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-loongson2ef/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         cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
  99         return 0;
 100 }
 101
 102 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 103 {
 104         clk_put(policy->clk);
 105         return 0;
 106 }
 107
 108 static struct cpufreq_driver loongson2_cpufreq_driver = {
 109         .name = "loongson2",
 110         .init = loongson2_cpufreq_cpu_init,
 111         .verify = cpufreq_generic_frequency_table_verify,
 112         .target_index = loongson2_cpufreq_target,
 113         .get = cpufreq_generic_get,
 114         .exit = loongson2_cpufreq_exit,
 115         .attr = cpufreq_generic_attr,
 116 };
 117
 118 static const struct platform_device_id platform_device_ids[] = {
 119         {
 120                 .name = "loongson2_cpufreq",
 121         },
 122         {}
 123 };
 124
 125 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 126
 127 static struct platform_driver platform_driver = {
 128         .driver = {
 129                 .name = "loongson2_cpufreq",
 130         },
 131         .id_table = platform_device_ids,
 132 };
 133
 134 /*
 135  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 136  * interrupt disabled context.
 137  */
 138
 139 static DEFINE_SPINLOCK(loongson2_wait_lock);
 140
 141 static void loongson2_cpu_wait(void)
 142 {
 143         unsigned long flags;
 144         u32 cpu_freq;
 145
 146         spin_lock_irqsave(&loongson2_wait_lock, flags);
 147         cpu_freq = readl(LOONGSON_CHIPCFG);
 148         /* Put CPU into wait mode */
 149         writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG);
 150         /* Restore CPU state */
 151         writel(cpu_freq, LOONGSON_CHIPCFG);
 152         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 153         local_irq_enable();
 154 }
 155
 156 static int __init cpufreq_init(void)
 157 {
 158         int ret;
 159
 160         /* Register platform stuff */
 161         ret = platform_driver_register(&platform_driver);
 162         if (ret)
 163                 return ret;
 164
 165         pr_info("Loongson-2F CPU frequency driver\n");
 166
 167         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 168                                   CPUFREQ_TRANSITION_NOTIFIER);
 169
 170         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 171
 172         if (!ret && !nowait) {
 173                 saved_cpu_wait = cpu_wait;
 174                 cpu_wait = loongson2_cpu_wait;
 175         }
 176
 177         return ret;
 178 }
 179
 180 static void __exit cpufreq_exit(void)
 181 {
 182         if (!nowait && saved_cpu_wait)
 183                 cpu_wait = saved_cpu_wait;
 184         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 185         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 186                                     CPUFREQ_TRANSITION_NOTIFIER);
 187
 188         platform_driver_unregister(&platform_driver);
 189 }
 190
 191 module_init(cpufreq_init);
 192 module_exit(cpufreq_exit);
 193
 194 module_param(nowait, uint, 0644);
 195 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 196
 197 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 198 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 199 MODULE_LICENSE("GPL");