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/delay.h>
  20 #include <linux/platform_device.h>
  21
  22 #include <asm/idle.h>
  23
  24 #include <asm/mach-loongson2ef/loongson.h>
  25
  26 static uint nowait;
  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 /*
  47  * Here we notify other drivers of the proposed change and the final change.
  48  */
  49 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
  50                                      unsigned int index)
  51 {
  52         unsigned int freq;
  53
  54         freq =
  55             ((cpu_clock_freq / 1000) *
  56              loongson2_clockmod_table[index].driver_data) / 8;
  57
  58         /* setting the cpu frequency */
  59         loongson2_cpu_set_rate(freq);
  60
  61         return 0;
  62 }
  63
  64 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
  65 {
  66         int i;
  67         unsigned long rate;
  68         int ret;
  69
  70         rate = cpu_clock_freq / 1000;
  71         if (!rate)
  72                 return -EINVAL;
  73
  74         /* clock table init */
  75         for (i = 2;
  76              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
  77              i++)
  78                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
  79
  80         ret = loongson2_cpu_set_rate(rate);
  81         if (ret)
  82                 return ret;
  83
  84         cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
  85         return 0;
  86 }
  87
  88 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
  89 {
  90         return 0;
  91 }
  92
  93 static struct cpufreq_driver loongson2_cpufreq_driver = {
  94         .name = "loongson2",
  95         .init = loongson2_cpufreq_cpu_init,
  96         .verify = cpufreq_generic_frequency_table_verify,
  97         .target_index = loongson2_cpufreq_target,
  98         .get = cpufreq_generic_get,
  99         .exit = loongson2_cpufreq_exit,
 100         .attr = cpufreq_generic_attr,
 101 };
 102
 103 static const struct platform_device_id platform_device_ids[] = {
 104         {
 105                 .name = "loongson2_cpufreq",
 106         },
 107         {}
 108 };
 109
 110 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 111
 112 static struct platform_driver platform_driver = {
 113         .driver = {
 114                 .name = "loongson2_cpufreq",
 115         },
 116         .id_table = platform_device_ids,
 117 };
 118
 119 /*
 120  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 121  * interrupt disabled context.
 122  */
 123
 124 static DEFINE_SPINLOCK(loongson2_wait_lock);
 125
 126 static void loongson2_cpu_wait(void)
 127 {
 128         unsigned long flags;
 129         u32 cpu_freq;
 130
 131         spin_lock_irqsave(&loongson2_wait_lock, flags);
 132         cpu_freq = readl(LOONGSON_CHIPCFG);
 133         /* Put CPU into wait mode */
 134         writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG);
 135         /* Restore CPU state */
 136         writel(cpu_freq, LOONGSON_CHIPCFG);
 137         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 138         local_irq_enable();
 139 }
 140
 141 static int __init cpufreq_init(void)
 142 {
 143         int ret;
 144
 145         /* Register platform stuff */
 146         ret = platform_driver_register(&platform_driver);
 147         if (ret)
 148                 return ret;
 149
 150         pr_info("Loongson-2F CPU frequency driver\n");
 151
 152         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 153                                   CPUFREQ_TRANSITION_NOTIFIER);
 154
 155         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 156
 157         if (!ret && !nowait) {
 158                 saved_cpu_wait = cpu_wait;
 159                 cpu_wait = loongson2_cpu_wait;
 160         }
 161
 162         return ret;
 163 }
 164
 165 static void __exit cpufreq_exit(void)
 166 {
 167         if (!nowait && saved_cpu_wait)
 168                 cpu_wait = saved_cpu_wait;
 169         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 170         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 171                                     CPUFREQ_TRANSITION_NOTIFIER);
 172
 173         platform_driver_unregister(&platform_driver);
 174 }
 175
 176 module_init(cpufreq_init);
 177 module_exit(cpufreq_exit);
 178
 179 module_param(nowait, uint, 0644);
 180 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 181
 182 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 183 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 184 MODULE_LICENSE("GPL");