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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 - 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#%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 
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 
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 
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 
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 

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