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
sh_cpufreq_get(unsigned int cpu)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 */
sh_cpufreq_target(struct cpufreq_policy * policy,unsigned int target_freq,unsigned int relation)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_ptr(current, cpumask_of(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_ptr(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
sh_cpufreq_cpu_init(struct cpufreq_policy * policy)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#%d clk\n",
86 policy->cpu);
87 return PTR_ERR(cpuclk);
88 }
89
90 /* cpuinfo and default policy values */
91 policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
92 policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
93 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
94
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 * Catch the cases where the clock framework hasn't been wired up
101 * properly to support scaling.
102 */
103 if (unlikely(policy->min == policy->max)) {
104 printk(KERN_ERR "cpufreq: clock framework rate rounding "
105 "not supported on CPU#%d.\n", policy->cpu);
106
107 clk_put(cpuclk);
108 return -EINVAL;
109 }
110
111 printk(KERN_INFO "cpufreq: CPU#%d Frequencies - Minimum %u.%03u MHz, "
112 "Maximum %u.%03u MHz.\n",
113 policy->cpu, policy->min / 1000, policy->min % 1000,
114 policy->max / 1000, policy->max % 1000);
115
116 return 0;
117 }
118
sh_cpufreq_verify(struct cpufreq_policy * policy)119 static int sh_cpufreq_verify(struct cpufreq_policy *policy)
120 {
121 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
122 policy->cpuinfo.max_freq);
123 return 0;
124 }
125
sh_cpufreq_exit(struct cpufreq_policy * policy)126 static int sh_cpufreq_exit(struct cpufreq_policy *policy)
127 {
128 clk_put(cpuclk);
129 return 0;
130 }
131
132 static struct cpufreq_driver sh_cpufreq_driver = {
133 .owner = THIS_MODULE,
134 .name = "sh",
135 .init = sh_cpufreq_cpu_init,
136 .verify = sh_cpufreq_verify,
137 .target = sh_cpufreq_target,
138 .get = sh_cpufreq_get,
139 .exit = sh_cpufreq_exit,
140 };
141
sh_cpufreq_module_init(void)142 static int __init sh_cpufreq_module_init(void)
143 {
144 printk(KERN_INFO "cpufreq: SuperH CPU frequency driver.\n");
145 return cpufreq_register_driver(&sh_cpufreq_driver);
146 }
147
sh_cpufreq_module_exit(void)148 static void __exit sh_cpufreq_module_exit(void)
149 {
150 cpufreq_unregister_driver(&sh_cpufreq_driver);
151 }
152
153 module_init(sh_cpufreq_module_init);
154 module_exit(sh_cpufreq_module_exit);
155
156 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
157 MODULE_DESCRIPTION("cpufreq driver for SuperH");
158 MODULE_LICENSE("GPL");
159