// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2000, 2001 Broadcom Corporation
 */
#include <linux/clocksource.h>
#include <linux/sched_clock.h>

#include <asm/addrspace.h>
#include <asm/io.h>
#include <asm/time.h>

#include <asm/sibyte/sb1250.h>
#include <asm/sibyte/sb1250_regs.h>
#include <asm/sibyte/sb1250_int.h>
#include <asm/sibyte/sb1250_scd.h>

#define SB1250_HPT_NUM          3
#define SB1250_HPT_VALUE        M_SCD_TIMER_CNT /* max value */

/*
 * The HPT is free running from SB1250_HPT_VALUE down to 0 then starts over
 * again.
 */
static inline u64 sb1250_hpt_get_cycles(void)
{
        unsigned int count;
        void __iomem *addr;

        addr = IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM, R_SCD_TIMER_CNT));
        count = G_SCD_TIMER_CNT(__raw_readq(addr));

        return SB1250_HPT_VALUE - count;
}

static u64 sb1250_hpt_read(struct clocksource *cs)
{
        return sb1250_hpt_get_cycles();
}

struct clocksource bcm1250_clocksource = {
        .name   = "bcm1250-counter-3",
        .rating = 200,
        .read   = sb1250_hpt_read,
        .mask   = CLOCKSOURCE_MASK(23),
        .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
};

static u64 notrace sb1250_read_sched_clock(void)
{
        return sb1250_hpt_get_cycles();
}

void __init sb1250_clocksource_init(void)
{
        struct clocksource *cs = &bcm1250_clocksource;

        /* Setup hpt using timer #3 but do not enable irq for it */
        __raw_writeq(0,
                     IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
                                                 R_SCD_TIMER_CFG)));
        __raw_writeq(SB1250_HPT_VALUE,
                     IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
                                                 R_SCD_TIMER_INIT)));
        __raw_writeq(M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
                     IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
                                                 R_SCD_TIMER_CFG)));

        clocksource_register_hz(cs, V_SCD_TIMER_FREQ);

        sched_clock_register(sb1250_read_sched_clock, 23, V_SCD_TIMER_FREQ);
}