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#include <linux/slab.h>
23
24static struct cpufreq_frequency_table *freq_table;
25
26static unsigned int	ref_freq;
27static unsigned long	loops_per_jiffy_ref;
28
29static int at32_set_target(struct cpufreq_policy *policy, unsigned int index)
30{
31	unsigned int old_freq, new_freq;
32
33	old_freq = policy->cur;
34	new_freq = freq_table[index].frequency;
35
36	if (!ref_freq) {
37		ref_freq = old_freq;
38		loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
39	}
40
41	if (old_freq < new_freq)
42		boot_cpu_data.loops_per_jiffy = cpufreq_scale(
43				loops_per_jiffy_ref, ref_freq, new_freq);
44	clk_set_rate(policy->clk, new_freq * 1000);
45	if (new_freq < old_freq)
46		boot_cpu_data.loops_per_jiffy = cpufreq_scale(
47				loops_per_jiffy_ref, ref_freq, new_freq);
48
49	return 0;
50}
51
52static int at32_cpufreq_driver_init(struct cpufreq_policy *policy)
53{
54	unsigned int frequency, rate, min_freq;
55	struct clk *cpuclk;
56	int retval, steps, i;
57
58	if (policy->cpu != 0)
59		return -EINVAL;
60
61	cpuclk = clk_get(NULL, "cpu");
62	if (IS_ERR(cpuclk)) {
63		pr_debug("cpufreq: could not get CPU clk\n");
64		retval = PTR_ERR(cpuclk);
65		goto out_err;
66	}
67
68	min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
69	frequency = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
70	policy->cpuinfo.transition_latency = 0;
71
72	/*
73	 * AVR32 CPU frequency rate scales in power of two between maximum and
74	 * minimum, also add space for the table end marker.
75	 *
76	 * Further validate that the frequency is usable, and append it to the
77	 * frequency table.
78	 */
79	steps = fls(frequency / min_freq) + 1;
80	freq_table = kzalloc(steps * sizeof(struct cpufreq_frequency_table),
81			GFP_KERNEL);
82	if (!freq_table) {
83		retval = -ENOMEM;
84		goto out_err_put_clk;
85	}
86
87	for (i = 0; i < (steps - 1); i++) {
88		rate = clk_round_rate(cpuclk, frequency * 1000) / 1000;
89
90		if (rate != frequency)
91			freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
92		else
93			freq_table[i].frequency = frequency;
94
95		frequency /= 2;
96	}
97
98	policy->clk = cpuclk;
99	freq_table[steps - 1].frequency = CPUFREQ_TABLE_END;
100
101	retval = cpufreq_table_validate_and_show(policy, freq_table);
102	if (!retval) {
103		printk("cpufreq: AT32AP CPU frequency driver\n");
104		return 0;
105	}
106
107	kfree(freq_table);
108out_err_put_clk:
109	clk_put(cpuclk);
110out_err:
111	return retval;
112}
113
114static struct cpufreq_driver at32_driver = {
115	.name		= "at32ap",
116	.init		= at32_cpufreq_driver_init,
117	.verify		= cpufreq_generic_frequency_table_verify,
118	.target_index	= at32_set_target,
119	.get		= cpufreq_generic_get,
120	.flags		= CPUFREQ_STICKY,
121};
122
123static int __init at32_cpufreq_init(void)
124{
125	return cpufreq_register_driver(&at32_driver);
126}
127late_initcall(at32_cpufreq_init);
128