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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/m68k/hp300/time.c
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// SPDX-License-Identifier: GPL-2.0

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/*

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 *  linux/arch/m68k/hp300/time.c

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 *

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 *  Copyright (C) 1998 Philip Blundell <[email protected]>

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 *

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 *  This file contains the HP300-specific time handling code.

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 */

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#include <asm/ptrace.h>

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#include <linux/clocksource.h>

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#include <linux/types.h>

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#include <linux/init.h>

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#include <linux/sched.h>

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#include <linux/kernel_stat.h>

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#include <linux/interrupt.h>

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#include <asm/machdep.h>

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#include <asm/irq.h>

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#include <asm/io.h>

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#include <asm/traps.h>

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#include <asm/blinken.h>

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#include "time.h"

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static u64 hp300_read_clk(struct clocksource *cs);

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static struct clocksource hp300_clk = {

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	.name   = "timer",

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	.rating = 250,

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	.read   = hp300_read_clk,

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	.mask   = CLOCKSOURCE_MASK(32),

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	.flags  = CLOCK_SOURCE_IS_CONTINUOUS,

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};

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static u32 clk_total, clk_offset;

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/* Clock hardware definitions */

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#define CLOCKBASE	0xf05f8000

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#define	CLKCR1		0x1

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#define	CLKCR2		0x3

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#define	CLKCR3		CLKCR1

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#define	CLKSR		CLKCR2

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#define	CLKMSB1		0x5

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#define	CLKLSB1		0x7

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#define	CLKMSB2		0x9

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#define	CLKMSB3		0xD

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#define	CLKSR_INT1	BIT(0)

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

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#define HP300_TIMER_CLOCK_FREQ 250000

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#define HP300_TIMER_CYCLES     (HP300_TIMER_CLOCK_FREQ / HZ)

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#define INTVAL                 (HP300_TIMER_CYCLES - 1)

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static irqreturn_t hp300_tick(int irq, void *dev_id)

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{

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	unsigned long flags;

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	unsigned long tmp;

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	local_irq_save(flags);

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	in_8(CLOCKBASE + CLKSR);

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

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	clk_total += INTVAL;

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	clk_offset = 0;

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	legacy_timer_tick(1);

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	timer_heartbeat();

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	local_irq_restore(flags);

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	/* Turn off the network and SCSI leds */

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	blinken_leds(0, 0xe0);

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	return IRQ_HANDLED;

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}

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static u64 hp300_read_clk(struct clocksource *cs)

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{

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	unsigned long flags;

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	unsigned char lsb, msb, msb_new;

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	u32 ticks;

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	local_irq_save(flags);

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	/* Read current timer 1 value */

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	msb = in_8(CLOCKBASE + CLKMSB1);

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again:

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	if ((in_8(CLOCKBASE + CLKSR) & CLKSR_INT1) && msb > 0)

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		clk_offset = INTVAL;

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	lsb = in_8(CLOCKBASE + CLKLSB1);

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	msb_new = in_8(CLOCKBASE + CLKMSB1);

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	if (msb_new != msb) {

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		msb = msb_new;

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		goto again;

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	}

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	ticks = INTVAL - ((msb << 8) | lsb);

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	ticks += clk_offset + clk_total;

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	local_irq_restore(flags);

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	return ticks;

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}

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void __init hp300_sched_init(void)

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{

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  out_8(CLOCKBASE + CLKCR2, 0x1);		/* select CR1 */

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  out_8(CLOCKBASE + CLKCR1, 0x1);		/* reset */

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

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  if (request_irq(IRQ_AUTO_6, hp300_tick, IRQF_TIMER, "timer tick", NULL))

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    pr_err("Couldn't register timer interrupt\n");

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  out_8(CLOCKBASE + CLKCR2, 0x1);		/* select CR1 */

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  out_8(CLOCKBASE + CLKCR1, 0x40);		/* enable irq */

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  clocksource_register_hz(&hp300_clk, HP300_TIMER_CLOCK_FREQ);

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}

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