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
33#include "clock.h"
34
35struct davinci_cpufreq {
36	struct device *dev;
37	struct clk *armclk;
38	struct clk *asyncclk;
39	unsigned long asyncrate;
40};
41static struct davinci_cpufreq cpufreq;
42
43static int davinci_verify_speed(struct cpufreq_policy *policy)
44{
45	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
46	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
47	struct clk *armclk = cpufreq.armclk;
48
49	if (freq_table)
50		return cpufreq_frequency_table_verify(policy, freq_table);
51
52	if (policy->cpu)
53		return -EINVAL;
54
55	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
56				     policy->cpuinfo.max_freq);
57
58	policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
59	policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
60	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
61						policy->cpuinfo.max_freq);
62	return 0;
63}
64
65static unsigned int davinci_getspeed(unsigned int cpu)
66{
67	if (cpu)
68		return 0;
69
70	return clk_get_rate(cpufreq.armclk) / 1000;
71}
72
73static int davinci_target(struct cpufreq_policy *policy,
74				unsigned int target_freq, unsigned int relation)
75{
76	int ret = 0;
77	unsigned int idx;
78	struct cpufreq_freqs freqs;
79	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
80	struct clk *armclk = cpufreq.armclk;
81
82	/*
83	 * Ensure desired rate is within allowed range.  Some govenors
84	 * (ondemand) will just pass target_freq=0 to get the minimum.
85	 */
86	if (target_freq < policy->cpuinfo.min_freq)
87		target_freq = policy->cpuinfo.min_freq;
88	if (target_freq > policy->cpuinfo.max_freq)
89		target_freq = policy->cpuinfo.max_freq;
90
91	freqs.old = davinci_getspeed(0);
92	freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;
93	freqs.cpu = 0;
94
95	if (freqs.old == freqs.new)
96		return ret;
97
98	dev_dbg(cpufreq.dev, "transition: %u --> %u\n", freqs.old, freqs.new);
99
100	ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
101						freqs.new, relation, &idx);
102	if (ret)
103		return -EINVAL;
104
105	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
106
107	/* if moving to higher frequency, up the voltage beforehand */
108	if (pdata->set_voltage && freqs.new > freqs.old) {
109		ret = pdata->set_voltage(idx);
110		if (ret)
111			goto out;
112	}
113
114	ret = clk_set_rate(armclk, idx);
115	if (ret)
116		goto out;
117
118	if (cpufreq.asyncclk) {
119		ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
120		if (ret)
121			goto out;
122	}
123
124	/* if moving to lower freq, lower the voltage after lowering freq */
125	if (pdata->set_voltage && freqs.new < freqs.old)
126		pdata->set_voltage(idx);
127
128out:
129	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
130
131	return ret;
132}
133
134static int davinci_cpu_init(struct cpufreq_policy *policy)
135{
136	int result = 0;
137	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
138	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
139
140	if (policy->cpu != 0)
141		return -EINVAL;
142
143	/* Finish platform specific initialization */
144	if (pdata->init) {
145		result = pdata->init();
146		if (result)
147			return result;
148	}
149
150	policy->cur = policy->min = policy->max = davinci_getspeed(0);
151
152	if (freq_table) {
153		result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
154		if (!result)
155			cpufreq_frequency_table_get_attr(freq_table,
156							policy->cpu);
157	} else {
158		policy->cpuinfo.min_freq = policy->min;
159		policy->cpuinfo.max_freq = policy->max;
160	}
161
162	policy->min = policy->cpuinfo.min_freq;
163	policy->max = policy->cpuinfo.max_freq;
164	policy->cur = davinci_getspeed(0);
165
166	/*
167	 * Time measurement across the target() function yields ~1500-1800us
168	 * time taken with no drivers on notification list.
169	 * Setting the latency to 2000 us to accommodate addition of drivers
170	 * to pre/post change notification list.
171	 */
172	policy->cpuinfo.transition_latency = 2000 * 1000;
173	return 0;
174}
175
176static int davinci_cpu_exit(struct cpufreq_policy *policy)
177{
178	cpufreq_frequency_table_put_attr(policy->cpu);
179	return 0;
180}
181
182static struct freq_attr *davinci_cpufreq_attr[] = {
183	&cpufreq_freq_attr_scaling_available_freqs,
184	NULL,
185};
186
187static struct cpufreq_driver davinci_driver = {
188	.flags		= CPUFREQ_STICKY,
189	.verify		= davinci_verify_speed,
190	.target		= davinci_target,
191	.get		= davinci_getspeed,
192	.init		= davinci_cpu_init,
193	.exit		= davinci_cpu_exit,
194	.name		= "davinci",
195	.attr		= davinci_cpufreq_attr,
196};
197
198static int __init davinci_cpufreq_probe(struct platform_device *pdev)
199{
200	struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
201	struct clk *asyncclk;
202
203	if (!pdata)
204		return -EINVAL;
205	if (!pdata->freq_table)
206		return -EINVAL;
207
208	cpufreq.dev = &pdev->dev;
209
210	cpufreq.armclk = clk_get(NULL, "arm");
211	if (IS_ERR(cpufreq.armclk)) {
212		dev_err(cpufreq.dev, "Unable to get ARM clock\n");
213		return PTR_ERR(cpufreq.armclk);
214	}
215
216	asyncclk = clk_get(cpufreq.dev, "async");
217	if (!IS_ERR(asyncclk)) {
218		cpufreq.asyncclk = asyncclk;
219		cpufreq.asyncrate = clk_get_rate(asyncclk);
220	}
221
222	return cpufreq_register_driver(&davinci_driver);
223}
224
225static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
226{
227	clk_put(cpufreq.armclk);
228
229	if (cpufreq.asyncclk)
230		clk_put(cpufreq.asyncclk);
231
232	return cpufreq_unregister_driver(&davinci_driver);
233}
234
235static struct platform_driver davinci_cpufreq_driver = {
236	.driver = {
237		.name	 = "cpufreq-davinci",
238		.owner	 = THIS_MODULE,
239	},
240	.remove = __exit_p(davinci_cpufreq_remove),
241};
242
243static int __init davinci_cpufreq_init(void)
244{
245	return platform_driver_probe(&davinci_cpufreq_driver,
246							davinci_cpufreq_probe);
247}
248late_initcall(davinci_cpufreq_init);
249
250