]>
Commit | Line | Data |
---|---|---|
fcfb632b MK |
1 | /* |
2 | * Cirrus Logic EP93xx timer support. | |
3 | * | |
4 | * Copyright (C) 2009, 2010 | |
5 | * Matthias Kaehlcke <matthias@kaehlcke.net> | |
6 | * | |
7 | * Copyright (C) 2004, 2005 | |
8 | * Cory T. Tusar, Videon Central, Inc., <ctusar@videon-central.com> | |
9 | * | |
10 | * Based on the original intr.c Cirrus Logic EP93xx Rev D. interrupt support, | |
11 | * author unknown. | |
12 | * | |
13 | * See file CREDITS for list of people who contributed to this project. | |
14 | * | |
15 | * This program is free software; you can redistribute it and/or modify | |
16 | * it under the terms of the GNU General Public License as published by | |
17 | * the Free Software Foundation; either version 2 of the License, or | |
18 | * (at your option) any later version. | |
19 | * | |
20 | * This program is distributed in the hope that it will be useful, but | |
21 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |
22 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
23 | * for more details. | |
24 | * | |
25 | * You should have received a copy of the GNU General Public License along | |
26 | * with this program; if not, write to the Free Software Foundation, Inc., | |
27 | * 675 Mass Ave, Cambridge, MA 02139, USA. | |
28 | */ | |
29 | ||
30 | #include <common.h> | |
31 | #include <linux/types.h> | |
32 | #include <asm/arch/ep93xx.h> | |
33 | #include <asm/io.h> | |
d9f505e3 | 34 | #include <div64.h> |
fcfb632b MK |
35 | |
36 | #define TIMER_CLKSEL (1 << 3) | |
37 | #define TIMER_MODE (1 << 6) | |
38 | #define TIMER_ENABLE (1 << 7) | |
39 | ||
40 | #define TIMER_FREQ 508469 | |
41 | #define TIMER_LOAD_VAL (TIMER_FREQ / CONFIG_SYS_HZ) | |
42 | ||
43 | static ulong timestamp; | |
44 | static ulong lastdec; | |
45 | ||
46 | static inline unsigned long clk_to_systicks(unsigned long clk_ticks) | |
47 | { | |
d9f505e3 MK |
48 | unsigned long long sys_ticks = (clk_ticks * CONFIG_SYS_HZ); |
49 | do_div(sys_ticks, TIMER_FREQ); | |
fcfb632b | 50 | |
d9f505e3 | 51 | return (unsigned long)sys_ticks; |
fcfb632b MK |
52 | } |
53 | ||
54 | static inline unsigned long usecs_to_ticks(unsigned long usecs) | |
55 | { | |
56 | unsigned long ticks; | |
57 | ||
58 | if (usecs >= 1000) { | |
59 | ticks = usecs / 1000; | |
60 | ticks *= (TIMER_LOAD_VAL * CONFIG_SYS_HZ); | |
61 | ticks /= 1000; | |
62 | } else { | |
63 | ticks = usecs * TIMER_LOAD_VAL * CONFIG_SYS_HZ; | |
64 | ticks /= (1000 * 1000); | |
65 | } | |
66 | ||
67 | return ticks; | |
68 | } | |
69 | ||
70 | static inline unsigned long read_timer(void) | |
71 | { | |
72 | struct timer_regs *timer = (struct timer_regs *)TIMER_BASE; | |
73 | ||
74 | return readl(&timer->timer3.value); | |
75 | } | |
76 | ||
77 | /* | |
78 | * timer without interrupts | |
79 | */ | |
80 | unsigned long long get_ticks(void) | |
81 | { | |
82 | const unsigned long now = read_timer(); | |
83 | ||
84 | if (lastdec >= now) { | |
85 | /* normal mode */ | |
86 | timestamp += lastdec - now; | |
87 | } else { | |
88 | /* we have an overflow ... */ | |
89 | timestamp += lastdec + TIMER_LOAD_VAL - now; | |
90 | } | |
91 | ||
92 | lastdec = now; | |
93 | ||
94 | return timestamp; | |
95 | } | |
96 | ||
97 | unsigned long get_timer_masked(void) | |
98 | { | |
99 | return clk_to_systicks(get_ticks()); | |
100 | } | |
101 | ||
102 | unsigned long get_timer(unsigned long base) | |
103 | { | |
104 | return get_timer_masked() - base; | |
105 | } | |
106 | ||
107 | void reset_timer_masked(void) | |
108 | { | |
109 | lastdec = read_timer(); | |
110 | timestamp = 0; | |
111 | } | |
112 | ||
113 | void reset_timer(void) | |
114 | { | |
115 | reset_timer_masked(); | |
116 | } | |
117 | ||
118 | void set_timer(unsigned long t) | |
119 | { | |
120 | timestamp = t; | |
121 | } | |
122 | ||
123 | void __udelay(unsigned long usec) | |
124 | { | |
125 | const unsigned long ticks = usecs_to_ticks(usec); | |
126 | const unsigned long target = clk_to_systicks(ticks) + get_timer(0); | |
127 | ||
128 | while (get_timer_masked() < target) | |
129 | /* noop */; | |
130 | } | |
131 | ||
132 | void udelay_masked(unsigned long usec) | |
133 | { | |
134 | const unsigned long ticks = usecs_to_ticks(usec); | |
135 | const unsigned long target = clk_to_systicks(ticks) + get_timer(0); | |
136 | ||
137 | reset_timer_masked(); | |
138 | ||
139 | while (get_timer_masked() < target) | |
140 | /* noop */; | |
141 | } | |
142 | ||
143 | int timer_init(void) | |
144 | { | |
145 | struct timer_regs *timer = (struct timer_regs *)TIMER_BASE; | |
146 | ||
147 | /* use timer 3 with 508KHz and free running */ | |
148 | writel(TIMER_CLKSEL, &timer->timer3.control); | |
149 | ||
150 | /* auto load, manual update of Timer 3 */ | |
151 | lastdec = TIMER_LOAD_VAL; | |
152 | writel(TIMER_LOAD_VAL, &timer->timer3.load); | |
153 | ||
154 | /* Enable the timer and periodic mode */ | |
155 | writel(TIMER_ENABLE | TIMER_MODE | TIMER_CLKSEL, | |
156 | &timer->timer3.control); | |
157 | ||
158 | reset_timer_masked(); | |
159 | ||
160 | return 0; | |
161 | } | |
162 | ||
163 | /* | |
164 | * This function is derived from PowerPC code (timebase clock frequency). | |
165 | * On ARM it returns the number of timer ticks per second. | |
166 | */ | |
167 | unsigned long get_tbclk(void) | |
168 | { | |
169 | return CONFIG_SYS_HZ; | |
170 | } |