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  */
sb1250_hpt_get_cycles(void)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 
sb1250_hpt_read(struct clocksource * cs)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 
sb1250_read_sched_clock(void)48 static u64 notrace sb1250_read_sched_clock(void)
49 {
50 	return sb1250_hpt_get_cycles();
51 }
52 
sb1250_clocksource_init(void)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