// SPDX-License-Identifier: GPL-2.0+
/*
 * Octeon Watchdog driver
 *
 * Copyright (C) 2007-2017 Cavium, Inc.
 *
 * Converted to use WATCHDOG_CORE by Aaro Koskinen <aaro.koskinen@iki.fi>.
 *
 * Some parts derived from wdt.c
 *
 *      (c) Copyright 1996-1997 Alan Cox <alan@lxorguk.ukuu.org.uk>,
 *                                              All Rights Reserved.
 *
 *      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>
 *
 * 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/interrupt.h>
#include <linux/watchdog.h>
#include <linux/cpumask.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>

#include <asm/mipsregs.h>
#include <asm/uasm.h>

#include <asm/octeon/octeon.h>
#include <asm/octeon/cvmx-boot-vector.h>
#include <asm/octeon/cvmx-ciu2-defs.h>
#include <asm/octeon/cvmx-rst-defs.h>

/* Watchdog interrupt major block number (8 MSBs of intsn) */
#define WD_BLOCK_NUMBER         0x01

static int divisor;

/* 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 bool do_countdown;
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 */

#define CVMX_GSERX_SCRATCH(offset) (CVMX_ADD_IO_SEG(0x0001180090000020ull) + ((offset) & 15) * 0x1000000ull)

static int heartbeat = WD_TIMO;
module_param(heartbeat, int, 0444);
MODULE_PARM_DESC(heartbeat,
        "Watchdog heartbeat in seconds. (0 < heartbeat, default="
                                __MODULE_STRING(WD_TIMO) ")");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0444);
MODULE_PARM_DESC(nowayout,
        "Watchdog cannot be stopped once started (default="
                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

static int disable;
module_param(disable, int, 0444);
MODULE_PARM_DESC(disable,
        "Disable the watchdog entirely (default=0)");

static struct cvmx_boot_vector_element *octeon_wdt_bootvector;

void octeon_wdt_nmi_stage2(void);

static int cpu2core(int cpu)
{
#ifdef CONFIG_SMP
        return cpu_logical_map(cpu) & 0x3f;
#else
        return cvmx_get_core_num();
#endif
}

/**
 * octeon_wdt_poke_irq - Poke the watchdog when an interrupt is received
 *
 * @cpl:
 * @dev_id:
 *
 * Returns
 */
static irqreturn_t octeon_wdt_poke_irq(int cpl, void *dev_id)
{
        int cpu = raw_smp_processor_id();
        unsigned int core = cpu2core(cpu);
        int node = cpu_to_node(cpu);

        if (do_countdown) {
                if (per_cpu_countdown[cpu] > 0) {
                        /* We're alive, poke the watchdog */
                        cvmx_write_csr_node(node, 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_node(node, CVMX_CIU_PP_POKEX(core), 1);
        }
        return IRQ_HANDLED;
}

/* From setup.c */
extern int prom_putchar(char c);

/**
 * octeon_wdt_write_string - 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++);
}

/**
 * octeon_wdt_write_hex() - 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);
        }
}

static const char reg_name[][3] = {
        "$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"
};

/**
 * octeon_wdt_nmi_stage3:
 *
 * 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. */
        udelay(85000 * coreid);

        octeon_wdt_write_string("\r\n*** NMI Watchdog interrupt on Core 0x");
        octeon_wdt_write_hex(coreid, 2);
        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");

        /* The CIU register is different for each Octeon model. */
        if (OCTEON_IS_MODEL(OCTEON_CN68XX)) {
                octeon_wdt_write_string("\tsrc_wd\t0x");
                octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_SRC_PPX_IP2_WDOG(coreid)), 16);
                octeon_wdt_write_string("\ten_wd\t0x");
                octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_EN_PPX_IP2_WDOG(coreid)), 16);
                octeon_wdt_write_string("\r\n");
                octeon_wdt_write_string("\tsrc_rml\t0x");
                octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_SRC_PPX_IP2_RML(coreid)), 16);
                octeon_wdt_write_string("\ten_rml\t0x");
                octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_EN_PPX_IP2_RML(coreid)), 16);
                octeon_wdt_write_string("\r\n");
                octeon_wdt_write_string("\tsum\t0x");
                octeon_wdt_write_hex(cvmx_read_csr(CVMX_CIU2_SUM_PPX_IP2(coreid)), 16);
                octeon_wdt_write_string("\r\n");
        } else if (!octeon_has_feature(OCTEON_FEATURE_CIU3)) {
                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");

