1/*
2 * CPU frequency scaling for DaVinci
3 *
4 * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
5 *
6 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
7 *
8 *  Copyright (C) 2005 Nokia Corporation
9 *  Written by Tony Lindgren <tony@atomide.com>
10 *
11 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
12 *
13 * Copyright (C) 2007-2008 Texas Instruments, Inc.
14 * Updated to support OMAP3
15 * Rajendra Nayak <rnayak@ti.com>
16 *
17 * This program is free software; you can redistribute it and/or modify
18 * it under the terms of the GNU General Public License version 2 as
19 * published by the Free Software Foundation.
20 */
21#include <linux/types.h>
22#include <linux/cpufreq.h>
23#include <linux/init.h>
24#include <linux/err.h>
25#include <linux/clk.h>
26#include <linux/platform_device.h>
27#include <linux/export.h>
28
29#include <mach/hardware.h>
30#include <mach/cpufreq.h>
31#include <mach/common.h>
32
33struct davinci_cpufreq {
34	struct device *dev;
35	struct clk *armclk;
36	struct clk *asyncclk;
37	unsigned long asyncrate;
38};
39static struct davinci_cpufreq cpufreq;
40
41static int davinci_verify_speed(struct cpufreq_policy *policy)
42{
43	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
44	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
45	struct clk *armclk = cpufreq.armclk;
46
47	if (freq_table)
48		return cpufreq_frequency_table_verify(policy, freq_table);
49
50	if (policy->cpu)
51		return -EINVAL;
52
53	cpufreq_verify_within_cpu_limits(policy);
54	policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
55	policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
56	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
57						policy->cpuinfo.max_freq);
58	return 0;
59}
60
61static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
62{
63	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
64	struct clk *armclk = cpufreq.armclk;
65	unsigned int old_freq, new_freq;
66	int ret = 0;
67
68	old_freq = policy->cur;
69	new_freq = pdata->freq_table[idx].frequency;
70
71	/* if moving to higher frequency, up the voltage beforehand */
72	if (pdata->set_voltage && new_freq > old_freq) {
73		ret = pdata->set_voltage(idx);
74		if (ret)
75			return ret;
76	}
77
78	ret = clk_set_rate(armclk, idx);
79	if (ret)
80		return ret;
81
82	if (cpufreq.asyncclk) {
83		ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
84		if (ret)
85			return ret;
86	}
87
88	/* if moving to lower freq, lower the voltage after lowering freq */
89	if (pdata->set_voltage && new_freq < old_freq)
90		pdata->set_voltage(idx);
91
92	return 0;
93}
94
95static int davinci_cpu_init(struct cpufreq_policy *policy)
96{
97	int result = 0;
98	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
99	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
100
101	if (policy->cpu != 0)
102		return -EINVAL;
103
104	/* Finish platform specific initialization */
105	if (pdata->init) {
106		result = pdata->init();
107		if (result)
108			return result;
109	}
110
111	policy->clk = cpufreq.armclk;
112
113	/*
114	 * Time measurement across the target() function yields ~1500-1800us
115	 * time taken with no drivers on notification list.
116	 * Setting the latency to 2000 us to accommodate addition of drivers
117	 * to pre/post change notification list.
118	 */
119	return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
120}
121
122static struct cpufreq_driver davinci_driver = {
123	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
124	.verify		= davinci_verify_speed,
125	.target_index	= davinci_target,
126	.get		= cpufreq_generic_get,
127	.init		= davinci_cpu_init,
128	.name		= "davinci",
129	.attr		= cpufreq_generic_attr,
130};
131
132static int __init davinci_cpufreq_probe(struct platform_device *pdev)
133{
134	struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
135	struct clk *asyncclk;
136
137	if (!pdata)
138		return -EINVAL;
139	if (!pdata->freq_table)
140		return -EINVAL;
141
142	cpufreq.dev = &pdev->dev;
143
144	cpufreq.armclk = clk_get(NULL, "arm");
145	if (IS_ERR(cpufreq.armclk)) {
146		dev_err(cpufreq.dev, "Unable to get ARM clock\n");
147		return PTR_ERR(cpufreq.armclk);
148	}
149
150	asyncclk = clk_get(cpufreq.dev, "async");
151	if (!IS_ERR(asyncclk)) {
152		cpufreq.asyncclk = asyncclk;
153		cpufreq.asyncrate = clk_get_rate(asyncclk);
154	}
155
156	return cpufreq_register_driver(&davinci_driver);
157}
158
159static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
160{
161	clk_put(cpufreq.armclk);
162
163	if (cpufreq.asyncclk)
164		clk_put(cpufreq.asyncclk);
165
166	return cpufreq_unregister_driver(&davinci_driver);
167}
168
169static struct platform_driver davinci_cpufreq_driver = {
170	.driver = {
171		.name	 = "cpufreq-davinci",
172	},
173	.remove = __exit_p(davinci_cpufreq_remove),
174};
175
176int __init davinci_cpufreq_init(void)
177{
178	return platform_driver_probe(&davinci_cpufreq_driver,
179							davinci_cpufreq_probe);
180}
181
182