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 struct davinci_cpufreq {
34 	struct device *dev;
35 	struct clk *armclk;
36 	struct clk *asyncclk;
37 	unsigned long asyncrate;
38 };
39 static struct davinci_cpufreq cpufreq;
40 
41 static 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, idx);
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 
75 static 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 
102 static 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 
112 static 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 
139 static 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 
149 static struct platform_driver davinci_cpufreq_driver = {
150 	.driver = {
151 		.name	 = "cpufreq-davinci",
152 	},
153 	.remove = __exit_p(davinci_cpufreq_remove),
154 };
155 
156 int __init davinci_cpufreq_init(void)
157 {
158 	return platform_driver_probe(&davinci_cpufreq_driver,
159 							davinci_cpufreq_probe);
160 }
161 
162