// SPDX-License-Identifier: GPL-2.0
/*
 * dma_timer.c -- Freescale ColdFire DMA Timer.
 *
 * Copyright (C) 2007, Benedikt Spranger <b.spranger@linutronix.de>
 * Copyright (C) 2008. Sebastian Siewior, Linutronix
 *
 */

#include <linux/clocksource.h>
#include <linux/io.h>

#include <asm/machdep.h>
#include <asm/coldfire.h>
#include <asm/mcfpit.h>
#include <asm/mcfsim.h>

#define DMA_TIMER_0     (0x00)
#define DMA_TIMER_1     (0x40)
#define DMA_TIMER_2     (0x80)
#define DMA_TIMER_3     (0xc0)

#define DTMR0   (MCF_IPSBAR + DMA_TIMER_0 + 0x400)
#define DTXMR0  (MCF_IPSBAR + DMA_TIMER_0 + 0x402)
#define DTER0   (MCF_IPSBAR + DMA_TIMER_0 + 0x403)
#define DTRR0   (MCF_IPSBAR + DMA_TIMER_0 + 0x404)
#define DTCR0   (MCF_IPSBAR + DMA_TIMER_0 + 0x408)
#define DTCN0   (MCF_IPSBAR + DMA_TIMER_0 + 0x40c)

#define DMA_FREQ    ((MCF_CLK / 2) / 16)

/* DTMR */
#define DMA_DTMR_RESTART        (1 << 3)
#define DMA_DTMR_CLK_DIV_1      (1 << 1)
#define DMA_DTMR_CLK_DIV_16     (2 << 1)
#define DMA_DTMR_ENABLE         (1 << 0)

static u64 cf_dt_get_cycles(struct clocksource *cs)
{
        return __raw_readl(DTCN0);
}

static struct clocksource clocksource_cf_dt = {
        .name           = "coldfire_dma_timer",
        .rating         = 200,
        .read           = cf_dt_get_cycles,
        .mask           = CLOCKSOURCE_MASK(32),
        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
};

static int __init init_cf_dt_clocksource(void)
{
        /*
         * We setup DMA timer 0 in free run mode. This incrementing counter is
         * used as a highly precious clock source. With MCF_CLOCK = 150 MHz we
         * get a ~213 ns resolution and the 32bit register will overflow almost
         * every 15 minutes.
         */
        __raw_writeb(0x00, DTXMR0);
        __raw_writeb(0x00, DTER0);
        __raw_writel(0x00000000, DTRR0);
        __raw_writew(DMA_DTMR_CLK_DIV_16 | DMA_DTMR_ENABLE, DTMR0);
        return clocksource_register_hz(&clocksource_cf_dt, DMA_FREQ);
}

arch_initcall(init_cf_dt_clocksource);

#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
#define CYC2NS_SCALE    ((1000000 << CYC2NS_SCALE_FACTOR) / (DMA_FREQ / 1000))

static unsigned long long cycles2ns(unsigned long cycl)
{
        return (unsigned long long) ((unsigned long long)cycl *
                        CYC2NS_SCALE) >> CYC2NS_SCALE_FACTOR;
}

unsigned long long sched_clock(void)
{
        unsigned long cycl = __raw_readl(DTCN0);

        return cycles2ns(cycl);
}