diff options
Diffstat (limited to 'drivers/watchdog/octeon-wdt-main.c')
| -rw-r--r-- | drivers/watchdog/octeon-wdt-main.c | 748 |
1 files changed, 748 insertions, 0 deletions
diff --git a/drivers/watchdog/octeon-wdt-main.c b/drivers/watchdog/octeon-wdt-main.c new file mode 100644 index 00000000..46120883 --- /dev/null +++ b/drivers/watchdog/octeon-wdt-main.c @@ -0,0 +1,748 @@ +/* + * 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); |