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 25 static u64 hp300_read_clk(struct clocksource *cs); 26 27 static 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 35 static 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 58 static 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 77 static 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); 86 again: 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 } 102 103 void __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 } 118