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1 | /* | |
2 | * clock scaling for the UniCore-II | |
3 | * | |
4 | * Code specific to PKUnity SoC and UniCore ISA | |
5 | * | |
6 | * Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn> | |
7 | * Copyright (C) 2001-2010 Guan Xuetao | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License version 2 as | |
11 | * published by the Free Software Foundation. | |
12 | */ | |
13 | ||
14 | #include <linux/err.h> | |
15 | #include <linux/kernel.h> | |
16 | #include <linux/types.h> | |
17 | #include <linux/init.h> | |
18 | #include <linux/clk.h> | |
19 | #include <linux/cpufreq.h> | |
20 | ||
21 | #include <mach/hardware.h> | |
22 | ||
23 | static struct cpufreq_driver ucv2_driver; | |
24 | ||
25 | /* make sure that only the "userspace" governor is run | |
26 | * -- anything else wouldn't make sense on this platform, anyway. | |
27 | */ | |
28 | static int ucv2_verify_speed(struct cpufreq_policy *policy) | |
29 | { | |
30 | if (policy->cpu) | |
31 | return -EINVAL; | |
32 | ||
33 | cpufreq_verify_within_cpu_limits(policy); | |
34 | return 0; | |
35 | } | |
36 | ||
37 | static int ucv2_target(struct cpufreq_policy *policy, | |
38 | unsigned int target_freq, | |
39 | unsigned int relation) | |
40 | { | |
41 | struct cpufreq_freqs freqs; | |
42 | int ret; | |
43 | ||
44 | freqs.old = policy->cur; | |
45 | freqs.new = target_freq; | |
46 | ||
47 | cpufreq_freq_transition_begin(policy, &freqs); | |
48 | ret = clk_set_rate(policy->clk, target_freq * 1000); | |
49 | cpufreq_freq_transition_end(policy, &freqs, ret); | |
50 | ||
51 | return ret; | |
52 | } | |
53 | ||
54 | static int __init ucv2_cpu_init(struct cpufreq_policy *policy) | |
55 | { | |
56 | if (policy->cpu != 0) | |
57 | return -EINVAL; | |
58 | ||
59 | policy->min = policy->cpuinfo.min_freq = 250000; | |
60 | policy->max = policy->cpuinfo.max_freq = 1000000; | |
61 | policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; | |
62 | policy->clk = clk_get(NULL, "MAIN_CLK"); | |
63 | return PTR_ERR_OR_ZERO(policy->clk); | |
64 | } | |
65 | ||
66 | static struct cpufreq_driver ucv2_driver = { | |
67 | .flags = CPUFREQ_STICKY, | |
68 | .verify = ucv2_verify_speed, | |
69 | .target = ucv2_target, | |
70 | .get = cpufreq_generic_get, | |
71 | .init = ucv2_cpu_init, | |
72 | .name = "UniCore-II", | |
73 | }; | |
74 | ||
75 | static int __init ucv2_cpufreq_init(void) | |
76 | { | |
77 | return cpufreq_register_driver(&ucv2_driver); | |
78 | } | |
79 | ||
80 | arch_initcall(ucv2_cpufreq_init); |