// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/arch/m68k/hp300/time.c
 *
 *  Copyright (C) 1998 Philip Blundell <philb@gnu.org>
 *
 *  This file contains the HP300-specific time handling code.
 */

#include <asm/ptrace.h>
#include <linux/clocksource.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
#include <asm/machdep.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/traps.h>
#include <asm/blinken.h>

#include "time.h"

static u64 hp300_read_clk(struct clocksource *cs);

static struct clocksource hp300_clk = {
        .name   = "timer",
        .rating = 250,
        .read   = hp300_read_clk,
        .mask   = CLOCKSOURCE_MASK(32),
        .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
};

static u32 clk_total, clk_offset;

/* Clock hardware definitions */

#define CLOCKBASE       0xf05f8000

#define CLKCR1          0x1
#define CLKCR2          0x3
#define CLKCR3          CLKCR1
#define CLKSR           CLKCR2
#define CLKMSB1         0x5
#define CLKLSB1         0x7
#define CLKMSB2         0x9
#define CLKMSB3         0xD

#define CLKSR_INT1      BIT(0)

/* This is for machines which generate the exact clock. */

#define HP300_TIMER_CLOCK_FREQ 250000
#define HP300_TIMER_CYCLES     (HP300_TIMER_CLOCK_FREQ / HZ)
#define INTVAL                 (HP300_TIMER_CYCLES - 1)

static irqreturn_t hp300_tick(int irq, void *dev_id)
{
        unsigned long flags;
        unsigned long tmp;

        local_irq_save(flags);
        in_8(CLOCKBASE + CLKSR);
        asm volatile ("movpw %1@(5),%0" : "=d" (tmp) : "a" (CLOCKBASE));
        clk_total += INTVAL;
        clk_offset = 0;
        legacy_timer_tick(1);
        timer_heartbeat();
        local_irq_restore(flags);

        /* Turn off the network and SCSI leds */
        blinken_leds(0, 0xe0);
        return IRQ_HANDLED;
}

static u64 hp300_read_clk(struct clocksource *cs)
{
        unsigned long flags;
        unsigned char lsb, msb, msb_new;
        u32 ticks;

        local_irq_save(flags);
        /* Read current timer 1 value */
        msb = in_8(CLOCKBASE + CLKMSB1);
again:
        if ((in_8(CLOCKBASE + CLKSR) & CLKSR_INT1) && msb > 0)
                clk_offset = INTVAL;
        lsb = in_8(CLOCKBASE + CLKLSB1);
        msb_new = in_8(CLOCKBASE + CLKMSB1);
        if (msb_new != msb) {
                msb = msb_new;
                goto again;
        }

        ticks = INTVAL - ((msb << 8) | lsb);
        ticks += clk_offset + clk_total;
        local_irq_restore(flags);

        return ticks;
}

void __init hp300_sched_init(void)
{
  out_8(CLOCKBASE + CLKCR2, 0x1);               /* select CR1 */
  out_8(CLOCKBASE + CLKCR1, 0x1);               /* reset */

  asm volatile(" movpw %0,%1@(5)" : : "d" (INTVAL), "a" (CLOCKBASE));

  if (request_irq(IRQ_AUTO_6, hp300_tick, IRQF_TIMER, "timer tick", NULL))
    pr_err("Couldn't register timer interrupt\n");

  out_8(CLOCKBASE + CLKCR2, 0x1);               /* select CR1 */
  out_8(CLOCKBASE + CLKCR1, 0x40);              /* enable irq */

  clocksource_register_hz(&hp300_clk, HP300_TIMER_CLOCK_FREQ);
}