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 cpu = policy->cpu;
  55         cpumask_t cpus_allowed;
  56         unsigned int freq;
  57
  58         cpus_allowed = current->cpus_allowed;
  59         set_cpus_allowed_ptr(current, cpumask_of(cpu));
  60
  61         freq =
  62             ((cpu_clock_freq / 1000) *
  63              loongson2_clockmod_table[index].driver_data) / 8;
  64
  65         set_cpus_allowed_ptr(current, &cpus_allowed);
  66
  67         /* setting the cpu frequency */
  68         clk_set_rate(policy->clk, freq * 1000);
  69
  70         return 0;
  71 }
  72
  73 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
  74 {
  75         struct clk *cpuclk;
  76         int i;
  77         unsigned long rate;
  78         int ret;
  79
  80         cpuclk = clk_get(NULL, "cpu_clk");
  81         if (IS_ERR(cpuclk)) {
  82                 pr_err("couldn't get CPU clk\n");
  83                 return PTR_ERR(cpuclk);
  84         }
  85
  86         rate = cpu_clock_freq / 1000;
  87         if (!rate) {
  88                 clk_put(cpuclk);
  89                 return -EINVAL;
  90         }
  91
  92         /* clock table init */
  93         for (i = 2;
  94              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
  95              i++)
  96                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
  97
  98         ret = clk_set_rate(cpuclk, rate * 1000);
  99         if (ret) {
 100                 clk_put(cpuclk);
 101                 return ret;
 102         }
 103
 104         policy->clk = cpuclk;
 105         return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
 106 }
 107
 108 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 109 {
 110         clk_put(policy->clk);
 111         return 0;
 112 }
 113
 114 static struct cpufreq_driver loongson2_cpufreq_driver = {
 115         .name = "loongson2",
 116         .init = loongson2_cpufreq_cpu_init,
 117         .verify = cpufreq_generic_frequency_table_verify,
 118         .target_index = loongson2_cpufreq_target,
 119         .get = cpufreq_generic_get,
 120         .exit = loongson2_cpufreq_exit,
 121         .attr = cpufreq_generic_attr,
 122 };
 123
 124 static struct platform_device_id platform_device_ids[] = {
 125         {
 126                 .name = "loongson2_cpufreq",
 127         },
 128         {}
 129 };
 130
 131 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 132
 133 static struct platform_driver platform_driver = {
 134         .driver = {
 135                 .name = "loongson2_cpufreq",
 136         },
 137         .id_table = platform_device_ids,
 138 };
 139
 140 /*
 141  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 142  * interrupt disabled context.
 143  */
 144
 145 static DEFINE_SPINLOCK(loongson2_wait_lock);
 146
 147 static void loongson2_cpu_wait(void)
 148 {
 149         unsigned long flags;
 150         u32 cpu_freq;
 151
 152         spin_lock_irqsave(&loongson2_wait_lock, flags);
 153         cpu_freq = LOONGSON_CHIPCFG(0);
 154         LOONGSON_CHIPCFG(0) &= ~0x7;    /* Put CPU into wait mode */
 155         LOONGSON_CHIPCFG(0) = cpu_freq; /* Restore CPU state */
 156         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 157         local_irq_enable();
 158 }
 159
 160 static int __init cpufreq_init(void)
 161 {
 162         int ret;
 163
 164         /* Register platform stuff */
 165         ret = platform_driver_register(&platform_driver);
 166         if (ret)
 167                 return ret;
 168
 169         pr_info("Loongson-2F CPU frequency driver\n");
 170
 171         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 172                                   CPUFREQ_TRANSITION_NOTIFIER);
 173
 174         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 175
 176         if (!ret && !nowait) {
 177                 saved_cpu_wait = cpu_wait;
 178                 cpu_wait = loongson2_cpu_wait;
 179         }
 180
 181         return ret;
 182 }
 183
 184 static void __exit cpufreq_exit(void)
 185 {
 186         if (!nowait && saved_cpu_wait)
 187                 cpu_wait = saved_cpu_wait;
 188         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 189         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 190                                     CPUFREQ_TRANSITION_NOTIFIER);
 191
 192         platform_driver_unregister(&platform_driver);
 193 }
 194
 195 module_init(cpufreq_init);
 196 module_exit(cpufreq_exit);
 197
 198 module_param(nowait, uint, 0644);
 199 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 200
 201 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 202 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 203 MODULE_LICENSE("GPL");