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 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].driver_data) / 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
 104 static 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
 122         /* clock table init */
 123         for (i = 2;
 124              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
 125              i++)
 126                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
 127
 128         ret = clk_set_rate(cpuclk, rate);
 129         if (ret) {
 130                 clk_put(cpuclk);
 131                 return ret;
 132         }
 133
 134         return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
 135 }
 136
 137 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 138 {
 139         cpufreq_frequency_table_put_attr(policy->cpu);
 140         clk_put(cpuclk);
 141         return 0;
 142 }
 143
 144 static struct cpufreq_driver loongson2_cpufreq_driver = {
 145         .name = "loongson2",
 146         .init = loongson2_cpufreq_cpu_init,
 147         .verify = cpufreq_generic_frequency_table_verify,
 148         .target = loongson2_cpufreq_target,
 149         .get = loongson2_cpufreq_get,
 150         .exit = loongson2_cpufreq_exit,
 151         .attr = cpufreq_generic_attr,
 152 };
 153
 154 static struct platform_device_id platform_device_ids[] = {
 155         {
 156                 .name = "loongson2_cpufreq",
 157         },
 158         {}
 159 };
 160
 161 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 162
 163 static struct platform_driver platform_driver = {
 164         .driver = {
 165                 .name = "loongson2_cpufreq",
 166                 .owner = THIS_MODULE,
 167         },
 168         .id_table = platform_device_ids,
 169 };
 170
 171 /*
 172  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 173  * interrupt disabled context.
 174  */
 175
 176 static DEFINE_SPINLOCK(loongson2_wait_lock);
 177
 178 static void loongson2_cpu_wait(void)
 179 {
 180         unsigned long flags;
 181         u32 cpu_freq;
 182
 183         spin_lock_irqsave(&loongson2_wait_lock, flags);
 184         cpu_freq = LOONGSON_CHIPCFG0;
 185         LOONGSON_CHIPCFG0 &= ~0x7;      /* Put CPU into wait mode */
 186         LOONGSON_CHIPCFG0 = cpu_freq;   /* Restore CPU state */
 187         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 188         local_irq_enable();
 189 }
 190
 191 static int __init cpufreq_init(void)
 192 {
 193         int ret;
 194
 195         /* Register platform stuff */
 196         ret = platform_driver_register(&platform_driver);
 197         if (ret)
 198                 return ret;
 199
 200         pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
 201
 202         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 203                                   CPUFREQ_TRANSITION_NOTIFIER);
 204
 205         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 206
 207         if (!ret && !nowait) {
 208                 saved_cpu_wait = cpu_wait;
 209                 cpu_wait = loongson2_cpu_wait;
 210         }
 211
 212         return ret;
 213 }
 214
 215 static void __exit cpufreq_exit(void)
 216 {
 217         if (!nowait && saved_cpu_wait)
 218                 cpu_wait = saved_cpu_wait;
 219         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 220         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 221                                     CPUFREQ_TRANSITION_NOTIFIER);
 222
 223         platform_driver_unregister(&platform_driver);
 224 }
 225
 226 module_init(cpufreq_init);
 227 module_exit(cpufreq_exit);
 228
 229 module_param(nowait, uint, 0644);
 230 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 231
 232 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 233 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 234 MODULE_LICENSE("GPL");