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		.owner	 = THIS_MODULE,
173	},
174	.remove = __exit_p(davinci_cpufreq_remove),
175};
176
177int __init davinci_cpufreq_init(void)
178{
179	return platform_driver_probe(&davinci_cpufreq_driver,
180							davinci_cpufreq_probe);
181}
182