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 <asm/mach-loongson/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         unsigned long rate;
 111         int ret;
 112
 113         if (!cpu_online(policy->cpu))
 114                 return -ENODEV;
 115
 116         cpuclk = clk_get(NULL, "cpu_clk");
 117         if (IS_ERR(cpuclk)) {
 118                 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
 119                 return PTR_ERR(cpuclk);
 120         }
 121
 122         rate = cpu_clock_freq / 1000;
 123         if (!rate) {
 124                 clk_put(cpuclk);
 125                 return -EINVAL;
 126         }
 127         ret = clk_set_rate(cpuclk, rate);
 128         if (ret) {
 129                 clk_put(cpuclk);
 130                 return ret;
 131         }
 132
 133         /* clock table init */
 134         for (i = 2;
 135              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
 136              i++)
 137                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
 138
 139         policy->cur = loongson2_cpufreq_get(policy->cpu);
 140
 141         cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
 142                                          policy->cpu);
 143
 144         return cpufreq_frequency_table_cpuinfo(policy,
 145                                             &loongson2_clockmod_table[0]);
 146 }
 147
 148 static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
 149 {
 150         return cpufreq_frequency_table_verify(policy,
 151                                               &loongson2_clockmod_table[0]);
 152 }
 153
 154 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 155 {
 156         clk_put(cpuclk);
 157         return 0;
 158 }
 159
 160 static struct freq_attr *loongson2_table_attr[] = {
 161         &cpufreq_freq_attr_scaling_available_freqs,
 162         NULL,
 163 };
 164
 165 static struct cpufreq_driver loongson2_cpufreq_driver = {
 166         .owner = THIS_MODULE,
 167         .name = "loongson2",
 168         .init = loongson2_cpufreq_cpu_init,
 169         .verify = loongson2_cpufreq_verify,
 170         .target = loongson2_cpufreq_target,
 171         .get = loongson2_cpufreq_get,
 172         .exit = loongson2_cpufreq_exit,
 173         .attr = loongson2_table_attr,
 174 };
 175
 176 static struct platform_device_id platform_device_ids[] = {
 177         {
 178                 .name = "loongson2_cpufreq",
 179         },
 180         {}
 181 };
 182
 183 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 184
 185 static struct platform_driver platform_driver = {
 186         .driver = {
 187                 .name = "loongson2_cpufreq",
 188                 .owner = THIS_MODULE,
 189         },
 190         .id_table = platform_device_ids,
 191 };
 192
 193 /*
 194  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 195  * interrupt disabled context.
 196  */
 197
 198 static DEFINE_SPINLOCK(loongson2_wait_lock);
 199
 200 static void loongson2_cpu_wait(void)
 201 {
 202         unsigned long flags;
 203         u32 cpu_freq;
 204
 205         spin_lock_irqsave(&loongson2_wait_lock, flags);
 206         cpu_freq = LOONGSON_CHIPCFG0;
 207         LOONGSON_CHIPCFG0 &= ~0x7;      /* Put CPU into wait mode */
 208         LOONGSON_CHIPCFG0 = cpu_freq;   /* Restore CPU state */
 209         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 210 }
 211
 212 static int __init cpufreq_init(void)
 213 {
 214         int ret;
 215
 216         /* Register platform stuff */
 217         ret = platform_driver_register(&platform_driver);
 218         if (ret)
 219                 return ret;
 220
 221         pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
 222
 223         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 224                                   CPUFREQ_TRANSITION_NOTIFIER);
 225
 226         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 227
 228         if (!ret && !nowait) {
 229                 saved_cpu_wait = cpu_wait;
 230                 cpu_wait = loongson2_cpu_wait;
 231         }
 232
 233         return ret;
 234 }
 235
 236 static void __exit cpufreq_exit(void)
 237 {
 238         if (!nowait && saved_cpu_wait)
 239                 cpu_wait = saved_cpu_wait;
 240         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 241         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 242                                     CPUFREQ_TRANSITION_NOTIFIER);
 243
 244         platform_driver_unregister(&platform_driver);
 245 }
 246
 247 module_init(cpufreq_init);
 248 module_exit(cpufreq_exit);
 249
 250 module_param(nowait, uint, 0644);
 251 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 252
 253 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 254 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 255 MODULE_LICENSE("GPL");