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>
27 #include <linux/export.h>
29 #include <mach/hardware.h>
30 #include <mach/cpufreq.h>
31 #include <mach/common.h>
33 struct davinci_cpufreq {
37 unsigned long asyncrate;
39 static struct davinci_cpufreq cpufreq;
41 static int davinci_verify_speed(struct cpufreq_policy *policy)
43 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
44 struct cpufreq_frequency_table *freq_table = pdata->freq_table;
45 struct clk *armclk = cpufreq.armclk;
48 return cpufreq_frequency_table_verify(policy, freq_table);
53 cpufreq_verify_within_cpu_limits(policy);
54 policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
55 policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
56 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
57 policy->cpuinfo.max_freq);
61 static unsigned int davinci_getspeed(unsigned int cpu)
66 return clk_get_rate(cpufreq.armclk) / 1000;
69 static int davinci_target(struct cpufreq_policy *policy,
70 unsigned int target_freq, unsigned int relation)
74 struct cpufreq_freqs freqs;
75 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
76 struct clk *armclk = cpufreq.armclk;
78 freqs.old = davinci_getspeed(0);
79 freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;
81 if (freqs.old == freqs.new)
84 dev_dbg(cpufreq.dev, "transition: %u --> %u\n", freqs.old, freqs.new);
86 ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
87 freqs.new, relation, &idx);
91 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
93 /* if moving to higher frequency, up the voltage beforehand */
94 if (pdata->set_voltage && freqs.new > freqs.old) {
95 ret = pdata->set_voltage(idx);
100 ret = clk_set_rate(armclk, idx);
104 if (cpufreq.asyncclk) {
105 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
110 /* if moving to lower freq, lower the voltage after lowering freq */
111 if (pdata->set_voltage && freqs.new < freqs.old)
112 pdata->set_voltage(idx);
116 freqs.new = freqs.old;
118 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
123 static int davinci_cpu_init(struct cpufreq_policy *policy)
126 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
127 struct cpufreq_frequency_table *freq_table = pdata->freq_table;
129 if (policy->cpu != 0)
132 /* Finish platform specific initialization */
134 result = pdata->init();
140 * Time measurement across the target() function yields ~1500-1800us
141 * time taken with no drivers on notification list.
142 * Setting the latency to 2000 us to accommodate addition of drivers
143 * to pre/post change notification list.
145 return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
148 static struct cpufreq_driver davinci_driver = {
149 .flags = CPUFREQ_STICKY,
150 .verify = davinci_verify_speed,
151 .target = davinci_target,
152 .get = davinci_getspeed,
153 .init = davinci_cpu_init,
154 .exit = cpufreq_generic_exit,
156 .attr = cpufreq_generic_attr,
159 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
161 struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
162 struct clk *asyncclk;
166 if (!pdata->freq_table)
169 cpufreq.dev = &pdev->dev;
171 cpufreq.armclk = clk_get(NULL, "arm");
172 if (IS_ERR(cpufreq.armclk)) {
173 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
174 return PTR_ERR(cpufreq.armclk);
177 asyncclk = clk_get(cpufreq.dev, "async");
178 if (!IS_ERR(asyncclk)) {
179 cpufreq.asyncclk = asyncclk;
180 cpufreq.asyncrate = clk_get_rate(asyncclk);
183 return cpufreq_register_driver(&davinci_driver);
186 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
188 clk_put(cpufreq.armclk);
190 if (cpufreq.asyncclk)
191 clk_put(cpufreq.asyncclk);
193 return cpufreq_unregister_driver(&davinci_driver);
196 static struct platform_driver davinci_cpufreq_driver = {
198 .name = "cpufreq-davinci",
199 .owner = THIS_MODULE,
201 .remove = __exit_p(davinci_cpufreq_remove),
204 int __init davinci_cpufreq_init(void)
206 return platform_driver_probe(&davinci_cpufreq_driver,
207 davinci_cpufreq_probe);