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 */
ucv2_verify_speed(struct cpufreq_policy * policy)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
ucv2_target(struct cpufreq_policy * policy,unsigned int target_freq,unsigned int relation)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
ucv2_cpu_init(struct cpufreq_policy * policy)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
ucv2_cpufreq_init(void)75 static int __init ucv2_cpufreq_init(void)
76 {
77 return cpufreq_register_driver(&ucv2_driver);
78 }
79
80 arch_initcall(ucv2_cpufreq_init);
81