LXR linux/drivers/cpufreq/loongson2

   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
  28static uint nowait;
  29
  30static void (*saved_cpu_wait) (void);
  31
  32static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  33                                        unsigned long val, void *data);
  34
  35static struct notifier_block loongson2_cpufreq_notifier_block = {
  36        .notifier_call = loongson2_cpu_freq_notifier
  37};
  38
  39static 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 */
  51static 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
  73static 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
 108static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 109{
 110        clk_put(policy->clk);
 111        return 0;
 112}
 113
 114static 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
 124static struct platform_device_id platform_device_ids[] = {
 125        {
 126                .name = "loongson2_cpufreq",
 127        },
 128        {}
 129};
 130
 131MODULE_DEVICE_TABLE(platform, platform_device_ids);
 132
 133static 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
 145static DEFINE_SPINLOCK(loongson2_wait_lock);
 146
 147static 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
 160static 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
 184static 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
 195module_init(cpufreq_init);
 196module_exit(cpufreq_exit);
 197
 198module_param(nowait, uint, 0644);
 199MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 200
 201MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 202MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 203MODULE_LICENSE("GPL");
 204