2 * CPU frequency scaling for OMAP using OPP information
4 * Copyright (C) 2005 Nokia Corporation
5 * Written by Tony Lindgren <tony@atomide.com>
7 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
9 * Copyright (C) 2007-2011 Texas Instruments, Inc.
10 * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2 as
14 * published by the Free Software Foundation.
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/sched.h>
19 #include <linux/cpufreq.h>
20 #include <linux/delay.h>
21 #include <linux/init.h>
22 #include <linux/err.h>
23 #include <linux/clk.h>
25 #include <linux/pm_opp.h>
26 #include <linux/cpu.h>
27 #include <linux/module.h>
28 #include <linux/platform_device.h>
29 #include <linux/regulator/consumer.h>
31 #include <asm/smp_plat.h>
34 /* OPP tolerance in percentage */
35 #define OPP_TOLERANCE 4
37 static struct cpufreq_frequency_table *freq_table;
38 static atomic_t freq_table_users = ATOMIC_INIT(0);
39 static struct clk *mpu_clk;
40 static struct device *mpu_dev;
41 static struct regulator *mpu_reg;
43 static unsigned int omap_getspeed(unsigned int cpu)
50 rate = clk_get_rate(mpu_clk) / 1000;
54 static int omap_target(struct cpufreq_policy *policy, unsigned int index)
57 struct dev_pm_opp *opp;
58 unsigned long freq, volt = 0, volt_old = 0, tol = 0;
59 unsigned int old_freq, new_freq;
61 old_freq = omap_getspeed(policy->cpu);
62 new_freq = freq_table[index].frequency;
64 freq = new_freq * 1000;
65 ret = clk_round_rate(mpu_clk, freq);
66 if (IS_ERR_VALUE(ret)) {
68 "CPUfreq: Cannot find matching frequency for %lu\n",
76 opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
79 dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
83 volt = dev_pm_opp_get_voltage(opp);
85 tol = volt * OPP_TOLERANCE / 100;
86 volt_old = regulator_get_voltage(mpu_reg);
89 dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
90 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
91 new_freq / 1000, volt ? volt / 1000 : -1);
93 /* scaling up? scale voltage before frequency */
94 if (mpu_reg && (new_freq > old_freq)) {
95 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
97 dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
103 ret = clk_set_rate(mpu_clk, new_freq * 1000);
105 /* scaling down? scale voltage after frequency */
106 if (mpu_reg && (new_freq < old_freq)) {
107 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
109 dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
111 clk_set_rate(mpu_clk, old_freq * 1000);
119 static inline void freq_table_free(void)
121 if (atomic_dec_and_test(&freq_table_users))
122 dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
125 static int omap_cpu_init(struct cpufreq_policy *policy)
129 mpu_clk = clk_get(NULL, "cpufreq_ck");
131 return PTR_ERR(mpu_clk);
134 result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
137 "%s: cpu%d: failed creating freq table[%d]\n",
138 __func__, policy->cpu, result);
143 atomic_inc_return(&freq_table_users);
145 /* FIXME: what's the actual transition time? */
146 result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
156 static int omap_cpu_exit(struct cpufreq_policy *policy)
158 cpufreq_frequency_table_put_attr(policy->cpu);
164 static struct cpufreq_driver omap_driver = {
165 .flags = CPUFREQ_STICKY,
166 .verify = cpufreq_generic_frequency_table_verify,
167 .target_index = omap_target,
168 .get = omap_getspeed,
169 .init = omap_cpu_init,
170 .exit = omap_cpu_exit,
172 .attr = cpufreq_generic_attr,
175 static int omap_cpufreq_probe(struct platform_device *pdev)
177 mpu_dev = get_cpu_device(0);
179 pr_warning("%s: unable to get the mpu device\n", __func__);
183 mpu_reg = regulator_get(mpu_dev, "vcc");
184 if (IS_ERR(mpu_reg)) {
185 pr_warning("%s: unable to get MPU regulator\n", __func__);
189 * Ensure physical regulator is present.
190 * (e.g. could be dummy regulator.)
192 if (regulator_get_voltage(mpu_reg) < 0) {
193 pr_warn("%s: physical regulator not present for MPU\n",
195 regulator_put(mpu_reg);
200 return cpufreq_register_driver(&omap_driver);
203 static int omap_cpufreq_remove(struct platform_device *pdev)
205 return cpufreq_unregister_driver(&omap_driver);
208 static struct platform_driver omap_cpufreq_platdrv = {
210 .name = "omap-cpufreq",
211 .owner = THIS_MODULE,
213 .probe = omap_cpufreq_probe,
214 .remove = omap_cpufreq_remove,
216 module_platform_driver(omap_cpufreq_platdrv);
218 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
219 MODULE_LICENSE("GPL");