xref: /openbmc/linux/arch/m68k/hp300/time.c (revision f9a01539)
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