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