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
hp300_tick(int irq,void * dev_id)56 static 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
hp300_read_clk(struct clocksource * cs)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
hp300_sched_init(void)101 void __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