1 /*
2 * Port on Texas Instruments TMS320C6x architecture
3 *
4 * Copyright (C) 2004, 2009, 2010, 2011 Texas Instruments Incorporated
5 * Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12 #include <linux/kernel.h>
13 #include <linux/clocksource.h>
14 #include <linux/errno.h>
15 #include <linux/sched.h>
16 #include <linux/param.h>
17 #include <linux/string.h>
18 #include <linux/mm.h>
19 #include <linux/interrupt.h>
20 #include <linux/timex.h>
21 #include <linux/profile.h>
22
23 #include <asm/special_insns.h>
24 #include <asm/timer64.h>
25
26 static u32 sched_clock_multiplier;
27 #define SCHED_CLOCK_SHIFT 16
28
tsc_read(struct clocksource * cs)29 static cycle_t tsc_read(struct clocksource *cs)
30 {
31 return get_cycles();
32 }
33
34 static struct clocksource clocksource_tsc = {
35 .name = "timestamp",
36 .rating = 300,
37 .read = tsc_read,
38 .mask = CLOCKSOURCE_MASK(64),
39 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
40 };
41
42 /*
43 * scheduler clock - returns current time in nanoseconds.
44 */
sched_clock(void)45 u64 sched_clock(void)
46 {
47 u64 tsc = get_cycles();
48
49 return (tsc * sched_clock_multiplier) >> SCHED_CLOCK_SHIFT;
50 }
51
time_init(void)52 void time_init(void)
53 {
54 u64 tmp = (u64)NSEC_PER_SEC << SCHED_CLOCK_SHIFT;
55
56 do_div(tmp, c6x_core_freq);
57 sched_clock_multiplier = tmp;
58
59 clocksource_register_hz(&clocksource_tsc, c6x_core_freq);
60
61 /* write anything into TSCL to enable counting */
62 set_creg(TSCL, 0);
63
64 /* probe for timer64 event timer */
65 timer64_init();
66 }
67