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Linux/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 void (*saved_cpu_wait) (void);
 28 
 29 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
 30                                         unsigned long val, void *data);
 31 
 32 static struct notifier_block loongson2_cpufreq_notifier_block = {
 33         .notifier_call = loongson2_cpu_freq_notifier
 34 };
 35 
 36 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
 37                                         unsigned long val, void *data)
 38 {
 39         if (val == CPUFREQ_POSTCHANGE)
 40                 current_cpu_data.udelay_val = loops_per_jiffy;
 41 
 42         return 0;
 43 }
 44 
 45 /*
 46  * Here we notify other drivers of the proposed change and the final change.
 47  */
 48 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
 49                                      unsigned int index)
 50 {
 51         unsigned int cpu = policy->cpu;
 52         cpumask_t cpus_allowed;
 53         unsigned int freq;
 54 
 55         cpus_allowed = current->cpus_allowed;
 56         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 57 
 58         freq =
 59             ((cpu_clock_freq / 1000) *
 60              loongson2_clockmod_table[index].driver_data) / 8;
 61 
 62         set_cpus_allowed_ptr(current, &cpus_allowed);
 63 
 64         /* setting the cpu frequency */
 65         clk_set_rate(policy->clk, freq * 1000);
 66 
 67         return 0;
 68 }
 69 
 70 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
 71 {
 72         struct clk *cpuclk;
 73         int i;
 74         unsigned long rate;
 75         int ret;
 76 
 77         cpuclk = clk_get(NULL, "cpu_clk");
 78         if (IS_ERR(cpuclk)) {
 79                 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
 80                 return PTR_ERR(cpuclk);
 81         }
 82 
 83         rate = cpu_clock_freq / 1000;
 84         if (!rate) {
 85                 clk_put(cpuclk);
 86                 return -EINVAL;
 87         }
 88 
 89         /* clock table init */
 90         for (i = 2;
 91              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
 92              i++)
 93                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
 94 
 95         ret = clk_set_rate(cpuclk, rate * 1000);
 96         if (ret) {
 97                 clk_put(cpuclk);
 98                 return ret;
 99         }
100 
101         policy->clk = cpuclk;
102         return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
103 }
104 
105 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
106 {
107         clk_put(policy->clk);
108         return 0;
109 }
110 
111 static struct cpufreq_driver loongson2_cpufreq_driver = {
112         .name = "loongson2",
113         .init = loongson2_cpufreq_cpu_init,
114         .verify = cpufreq_generic_frequency_table_verify,
115         .target_index = loongson2_cpufreq_target,
116         .get = cpufreq_generic_get,
117         .exit = loongson2_cpufreq_exit,
118         .attr = cpufreq_generic_attr,
119 };
120 
121 static struct platform_device_id platform_device_ids[] = {
122         {
123                 .name = "loongson2_cpufreq",
124         },
125         {}
126 };
127 
128 MODULE_DEVICE_TABLE(platform, platform_device_ids);
129 
130 static struct platform_driver platform_driver = {
131         .driver = {
132                 .name = "loongson2_cpufreq",
133         },
134         .id_table = platform_device_ids,
135 };
136 
137 /*
138  * This is the simple version of Loongson-2 wait, Maybe we need do this in
139  * interrupt disabled context.
140  */
141 
142 static DEFINE_SPINLOCK(loongson2_wait_lock);
143 
144 static void loongson2_cpu_wait(void)
145 {
146         unsigned long flags;
147         u32 cpu_freq;
148 
149         spin_lock_irqsave(&loongson2_wait_lock, flags);
150         cpu_freq = LOONGSON_CHIPCFG(0);
151         LOONGSON_CHIPCFG(0) &= ~0x7;    /* Put CPU into wait mode */
152         LOONGSON_CHIPCFG(0) = cpu_freq; /* Restore CPU state */
153         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
154         local_irq_enable();
155 }
156 
157 static int __init cpufreq_init(void)
158 {
159         int ret;
160 
161         /* Register platform stuff */
162         ret = platform_driver_register(&platform_driver);
163         if (ret)
164                 return ret;
165 
166         pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");
167 
168         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
169                                   CPUFREQ_TRANSITION_NOTIFIER);
170 
171         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
172 
173         if (!ret && !nowait) {
174                 saved_cpu_wait = cpu_wait;
175                 cpu_wait = loongson2_cpu_wait;
176         }
177 
178         return ret;
179 }
180 
181 static void __exit cpufreq_exit(void)
182 {
183         if (!nowait && saved_cpu_wait)
184                 cpu_wait = saved_cpu_wait;
185         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
186         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
187                                     CPUFREQ_TRANSITION_NOTIFIER);
188 
189         platform_driver_unregister(&platform_driver);
190 }
191 
192 module_init(cpufreq_init);
193 module_exit(cpufreq_exit);
194 
195 module_param(nowait, uint, 0644);
196 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
197 
198 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
199 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
200 MODULE_LICENSE("GPL");
201 

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