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cpufreq.c
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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 <[email protected]>
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 <[email protected]>
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 #include "clock.h"
34 
36  struct device *dev;
37  struct clk *armclk;
38  struct clk *asyncclk;
39  unsigned long asyncrate;
40 };
41 static struct davinci_cpufreq cpufreq;
42 
43 static int davinci_verify_speed(struct cpufreq_policy *policy)
44 {
45  struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
47  struct clk *armclk = cpufreq.armclk;
48 
49  if (freq_table)
50  return cpufreq_frequency_table_verify(policy, freq_table);
51 
52  if (policy->cpu)
53  return -EINVAL;
54 
55  cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
56  policy->cpuinfo.max_freq);
57 
58  policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
59  policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
60  cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
61  policy->cpuinfo.max_freq);
62  return 0;
63 }
64 
65 static unsigned int davinci_getspeed(unsigned int cpu)
66 {
67  if (cpu)
68  return 0;
69 
70  return clk_get_rate(cpufreq.armclk) / 1000;
71 }
72 
73 static int davinci_target(struct cpufreq_policy *policy,
74  unsigned int target_freq, unsigned int relation)
75 {
76  int ret = 0;
77  unsigned int idx;
78  struct cpufreq_freqs freqs;
79  struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
80  struct clk *armclk = cpufreq.armclk;
81 
82  /*
83  * Ensure desired rate is within allowed range. Some govenors
84  * (ondemand) will just pass target_freq=0 to get the minimum.
85  */
86  if (target_freq < policy->cpuinfo.min_freq)
87  target_freq = policy->cpuinfo.min_freq;
88  if (target_freq > policy->cpuinfo.max_freq)
89  target_freq = policy->cpuinfo.max_freq;
90 
91  freqs.old = davinci_getspeed(0);
92  freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;
93  freqs.cpu = 0;
94 
95  if (freqs.old == freqs.new)
96  return ret;
97 
98  dev_dbg(cpufreq.dev, "transition: %u --> %u\n", freqs.old, freqs.new);
99 
100  ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
101  freqs.new, relation, &idx);
102  if (ret)
103  return -EINVAL;
104 
106 
107  /* if moving to higher frequency, up the voltage beforehand */
108  if (pdata->set_voltage && freqs.new > freqs.old) {
109  ret = pdata->set_voltage(idx);
110  if (ret)
111  goto out;
112  }
113 
114  ret = clk_set_rate(armclk, idx);
115  if (ret)
116  goto out;
117 
118  if (cpufreq.asyncclk) {
119  ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
120  if (ret)
121  goto out;
122  }
123 
124  /* if moving to lower freq, lower the voltage after lowering freq */
125  if (pdata->set_voltage && freqs.new < freqs.old)
126  pdata->set_voltage(idx);
127 
128 out:
130 
131  return ret;
132 }
133 
134 static int davinci_cpu_init(struct cpufreq_policy *policy)
135 {
136  int result = 0;
137  struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
138  struct cpufreq_frequency_table *freq_table = pdata->freq_table;
139 
140  if (policy->cpu != 0)
141  return -EINVAL;
142 
143  /* Finish platform specific initialization */
144  if (pdata->init) {
145  result = pdata->init();
146  if (result)
147  return result;
148  }
149 
150  policy->cur = policy->min = policy->max = davinci_getspeed(0);
151 
152  if (freq_table) {
153  result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
154  if (!result)
156  policy->cpu);
157  } else {
158  policy->cpuinfo.min_freq = policy->min;
159  policy->cpuinfo.max_freq = policy->max;
160  }
161 
162  policy->min = policy->cpuinfo.min_freq;
163  policy->max = policy->cpuinfo.max_freq;
164  policy->cur = davinci_getspeed(0);
165 
166  /*
167  * Time measurement across the target() function yields ~1500-1800us
168  * time taken with no drivers on notification list.
169  * Setting the latency to 2000 us to accommodate addition of drivers
170  * to pre/post change notification list.
171  */
172  policy->cpuinfo.transition_latency = 2000 * 1000;
173  return 0;
174 }
175 
176 static int davinci_cpu_exit(struct cpufreq_policy *policy)
177 {
179  return 0;
180 }
181 
182 static struct freq_attr *davinci_cpufreq_attr[] = {
184  NULL,
185 };
186 
187 static struct cpufreq_driver davinci_driver = {
188  .flags = CPUFREQ_STICKY,
189  .verify = davinci_verify_speed,
190  .target = davinci_target,
191  .get = davinci_getspeed,
192  .init = davinci_cpu_init,
193  .exit = davinci_cpu_exit,
194  .name = "davinci",
195  .attr = davinci_cpufreq_attr,
196 };
197 
198 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
199 {
200  struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
201  struct clk *asyncclk;
202 
203  if (!pdata)
204  return -EINVAL;
205  if (!pdata->freq_table)
206  return -EINVAL;
207 
208  cpufreq.dev = &pdev->dev;
209 
210  cpufreq.armclk = clk_get(NULL, "arm");
211  if (IS_ERR(cpufreq.armclk)) {
212  dev_err(cpufreq.dev, "Unable to get ARM clock\n");
213  return PTR_ERR(cpufreq.armclk);
214  }
215 
216  asyncclk = clk_get(cpufreq.dev, "async");
217  if (!IS_ERR(asyncclk)) {
218  cpufreq.asyncclk = asyncclk;
219  cpufreq.asyncrate = clk_get_rate(asyncclk);
220  }
221 
222  return cpufreq_register_driver(&davinci_driver);
223 }
224 
225 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
226 {
227  clk_put(cpufreq.armclk);
228 
229  if (cpufreq.asyncclk)
230  clk_put(cpufreq.asyncclk);
231 
232  return cpufreq_unregister_driver(&davinci_driver);
233 }
234 
235 static struct platform_driver davinci_cpufreq_driver = {
236  .driver = {
237  .name = "cpufreq-davinci",
238  .owner = THIS_MODULE,
239  },
240  .remove = __exit_p(davinci_cpufreq_remove),
241 };
242 
244 {
245  return platform_driver_probe(&davinci_cpufreq_driver,
246  davinci_cpufreq_probe);
247 }
248