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_data/davinci-cpufreq.h>
27 #include <linux/platform_device.h>
28 #include <linux/export.h>
29 
30 struct davinci_cpufreq {
31 	struct device *dev;
32 	struct clk *armclk;
33 	struct clk *asyncclk;
34 	unsigned long asyncrate;
35 };
36 static struct davinci_cpufreq cpufreq;
37 
38 static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
39 {
40 	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
41 	struct clk *armclk = cpufreq.armclk;
42 	unsigned int old_freq, new_freq;
43 	int ret = 0;
44 
45 	old_freq = policy->cur;
46 	new_freq = pdata->freq_table[idx].frequency;
47 
48 	/* if moving to higher frequency, up the voltage beforehand */
49 	if (pdata->set_voltage && new_freq > old_freq) {
50 		ret = pdata->set_voltage(idx);
51 		if (ret)
52 			return ret;
53 	}
54 
55 	ret = clk_set_rate(armclk, new_freq * 1000);
56 	if (ret)
57 		return ret;
58 
59 	if (cpufreq.asyncclk) {
60 		ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
61 		if (ret)
62 			return ret;
63 	}
64 
65 	/* if moving to lower freq, lower the voltage after lowering freq */
66 	if (pdata->set_voltage && new_freq < old_freq)
67 		pdata->set_voltage(idx);
68 
69 	return 0;
70 }
71 
72 static int davinci_cpu_init(struct cpufreq_policy *policy)
73 {
74 	int result = 0;
75 	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
76 	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
77 
78 	if (policy->cpu != 0)
79 		return -EINVAL;
80 
81 	/* Finish platform specific initialization */
82 	if (pdata->init) {
83 		result = pdata->init();
84 		if (result)
85 			return result;
86 	}
87 
88 	policy->clk = cpufreq.armclk;
89 
90 	/*
91 	 * Time measurement across the target() function yields ~1500-1800us
92 	 * time taken with no drivers on notification list.
93 	 * Setting the latency to 2000 us to accommodate addition of drivers
94 	 * to pre/post change notification list.
95 	 */
96 	return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
97 }
98 
99 static struct cpufreq_driver davinci_driver = {
100 	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
101 	.verify		= cpufreq_generic_frequency_table_verify,
102 	.target_index	= davinci_target,
103 	.get		= cpufreq_generic_get,
104 	.init		= davinci_cpu_init,
105 	.name		= "davinci",
106 	.attr		= cpufreq_generic_attr,
107 };
108 
109 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
110 {
111 	struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
112 	struct clk *asyncclk;
113 
114 	if (!pdata)
115 		return -EINVAL;
116 	if (!pdata->freq_table)
117 		return -EINVAL;
118 
119 	cpufreq.dev = &pdev->dev;
120 
121 	cpufreq.armclk = clk_get(NULL, "arm");
122 	if (IS_ERR(cpufreq.armclk)) {
123 		dev_err(cpufreq.dev, "Unable to get ARM clock\n");
124 		return PTR_ERR(cpufreq.armclk);
125 	}
126 
127 	asyncclk = clk_get(cpufreq.dev, "async");
128 	if (!IS_ERR(asyncclk)) {
129 		cpufreq.asyncclk = asyncclk;
130 		cpufreq.asyncrate = clk_get_rate(asyncclk);
131 	}
132 
133 	return cpufreq_register_driver(&davinci_driver);
134 }
135 
136 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
137 {
138 	clk_put(cpufreq.armclk);
139 
140 	if (cpufreq.asyncclk)
141 		clk_put(cpufreq.asyncclk);
142 
143 	return cpufreq_unregister_driver(&davinci_driver);
144 }
145 
146 static struct platform_driver davinci_cpufreq_driver = {
147 	.driver = {
148 		.name	 = "cpufreq-davinci",
149 	},
150 	.remove = __exit_p(davinci_cpufreq_remove),
151 };
152 
153 int __init davinci_cpufreq_init(void)
154 {
155 	return platform_driver_probe(&davinci_cpufreq_driver,
156 							davinci_cpufreq_probe);
157 }
158 
159