c7668971ba6c6a2a4f6446c620eec6334e8eab7a
[sfrench/cifs-2.6.git] / arch / sh / kernel / cpufreq.c
1 /*
2  * arch/sh/kernel/cpufreq.c
3  *
4  * cpufreq driver for the SuperH processors.
5  *
6  * Copyright (C) 2002 - 2007 Paul Mundt
7  * Copyright (C) 2002 M. R. Brown
8  *
9  * Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
10  *
11  *   Copyright (C) 2004-2007 Atmel Corporation
12  *
13  * This file is subject to the terms and conditions of the GNU General Public
14  * License.  See the file "COPYING" in the main directory of this archive
15  * for more details.
16  */
17 #include <linux/types.h>
18 #include <linux/cpufreq.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/init.h>
22 #include <linux/err.h>
23 #include <linux/cpumask.h>
24 #include <linux/smp.h>
25 #include <linux/sched.h>        /* set_cpus_allowed() */
26 #include <linux/clk.h>
27
28 static struct clk *cpuclk;
29
30 static unsigned int sh_cpufreq_get(unsigned int cpu)
31 {
32         return (clk_get_rate(cpuclk) + 500) / 1000;
33 }
34
35 /*
36  * Here we notify other drivers of the proposed change and the final change.
37  */
38 static int sh_cpufreq_target(struct cpufreq_policy *policy,
39                              unsigned int target_freq,
40                              unsigned int relation)
41 {
42         unsigned int cpu = policy->cpu;
43         cpumask_t cpus_allowed;
44         struct cpufreq_freqs freqs;
45         long freq;
46
47         if (!cpu_online(cpu))
48                 return -ENODEV;
49
50         cpus_allowed = current->cpus_allowed;
51         set_cpus_allowed(current, cpumask_of_cpu(cpu));
52
53         BUG_ON(smp_processor_id() != cpu);
54
55         /* Convert target_freq from kHz to Hz */
56         freq = clk_round_rate(cpuclk, target_freq * 1000);
57
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.cpu       = cpu;
64         freqs.old       = sh_cpufreq_get(cpu);
65         freqs.new       = (freq + 500) / 1000;
66         freqs.flags     = 0;
67
68         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
69         set_cpus_allowed(current, cpus_allowed);
70         clk_set_rate(cpuclk, freq);
71         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
72
73         pr_debug("cpufreq: set frequency %lu Hz\n", freq);
74
75         return 0;
76 }
77
78 static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
79 {
80         if (!cpu_online(policy->cpu))
81                 return -ENODEV;
82
83         cpuclk = clk_get(NULL, "cpu_clk");
84         if (IS_ERR(cpuclk)) {
85                 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
86                 return PTR_ERR(cpuclk);
87         }
88
89         /* cpuinfo and default policy values */
90         policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
91         policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
92         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
93
94         policy->governor        = CPUFREQ_DEFAULT_GOVERNOR;
95         policy->cur             = sh_cpufreq_get(policy->cpu);
96         policy->min             = policy->cpuinfo.min_freq;
97         policy->max             = policy->cpuinfo.max_freq;
98
99
100         /*
101          * Catch the cases where the clock framework hasn't been wired up
102          * properly to support scaling.
103          */
104         if (unlikely(policy->min == policy->max)) {
105                 printk(KERN_ERR "cpufreq: clock framework rate rounding "
106                        "not supported on this CPU.\n");
107
108                 clk_put(cpuclk);
109                 return -EINVAL;
110         }
111
112         printk(KERN_INFO "cpufreq: Frequencies - Minimum %u.%03u MHz, "
113                "Maximum %u.%03u MHz.\n",
114                policy->min / 1000, policy->min % 1000,
115                policy->max / 1000, policy->max % 1000);
116
117         return 0;
118 }
119
120 static int sh_cpufreq_verify(struct cpufreq_policy *policy)
121 {
122         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
123                                      policy->cpuinfo.max_freq);
124         return 0;
125 }
126
127 static int sh_cpufreq_exit(struct cpufreq_policy *policy)
128 {
129         clk_put(cpuclk);
130         return 0;
131 }
132
133 static struct cpufreq_driver sh_cpufreq_driver = {
134         .owner          = THIS_MODULE,
135         .name           = "sh",
136         .init           = sh_cpufreq_cpu_init,
137         .verify         = sh_cpufreq_verify,
138         .target         = sh_cpufreq_target,
139         .get            = sh_cpufreq_get,
140         .exit           = sh_cpufreq_exit,
141 };
142
143 static int __init sh_cpufreq_module_init(void)
144 {
145         printk(KERN_INFO "cpufreq: SuperH CPU frequency driver.\n");
146         return cpufreq_register_driver(&sh_cpufreq_driver);
147 }
148
149 static void __exit sh_cpufreq_module_exit(void)
150 {
151         cpufreq_unregister_driver(&sh_cpufreq_driver);
152 }
153
154 module_init(sh_cpufreq_module_init);
155 module_exit(sh_cpufreq_module_exit);
156
157 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
158 MODULE_DESCRIPTION("cpufreq driver for SuperH");
159 MODULE_LICENSE("GPL");