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].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
 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         policy->cur = loongson2_cpufreq_get(policy->cpu);
 135
 136         cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
 137                                          policy->cpu);
 138
 139         return cpufreq_frequency_table_cpuinfo(policy,
 140                                             &loongson2_clockmod_table[0]);
 141 }
 142
 143 static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
 144 {
 145         return cpufreq_frequency_table_verify(policy,
 146                                               &loongson2_clockmod_table[0]);
 147 }
 148
 149 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
 150 {
 151         clk_put(cpuclk);
 152         return 0;
 153 }
 154
 155 static struct freq_attr *loongson2_table_attr[] = {
 156         &cpufreq_freq_attr_scaling_available_freqs,
 157         NULL,
 158 };
 159
 160 static struct cpufreq_driver loongson2_cpufreq_driver = {
 161         .owner = THIS_MODULE,
 162         .name = "loongson2",
 163         .init = loongson2_cpufreq_cpu_init,
 164         .verify = loongson2_cpufreq_verify,
 165         .target = loongson2_cpufreq_target,
 166         .get = loongson2_cpufreq_get,
 167         .exit = loongson2_cpufreq_exit,
 168         .attr = loongson2_table_attr,
 169 };
 170
 171 static struct platform_device_id platform_device_ids[] = {
 172         {
 173                 .name = "loongson2_cpufreq",
 174         },
 175         {}
 176 };
 177
 178 MODULE_DEVICE_TABLE(platform, platform_device_ids);
 179
 180 static struct platform_driver platform_driver = {
 181         .driver = {
 182                 .name = "loongson2_cpufreq",
 183                 .owner = THIS_MODULE,
 184         },
 185         .id_table = platform_device_ids,
 186 };
 187
 188 /*
 189  * This is the simple version of Loongson-2 wait, Maybe we need do this in
 190  * interrupt disabled context.
 191  */
 192
 193 static DEFINE_SPINLOCK(loongson2_wait_lock);
 194
 195 static void loongson2_cpu_wait(void)
 196 {
 197         unsigned long flags;
 198         u32 cpu_freq;
 199
 200         spin_lock_irqsave(&loongson2_wait_lock, flags);
 201         cpu_freq = LOONGSON_CHIPCFG0;
 202         LOONGSON_CHIPCFG0 &= ~0x7;      /* Put CPU into wait mode */
 203         LOONGSON_CHIPCFG0 = cpu_freq;   /* Restore CPU state */
 204         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
 205         local_irq_enable();
 206 }
 207
 208 static int __init cpufreq_init(void)
 209 {
 210         int ret;
 211
 212         /* Register platform stuff */
 213         ret = platform_driver_register(&platform_driver);
 214         if (ret)
 215                 return ret;
 216
 217         pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
 218
 219         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
 220                                   CPUFREQ_TRANSITION_NOTIFIER);
 221
 222         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
 223
 224         if (!ret && !nowait) {
 225                 saved_cpu_wait = cpu_wait;
 226                 cpu_wait = loongson2_cpu_wait;
 227         }
 228
 229         return ret;
 230 }
 231
 232 static void __exit cpufreq_exit(void)
 233 {
 234         if (!nowait && saved_cpu_wait)
 235                 cpu_wait = saved_cpu_wait;
 236         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
 237         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
 238                                     CPUFREQ_TRANSITION_NOTIFIER);
 239
 240         platform_driver_unregister(&platform_driver);
 241 }
 242
 243 module_init(cpufreq_init);
 244 module_exit(cpufreq_exit);
 245
 246 module_param(nowait, uint, 0644);
 247 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
 248
 249 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
 250 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
 251 MODULE_LICENSE("GPL");