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_target(struct cpufreq_policy *policy, unsigned int idx)
 42{
 43	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 44	struct clk *armclk = cpufreq.armclk;
 45	unsigned int old_freq, new_freq;
 46	int ret = 0;
 47
 48	old_freq = policy->cur;
 49	new_freq = pdata->freq_table[idx].frequency;
 50
 51	/* if moving to higher frequency, up the voltage beforehand */
 52	if (pdata->set_voltage && new_freq > old_freq) {
 53		ret = pdata->set_voltage(idx);
 54		if (ret)
 55			return ret;
 56	}
 57
 58	ret = clk_set_rate(armclk, new_freq * 1000);
 59	if (ret)
 60		return ret;
 61
 62	if (cpufreq.asyncclk) {
 63		ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
 64		if (ret)
 65			return ret;
 66	}
 67
 68	/* if moving to lower freq, lower the voltage after lowering freq */
 69	if (pdata->set_voltage && new_freq < old_freq)
 70		pdata->set_voltage(idx);
 71
 72	return 0;
 73}
 74
 75static int davinci_cpu_init(struct cpufreq_policy *policy)
 76{
 77	int result = 0;
 78	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 79	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 80
 81	if (policy->cpu != 0)
 82		return -EINVAL;
 83
 84	/* Finish platform specific initialization */
 85	if (pdata->init) {
 86		result = pdata->init();
 87		if (result)
 88			return result;
 89	}
 90
 91	policy->clk = cpufreq.armclk;
 92
 93	/*
 94	 * Time measurement across the target() function yields ~1500-1800us
 95	 * time taken with no drivers on notification list.
 96	 * Setting the latency to 2000 us to accommodate addition of drivers
 97	 * to pre/post change notification list.
 98	 */
 99	return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
100}
101
102static struct cpufreq_driver davinci_driver = {
103	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
104	.verify		= cpufreq_generic_frequency_table_verify,
105	.target_index	= davinci_target,
106	.get		= cpufreq_generic_get,
107	.init		= davinci_cpu_init,
108	.name		= "davinci",
109	.attr		= cpufreq_generic_attr,
110};
111
112static int __init davinci_cpufreq_probe(struct platform_device *pdev)
113{
114	struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
115	struct clk *asyncclk;
116
117	if (!pdata)
118		return -EINVAL;
119	if (!pdata->freq_table)
120		return -EINVAL;
121
122	cpufreq.dev = &pdev->dev;
123
124	cpufreq.armclk = clk_get(NULL, "arm");
125	if (IS_ERR(cpufreq.armclk)) {
126		dev_err(cpufreq.dev, "Unable to get ARM clock\n");
127		return PTR_ERR(cpufreq.armclk);
128	}
129
130	asyncclk = clk_get(cpufreq.dev, "async");
131	if (!IS_ERR(asyncclk)) {
132		cpufreq.asyncclk = asyncclk;
133		cpufreq.asyncrate = clk_get_rate(asyncclk);
134	}
135
136	return cpufreq_register_driver(&davinci_driver);
137}
138
139static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
140{
141	clk_put(cpufreq.armclk);
142
143	if (cpufreq.asyncclk)
144		clk_put(cpufreq.asyncclk);
145
146	return cpufreq_unregister_driver(&davinci_driver);
147}
148
149static struct platform_driver davinci_cpufreq_driver = {
150	.driver = {
151		.name	 = "cpufreq-davinci",
152	},
153	.remove = __exit_p(davinci_cpufreq_remove),
154};
155
156int __init davinci_cpufreq_init(void)
157{
158	return platform_driver_probe(&davinci_cpufreq_driver,
159							davinci_cpufreq_probe);
160}
161