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1 | /* |
2 | * Copyright (C) ST-Ericsson SA 2011 | |
3 | * | |
4 | * License Terms: GNU General Public License v2 | |
5 | * Author: Mattias Wallin <mattias.wallin@stericsson.com> for ST-Ericsson | |
6 | * Author: Sundar Iyer for ST-Ericsson | |
7 | * sched_clock implementation is based on: | |
8 | * plat-nomadik/timer.c Linus Walleij <linus.walleij@stericsson.com> | |
9 | * | |
10 | * DBx500-PRCMU Timer | |
11 | * The PRCMU has 5 timers which are available in a always-on | |
12 | * power domain. We use the Timer 4 for our always-on clock | |
13 | * source on DB8500 and Timer 3 on DB5500. | |
14 | */ | |
15 | #include <linux/clockchips.h> | |
16 | #include <linux/clksrc-dbx500-prcmu.h> | |
17 | ||
18 | #include <asm/sched_clock.h> | |
19 | ||
20 | #include <mach/setup.h> | |
21 | #include <mach/hardware.h> | |
22 | ||
23 | #define RATE_32K 32768 | |
24 | ||
25 | #define TIMER_MODE_CONTINOUS 0x1 | |
26 | #define TIMER_DOWNCOUNT_VAL 0xffffffff | |
27 | ||
28 | #define PRCMU_TIMER_REF 0 | |
29 | #define PRCMU_TIMER_DOWNCOUNT 0x4 | |
30 | #define PRCMU_TIMER_MODE 0x8 | |
31 | ||
32 | #define SCHED_CLOCK_MIN_WRAP 131072 /* 2^32 / 32768 */ | |
33 | ||
34 | void __iomem *clksrc_dbx500_timer_base; | |
35 | ||
36 | static cycle_t clksrc_dbx500_prcmu_read(struct clocksource *cs) | |
37 | { | |
38 | u32 count, count2; | |
39 | ||
40 | do { | |
41 | count = readl(clksrc_dbx500_timer_base + | |
42 | PRCMU_TIMER_DOWNCOUNT); | |
43 | count2 = readl(clksrc_dbx500_timer_base + | |
44 | PRCMU_TIMER_DOWNCOUNT); | |
45 | } while (count2 != count); | |
46 | ||
47 | /* Negate because the timer is a decrementing counter */ | |
48 | return ~count; | |
49 | } | |
50 | ||
51 | static struct clocksource clocksource_dbx500_prcmu = { | |
52 | .name = "dbx500-prcmu-timer", | |
53 | .rating = 300, | |
54 | .read = clksrc_dbx500_prcmu_read, | |
55 | .shift = 10, | |
56 | .mask = CLOCKSOURCE_MASK(32), | |
57 | .flags = CLOCK_SOURCE_IS_CONTINUOUS, | |
58 | }; | |
59 | ||
60 | #ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK | |
61 | static DEFINE_CLOCK_DATA(cd); | |
62 | ||
63 | unsigned long long notrace sched_clock(void) | |
64 | { | |
65 | u32 cyc; | |
66 | ||
67 | if (unlikely(!clksrc_dbx500_timer_base)) | |
68 | return 0; | |
69 | ||
70 | cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu); | |
71 | ||
72 | return cyc_to_sched_clock(&cd, cyc, (u32)~0); | |
73 | } | |
74 | ||
75 | static void notrace clksrc_dbx500_prcmu_update_sched_clock(void) | |
76 | { | |
77 | u32 cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu); | |
78 | update_sched_clock(&cd, cyc, (u32)~0); | |
79 | } | |
80 | #endif | |
81 | ||
82 | void __init clksrc_dbx500_prcmu_init(void) | |
83 | { | |
84 | /* | |
85 | * The A9 sub system expects the timer to be configured as | |
86 | * a continous looping timer. | |
87 | * The PRCMU should configure it but if it for some reason | |
88 | * don't we do it here. | |
89 | */ | |
90 | if (readl(clksrc_dbx500_timer_base + PRCMU_TIMER_MODE) != | |
91 | TIMER_MODE_CONTINOUS) { | |
92 | writel(TIMER_MODE_CONTINOUS, | |
93 | clksrc_dbx500_timer_base + PRCMU_TIMER_MODE); | |
94 | writel(TIMER_DOWNCOUNT_VAL, | |
95 | clksrc_dbx500_timer_base + PRCMU_TIMER_REF); | |
96 | } | |
97 | #ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK | |
98 | init_sched_clock(&cd, clksrc_dbx500_prcmu_update_sched_clock, | |
99 | 32, RATE_32K); | |
100 | #endif | |
101 | clocksource_calc_mult_shift(&clocksource_dbx500_prcmu, | |
102 | RATE_32K, SCHED_CLOCK_MIN_WRAP); | |
103 | clocksource_register(&clocksource_dbx500_prcmu); | |
104 | } |