linux/drivers/cpufreq/loongson2_cpufreq.c
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   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
  25static uint nowait;
  26
  27static struct clk *cpuclk;
  28
  29static void (*saved_cpu_wait) (void);
  30
  31static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  32                                        unsigned long val, void *data);
  33
  34static struct notifier_block loongson2_cpufreq_notifier_block = {
  35        .notifier_call = loongson2_cpu_freq_notifier
  36};
  37
  38static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  39                                        unsigned long val, void *data)
  40{
  41        if (val == CPUFREQ_POSTCHANGE)
  42                current_cpu_data.udelay_val = loops_per_jiffy;
  43
  44        return 0;
  45}
  46
  47static unsigned int loongson2_cpufreq_get(unsigned int cpu)
  48{
  49        return clk_get_rate(cpuclk);
  50}
  51
  52/*
  53 * Here we notify other drivers of the proposed change and the final change.
  54 */
  55static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
  56                                     unsigned int target_freq,
  57                                     unsigned int relation)
  58{
  59        unsigned int cpu = policy->cpu;
  60        unsigned int newstate = 0;
  61        cpumask_t cpus_allowed;
  62        struct cpufreq_freqs freqs;
  63        unsigned int freq;
  64
  65        cpus_allowed = current->cpus_allowed;
  66        set_cpus_allowed_ptr(current, cpumask_of(cpu));
  67
  68        if (cpufreq_frequency_table_target
  69            (policy, &loongson2_clockmod_table[0], target_freq, relation,
  70             &newstate))
  71                return -EINVAL;
  72
  73        freq =
  74            ((cpu_clock_freq / 1000) *
  75             loongson2_clockmod_table[newstate].index) / 8;
  76        if (freq < policy->min || freq > policy->max)
  77                return -EINVAL;
  78
  79        pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
  80
  81        freqs.old = loongson2_cpufreq_get(cpu);
  82        freqs.new = freq;
  83        freqs.flags = 0;
  84
  85        if (freqs.new == freqs.old)
  86                return 0;
  87
  88        /* notifiers */
  89        cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  90
  91        set_cpus_allowed_ptr(current, &cpus_allowed);
  92
  93        /* setting the cpu frequency */
  94        clk_set_rate(cpuclk, freq);
  95
  96        /* notifiers */
  97        cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
  98
  99        pr_debug("cpufreq: set frequency %u kHz\n", freq);
 100
 101        return 0;
 102}
 103
 104static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
 105{
 106        int i;
 107        unsigned long rate;
 108        int ret;
 109
 110        cpuclk = clk_get(NULL, "cpu_clk");
 111        if (IS_ERR(cpuclk)) {
 112                printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
 113                return PTR_ERR(cpuclk);
 114        }
 115
 116        rate = cpu_clock_freq / 1000;
 117        if (!rate) {
 118                clk_put(cpuclk);
 119                return -EINVAL;
 120        }
 121        ret = clk_set_rate(cpuclk, rate);
 122        if (ret) {
 123                clk_put(cpuclk);
 124                return ret;
 125        }
 126
 127        /* clock table init */
 128        for (i = 2;
 129             (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
 130             i++)
 131                loongson2_clockmod_table[i].frequency = (rate * i) / 8;
 132
 133        policy->cur = loongson2_cpufreq_get(policy->cpu);
 134
 135        cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
 136                                         policy->cpu);
 137
 138        return cpufreq_frequency_table_cpuinfo(policy,
 139                                            &loongson2_clockmod_table[0]);
 140}
 141
 142static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
 143{
 144        return cpufreq_frequency_table_verify(policy,
 145                                              &loongson2_clockmod_table[0]);
 146}
 147
 148static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 149{
 150        clk_put(cpuclk);
 151        return 0;
 152}
 153
 154static struct freq_attr *loongson2_table_attr[] = {
 155        &cpufreq_freq_attr_scaling_available_freqs,
 156        NULL,
 157};
 158
 159static struct cpufreq_driver loongson2_cpufreq_driver = {
 160        .owner = THIS_MODULE,
 161        .name = "loongson2",
 162        .init = loongson2_cpufreq_cpu_init,
 163        .verify = loongson2_cpufreq_verify,
 164        .target = loongson2_cpufreq_target,
 165        .get = loongson2_cpufreq_get,
 166        .exit = loongson2_cpufreq_exit,
 167        .attr = loongson2_table_attr,
 168};
 169
 170static struct platform_device_id platform_device_ids[] = {
 171        {
 172                .name = "loongson2_cpufreq",
 173        },
 174        {}
 175};
 176
 177MODULE_DEVICE_TABLE(platform, platform_device_ids);
 178
 179static struct platform_driver platform_driver = {
 180        .driver = {
 181                .name = "loongson2_cpufreq",
 182                .owner = THIS_MODULE,
 183        },
 184        .id_table = platform_device_ids,
 185};
 186
 187/*
 188 * This is the simple version of Loongson-2 wait, Maybe we need do this in
 189 * interrupt disabled context.
 190 */
 191
 192static DEFINE_SPINLOCK(loongson2_wait_lock);
 193
 194static void loongson2_cpu_wait(void)
 195{
 196        unsigned long flags;
 197        u32 cpu_freq;
 198
 199        spin_lock_irqsave(&loongson2_wait_lock, flags);
 200        cpu_freq = LOONGSON_CHIPCFG0;
 201        LOONGSON_CHIPCFG0 &= ~0x7;      /* Put CPU into wait mode */
 202        LOONGSON_CHIPCFG0 = cpu_freq;   /* Restore CPU state */
 203        spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 204        local_irq_enable();
 205}
 206
 207static int __init cpufreq_init(void)
 208{
 209        int ret;
 210
 211        /* Register platform stuff */
 212        ret = platform_driver_register(&platform_driver);
 213        if (ret)
 214                return ret;
 215
 216        pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
 217
 218        cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 219                                  CPUFREQ_TRANSITION_NOTIFIER);
 220
 221        ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 222
 223        if (!ret && !nowait) {
 224                saved_cpu_wait = cpu_wait;
 225                cpu_wait = loongson2_cpu_wait;
 226        }
 227
 228        return ret;
 229}
 230
 231static void __exit cpufreq_exit(void)
 232{
 233        if (!nowait && saved_cpu_wait)
 234                cpu_wait = saved_cpu_wait;
 235        cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 236        cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 237                                    CPUFREQ_TRANSITION_NOTIFIER);
 238
 239        platform_driver_unregister(&platform_driver);
 240}
 241
 242module_init(cpufreq_init);
 243module_exit(cpufreq_exit);
 244
 245module_param(nowait, uint, 0644);
 246MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 247
 248MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 249MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 250MODULE_LICENSE("GPL");
 251
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