drivers/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         cpus_allowed = current->cpus_allowed;
  65         set_cpus_allowed_ptr(current, cpumask_of(cpu));
  66
  67         if (cpufreq_frequency_table_target
  68             (policy, &loongson2_clockmod_table[0], target_freq, relation,
  69              &newstate))
  70                 return -EINVAL;
  71
  72         freq =
  73             ((cpu_clock_freq / 1000) *
  74              loongson2_clockmod_table[newstate].index) / 8;
  75         if (freq < policy->min || freq > policy->max)
  76                 return -EINVAL;
  77
  78         pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
  79
  80         freqs.old = loongson2_cpufreq_get(cpu);
  81         freqs.new = freq;
  82         freqs.flags = 0;
  83
  84         if (freqs.new == freqs.old)
  85                 return 0;
  86
  87         /* notifiers */
  88         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  89
  90         set_cpus_allowed_ptr(current, &cpus_allowed);
  91
  92         /* setting the cpu frequency */
  93         clk_set_rate(cpuclk, freq);
  94
  95         /* notifiers */
  96         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
  97
  98         pr_debug("cpufreq: set frequency %u kHz\n", freq);
  99
 100         return 0;
 101 }
 102
 103 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
 104 {
 105         int i;
 106         unsigned long rate;
 107         int ret;
 108
 109         cpuclk = clk_get(NULL, "cpu_clk");
 110         if (IS_ERR(cpuclk)) {
 111                 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
 112                 return PTR_ERR(cpuclk);
 113         }
 114
 115         rate = cpu_clock_freq / 1000;
 116         if (!rate) {
 117                 clk_put(cpuclk);
 118                 return -EINVAL;
 119         }
 120         ret = clk_set_rate(cpuclk, rate);
 121         if (ret) {
 122                 clk_put(cpuclk);
 123                 return ret;
 124         }
 125
 126         /* clock table init */
 127         for (i = 2;
 128              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
 129              i++)
 130                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
 131
 132         policy->cur = loongson2_cpufreq_get(policy->cpu);
 133
 134         cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
 135                                          policy->cpu);
 136
 137         return cpufreq_frequency_table_cpuinfo(policy,
 138                                             &loongson2_clockmod_table[0]);
 139 }
 140
 141 static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
 142 {
 143         return cpufreq_frequency_table_verify(policy,
 144                                               &loongson2_clockmod_table[0]);
 145 }
 146
 147 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 148 {
 149         clk_put(cpuclk);
 150         return 0;
 151 }
 152
 153 static struct freq_attr *loongson2_table_attr[] = {
 154         &cpufreq_freq_attr_scaling_available_freqs,
 155         NULL,
 156 };
 157
 158 static struct cpufreq_driver loongson2_cpufreq_driver = {
 159         .owner = THIS_MODULE,
 160         .name = "loongson2",
 161         .init = loongson2_cpufreq_cpu_init,
 162         .verify = loongson2_cpufreq_verify,
 163         .target = loongson2_cpufreq_target,
 164         .get = loongson2_cpufreq_get,
 165         .exit = loongson2_cpufreq_exit,
 166         .attr = loongson2_table_attr,
 167 };
 168
 169 static struct platform_device_id platform_device_ids[] = {
 170         {
 171                 .name = "loongson2_cpufreq",
 172         },
 173         {}
 174 };
 175
 176 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 177
 178 static struct platform_driver platform_driver = {
 179         .driver = {
 180                 .name = "loongson2_cpufreq",
 181                 .owner = THIS_MODULE,
 182         },
 183         .id_table = platform_device_ids,
 184 };
 185
 186 /*
 187  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 188  * interrupt disabled context.
 189  */
 190
 191 static DEFINE_SPINLOCK(loongson2_wait_lock);
 192
 193 static void loongson2_cpu_wait(void)
 194 {
 195         unsigned long flags;
 196         u32 cpu_freq;
 197
 198         spin_lock_irqsave(&loongson2_wait_lock, flags);
 199         cpu_freq = LOONGSON_CHIPCFG0;
 200         LOONGSON_CHIPCFG0 &= ~0x7;      /* Put CPU into wait mode */
 201         LOONGSON_CHIPCFG0 = cpu_freq;   /* Restore CPU state */
 202         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 203 }
 204
 205 static int __init cpufreq_init(void)
 206 {
 207         int ret;
 208
 209         /* Register platform stuff */
 210         ret = platform_driver_register(&platform_driver);
 211         if (ret)
 212                 return ret;
 213
 214         pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
 215
 216         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 217                                   CPUFREQ_TRANSITION_NOTIFIER);
 218
 219         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 220
 221         if (!ret && !nowait) {
 222                 saved_cpu_wait = cpu_wait;
 223                 cpu_wait = loongson2_cpu_wait;
 224         }
 225
 226         return ret;
 227 }
 228
 229 static void __exit cpufreq_exit(void)
 230 {
 231         if (!nowait && saved_cpu_wait)
 232                 cpu_wait = saved_cpu_wait;
 233         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 234         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 235                                     CPUFREQ_TRANSITION_NOTIFIER);
 236
 237         platform_driver_unregister(&platform_driver);
 238 }
 239
 240 module_init(cpufreq_init);
 241 module_exit(cpufreq_exit);
 242
 243 module_param(nowait, uint, 0644);
 244 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 245
 246 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 247 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 248 MODULE_LICENSE("GPL");