2 * CPU frequency scaling for DaVinci
4 * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
6 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
8 * Copyright (C) 2005 Nokia Corporation
9 * Written by Tony Lindgren <tony@atomide.com>
11 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
13 * Copyright (C) 2007-2008 Texas Instruments, Inc.
14 * Updated to support OMAP3
15 * Rajendra Nayak <rnayak@ti.com>
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.
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>
28 #include <mach/hardware.h>
29 #include <mach/cpufreq.h>
30 #include <mach/common.h>
34 struct davinci_cpufreq {
38 unsigned long asyncrate;
40 static struct davinci_cpufreq cpufreq;
42 static int davinci_verify_speed(struct cpufreq_policy *policy)
44 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
45 struct cpufreq_frequency_table *freq_table = pdata->freq_table;
46 struct clk *armclk = cpufreq.armclk;
49 return cpufreq_frequency_table_verify(policy, freq_table);
54 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
55 policy->cpuinfo.max_freq);
57 policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
58 policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
59 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
60 policy->cpuinfo.max_freq);
64 static unsigned int davinci_getspeed(unsigned int cpu)
69 return clk_get_rate(cpufreq.armclk) / 1000;
72 static int davinci_target(struct cpufreq_policy *policy,
73 unsigned int target_freq, unsigned int relation)
77 struct cpufreq_freqs freqs;
78 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
79 struct clk *armclk = cpufreq.armclk;
82 * Ensure desired rate is within allowed range. Some govenors
83 * (ondemand) will just pass target_freq=0 to get the minimum.
85 if (target_freq < policy->cpuinfo.min_freq)
86 target_freq = policy->cpuinfo.min_freq;
87 if (target_freq > policy->cpuinfo.max_freq)
88 target_freq = policy->cpuinfo.max_freq;
90 freqs.old = davinci_getspeed(0);
91 freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;
94 if (freqs.old == freqs.new)
97 cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER,
98 dev_driver_string(cpufreq.dev),
99 "transition: %u --> %u\n", freqs.old, freqs.new);
101 ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
102 freqs.new, relation, &idx);
106 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
108 /* if moving to higher frequency, up the voltage beforehand */
109 if (pdata->set_voltage && freqs.new > freqs.old) {
110 ret = pdata->set_voltage(idx);
115 ret = clk_set_rate(armclk, idx);
119 if (cpufreq.asyncclk) {
120 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
125 /* if moving to lower freq, lower the voltage after lowering freq */
126 if (pdata->set_voltage && freqs.new < freqs.old)
127 pdata->set_voltage(idx);
130 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
135 static int davinci_cpu_init(struct cpufreq_policy *policy)
138 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
139 struct cpufreq_frequency_table *freq_table = pdata->freq_table;
141 if (policy->cpu != 0)
144 /* Finish platform specific initialization */
146 result = pdata->init();
151 policy->cur = policy->min = policy->max = davinci_getspeed(0);
154 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
156 cpufreq_frequency_table_get_attr(freq_table,
159 policy->cpuinfo.min_freq = policy->min;
160 policy->cpuinfo.max_freq = policy->max;
163 policy->min = policy->cpuinfo.min_freq;
164 policy->max = policy->cpuinfo.max_freq;
165 policy->cur = davinci_getspeed(0);
168 * Time measurement across the target() function yields ~1500-1800us
169 * time taken with no drivers on notification list.
170 * Setting the latency to 2000 us to accommodate addition of drivers
171 * to pre/post change notification list.
173 policy->cpuinfo.transition_latency = 2000 * 1000;
177 static int davinci_cpu_exit(struct cpufreq_policy *policy)
179 cpufreq_frequency_table_put_attr(policy->cpu);
183 static struct freq_attr *davinci_cpufreq_attr[] = {
184 &cpufreq_freq_attr_scaling_available_freqs,
188 static struct cpufreq_driver davinci_driver = {
189 .flags = CPUFREQ_STICKY,
190 .verify = davinci_verify_speed,
191 .target = davinci_target,
192 .get = davinci_getspeed,
193 .init = davinci_cpu_init,
194 .exit = davinci_cpu_exit,
196 .attr = davinci_cpufreq_attr,
199 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
201 struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
202 struct clk *asyncclk;
206 if (!pdata->freq_table)
209 cpufreq.dev = &pdev->dev;
211 cpufreq.armclk = clk_get(NULL, "arm");
212 if (IS_ERR(cpufreq.armclk)) {
213 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
214 return PTR_ERR(cpufreq.armclk);
217 asyncclk = clk_get(cpufreq.dev, "async");
218 if (!IS_ERR(asyncclk)) {
219 cpufreq.asyncclk = asyncclk;
220 cpufreq.asyncrate = clk_get_rate(asyncclk);
223 return cpufreq_register_driver(&davinci_driver);
226 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
228 clk_put(cpufreq.armclk);
230 if (cpufreq.asyncclk)
231 clk_put(cpufreq.asyncclk);
233 return cpufreq_unregister_driver(&davinci_driver);
236 static struct platform_driver davinci_cpufreq_driver = {
238 .name = "cpufreq-davinci",
239 .owner = THIS_MODULE,
241 .remove = __exit_p(davinci_cpufreq_remove),
244 static int __init davinci_cpufreq_init(void)
246 return platform_driver_probe(&davinci_cpufreq_driver,
247 davinci_cpufreq_probe);
249 late_initcall(davinci_cpufreq_init);