1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2000, 2001 Broadcom Corporation
4 */
5#include <linux/clocksource.h>
6#include <linux/sched_clock.h>
7
8#include <asm/addrspace.h>
9#include <asm/io.h>
10#include <asm/time.h>
11
12#include <asm/sibyte/sb1250.h>
13#include <asm/sibyte/sb1250_regs.h>
14#include <asm/sibyte/sb1250_int.h>
15#include <asm/sibyte/sb1250_scd.h>
16
17#define SB1250_HPT_NUM 3
18#define SB1250_HPT_VALUE M_SCD_TIMER_CNT /* max value */
19
20/*
21 * The HPT is free running from SB1250_HPT_VALUE down to 0 then starts over
22 * again.
23 */
24static inline u64 sb1250_hpt_get_cycles(void)
25{
26 unsigned int count;
27 void __iomem *addr;
28
29 addr = IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM, R_SCD_TIMER_CNT));
30 count = G_SCD_TIMER_CNT(__raw_readq(addr));
31
32 return SB1250_HPT_VALUE - count;
33}
34
35static u64 sb1250_hpt_read(struct clocksource *cs)
36{
37 return sb1250_hpt_get_cycles();
38}
39
40struct clocksource bcm1250_clocksource = {
41 .name = "bcm1250-counter-3",
42 .rating = 200,
43 .read = sb1250_hpt_read,
44 .mask = CLOCKSOURCE_MASK(23),
45 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
46};
47
48static u64 notrace sb1250_read_sched_clock(void)
49{
50 return sb1250_hpt_get_cycles();
51}
52
53void __init sb1250_clocksource_init(void)
54{
55 struct clocksource *cs = &bcm1250_clocksource;
56
57 /* Setup hpt using timer #3 but do not enable irq for it */
58 __raw_writeq(val: 0,
59 addr: IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
60 R_SCD_TIMER_CFG)));
61 __raw_writeq(SB1250_HPT_VALUE,
62 addr: IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
63 R_SCD_TIMER_INIT)));
64 __raw_writeq(val: M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
65 addr: IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
66 R_SCD_TIMER_CFG)));
67
68 clocksource_register_hz(cs, hz: V_SCD_TIMER_FREQ);
69
70 sched_clock_register(read: sb1250_read_sched_clock, bits: 23, rate: V_SCD_TIMER_FREQ);
71}
72

source code of linux/arch/mips/kernel/csrc-sb1250.c