GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / cpufreq / unicore2-cpufreq.c
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);