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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. & Institute 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 
 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 15 
 16 #include <linux/cpufreq.h>
 17 #include <linux/module.h>
 18 #include <linux/err.h>
 19 #include <linux/sched.h>        /* set_cpus_allowed() */
 20 #include <linux/delay.h>
 21 #include <linux/platform_device.h>
 22 
 23 #include <asm/clock.h>
 24 #include <asm/idle.h>
 25 
 26 #include <asm/mach-loongson64/loongson.h>
 27 
 28 static uint nowait;
 29 
 30 static void (*saved_cpu_wait) (void);
 31 
 32 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
 33                                         unsigned long val, void *data);
 34 
 35 static struct notifier_block loongson2_cpufreq_notifier_block = {
 36         .notifier_call = loongson2_cpu_freq_notifier
 37 };
 38 
 39 static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
 40                                         unsigned long val, void *data)
 41 {
 42         if (val == CPUFREQ_POSTCHANGE)
 43                 current_cpu_data.udelay_val = loops_per_jiffy;
 44 
 45         return 0;
 46 }
 47 
 48 /*
 49  * Here we notify other drivers of the proposed change and the final change.
 50  */
 51 static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
 52                                      unsigned int index)
 53 {
 54         unsigned int cpu = policy->cpu;
 55         cpumask_t cpus_allowed;
 56         unsigned int freq;
 57 
 58         cpus_allowed = current->cpus_allowed;
 59         set_cpus_allowed_ptr(current, cpumask_of(cpu));
 60 
 61         freq =
 62             ((cpu_clock_freq / 1000) *
 63              loongson2_clockmod_table[index].driver_data) / 8;
 64 
 65         set_cpus_allowed_ptr(current, &cpus_allowed);
 66 
 67         /* setting the cpu frequency */
 68         clk_set_rate(policy->clk, freq * 1000);
 69 
 70         return 0;
 71 }
 72 
 73 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
 74 {
 75         struct clk *cpuclk;
 76         int i;
 77         unsigned long rate;
 78         int ret;
 79 
 80         cpuclk = clk_get(NULL, "cpu_clk");
 81         if (IS_ERR(cpuclk)) {
 82                 pr_err("couldn't get CPU clk\n");
 83                 return PTR_ERR(cpuclk);
 84         }
 85 
 86         rate = cpu_clock_freq / 1000;
 87         if (!rate) {
 88                 clk_put(cpuclk);
 89                 return -EINVAL;
 90         }
 91 
 92         /* clock table init */
 93         for (i = 2;
 94              (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
 95              i++)
 96                 loongson2_clockmod_table[i].frequency = (rate * i) / 8;
 97 
 98         ret = clk_set_rate(cpuclk, rate * 1000);
 99         if (ret) {
100                 clk_put(cpuclk);
101                 return ret;
102         }
103 
104         policy->clk = cpuclk;
105         return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
106 }
107 
108 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
109 {
110         clk_put(policy->clk);
111         return 0;
112 }
113 
114 static struct cpufreq_driver loongson2_cpufreq_driver = {
115         .name = "loongson2",
116         .init = loongson2_cpufreq_cpu_init,
117         .verify = cpufreq_generic_frequency_table_verify,
118         .target_index = loongson2_cpufreq_target,
119         .get = cpufreq_generic_get,
120         .exit = loongson2_cpufreq_exit,
121         .attr = cpufreq_generic_attr,
122 };
123 
124 static struct platform_device_id platform_device_ids[] = {
125         {
126                 .name = "loongson2_cpufreq",
127         },
128         {}
129 };
130 
131 MODULE_DEVICE_TABLE(platform, platform_device_ids);
132 
133 static struct platform_driver platform_driver = {
134         .driver = {
135                 .name = "loongson2_cpufreq",
136         },
137         .id_table = platform_device_ids,
138 };
139 
140 /*
141  * This is the simple version of Loongson-2 wait, Maybe we need do this in
142  * interrupt disabled context.
143  */
144 
145 static DEFINE_SPINLOCK(loongson2_wait_lock);
146 
147 static void loongson2_cpu_wait(void)
148 {
149         unsigned long flags;
150         u32 cpu_freq;
151 
152         spin_lock_irqsave(&loongson2_wait_lock, flags);
153         cpu_freq = LOONGSON_CHIPCFG(0);
154         LOONGSON_CHIPCFG(0) &= ~0x7;    /* Put CPU into wait mode */
155         LOONGSON_CHIPCFG(0) = cpu_freq; /* Restore CPU state */
156         spin_unlock_irqrestore(&loongson2_wait_lock, flags);
157         local_irq_enable();
158 }
159 
160 static int __init cpufreq_init(void)
161 {
162         int ret;
163 
164         /* Register platform stuff */
165         ret = platform_driver_register(&platform_driver);
166         if (ret)
167                 return ret;
168 
169         pr_info("Loongson-2F CPU frequency driver\n");
170 
171         cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
172                                   CPUFREQ_TRANSITION_NOTIFIER);
173 
174         ret = cpufreq_register_driver(&loongson2_cpufreq_driver);
175 
176         if (!ret && !nowait) {
177                 saved_cpu_wait = cpu_wait;
178                 cpu_wait = loongson2_cpu_wait;
179         }
180 
181         return ret;
182 }
183 
184 static void __exit cpufreq_exit(void)
185 {
186         if (!nowait && saved_cpu_wait)
187                 cpu_wait = saved_cpu_wait;
188         cpufreq_unregister_driver(&loongson2_cpufreq_driver);
189         cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
190                                     CPUFREQ_TRANSITION_NOTIFIER);
191 
192         platform_driver_unregister(&platform_driver);
193 }
194 
195 module_init(cpufreq_init);
196 module_exit(cpufreq_exit);
197 
198 module_param(nowait, uint, 0644);
199 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");
200 
201 MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
202 MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
203 MODULE_LICENSE("GPL");
204 

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