEOUT:
return put_user(heartbeat, p);
default:
return -ENOTTY;
}
}
/**
* octeon_wdt_open:
* @inode: inode of device
* @file: file handle to device
*
* The watchdog device has been opened. The watchdog device is single
* open and on opening we do a ping to reset the counters.
*/
static int octeon_wdt_open(struct inode *inode, struct file *file)
{
if (test_and_set_bit(0, &octeon_wdt_is_open))
return -EBUSY;
/*
* Activate
*/
octeon_wdt_ping();
do_coundown = 1;
return nonseekable_open(inode, file);
}
/**
* octeon_wdt_release:
* @inode: inode to board
* @file: file handle to board
*
* The watchdog has a configurable API. There is a religious dispute
* between people who want their watchdog to be able to shut down and
* those who want to be sure if the watchdog manager dies the machine
* reboots. In the former case we disable the counters, in the latter
* case you have to open it again very soon.
*/
static int octeon_wdt_release(struct inode *inode, struct file *file)
{
if (expect_close) {
do_coundown = 0;
octeon_wdt_ping();
} else {
pr_crit("WDT device closed unexpectedly. WDT will not stop!\n");
}
clear_bit(0, &octeon_wdt_is_open);
expect_close = 0;
return 0;
}
static const struct file_operations octeon_wdt_fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.write = octeon_wdt_write,
.unlocked_ioctl = octeon_wdt_ioctl,
.open = octeon_wdt_open,
.release = octeon_wdt_release,
};
static struct miscdevice octeon_wdt_miscdev = {
.minor = WATCHDOG_MINOR,
.name = "watchdog",
.fops = &octeon_wdt_fops,
};
static struct notifier_block octeon_wdt_cpu_notifier = {
.notifier_call = octeon_wdt_cpu_callback,
};
/**
* Module/ driver initialization.
*
* Returns Zero on success
*/
static int __init octeon_wdt_init(void)
{
int i;
int ret;
int cpu;
u64 *ptr;
/*
* Watchdog time expiration length = The 16 bits of LEN
* represent the most significant bits of a 24 bit decrementer
* that decrements every 256 cycles.
*
* Try for a timeout of 5 sec, if that fails a smaller number
* of even seconds,
*/
max_timeout_sec = 6;
do {
max_timeout_sec--;
timeout_cnt = ((octeon_get_io_clock_rate() >> 8) * max_timeout_sec) >> 8;
} while (timeout_cnt > 65535);
BUG_ON(timeout_cnt == 0);
octeon_wdt_calc_parameters(heartbeat);
pr_info("Initial granularity %d Sec\n", timeout_sec);
ret = misc_register(&octeon_wdt_miscdev);
if (ret) {
pr_err("cannot register miscdev on minor=%d (err=%d)\n",
WATCHDOG_MINOR, ret);
goto out;
}
/* Build the NMI handler ... */
octeon_wdt_build_stage1();
/* ... and install it. */
ptr = (u64 *) nmi_stage1_insns;
for (i = 0; i < 16; i++) {
cvmx_write_csr(CVMX_MIO_BOOT_LOC_ADR, i * 8);
cvmx_write_csr(CVMX_MIO_BOOT_LOC_DAT, ptr[i]);
}
cvmx_write_csr(CVMX_MIO_BOOT_LOC_CFGX(0), 0x81fc0000);
cpumask_clear(&irq_enabled_cpus);
for_each_online_cpu(cpu)
octeon_wdt_setup_interrupt(cpu);
register_hotcpu_notifier(&octeon_wdt_cpu_notifier);
out:
return ret;
}
/**
* Module / driver shutdown
*/
static void __exit octeon_wdt_cleanup(void)
{
int cpu;
misc_deregister(&octeon_wdt_miscdev);
unregister_hotcpu_notifier(&octeon_wdt_cpu_notifier);
for_each_online_cpu(cpu) {
int core = cpu2core(cpu);
/* Disable the watchdog */
cvmx_write_csr(CVMX_CIU_WDOGX(core), 0);
/* Free the interrupt handler */
free_irq(OCTEON_IRQ_WDOG0 + core, octeon_wdt_poke_irq);
}
/*
* Disable the boot-bus memory, the code it points to is soon
* to go missing.
*/
cvmx_write_csr(CVMX_MIO_BOOT_LOC_CFGX(0), 0);
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Cavium Networks <support@caviumnetworks.com>");
MODULE_DESCRIPTION("Cavium Networks Octeon Watchdog driver.");
module_init(octeon_wdt_init);
module_exit(octeon_wdt_cleanup);