release/src-rt-6.x.4708/linux/linux-2.6.36/arch/mips/kernel/cpufreq/loongson2_cpufreq.c

   1 /*
   2  * Cpufreq driver for the loongson-2 processors
   3  *
   4  * The 2E revision of loongson processor not support this feature.
   5  *
   6  * Copyright (C) 2006 - 2008 Lemote Inc. & Insititute of Computing Technology
   7  * Author: Yanhua, yanh@lemote.com
   8  *
   9  * This file is subject to the terms and conditions of the GNU General Public
  10  * License.  See the file "COPYING" in the main directory of this archive
  11  * for more details.
  12  */
  13 #include <linux/cpufreq.h>
  14 #include <linux/module.h>
  15 #include <linux/err.h>
  16 #include <linux/sched.h>        /* set_cpus_allowed() */
  17 #include <linux/delay.h>
  18 #include <linux/platform_device.h>
  19
  20 #include <asm/clock.h>
  21
  22 #include <loongson.h>
  23
  24 static uint nowait;
  25
  26 static struct clk *cpuclk;
  27
  28 static void (*saved_cpu_wait) (void);
  29
  30 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  31                                         unsigned long val, void *data);
  32
  33 static struct notifier_block loongson2_cpufreq_notifier_block = {
  34         .notifier_call = loongson2_cpu_freq_notifier
  35 };
  36
  37 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  38                                         unsigned long val, void *data)
  39 {
  40         if (val == CPUFREQ_POSTCHANGE)
  41                 current_cpu_data.udelay_val = loops_per_jiffy;
  42
  43         return 0;
  44 }
  45
  46 static unsigned int loongson2_cpufreq_get(unsigned int cpu)
  47 {
  48         return clk_get_rate(cpuclk);
  49 }
  50
  51 /*
  52  * Here we notify other drivers of the proposed change and the final change.
  53  */
  54 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
  55                                      unsigned int target_freq,
  56                                      unsigned int relation)
  57 {
  58         unsigned int cpu = policy->cpu;
  59         unsigned int newstate = 0;
  60         cpumask_t cpus_allowed;
  61         struct cpufreq_freqs freqs;
  62         unsigned int freq;
  63
  64         if (!cpu_online(cpu))
  65                 return -ENODEV;
  66
  67         cpus_allowed = current->cpus_allowed;
  68         set_cpus_allowed_ptr(current, cpumask_of(cpu));
  69
  70         if (cpufreq_frequency_table_target
  71             (policy, &loongson2_clockmod_table[0], target_freq, relation,
  72              &newstate))
  73                 return -EINVAL;
  74
  75         freq =
  76             ((cpu_clock_freq / 1000) *
  77              loongson2_clockmod_table[newstate].index) / 8;
  78         if (freq < policy->min || freq > policy->max)
  79                 return -EINVAL;
  80
  81         pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
  82
  83         freqs.cpu = cpu;
  84         freqs.old = loongson2_cpufreq_get(cpu);
  85         freqs.new = freq;
  86         freqs.flags = 0;
  87
  88         if (freqs.new == freqs.old)
  89                 return 0;
  90
  91         /* notifiers */
  92         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  93
  94         set_cpus_allowed_ptr(current, &cpus_allowed);
  95
  96         /* setting the cpu frequency */
  97         clk_set_rate(cpuclk, freq);
  98
  99         /* notifiers */
 100         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 101
 102         pr_debug("cpufreq: set frequency %u kHz\n", freq);
 103
 104         return 0;
 105 }
 106
 107 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
 108 {
 109         int i;
 110
 111         if (!cpu_online(policy->cpu))
 112                 return -ENODEV;
 113
 114         cpuclk = clk_get(NULL, "cpu_clk");
 115         if (IS_ERR(cpuclk)) {
 116                 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
 117                 return PTR_ERR(cpuclk);
 118         }
 119
 120         cpuclk->rate = cpu_clock_freq / 1000;
 121         if (!cpuclk->rate)
 122                 return -EINVAL;
 123
 124         /* clock table init */
 125         for (i = 2;
 126              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
 127              i++)
 128                 loongson2_clockmod_table[i].frequency = (cpuclk->rate * i) / 8;
 129
 130         policy->cur = loongson2_cpufreq_get(policy->cpu);
 131
 132         cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
 133                                          policy->cpu);
 134
 135         return cpufreq_frequency_table_cpuinfo(policy,
 136                                             &loongson2_clockmod_table[0]);
 137 }
 138
 139 static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
 140 {
 141         return cpufreq_frequency_table_verify(policy,
 142                                               &loongson2_clockmod_table[0]);
 143 }
 144
 145 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 146 {
 147         clk_put(cpuclk);
 148         return 0;
 149 }
 150
 151 static struct freq_attr *loongson2_table_attr[] = {
 152         &cpufreq_freq_attr_scaling_available_freqs,
 153         NULL,
 154 };
 155
 156 static struct cpufreq_driver loongson2_cpufreq_driver = {
 157         .owner = THIS_MODULE,
 158         .name = "loongson2",
 159         .init = loongson2_cpufreq_cpu_init,
 160         .verify = loongson2_cpufreq_verify,
 161         .target = loongson2_cpufreq_target,
 162         .get = loongson2_cpufreq_get,
 163         .exit = loongson2_cpufreq_exit,
 164         .attr = loongson2_table_attr,
 165 };
 166
 167 static struct platform_device_id platform_device_ids[] = {
 168         {
 169                 .name = "loongson2_cpufreq",
 170         },
 171         {}
 172 };
 173
 174 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 175
 176 static struct platform_driver platform_driver = {
 177         .driver = {
 178                 .name = "loongson2_cpufreq",
 179                 .owner = THIS_MODULE,
 180         },
 181         .id_table = platform_device_ids,
 182 };
 183
 184 static int __init cpufreq_init(void)
 185 {
 186         int ret;
 187
 188         /* Register platform stuff */
 189         ret = platform_driver_register(&platform_driver);
 190         if (ret)
 191                 return ret;
 192
 193         pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
 194
 195         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 196                                   CPUFREQ_TRANSITION_NOTIFIER);
 197
 198         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 199
 200         if (!ret && !nowait) {
 201                 saved_cpu_wait = cpu_wait;
 202                 cpu_wait = loongson2_cpu_wait;
 203         }
 204
 205         return ret;
 206 }
 207
 208 static void __exit cpufreq_exit(void)
 209 {
 210         if (!nowait && saved_cpu_wait)
 211                 cpu_wait = saved_cpu_wait;
 212         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 213         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 214                                     CPUFREQ_TRANSITION_NOTIFIER);
 215
 216         platform_driver_unregister(&platform_driver);
 217 }
 218
 219 module_init(cpufreq_init);
 220 module_exit(cpufreq_exit);
 221
 222 module_param(nowait, uint, 0644);
 223 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 224
 225 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 226 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 227 MODULE_LICENSE("GPL");