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. & Institute 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
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/cpufreq.h>
  17 #include <linux/module.h>
  18 #include <linux/err.h>
  19 #include <linux/sched.h>        /* set_cpus_allowed() */
  20 #include <linux/delay.h>
  21 #include <linux/platform_device.h>
  22
  23 #include <asm/clock.h>
  24 #include <asm/idle.h>
  25
  26 #include <asm/mach-loongson64/loongson.h>
  27
  28 static uint nowait;
  29
  30 static void (*saved_cpu_wait) (void);
  31
  32 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  33                                         unsigned long val, void *data);
  34
  35 static struct notifier_block loongson2_cpufreq_notifier_block = {
  36         .notifier_call = loongson2_cpu_freq_notifier
  37 };
  38
  39 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  40                                         unsigned long val, void *data)
  41 {
  42         if (val == CPUFREQ_POSTCHANGE)
  43                 current_cpu_data.udelay_val = loops_per_jiffy;
  44
  45         return 0;
  46 }
  47
  48 /*
  49  * Here we notify other drivers of the proposed change and the final change.
  50  */
  51 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
  52                                      unsigned int index)
  53 {
  54         unsigned int freq;
  55
  56         freq =
  57             ((cpu_clock_freq / 1000) *
  58              loongson2_clockmod_table[index].driver_data) / 8;
  59
  60         /* setting the cpu frequency */
  61         clk_set_rate(policy->clk, freq * 1000);
  62
  63         return 0;
  64 }
  65
  66 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
  67 {
  68         struct clk *cpuclk;
  69         int i;
  70         unsigned long rate;
  71         int ret;
  72
  73         cpuclk = clk_get(NULL, "cpu_clk");
  74         if (IS_ERR(cpuclk)) {
  75                 pr_err("couldn't get CPU clk\n");
  76                 return PTR_ERR(cpuclk);
  77         }
  78
  79         rate = cpu_clock_freq / 1000;
  80         if (!rate) {
  81                 clk_put(cpuclk);
  82                 return -EINVAL;
  83         }
  84
  85         /* clock table init */
  86         for (i = 2;
  87              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
  88              i++)
  89                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
  90
  91         ret = clk_set_rate(cpuclk, rate * 1000);
  92         if (ret) {
  93                 clk_put(cpuclk);
  94                 return ret;
  95         }
  96
  97         policy->clk = cpuclk;
  98         return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
  99 }
 100
 101 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 102 {
 103         clk_put(policy->clk);
 104         return 0;
 105 }
 106
 107 static struct cpufreq_driver loongson2_cpufreq_driver = {
 108         .name = "loongson2",
 109         .init = loongson2_cpufreq_cpu_init,
 110         .verify = cpufreq_generic_frequency_table_verify,
 111         .target_index = loongson2_cpufreq_target,
 112         .get = cpufreq_generic_get,
 113         .exit = loongson2_cpufreq_exit,
 114         .attr = cpufreq_generic_attr,
 115 };
 116
 117 static struct platform_device_id platform_device_ids[] = {
 118         {
 119                 .name = "loongson2_cpufreq",
 120         },
 121         {}
 122 };
 123
 124 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 125
 126 static struct platform_driver platform_driver = {
 127         .driver = {
 128                 .name = "loongson2_cpufreq",
 129         },
 130         .id_table = platform_device_ids,
 131 };
 132
 133 /*
 134  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 135  * interrupt disabled context.
 136  */
 137
 138 static DEFINE_SPINLOCK(loongson2_wait_lock);
 139
 140 static void loongson2_cpu_wait(void)
 141 {
 142         unsigned long flags;
 143         u32 cpu_freq;
 144
 145         spin_lock_irqsave(&loongson2_wait_lock, flags);
 146         cpu_freq = LOONGSON_CHIPCFG(0);
 147         LOONGSON_CHIPCFG(0) &= ~0x7;    /* Put CPU into wait mode */
 148         LOONGSON_CHIPCFG(0) = cpu_freq; /* Restore CPU state */
 149         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 150         local_irq_enable();
 151 }
 152
 153 static int __init cpufreq_init(void)
 154 {
 155         int ret;
 156
 157         /* Register platform stuff */
 158         ret = platform_driver_register(&platform_driver);
 159         if (ret)
 160                 return ret;
 161
 162         pr_info("Loongson-2F CPU frequency driver\n");
 163
 164         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 165                                   CPUFREQ_TRANSITION_NOTIFIER);
 166
 167         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 168
 169         if (!ret && !nowait) {
 170                 saved_cpu_wait = cpu_wait;
 171                 cpu_wait = loongson2_cpu_wait;
 172         }
 173
 174         return ret;
 175 }
 176
 177 static void __exit cpufreq_exit(void)
 178 {
 179         if (!nowait && saved_cpu_wait)
 180                 cpu_wait = saved_cpu_wait;
 181         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 182         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 183                                     CPUFREQ_TRANSITION_NOTIFIER);
 184
 185         platform_driver_unregister(&platform_driver);
 186 }
 187
 188 module_init(cpufreq_init);
 189 module_exit(cpufreq_exit);
 190
 191 module_param(nowait, uint, 0644);
 192 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 193
 194 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 195 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 196 MODULE_LICENSE("GPL");