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Linux/arch/sh/kernel/cpufreq.c

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  1 /*
  2  * arch/sh/kernel/cpufreq.c
  3  *
  4  * cpufreq driver for the SuperH processors.
  5  *
  6  * Copyright (C) 2002 - 2012 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 #define pr_fmt(fmt) "cpufreq: " fmt
 18 
 19 #include <linux/types.h>
 20 #include <linux/cpufreq.h>
 21 #include <linux/kernel.h>
 22 #include <linux/module.h>
 23 #include <linux/init.h>
 24 #include <linux/err.h>
 25 #include <linux/cpumask.h>
 26 #include <linux/cpu.h>
 27 #include <linux/smp.h>
 28 #include <linux/sched.h>        /* set_cpus_allowed() */
 29 #include <linux/clk.h>
 30 #include <linux/percpu.h>
 31 #include <linux/sh_clk.h>
 32 
 33 static DEFINE_PER_CPU(struct clk, sh_cpuclk);
 34 
 35 static unsigned int sh_cpufreq_get(unsigned int cpu)
 36 {
 37         return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
 38 }
 39 
 40 /*
 41  * Here we notify other drivers of the proposed change and the final change.
 42  */
 43 static int sh_cpufreq_target(struct cpufreq_policy *policy,
 44                              unsigned int target_freq,
 45                              unsigned int relation)
 46 {
 47         unsigned int cpu = policy->cpu;
 48         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
 49         cpumask_t cpus_allowed;
 50         struct cpufreq_freqs freqs;
 51         struct device *dev;
 52         long freq;
 53 
 54         if (!cpu_online(cpu))
 55                 return -ENODEV;
 56 
 57         cpus_allowed = current->cpus_allowed;
 58         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 59 
 60         BUG_ON(smp_processor_id() != cpu);
 61 
 62         dev = get_cpu_device(cpu);
 63 
 64         /* Convert target_freq from kHz to Hz */
 65         freq = clk_round_rate(cpuclk, target_freq * 1000);
 66 
 67         if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
 68                 return -EINVAL;
 69 
 70         dev_dbg(dev, "requested frequency %u Hz\n", target_freq * 1000);
 71 
 72         freqs.cpu       = cpu;
 73         freqs.old       = sh_cpufreq_get(cpu);
 74         freqs.new       = (freq + 500) / 1000;
 75         freqs.flags     = 0;
 76 
 77         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 78         set_cpus_allowed_ptr(current, &cpus_allowed);
 79         clk_set_rate(cpuclk, freq);
 80         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 81 
 82         dev_dbg(dev, "set frequency %lu Hz\n", freq);
 83 
 84         return 0;
 85 }
 86 
 87 static int sh_cpufreq_verify(struct cpufreq_policy *policy)
 88 {
 89         struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
 90         struct cpufreq_frequency_table *freq_table;
 91 
 92         freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
 93         if (freq_table)
 94                 return cpufreq_frequency_table_verify(policy, freq_table);
 95 
 96         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
 97                                      policy->cpuinfo.max_freq);
 98 
 99         policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
100         policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
101 
102         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
103                                      policy->cpuinfo.max_freq);
104 
105         return 0;
106 }
107 
108 static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
109 {
110         unsigned int cpu = policy->cpu;
111         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
112         struct cpufreq_frequency_table *freq_table;
113         struct device *dev;
114 
115         if (!cpu_online(cpu))
116                 return -ENODEV;
117 
118         dev = get_cpu_device(cpu);
119 
120         cpuclk = clk_get(dev, "cpu_clk");
121         if (IS_ERR(cpuclk)) {
122                 dev_err(dev, "couldn't get CPU clk\n");
123                 return PTR_ERR(cpuclk);
124         }
125 
126         policy->cur = policy->min = policy->max = sh_cpufreq_get(cpu);
127 
128         freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
129         if (freq_table) {
130                 int result;
131 
132                 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
133                 if (!result)
134                         cpufreq_frequency_table_get_attr(freq_table, cpu);
135         } else {
136                 dev_notice(dev, "no frequency table found, falling back "
137                            "to rate rounding.\n");
138 
139                 policy->cpuinfo.min_freq =
140                         (clk_round_rate(cpuclk, 1) + 500) / 1000;
141                 policy->cpuinfo.max_freq =
142                         (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
143         }
144 
145         policy->min = policy->cpuinfo.min_freq;
146         policy->max = policy->cpuinfo.max_freq;
147 
148         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
149 
150         dev_info(dev, "CPU Frequencies - Minimum %u.%03u MHz, "
151                "Maximum %u.%03u MHz.\n",
152                policy->min / 1000, policy->min % 1000,
153                policy->max / 1000, policy->max % 1000);
154 
155         return 0;
156 }
157 
158 static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
159 {
160         unsigned int cpu = policy->cpu;
161         struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
162 
163         cpufreq_frequency_table_put_attr(cpu);
164         clk_put(cpuclk);
165 
166         return 0;
167 }
168 
169 static struct freq_attr *sh_freq_attr[] = {
170         &cpufreq_freq_attr_scaling_available_freqs,
171         NULL,
172 };
173 
174 static struct cpufreq_driver sh_cpufreq_driver = {
175         .owner          = THIS_MODULE,
176         .name           = "sh",
177         .get            = sh_cpufreq_get,
178         .target         = sh_cpufreq_target,
179         .verify         = sh_cpufreq_verify,
180         .init           = sh_cpufreq_cpu_init,
181         .exit           = sh_cpufreq_cpu_exit,
182         .attr           = sh_freq_attr,
183 };
184 
185 static int __init sh_cpufreq_module_init(void)
186 {
187         pr_notice("SuperH CPU frequency driver.\n");
188         return cpufreq_register_driver(&sh_cpufreq_driver);
189 }
190 
191 static void __exit sh_cpufreq_module_exit(void)
192 {
193         cpufreq_unregister_driver(&sh_cpufreq_driver);
194 }
195 
196 module_init(sh_cpufreq_module_init);
197 module_exit(sh_cpufreq_module_exit);
198 
199 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
200 MODULE_DESCRIPTION("cpufreq driver for SuperH");
201 MODULE_LICENSE("GPL");
202 

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