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
davinci_target(struct cpufreq_policy * policy,unsigned int idx)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, 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
davinci_cpu_init(struct cpufreq_policy * policy)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
davinci_cpufreq_probe(struct platform_device * pdev)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
davinci_cpufreq_remove(struct platform_device * pdev)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
davinci_cpufreq_init(void)156 int __init davinci_cpufreq_init(void)
157 {
158 return platform_driver_probe(&davinci_cpufreq_driver,
159 davinci_cpufreq_probe);
160 }
161
162