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/idle.h>
  24
  25 #include <asm/mach-loongson2ef/loongson.h>
  26
  27 static uint nowait;
  28
  29 static void (*saved_cpu_wait) (void);
  30
  31 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  32                                         unsigned long val, void *data);
  33
  34 static struct notifier_block loongson2_cpufreq_notifier_block = {
  35         .notifier_call = loongson2_cpu_freq_notifier
  36 };
  37
  38 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  39                                         unsigned long val, void *data)
  40 {
  41         if (val == CPUFREQ_POSTCHANGE)
  42                 current_cpu_data.udelay_val = loops_per_jiffy;
  43
  44         return 0;
  45 }
  46
  47 /*
  48  * Here we notify other drivers of the proposed change and the final change.
  49  */
  50 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
  51                                      unsigned int index)
  52 {
  53         unsigned int freq;
  54
  55         freq =
  56             ((cpu_clock_freq / 1000) *
  57              loongson2_clockmod_table[index].driver_data) / 8;
  58
  59         /* setting the cpu frequency */
  60         loongson2_cpu_set_rate(freq);
  61
  62         return 0;
  63 }
  64
  65 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
  66 {
  67         int i;
  68         unsigned long rate;
  69         int ret;
  70
  71         rate = cpu_clock_freq / 1000;
  72         if (!rate)
  73                 return -EINVAL;
  74
  75         /* clock table init */
  76         for (i = 2;
  77              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
  78              i++)
  79                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
  80
  81         ret = loongson2_cpu_set_rate(rate);
  82         if (ret)
  83                 return ret;
  84
  85         cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
  86         return 0;
  87 }
  88
  89 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
  90 {
  91         return 0;
  92 }
  93
  94 static struct cpufreq_driver loongson2_cpufreq_driver = {
  95         .name = "loongson2",
  96         .init = loongson2_cpufreq_cpu_init,
  97         .verify = cpufreq_generic_frequency_table_verify,
  98         .target_index = loongson2_cpufreq_target,
  99         .get = cpufreq_generic_get,
 100         .exit = loongson2_cpufreq_exit,
 101         .attr = cpufreq_generic_attr,
 102 };
 103
 104 static const struct platform_device_id platform_device_ids[] = {
 105         {
 106                 .name = "loongson2_cpufreq",
 107         },
 108         {}
 109 };
 110
 111 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 112
 113 static struct platform_driver platform_driver = {
 114         .driver = {
 115                 .name = "loongson2_cpufreq",
 116         },
 117         .id_table = platform_device_ids,
 118 };
 119
 120 /*
 121  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 122  * interrupt disabled context.
 123  */
 124
 125 static DEFINE_SPINLOCK(loongson2_wait_lock);
 126
 127 static void loongson2_cpu_wait(void)
 128 {
 129         unsigned long flags;
 130         u32 cpu_freq;
 131
 132         spin_lock_irqsave(&loongson2_wait_lock, flags);
 133         cpu_freq = readl(LOONGSON_CHIPCFG);
 134         /* Put CPU into wait mode */
 135         writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG);
 136         /* Restore CPU state */
 137         writel(cpu_freq, LOONGSON_CHIPCFG);
 138         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 139         local_irq_enable();
 140 }
 141
 142 static int __init cpufreq_init(void)
 143 {
 144         int ret;
 145
 146         /* Register platform stuff */
 147         ret = platform_driver_register(&platform_driver);
 148         if (ret)
 149                 return ret;
 150
 151         pr_info("Loongson-2F CPU frequency driver\n");
 152
 153         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 154                                   CPUFREQ_TRANSITION_NOTIFIER);
 155
 156         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 157
 158         if (!ret && !nowait) {
 159                 saved_cpu_wait = cpu_wait;
 160                 cpu_wait = loongson2_cpu_wait;
 161         }
 162
 163         return ret;
 164 }
 165
 166 static void __exit cpufreq_exit(void)
 167 {
 168         if (!nowait && saved_cpu_wait)
 169                 cpu_wait = saved_cpu_wait;
 170         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 171         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 172                                     CPUFREQ_TRANSITION_NOTIFIER);
 173
 174         platform_driver_unregister(&platform_driver);
 175 }
 176
 177 module_init(cpufreq_init);
 178 module_exit(cpufreq_exit);
 179
 180 module_param(nowait, uint, 0644);
 181 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 182
 183 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 184 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 185 MODULE_LICENSE("GPL");