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. & Insititute 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 #include <linux/cpufreq.h>
  14 #include <linux/module.h>
  15 #include <linux/err.h>
  16 #include <linux/sched.h>        /* set_cpus_allowed() */
  17 #include <linux/delay.h>
  18 #include <linux/platform_device.h>
  19
  20 #include <asm/clock.h>
  21 #include <asm/idle.h>
  22
  23 #include <asm/mach-loongson/loongson.h>
  24
  25 static uint nowait;
  26
  27 static void (*saved_cpu_wait) (void);
  28
  29 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  30                                         unsigned long val, void *data);
  31
  32 static struct notifier_block loongson2_cpufreq_notifier_block = {
  33         .notifier_call = loongson2_cpu_freq_notifier
  34 };
  35
  36 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  37                                         unsigned long val, void *data)
  38 {
  39         if (val == CPUFREQ_POSTCHANGE)
  40                 current_cpu_data.udelay_val = loops_per_jiffy;
  41
  42         return 0;
  43 }
  44
  45 /*
  46  * Here we notify other drivers of the proposed change and the final change.
  47  */
  48 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
  49                                      unsigned int index)
  50 {
  51         unsigned int cpu = policy->cpu;
  52         cpumask_t cpus_allowed;
  53         unsigned int freq;
  54
  55         cpus_allowed = current->cpus_allowed;
  56         set_cpus_allowed_ptr(current, cpumask_of(cpu));
  57
  58         freq =
  59             ((cpu_clock_freq / 1000) *
  60              loongson2_clockmod_table[index].driver_data) / 8;
  61
  62         set_cpus_allowed_ptr(current, &cpus_allowed);
  63
  64         /* setting the cpu frequency */
  65         clk_set_rate(policy->clk, freq);
  66
  67         return 0;
  68 }
  69
  70 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
  71 {
  72         static struct clk *cpuclk;
  73         int i;
  74         unsigned long rate;
  75         int ret;
  76
  77         cpuclk = clk_get(NULL, "cpu_clk");
  78         if (IS_ERR(cpuclk)) {
  79                 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
  80                 return PTR_ERR(cpuclk);
  81         }
  82
  83         rate = cpu_clock_freq / 1000;
  84         if (!rate) {
  85                 clk_put(cpuclk);
  86                 return -EINVAL;
  87         }
  88
  89         /* clock table init */
  90         for (i = 2;
  91              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
  92              i++)
  93                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
  94
  95         ret = clk_set_rate(cpuclk, rate);
  96         if (ret) {
  97                 clk_put(cpuclk);
  98                 return ret;
  99         }
 100
 101         policy->clk = cpuclk;
 102         return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
 103 }
 104
 105 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 106 {
 107         clk_put(policy->clk);
 108         return 0;
 109 }
 110
 111 static struct cpufreq_driver loongson2_cpufreq_driver = {
 112         .name = "loongson2",
 113         .init = loongson2_cpufreq_cpu_init,
 114         .verify = cpufreq_generic_frequency_table_verify,
 115         .target_index = loongson2_cpufreq_target,
 116         .get = cpufreq_generic_get,
 117         .exit = loongson2_cpufreq_exit,
 118         .attr = cpufreq_generic_attr,
 119 };
 120
 121 static struct platform_device_id platform_device_ids[] = {
 122         {
 123                 .name = "loongson2_cpufreq",
 124         },
 125         {}
 126 };
 127
 128 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 129
 130 static struct platform_driver platform_driver = {
 131         .driver = {
 132                 .name = "loongson2_cpufreq",
 133                 .owner = THIS_MODULE,
 134         },
 135         .id_table = platform_device_ids,
 136 };
 137
 138 /*
 139  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 140  * interrupt disabled context.
 141  */
 142
 143 static DEFINE_SPINLOCK(loongson2_wait_lock);
 144
 145 static void loongson2_cpu_wait(void)
 146 {
 147         unsigned long flags;
 148         u32 cpu_freq;
 149
 150         spin_lock_irqsave(&loongson2_wait_lock, flags);
 151         cpu_freq = LOONGSON_CHIPCFG0;
 152         LOONGSON_CHIPCFG0 &= ~0x7;      /* Put CPU into wait mode */
 153         LOONGSON_CHIPCFG0 = cpu_freq;   /* Restore CPU state */
 154         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 155         local_irq_enable();
 156 }
 157
 158 static int __init cpufreq_init(void)
 159 {
 160         int ret;
 161
 162         /* Register platform stuff */
 163         ret = platform_driver_register(&platform_driver);
 164         if (ret)
 165                 return ret;
 166
 167         pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
 168
 169         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 170                                   CPUFREQ_TRANSITION_NOTIFIER);
 171
 172         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 173
 174         if (!ret && !nowait) {
 175                 saved_cpu_wait = cpu_wait;
 176                 cpu_wait = loongson2_cpu_wait;
 177         }
 178
 179         return ret;
 180 }
 181
 182 static void __exit cpufreq_exit(void)
 183 {
 184         if (!nowait && saved_cpu_wait)
 185                 cpu_wait = saved_cpu_wait;
 186         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 187         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 188                                     CPUFREQ_TRANSITION_NOTIFIER);
 189
 190         platform_driver_unregister(&platform_driver);
 191 }
 192
 193 module_init(cpufreq_init);
 194 module_exit(cpufreq_exit);
 195
 196 module_param(nowait, uint, 0644);
 197 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 198
 199 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 200 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 201 MODULE_LICENSE("GPL");