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1 /*
2  * Copyright (C) 2004-2007 Atmel Corporation
3  *
4  * Based on MIPS implementation arch/mips/kernel/time.c
5  *   Copyright 2001 MontaVista Software Inc.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  */
11 
12 /*#define DEBUG*/
13 
14 #include <linux/kernel.h>
15 #include <linux/types.h>
16 #include <linux/init.h>
17 #include <linux/cpufreq.h>
18 #include <linux/io.h>
19 #include <linux/clk.h>
20 #include <linux/err.h>
21 #include <linux/export.h>
22 
23 static struct clk *cpuclk;
24 
at32_verify_speed(struct cpufreq_policy * policy)25 static int at32_verify_speed(struct cpufreq_policy *policy)
26 {
27 	if (policy->cpu != 0)
28 		return -EINVAL;
29 
30 	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
31 			policy->cpuinfo.max_freq);
32 	return 0;
33 }
34 
at32_get_speed(unsigned int cpu)35 static unsigned int at32_get_speed(unsigned int cpu)
36 {
37 	/* No SMP support */
38 	if (cpu)
39 		return 0;
40 	return (unsigned int)((clk_get_rate(cpuclk) + 500) / 1000);
41 }
42 
43 static unsigned int	ref_freq;
44 static unsigned long	loops_per_jiffy_ref;
45 
at32_set_target(struct cpufreq_policy * policy,unsigned int target_freq,unsigned int relation)46 static int at32_set_target(struct cpufreq_policy *policy,
47 			  unsigned int target_freq,
48 			  unsigned int relation)
49 {
50 	struct cpufreq_freqs freqs;
51 	long freq;
52 
53 	/* Convert target_freq from kHz to Hz */
54 	freq = clk_round_rate(cpuclk, target_freq * 1000);
55 
56 	/* Check if policy->min <= new_freq <= policy->max */
57 	if(freq < (policy->min * 1000) || freq > (policy->max * 1000))
58 		return -EINVAL;
59 
60 	pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);
61 
62 	freqs.old = at32_get_speed(0);
63 	freqs.new = (freq + 500) / 1000;
64 	freqs.cpu = 0;
65 	freqs.flags = 0;
66 
67 	if (!ref_freq) {
68 		ref_freq = freqs.old;
69 		loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
70 	}
71 
72 	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
73 	if (freqs.old < freqs.new)
74 		boot_cpu_data.loops_per_jiffy = cpufreq_scale(
75 				loops_per_jiffy_ref, ref_freq, freqs.new);
76 	clk_set_rate(cpuclk, freq);
77 	if (freqs.new < freqs.old)
78 		boot_cpu_data.loops_per_jiffy = cpufreq_scale(
79 				loops_per_jiffy_ref, ref_freq, freqs.new);
80 	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
81 
82 	pr_debug("cpufreq: set frequency %lu Hz\n", freq);
83 
84 	return 0;
85 }
86 
at32_cpufreq_driver_init(struct cpufreq_policy * policy)87 static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy)
88 {
89 	if (policy->cpu != 0)
90 		return -EINVAL;
91 
92 	cpuclk = clk_get(NULL, "cpu");
93 	if (IS_ERR(cpuclk)) {
94 		pr_debug("cpufreq: could not get CPU clk\n");
95 		return PTR_ERR(cpuclk);
96 	}
97 
98 	policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
99 	policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
100 	policy->cpuinfo.transition_latency = 0;
101 	policy->cur = at32_get_speed(0);
102 	policy->min = policy->cpuinfo.min_freq;
103 	policy->max = policy->cpuinfo.max_freq;
104 
105 	printk("cpufreq: AT32AP CPU frequency driver\n");
106 
107 	return 0;
108 }
109 
110 static struct cpufreq_driver at32_driver = {
111 	.name		= "at32ap",
112 	.owner		= THIS_MODULE,
113 	.init		= at32_cpufreq_driver_init,
114 	.verify		= at32_verify_speed,
115 	.target		= at32_set_target,
116 	.get		= at32_get_speed,
117 	.flags		= CPUFREQ_STICKY,
118 };
119 
at32_cpufreq_init(void)120 static int __init at32_cpufreq_init(void)
121 {
122 	return cpufreq_register_driver(&at32_driver);
123 }
124 late_initcall(at32_cpufreq_init);
125