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Linux/arch/m68k/hp300/time.c

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  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 static u64 hp300_read_clk(struct clocksource *cs);
 24 
 25 static 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 
 33 static 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 
 56 static irqreturn_t hp300_tick(int irq, void *dev_id)
 57 {
 58         irq_handler_t timer_routine = dev_id;
 59         unsigned long flags;
 60         unsigned long tmp;
 61 
 62         local_irq_save(flags);
 63         in_8(CLOCKBASE + CLKSR);
 64         asm volatile ("movpw %1@(5),%0" : "=d" (tmp) : "a" (CLOCKBASE));
 65         clk_total += INTVAL;
 66         clk_offset = 0;
 67         timer_routine(0, NULL);
 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 
 75 static 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);
 84 again:
 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 
101 void __init hp300_sched_init(irq_handler_t vector)
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", vector))
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 

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