time.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *  linux/arch/m68k/hp300/time.c
  4 *
  5 *  Copyright (C) 1998 Philip Blundell <philb@gnu.org>
  6 *
  7 *  This file contains the HP300-specific time handling code.
  8 */
  9
 10#include <asm/ptrace.h>
 11#include <linux/clocksource.h>
 12#include <linux/types.h>
 13#include <linux/init.h>
 14#include <linux/sched.h>
 15#include <linux/kernel_stat.h>
 16#include <linux/interrupt.h>
 17#include <asm/machdep.h>
 18#include <asm/irq.h>
 19#include <asm/io.h>
 20#include <asm/traps.h>
 21#include <asm/blinken.h>
 22
 23#include "time.h"
 24
 25static u64 hp300_read_clk(struct clocksource *cs);
 26
 27static struct clocksource hp300_clk = {
 28	.name   = "timer",
 29	.rating = 250,
 30	.read   = hp300_read_clk,
 31	.mask   = CLOCKSOURCE_MASK(32),
 32	.flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 33};
 34
 35static u32 clk_total, clk_offset;
 36
 37/* Clock hardware definitions */
 38
 39#define CLOCKBASE	0xf05f8000
 40
 41#define	CLKCR1		0x1
 42#define	CLKCR2		0x3
 43#define	CLKCR3		CLKCR1
 44#define	CLKSR		CLKCR2
 45#define	CLKMSB1		0x5
 46#define	CLKLSB1		0x7
 47#define	CLKMSB2		0x9
 48#define	CLKMSB3		0xD
 49
 50#define	CLKSR_INT1	BIT(0)
 51
 52/* This is for machines which generate the exact clock. */
 53
 54#define HP300_TIMER_CLOCK_FREQ 250000
 55#define HP300_TIMER_CYCLES     (HP300_TIMER_CLOCK_FREQ / HZ)
 56#define INTVAL                 (HP300_TIMER_CYCLES - 1)
 57
 58static irqreturn_t hp300_tick(int irq, void *dev_id)
 59{
 60	unsigned long flags;
 61	unsigned long tmp;
 62
 63	local_irq_save(flags);
 64	in_8(CLOCKBASE + CLKSR);
 65	asm volatile ("movpw %1@(5),%0" : "=d" (tmp) : "a" (CLOCKBASE));
 66	clk_total += INTVAL;
 67	clk_offset = 0;
 68	legacy_timer_tick(1);
 69	timer_heartbeat();
 70	local_irq_restore(flags);
 71
 72	/* Turn off the network and SCSI leds */
 73	blinken_leds(0, 0xe0);
 74	return IRQ_HANDLED;
 75}
 76
 77static u64 hp300_read_clk(struct clocksource *cs)
 78{
 79	unsigned long flags;
 80	unsigned char lsb, msb, msb_new;
 81	u32 ticks;
 82
 83	local_irq_save(flags);
 84	/* Read current timer 1 value */
 85	msb = in_8(CLOCKBASE + CLKMSB1);
 86again:
 87	if ((in_8(CLOCKBASE + CLKSR) & CLKSR_INT1) && msb > 0)
 88		clk_offset = INTVAL;
 89	lsb = in_8(CLOCKBASE + CLKLSB1);
 90	msb_new = in_8(CLOCKBASE + CLKMSB1);
 91	if (msb_new != msb) {
 92		msb = msb_new;
 93		goto again;
 94	}
 95
 96	ticks = INTVAL - ((msb << 8) | lsb);
 97	ticks += clk_offset + clk_total;
 98	local_irq_restore(flags);
 99
100	return ticks;
101}
102
103void __init hp300_sched_init(void)
104{
105  out_8(CLOCKBASE + CLKCR2, 0x1);		/* select CR1 */
106  out_8(CLOCKBASE + CLKCR1, 0x1);		/* reset */
107
108  asm volatile(" movpw %0,%1@(5)" : : "d" (INTVAL), "a" (CLOCKBASE));
109
110  if (request_irq(IRQ_AUTO_6, hp300_tick, IRQF_TIMER, "timer tick", NULL))
111    pr_err("Couldn't register timer interrupt\n");
112
113  out_8(CLOCKBASE + CLKCR2, 0x1);		/* select CR1 */
114  out_8(CLOCKBASE + CLKCR1, 0x40);		/* enable irq */
115
116  clocksource_register_hz(&hp300_clk, HP300_TIMER_CLOCK_FREQ);
117}