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9e58e185 HCE |
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> | |
09cf6a29 | 21 | #include <linux/export.h> |
9e58e185 HCE |
22 | |
23 | static struct clk *cpuclk; | |
24 | ||
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 | ||
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 | ||
e3f91ca4 HS |
43 | static unsigned int ref_freq; |
44 | static unsigned long loops_per_jiffy_ref; | |
45 | ||
9e58e185 HCE |
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; | |
9e58e185 HCE |
64 | freqs.flags = 0; |
65 | ||
e3f91ca4 HS |
66 | if (!ref_freq) { |
67 | ref_freq = freqs.old; | |
68 | loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy; | |
69 | } | |
70 | ||
b43a7ffb | 71 | cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); |
e3f91ca4 HS |
72 | if (freqs.old < freqs.new) |
73 | boot_cpu_data.loops_per_jiffy = cpufreq_scale( | |
74 | loops_per_jiffy_ref, ref_freq, freqs.new); | |
9e58e185 | 75 | clk_set_rate(cpuclk, freq); |
e3f91ca4 HS |
76 | if (freqs.new < freqs.old) |
77 | boot_cpu_data.loops_per_jiffy = cpufreq_scale( | |
78 | loops_per_jiffy_ref, ref_freq, freqs.new); | |
b43a7ffb | 79 | cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); |
9e58e185 HCE |
80 | |
81 | pr_debug("cpufreq: set frequency %lu Hz\n", freq); | |
82 | ||
83 | return 0; | |
84 | } | |
85 | ||
86 | static int __init at32_cpufreq_driver_init(struct cpufreq_policy *policy) | |
87 | { | |
88 | if (policy->cpu != 0) | |
89 | return -EINVAL; | |
90 | ||
91 | cpuclk = clk_get(NULL, "cpu"); | |
92 | if (IS_ERR(cpuclk)) { | |
93 | pr_debug("cpufreq: could not get CPU clk\n"); | |
94 | return PTR_ERR(cpuclk); | |
95 | } | |
96 | ||
97 | policy->cpuinfo.min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000; | |
98 | policy->cpuinfo.max_freq = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000; | |
99 | policy->cpuinfo.transition_latency = 0; | |
100 | policy->cur = at32_get_speed(0); | |
101 | policy->min = policy->cpuinfo.min_freq; | |
102 | policy->max = policy->cpuinfo.max_freq; | |
9e58e185 HCE |
103 | |
104 | printk("cpufreq: AT32AP CPU frequency driver\n"); | |
105 | ||
106 | return 0; | |
107 | } | |
108 | ||
109 | static struct cpufreq_driver at32_driver = { | |
110 | .name = "at32ap", | |
111 | .owner = THIS_MODULE, | |
112 | .init = at32_cpufreq_driver_init, | |
113 | .verify = at32_verify_speed, | |
114 | .target = at32_set_target, | |
115 | .get = at32_get_speed, | |
116 | .flags = CPUFREQ_STICKY, | |
117 | }; | |
118 | ||
119 | static int __init at32_cpufreq_init(void) | |
120 | { | |
121 | return cpufreq_register_driver(&at32_driver); | |
122 | } | |
f04d264a | 123 | late_initcall(at32_cpufreq_init); |