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