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1 | /** |
2 | * timer-ti-32k.c - OMAP2 32k Timer Support | |
3 | * | |
4 | * Copyright (C) 2009 Nokia Corporation | |
5 | * | |
6 | * Update to use new clocksource/clockevent layers | |
7 | * Author: Kevin Hilman, MontaVista Software, Inc. <source@mvista.com> | |
8 | * Copyright (C) 2007 MontaVista Software, Inc. | |
9 | * | |
10 | * Original driver: | |
11 | * Copyright (C) 2005 Nokia Corporation | |
12 | * Author: Paul Mundt <paul.mundt@nokia.com> | |
13 | * Juha Yrjölä <juha.yrjola@nokia.com> | |
14 | * OMAP Dual-mode timer framework support by Timo Teras | |
15 | * | |
16 | * Some parts based off of TI's 24xx code: | |
17 | * | |
18 | * Copyright (C) 2004-2009 Texas Instruments, Inc. | |
19 | * | |
20 | * Roughly modelled after the OMAP1 MPU timer code. | |
21 | * Added OMAP4 support - Santosh Shilimkar <santosh.shilimkar@ti.com> | |
22 | * | |
23 | * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com | |
24 | * | |
25 | * This program is free software: you can redistribute it and/or modify | |
26 | * it under the terms of the GNU General Public License version 2 of | |
27 | * the License as published by the Free Software Foundation. | |
28 | * | |
29 | * This program is distributed in the hope that it will be useful, | |
30 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
31 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
32 | * GNU General Public License for more details. | |
33 | * | |
34 | * You should have received a copy of the GNU General Public License | |
35 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
36 | */ | |
37 | ||
38 | #include <linux/init.h> | |
39 | #include <linux/time.h> | |
40 | #include <linux/sched_clock.h> | |
41 | #include <linux/clocksource.h> | |
42 | #include <linux/of.h> | |
43 | #include <linux/of_address.h> | |
44 | ||
45 | /* | |
46 | * 32KHz clocksource ... always available, on pretty most chips except | |
47 | * OMAP 730 and 1510. Other timers could be used as clocksources, with | |
48 | * higher resolution in free-running counter modes (e.g. 12 MHz xtal), | |
49 | * but systems won't necessarily want to spend resources that way. | |
50 | */ | |
51 | ||
52 | #define OMAP2_32KSYNCNT_REV_OFF 0x0 | |
53 | #define OMAP2_32KSYNCNT_REV_SCHEME (0x3 << 30) | |
54 | #define OMAP2_32KSYNCNT_CR_OFF_LOW 0x10 | |
55 | #define OMAP2_32KSYNCNT_CR_OFF_HIGH 0x30 | |
56 | ||
57 | struct ti_32k { | |
58 | void __iomem *base; | |
59 | void __iomem *counter; | |
60 | struct clocksource cs; | |
61 | }; | |
62 | ||
63 | static inline struct ti_32k *to_ti_32k(struct clocksource *cs) | |
64 | { | |
65 | return container_of(cs, struct ti_32k, cs); | |
66 | } | |
67 | ||
68 | static cycle_t ti_32k_read_cycles(struct clocksource *cs) | |
69 | { | |
70 | struct ti_32k *ti = to_ti_32k(cs); | |
71 | ||
72 | return (cycle_t)readl_relaxed(ti->counter); | |
73 | } | |
74 | ||
75 | static struct ti_32k ti_32k_timer = { | |
76 | .cs = { | |
77 | .name = "32k_counter", | |
78 | .rating = 250, | |
79 | .read = ti_32k_read_cycles, | |
80 | .mask = CLOCKSOURCE_MASK(32), | |
81 | .flags = CLOCK_SOURCE_IS_CONTINUOUS | | |
82 | CLOCK_SOURCE_SUSPEND_NONSTOP, | |
83 | }, | |
84 | }; | |
85 | ||
86 | static u64 notrace omap_32k_read_sched_clock(void) | |
87 | { | |
88 | return ti_32k_read_cycles(&ti_32k_timer.cs); | |
89 | } | |
90 | ||
91 | static void __init ti_32k_timer_init(struct device_node *np) | |
92 | { | |
93 | int ret; | |
94 | ||
95 | ti_32k_timer.base = of_iomap(np, 0); | |
96 | if (!ti_32k_timer.base) { | |
97 | pr_err("Can't ioremap 32k timer base\n"); | |
98 | return; | |
99 | } | |
100 | ||
101 | ti_32k_timer.counter = ti_32k_timer.base; | |
102 | ||
103 | /* | |
104 | * 32k sync Counter IP register offsets vary between the highlander | |
105 | * version and the legacy ones. | |
106 | * | |
107 | * The 'SCHEME' bits(30-31) of the revision register is used to identify | |
108 | * the version. | |
109 | */ | |
110 | if (readl_relaxed(ti_32k_timer.base + OMAP2_32KSYNCNT_REV_OFF) & | |
111 | OMAP2_32KSYNCNT_REV_SCHEME) | |
112 | ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_HIGH; | |
113 | else | |
114 | ti_32k_timer.counter += OMAP2_32KSYNCNT_CR_OFF_LOW; | |
115 | ||
116 | ret = clocksource_register_hz(&ti_32k_timer.cs, 32768); | |
117 | if (ret) { | |
118 | pr_err("32k_counter: can't register clocksource\n"); | |
119 | return; | |
120 | } | |
121 | ||
122 | sched_clock_register(omap_32k_read_sched_clock, 32, 32768); | |
123 | pr_info("OMAP clocksource: 32k_counter at 32768 Hz\n"); | |
124 | } | |
125 | CLOCKSOURCE_OF_DECLARE(ti_32k_timer, "ti,omap-counter32k", | |
126 | ti_32k_timer_init); |