/* * 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); cpu_notifier_register_begin(); for_each_online_cpu(cpu) octeon_wdt_setup_interrupt(cpu); __register_hotcpu_notifier(&octeon_wdt_cpu_notifier); cpu_notifier_register_done(); out: return ret; } /** * Module / driver shutdown */ static void __exit octeon_wdt_cleanup(void) { int cpu; misc_deregister(&octeon_wdt_miscdev); cpu_notifier_register_begin(); __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); } cpu_notifier_register_done(); /* * 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);