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 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
  66static 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        return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
  99}
 100
 101static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 102{
 103        clk_put(policy->clk);
 104        return 0;
 105}
 106
 107static struct cpufreq_driver loongson2_cpufreq_driver = {
 108        .name = "loongson2",
 109        .init = loongson2_cpufreq_cpu_init,
 110        .verify = cpufreq_generic_frequency_table_verify,
 111        .target_index = loongson2_cpufreq_target,
 112        .get = cpufreq_generic_get,
 113        .exit = loongson2_cpufreq_exit,
 114        .attr = cpufreq_generic_attr,
 115};
 116
 117static const struct platform_device_id platform_device_ids[] = {
 118        {
 119                .name = "loongson2_cpufreq",
 120        },
 121        {}
 122};
 123
 124MODULE_DEVICE_TABLE(platform, platform_device_ids);
 125
 126static struct platform_driver platform_driver = {
 127        .driver = {
 128                .name = "loongson2_cpufreq",
 129        },
 130        .id_table = platform_device_ids,
 131};
 132
 133/*
 134 * This is the simple version of Loongson-2 wait, Maybe we need do this in
 135 * interrupt disabled context.
 136 */
 137
 138static DEFINE_SPINLOCK(loongson2_wait_lock);
 139
 140static void loongson2_cpu_wait(void)
 141{
 142        unsigned long flags;
 143        u32 cpu_freq;
 144
 145        spin_lock_irqsave(&loongson2_wait_lock, flags);
 146        cpu_freq = LOONGSON_CHIPCFG(0);
 147        LOONGSON_CHIPCFG(0) &= ~0x7;    /* Put CPU into wait mode */
 148        LOONGSON_CHIPCFG(0) = cpu_freq; /* Restore CPU state */
 149        spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 150        local_irq_enable();
 151}
 152
 153static int __init cpufreq_init(void)
 154{
 155        int ret;
 156
 157        /* Register platform stuff */
 158        ret = platform_driver_register(&platform_driver);
 159        if (ret)
 160                return ret;
 161
 162        pr_info("Loongson-2F CPU frequency driver\n");
 163
 164        cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 165                                  CPUFREQ_TRANSITION_NOTIFIER);
 166
 167        ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 168
 169        if (!ret && !nowait) {
 170                saved_cpu_wait = cpu_wait;
 171                cpu_wait = loongson2_cpu_wait;
 172        }
 173
 174        return ret;
 175}
 176
 177static void __exit cpufreq_exit(void)
 178{
 179        if (!nowait && saved_cpu_wait)
 180                cpu_wait = saved_cpu_wait;
 181        cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 182        cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 183                                    CPUFREQ_TRANSITION_NOTIFIER);
 184
 185        platform_driver_unregister(&platform_driver);
 186}
 187
 188module_init(cpufreq_init);
 189module_exit(cpufreq_exit);
 190
 191module_param(nowait, uint, 0644);
 192MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 193
 194MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 195MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 196MODULE_LICENSE("GPL");
 197