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
hp300_tick(int irq,void * dev_id)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
hp300_read_clk(struct clocksource * cs)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
hp300_sched_init(void)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