avr32: add export.h to arch/avr32 for EXPORT_SYMBOL/THIS_MODULE
[linux-2.6.git] / arch / avr32 / mach-at32ap / cpufreq.c
1 /*
2  * Copyright (C) 2004-2007 Atmel Corporation
3  *
4  * Based on MIPS implementation arch/mips/kernel/time.c
5  *   Copyright 2001 MontaVista Software Inc.
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 /*#define DEBUG*/
13
14 #include <linux/kernel.h>
15 #include <linux/types.h>
16 #include <linux/init.h>
17 #include <linux/cpufreq.h>
18 #include <linux/io.h>
19 #include <linux/clk.h>
20 #include <linux/err.h>
21 #include <linux/export.h>
22 #include <asm/system.h>
23
24 static struct clk *cpuclk;
25
26 static int at32_verify_speed(struct cpufreq_policy *policy)
27 {
28         if (policy->cpu != 0)
29                 return -EINVAL;
30
31         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
32                         policy->cpuinfo.max_freq);
33         return 0;
34 }
35
36 static unsigned int at32_get_speed(unsigned int cpu)
37 {
38         /* No SMP support */
39         if (cpu)
40                 return 0;
41         return (unsigned int)((clk_get_rate(cpuclk) + 500) / 1000);
42 }
43
44 static unsigned int     ref_freq;
45 static unsigned long    loops_per_jiffy_ref;
46
47 static int at32_set_target(struct cpufreq_policy *policy,
48                           unsigned int target_freq,
49                           unsigned int relation)
50 {
51         struct cpufreq_freqs freqs;
52         long freq;
53
54         /* Convert target_freq from kHz to Hz */
55         freq = clk_round_rate(cpuclk, target_freq * 1000);
56
57         /* Check if policy->min <= new_freq <= policy->max */
58         if(freq < (policy->min * 1000) || freq > (policy->max * 1000))
59                 return -EINVAL;
60
61         pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
62
63         freqs.old = at32_get_speed(0);
64         freqs.new = (freq + 500) / 1000;
65         freqs.cpu = 0;
66         freqs.flags = 0;
67
68         if (!ref_freq) {
69                 ref_freq = freqs.old;
70                 loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
71         }
72
73         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
74         if (freqs.old < freqs.new)
75                 boot_cpu_data.loops_per_jiffy = cpufreq_scale(
76                                 loops_per_jiffy_ref, ref_freq, freqs.new);
77         clk_set_rate(cpuclk, freq);
78         if (freqs.new < freqs.old)
79                 boot_cpu_data.loops_per_jiffy = cpufreq_scale(
80                                 loops_per_jiffy_ref, ref_freq, freqs.new);
81         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
82
83         pr_debug("cpufreq: set frequency %lu Hz\n", freq);
84
85         return 0;
86 }
87
88 static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy)
89 {
90         if (policy->cpu != 0)
91                 return -EINVAL;
92
93         cpuclk = clk_get(NULL, "cpu");
94         if (IS_ERR(cpuclk)) {
95                 pr_debug("cpufreq: could not get CPU clk\n");
96                 return PTR_ERR(cpuclk);
97         }
98
99         policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
100         policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
101         policy->cpuinfo.transition_latency = 0;
102         policy->cur = at32_get_speed(0);
103         policy->min = policy->cpuinfo.min_freq;
104         policy->max = policy->cpuinfo.max_freq;
105
106         printk("cpufreq: AT32AP CPU frequency driver\n");
107
108         return 0;
109 }
110
111 static struct cpufreq_driver at32_driver = {
112         .name           = "at32ap",
113         .owner          = THIS_MODULE,
114         .init           = at32_cpufreq_driver_init,
115         .verify         = at32_verify_speed,
116         .target         = at32_set_target,
117         .get            = at32_get_speed,
118         .flags          = CPUFREQ_STICKY,
119 };
120
121 static int __init at32_cpufreq_init(void)
122 {
123         return cpufreq_register_driver(&at32_driver);
124 }
125 late_initcall(at32_cpufreq_init);