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9e58e185 HCE |
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 <asm/system.h> | |
22 | ||
23 | static struct clk *cpuclk; | |
24 | ||
25 | static int at32_verify_speed(struct cpufreq_policy *policy) | |
26 | { | |
27 | if (policy->cpu != 0) | |
28 | return -EINVAL; | |
29 | ||
30 | cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, | |
31 | policy->cpuinfo.max_freq); | |
32 | return 0; | |
33 | } | |
34 | ||
35 | static unsigned int at32_get_speed(unsigned int cpu) | |
36 | { | |
37 | /* No SMP support */ | |
38 | if (cpu) | |
39 | return 0; | |
40 | return (unsigned int)((clk_get_rate(cpuclk) + 500) / 1000); | |
41 | } | |
42 | ||
43 | static int at32_set_target(struct cpufreq_policy *policy, | |
44 | unsigned int target_freq, | |
45 | unsigned int relation) | |
46 | { | |
47 | struct cpufreq_freqs freqs; | |
48 | long freq; | |
49 | ||
50 | /* Convert target_freq from kHz to Hz */ | |
51 | freq = clk_round_rate(cpuclk, target_freq * 1000); | |
52 | ||
53 | /* Check if policy->min <= new_freq <= policy->max */ | |
54 | if(freq < (policy->min * 1000) || freq > (policy->max * 1000)) | |
55 | return -EINVAL; | |
56 | ||
57 | pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000); | |
58 | ||
59 | freqs.old = at32_get_speed(0); | |
60 | freqs.new = (freq + 500) / 1000; | |
61 | freqs.cpu = 0; | |
62 | freqs.flags = 0; | |
63 | ||
64 | cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); | |
65 | clk_set_rate(cpuclk, freq); | |
66 | cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); | |
67 | ||
68 | pr_debug("cpufreq: set frequency %lu Hz\n", freq); | |
69 | ||
70 | return 0; | |
71 | } | |
72 | ||
73 | static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy) | |
74 | { | |
75 | if (policy->cpu != 0) | |
76 | return -EINVAL; | |
77 | ||
78 | cpuclk = clk_get(NULL, "cpu"); | |
79 | if (IS_ERR(cpuclk)) { | |
80 | pr_debug("cpufreq: could not get CPU clk\n"); | |
81 | return PTR_ERR(cpuclk); | |
82 | } | |
83 | ||
84 | policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000; | |
85 | policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000; | |
86 | policy->cpuinfo.transition_latency = 0; | |
87 | policy->cur = at32_get_speed(0); | |
88 | policy->min = policy->cpuinfo.min_freq; | |
89 | policy->max = policy->cpuinfo.max_freq; | |
90 | policy->governor = CPUFREQ_DEFAULT_GOVERNOR; | |
91 | ||
92 | printk("cpufreq: AT32AP CPU frequency driver\n"); | |
93 | ||
94 | return 0; | |
95 | } | |
96 | ||
97 | static struct cpufreq_driver at32_driver = { | |
98 | .name = "at32ap", | |
99 | .owner = THIS_MODULE, | |
100 | .init = at32_cpufreq_driver_init, | |
101 | .verify = at32_verify_speed, | |
102 | .target = at32_set_target, | |
103 | .get = at32_get_speed, | |
104 | .flags = CPUFREQ_STICKY, | |
105 | }; | |
106 | ||
107 | static int __init at32_cpufreq_init(void) | |
108 | { | |
109 | return cpufreq_register_driver(&at32_driver); | |
110 | } | |
111 | ||
112 | arch_initcall(at32_cpufreq_init); |