        /*
         * G-30204: We must trigger a soft reset before watchdog
         * does an incomplete job of doing it.
         */
        if (OCTEON_IS_OCTEON3() && !OCTEON_IS_MODEL(OCTEON_CN70XX)) {
                u64 scr;
                unsigned int node = cvmx_get_node_num();
                unsigned int lcore = cvmx_get_local_core_num();
                union cvmx_ciu_wdogx ciu_wdog;

                /*
                 * Wait for other cores to print out information, but
                 * not too long.  Do the soft reset before watchdog
                 * can trigger it.
                 */
                do {
                        ciu_wdog.u64 = cvmx_read_csr_node(node, CVMX_CIU_WDOGX(lcore));
                } while (ciu_wdog.s.cnt > 0x10000);

                scr = cvmx_read_csr_node(0, CVMX_GSERX_SCRATCH(0));
                scr |= 1 << 11; /* Indicate watchdog in bit 11 */
                cvmx_write_csr_node(0, CVMX_GSERX_SCRATCH(0), scr);
                cvmx_write_csr_node(0, CVMX_RST_SOFT_RST, 1);
        }
}

static int octeon_wdt_cpu_to_irq(int cpu)
{
        unsigned int coreid;
        int node;
        int irq;

        coreid = cpu2core(cpu);
        node = cpu_to_node(cpu);

        if (octeon_has_feature(OCTEON_FEATURE_CIU3)) {
                struct irq_domain *domain;
                int hwirq;

                domain = octeon_irq_get_block_domain(node,
                                                     WD_BLOCK_NUMBER);
                hwirq = WD_BLOCK_NUMBER << 12 | 0x200 | coreid;
                irq = irq_find_mapping(domain, hwirq);
        } else {
                irq = OCTEON_IRQ_WDOG0 + coreid;
        }
        return irq;
}

static int octeon_wdt_cpu_pre_down(unsigned int cpu)
{
        unsigned int core;
        int node;
        union cvmx_ciu_wdogx ciu_wdog;

        core = cpu2core(cpu);

        node = cpu_to_node(cpu);

        /* Poke the watchdog to clear out its state */
        cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(core), 1);

        /* Disable the hardware. */
        ciu_wdog.u64 = 0;
        cvmx_write_csr_node(node, CVMX_CIU_WDOGX(core), ciu_wdog.u64);

        free_irq(octeon_wdt_cpu_to_irq(cpu), octeon_wdt_poke_irq);
        return 0;
}

static int octeon_wdt_cpu_online(unsigned int cpu)
{
        unsigned int core;
        unsigned int irq;
        union cvmx_ciu_wdogx ciu_wdog;
        int node;
        struct irq_domain *domain;
        int hwirq;

        core = cpu2core(cpu);
        node = cpu_to_node(cpu);

        octeon_wdt_bootvector[core].target_ptr = (u64)octeon_wdt_nmi_stage2;

        /* Disable it before doing anything with the interrupts. */
        ciu_wdog.u64 = 0;
        cvmx_write_csr_node(node, CVMX_CIU_WDOGX(core), ciu_wdog.u64);

        per_cpu_countdown[cpu] = countdown_reset;

        if (octeon_has_feature(OCTEON_FEATURE_CIU3)) {
                /* Must get the domain for the watchdog block */
                domain = octeon_irq_get_block_domain(node, WD_BLOCK_NUMBER);

                /* Get a irq for the wd intsn (hardware interrupt) */
                hwirq = WD_BLOCK_NUMBER << 12 | 0x200 | core;
                irq = irq_create_mapping(domain, hwirq);
                irqd_set_trigger_type(irq_get_irq_data(irq),
                                      IRQ_TYPE_EDGE_RISING);
        } else
                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);

        /* Must set the irq affinity here */
        if (octeon_has_feature(OCTEON_FEATURE_CIU3)) {
                irq_set_affinity(irq, cpumask_of(cpu));
        }

        cpumask_set_cpu(cpu, &irq_enabled_cpus);

