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