arch/mips/kernel/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
  22 #include <asm/mach-loongson/loongson.h>
  23
  24 static uint nowait;
  25
  26 static struct clk *cpuclk;
  27
  28 static void (*saved_cpu_wait) (void);
  29
  30 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  31                                         unsigned long val, void *data);
  32
  33 static struct notifier_block loongson2_cpufreq_notifier_block = {
  34         .notifier_call = loongson2_cpu_freq_notifier
  35 };
  36
  37 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
  38                                         unsigned long val, void *data)
  39 {
  40         if (val == CPUFREQ_POSTCHANGE)
  41                 current_cpu_data.udelay_val = loops_per_jiffy;
  42
  43         return 0;
  44 }
  45
  46 static unsigned int loongson2_cpufreq_get(unsigned int cpu)
  47 {
  48         return clk_get_rate(cpuclk);
  49 }
  50
  51 /*
  52  * Here we notify other drivers of the proposed change and the final change.
  53  */
  54 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
  55                                      unsigned int target_freq,
  56                                      unsigned int relation)
  57 {
  58         unsigned int cpu = policy->cpu;
  59         unsigned int newstate = 0;
  60         cpumask_t cpus_allowed;
  61         struct cpufreq_freqs freqs;
  62         unsigned int freq;
  63
  64         if (!cpu_online(cpu))
  65                 return -ENODEV;
  66
  67         cpus_allowed = current->cpus_allowed;
  68         set_cpus_allowed_ptr(current, cpumask_of(cpu));
  69
  70         if (cpufreq_frequency_table_target
  71             (policy, &loongson2_clockmod_table[0], target_freq, relation,
  72              &newstate))
  73                 return -EINVAL;
  74
  75         freq =
  76             ((cpu_clock_freq / 1000) *
  77              loongson2_clockmod_table[newstate].index) / 8;
  78         if (freq < policy->min || freq > policy->max)
  79                 return -EINVAL;
  80
  81         pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
  82
  83         freqs.old = loongson2_cpufreq_get(cpu);
  84         freqs.new = freq;
  85         freqs.flags = 0;
  86
  87         if (freqs.new == freqs.old)
  88                 return 0;
  89
  90         /* notifiers */
  91         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  92
  93         set_cpus_allowed_ptr(current, &cpus_allowed);
  94
  95         /* setting the cpu frequency */
  96         clk_set_rate(cpuclk, freq);
  97
  98         /* notifiers */
  99         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 100
 101         pr_debug("cpufreq: set frequency %u kHz\n", freq);
 102
 103         return 0;
 104 }
 105
 106 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
 107 {
 108         int i;
 109         unsigned long rate;
 110         int ret;
 111
 112         if (!cpu_online(policy->cpu))
 113                 return -ENODEV;
 114
 115         cpuclk = clk_get(NULL, "cpu_clk");
 116         if (IS_ERR(cpuclk)) {
 117                 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
 118                 return PTR_ERR(cpuclk);
 119         }
 120
 121         rate = cpu_clock_freq / 1000;
 122         if (!rate) {
 123                 clk_put(cpuclk);
 124                 return -EINVAL;
 125         }
 126         ret = clk_set_rate(cpuclk, rate);
 127         if (ret) {
 128                 clk_put(cpuclk);
 129                 return ret;
 130         }
 131
 132         /* clock table init */
 133         for (i = 2;
 134              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
 135              i++)
 136                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
 137
 138         policy->cur = loongson2_cpufreq_get(policy->cpu);
 139
 140         cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
 141                                          policy->cpu);
 142
 143         return cpufreq_frequency_table_cpuinfo(policy,
 144                                             &loongson2_clockmod_table[0]);
 145 }
 146
 147 static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
 148 {
 149         return cpufreq_frequency_table_verify(policy,
 150                                               &loongson2_clockmod_table[0]);
 151 }
 152
 153 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 154 {
 155         clk_put(cpuclk);
 156         return 0;
 157 }
 158
 159 static struct freq_attr *loongson2_table_attr[] = {
 160         &cpufreq_freq_attr_scaling_available_freqs,
 161         NULL,
 162 };
 163
 164 static struct cpufreq_driver loongson2_cpufreq_driver = {
 165         .owner = THIS_MODULE,
 166         .name = "loongson2",
 167         .init = loongson2_cpufreq_cpu_init,
 168         .verify = loongson2_cpufreq_verify,
 169         .target = loongson2_cpufreq_target,
 170         .get = loongson2_cpufreq_get,
 171         .exit = loongson2_cpufreq_exit,
 172         .attr = loongson2_table_attr,
 173 };
 174
 175 static struct platform_device_id platform_device_ids[] = {
 176         {
 177                 .name = "loongson2_cpufreq",
 178         },
 179         {}
 180 };
 181
 182 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 183
 184 static struct platform_driver platform_driver = {
 185         .driver = {
 186                 .name = "loongson2_cpufreq",
 187                 .owner = THIS_MODULE,
 188         },
 189         .id_table = platform_device_ids,
 190 };
 191
 192 /*
 193  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 194  * interrupt disabled context.
 195  */
 196
 197 static DEFINE_SPINLOCK(loongson2_wait_lock);
 198
 199 static void loongson2_cpu_wait(void)
 200 {
 201         unsigned long flags;
 202         u32 cpu_freq;
 203
 204         spin_lock_irqsave(&loongson2_wait_lock, flags);
 205         cpu_freq = LOONGSON_CHIPCFG0;
 206         LOONGSON_CHIPCFG0 &= ~0x7;      /* Put CPU into wait mode */
 207         LOONGSON_CHIPCFG0 = cpu_freq;   /* Restore CPU state */
 208         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 209 }
 210
 211 static int __init cpufreq_init(void)
 212 {
 213         int ret;
 214
 215         /* Register platform stuff */
 216         ret = platform_driver_register(&platform_driver);
 217         if (ret)
 218                 return ret;
 219
 220         pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
 221
 222         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 223                                   CPUFREQ_TRANSITION_NOTIFIER);
 224
 225         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 226
 227         if (!ret && !nowait) {
 228                 saved_cpu_wait = cpu_wait;
 229                 cpu_wait = loongson2_cpu_wait;
 230         }
 231
 232         return ret;
 233 }
 234
 235 static void __exit cpufreq_exit(void)
 236 {
 237         if (!nowait && saved_cpu_wait)
 238                 cpu_wait = saved_cpu_wait;
 239         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 240         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 241                                     CPUFREQ_TRANSITION_NOTIFIER);
 242
 243         platform_driver_unregister(&platform_driver);
 244 }
 245
 246 module_init(cpufreq_init);
 247 module_exit(cpufreq_exit);
 248
 249 module_param(nowait, uint, 0644);
 250 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 251
 252 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 253 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 254 MODULE_LICENSE("GPL");