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