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 */
24 static 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
35 static u64 sb1250_hpt_read(struct clocksource *cs)
36 {
37 return sb1250_hpt_get_cycles();
38 }
39
40 struct 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
48 static u64 notrace sb1250_read_sched_clock(void)
49 {
50 return sb1250_hpt_get_cycles();
51 }
52
53 void __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(0,
59 IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
60 R_SCD_TIMER_CFG)));
61 __raw_writeq(SB1250_HPT_VALUE,
62 IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
63 R_SCD_TIMER_INIT)));
64 __raw_writeq(M_SCD_TIMER_ENABLE | M_SCD_TIMER_MODE_CONTINUOUS,
65 IOADDR(A_SCD_TIMER_REGISTER(SB1250_HPT_NUM,
66 R_SCD_TIMER_CFG)));
67
68 clocksource_register_hz(cs, V_SCD_TIMER_FREQ);
69
70 sched_clock_register(sb1250_read_sched_clock, 23, V_SCD_TIMER_FREQ);
71 }
72
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