/*
 * 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.
 *
 * Copyright (C) 1997, 1998, 2001, 03, 05, 06 by Ralf Baechle
 */
#include <linux/linkage.h>
#include <linux/init.h>
#include <linux/rtc/ds1286.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/sched/signal.h>
#include <linux/notifier.h>
#include <linux/pm.h>
#include <linux/timer.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/reboot.h>
#include <asm/sgialib.h>
#include <asm/sgi/ioc.h>
#include <asm/sgi/hpc3.h>
#include <asm/sgi/mc.h>
#include <asm/sgi/ip22.h>

/*
 * Just powerdown if init hasn't done after POWERDOWN_TIMEOUT seconds.
 * I'm not sure if this feature is a good idea, for now it's here just to
 * make the power button make behave just like under IRIX.
 */
#define POWERDOWN_TIMEOUT       120

/*
 * Blink frequency during reboot grace period and when panicked.
 */
#define POWERDOWN_FREQ          (HZ / 4)
#define PANIC_FREQ              (HZ / 8)

static struct timer_list power_timer, blink_timer, debounce_timer;
static unsigned long blink_timer_timeout;

#define MACHINE_PANICED         1
#define MACHINE_SHUTTING_DOWN   2

static int machine_state;

static void __noreturn sgi_machine_power_off(void)
{
        unsigned int tmp;

        local_irq_disable();

        /* Disable watchdog */
        tmp = hpc3c0->rtcregs[RTC_CMD] & 0xff;
        hpc3c0->rtcregs[RTC_CMD] = tmp | RTC_WAM;
        hpc3c0->rtcregs[RTC_WSEC] = 0;
        hpc3c0->rtcregs[RTC_WHSEC] = 0;

        while (1) {
                sgioc->panel = ~SGIOC_PANEL_POWERON;
                /* Good bye cruel world ...  */

                /* If we're still running, we probably got sent an alarm
                   interrupt.  Read the flag to clear it.  */
                tmp = hpc3c0->rtcregs[RTC_HOURS_ALARM];
        }
}

static void __noreturn sgi_machine_restart(char *command)
{
        if (machine_state & MACHINE_SHUTTING_DOWN)
                sgi_machine_power_off();
        sgimc->cpuctrl0 |= SGIMC_CCTRL0_SYSINIT;
        while (1);
}

static void __noreturn sgi_machine_halt(void)
{
        if (machine_state & MACHINE_SHUTTING_DOWN)
                sgi_machine_power_off();
        ArcEnterInteractiveMode();
}

static void power_timeout(struct timer_list *unused)
{
        sgi_machine_power_off();
}

static void blink_timeout(struct timer_list *unused)
{
        /* XXX fix this for fullhouse  */
        sgi_ioc_reset ^= (SGIOC_RESET_LC0OFF|SGIOC_RESET_LC1OFF);
        sgioc->reset = sgi_ioc_reset;

        mod_timer(&blink_timer, jiffies + blink_timer_timeout);
}

static void debounce(struct timer_list *unused)
{
        del_timer(&debounce_timer);
        if (sgint->istat1 & SGINT_ISTAT1_PWR) {
                /* Interrupt still being sent. */
                debounce_timer.expires = jiffies + (HZ / 20); /* 0.05s  */
                add_timer(&debounce_timer);

                sgioc->panel = SGIOC_PANEL_POWERON | SGIOC_PANEL_POWERINTR |
                               SGIOC_PANEL_VOLDNINTR | SGIOC_PANEL_VOLDNHOLD |
                               SGIOC_PANEL_VOLUPINTR | SGIOC_PANEL_VOLUPHOLD;

                return;
        }

        if (machine_state & MACHINE_PANICED)
                sgimc->cpuctrl0 |= SGIMC_CCTRL0_SYSINIT;

        enable_irq(SGI_PANEL_IRQ);
}

static inline void power_button(void)
{
        if (machine_state & MACHINE_PANICED)
                return;

        if ((machine_state & MACHINE_SHUTTING_DOWN) ||
                        kill_cad_pid(SIGINT, 1)) {
                /* No init process or button pressed twice.  */
                sgi_machine_power_off();
        }

        machine_state |= MACHINE_SHUTTING_DOWN;
        blink_timer_timeout = POWERDOWN_FREQ;
        blink_timeout(&blink_timer);

        timer_setup(&power_timer, power_timeout, 0);
        power_timer.expires = jiffies + POWERDOWN_TIMEOUT * HZ;
        add_timer(&power_timer);
}

static irqreturn_t panel_int(int irq, void *dev_id)
{
        unsigned int buttons;

        buttons = sgioc->panel;
        sgioc->panel = SGIOC_PANEL_POWERON | SGIOC_PANEL_POWERINTR;

        if (sgint->istat1 & SGINT_ISTAT1_PWR) {
                /* Wait until interrupt goes away */
                disable_irq_nosync(SGI_PANEL_IRQ);
                timer_setup(&debounce_timer, debounce, 0);
                debounce_timer.expires = jiffies + 5;
                add_timer(&debounce_timer);
        }

        /* Power button was pressed
         * ioc.ps page 22: "The Panel Register is called Power Control by Full
         * House. Only lowest 2 bits are used. Guiness uses upper four bits
         * for volume control". This is not true, all bits are pulled high
         * on fullhouse */
        if (!(buttons & SGIOC_PANEL_POWERINTR))
                power_button();

        return IRQ_HANDLED;
}

static int panic_event(struct notifier_block *this, unsigned long event,
                      void *ptr)
{
        if (machine_state & MACHINE_PANICED)
                return NOTIFY_DONE;
        machine_state |= MACHINE_PANICED;

        blink_timer_timeout = PANIC_FREQ;
        blink_timeout(&blink_timer);

        return NOTIFY_DONE;
}

static struct notifier_block panic_block = {
        .notifier_call  = panic_event,
};

static int __init reboot_setup(void)
{
        int res;

        _machine_restart = sgi_machine_restart;
        _machine_halt = sgi_machine_halt;
        pm_power_off = sgi_machine_power_off;

        res = request_irq(SGI_PANEL_IRQ, panel_int, 0, "Front Panel", NULL);
        if (res) {
                printk(KERN_ERR "Allocation of front panel IRQ failed\n");
                return res;
        }

        timer_setup(&blink_timer, blink_timeout, 0);
        atomic_notifier_chain_register(&panic_notifier_list, &panic_block);

        return 0;
}

subsys_initcall(reboot_setup);