        /* Poke the watchdog to clear out its state */
        cvmx_write_csr_node(node, 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_node(node, CVMX_CIU_WDOGX(core), ciu_wdog.u64);

        return 0;
}

static int octeon_wdt_ping(struct watchdog_device __always_unused *wdog)
{
        int cpu;
        int coreid;
        int node;

        if (disable)
                return 0;

        for_each_online_cpu(cpu) {
                coreid = cpu2core(cpu);
                node = cpu_to_node(cpu);
                cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(coreid), 1);
                per_cpu_countdown[cpu] = countdown_reset;
                if ((countdown_reset || !do_countdown) &&
                    !cpumask_test_cpu(cpu, &irq_enabled_cpus)) {
                        /* We have to enable the irq */
                        enable_irq(octeon_wdt_cpu_to_irq(cpu));
                        cpumask_set_cpu(cpu, &irq_enabled_cpus);
                }
        }
        return 0;
}

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() / divisor) * timeout_sec) >> 8;
}

static int octeon_wdt_set_timeout(struct watchdog_device *wdog,
                                  unsigned int t)
{
        int cpu;
        int coreid;
        union cvmx_ciu_wdogx ciu_wdog;
        int node;

        if (t <= 0)
                return -1;

        octeon_wdt_calc_parameters(t);

        if (disable)
                return 0;

        for_each_online_cpu(cpu) {
                coreid = cpu2core(cpu);
                node = cpu_to_node(cpu);
                cvmx_write_csr_node(node, 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_node(node, CVMX_CIU_WDOGX(coreid), ciu_wdog.u64);
                cvmx_write_csr_node(node, CVMX_CIU_PP_POKEX(coreid), 1);
        }
        octeon_wdt_ping(wdog); /* Get the irqs back on. */
        return 0;
}

static int octeon_wdt_start(struct watchdog_device *wdog)
{
        octeon_wdt_ping(wdog);
        do_countdown = 1;
        return 0;
}

static int octeon_wdt_stop(struct watchdog_device *wdog)
{
        do_countdown = 0;
        octeon_wdt_ping(wdog);
        return 0;
}

static const struct watchdog_info octeon_wdt_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
        .identity = "OCTEON",
};

static const struct watchdog_ops octeon_wdt_ops = {
        .owner          = THIS_MODULE,
        .start          = octeon_wdt_start,
        .stop           = octeon_wdt_stop,
        .ping           = octeon_wdt_ping,
        .set_timeout    = octeon_wdt_set_timeout,
};

static struct watchdog_device octeon_wdt = {
        .info   = &octeon_wdt_info,
        .ops    = &octeon_wdt_ops,
};

static enum cpuhp_state octeon_wdt_online;
/**
 * octeon_wdt_init - Module/ driver initialization.
 *
 * Returns Zero on success
 */
static int __init octeon_wdt_init(void)
{
        int ret;

        octeon_wdt_bootvector = cvmx_boot_vector_get();
        if (!octeon_wdt_bootvector) {
                pr_err("Error: Cannot allocate boot vector.\n");
                return -ENOMEM;
        }

        if (OCTEON_IS_MODEL(OCTEON_CN68XX))
                divisor = 0x200;
        else if (OCTEON_IS_MODEL(OCTEON_CN78XX))
                divisor = 0x400;
        else
                divisor = 0x100;

        /*
         * Watchdog time expiration length = The 16 bits of LEN
         * represent the most significant bits of a 24 bit decrementer
         * that decrements every divisor cycle.
         *
         * 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() / divisor) * 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);

        octeon_wdt.timeout      = timeout_sec;
        octeon_wdt.max_timeout  = UINT_MAX;

        watchdog_set_nowayout(&octeon_wdt, nowayout);

        ret = watchdog_register_device(&octeon_wdt);
        if (ret)
                return ret;

        if (disable) {
                pr_notice("disabled\n");
                return 0;
        }

        cpumask_clear(&irq_enabled_cpus);

        ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "watchdog/octeon:online",
                                octeon_wdt_cpu_online, octeon_wdt_cpu_pre_down);
        if (ret < 0)
                goto err;
        octeon_wdt_online = ret;
        return 0;
err:
        cvmx_write_csr(CVMX_MIO_BOOT_LOC_CFGX(0), 0);
        watchdog_unregister_device(&octeon_wdt);
        return ret;
}

/**
 * octeon_wdt_cleanup - Module / driver shutdown
 */
static void __exit octeon_wdt_cleanup(void)
{
        watchdog_unregister_device(&octeon_wdt);

        if (disable)
                return;

        cpuhp_remove_state(octeon_wdt_online);

        /*
         * 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 Inc. <support@cavium.com>");
MODULE_DESCRIPTION("Cavium Inc. OCTEON Watchdog driver.");
module_init(octeon_wdt_init);
module_exit(octeon_wdt_cleanup);