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 device *mpu_dev;
40 static struct regulator *mpu_reg;
42 static int omap_target(struct cpufreq_policy *policy, unsigned int index)
45 struct dev_pm_opp *opp;
46 unsigned long freq, volt = 0, volt_old = 0, tol = 0;
47 unsigned int old_freq, new_freq;
49 old_freq = policy->cur;
50 new_freq = freq_table[index].frequency;
52 freq = new_freq * 1000;
53 ret = clk_round_rate(policy->clk, freq);
54 if (IS_ERR_VALUE(ret)) {
56 "CPUfreq: Cannot find matching frequency for %lu\n",
64 opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
67 dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
71 volt = dev_pm_opp_get_voltage(opp);
73 tol = volt * OPP_TOLERANCE / 100;
74 volt_old = regulator_get_voltage(mpu_reg);
77 dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
78 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
79 new_freq / 1000, volt ? volt / 1000 : -1);
81 /* scaling up? scale voltage before frequency */
82 if (mpu_reg && (new_freq > old_freq)) {
83 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
85 dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
91 ret = clk_set_rate(policy->clk, new_freq * 1000);
93 /* scaling down? scale voltage after 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 down.\n",
99 clk_set_rate(policy->clk, old_freq * 1000);
107 static inline void freq_table_free(void)
109 if (atomic_dec_and_test(&freq_table_users))
110 dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
113 static int omap_cpu_init(struct cpufreq_policy *policy)
117 policy->clk = clk_get(NULL, "cpufreq_ck");
118 if (IS_ERR(policy->clk))
119 return PTR_ERR(policy->clk);
122 result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
125 "%s: cpu%d: failed creating freq table[%d]\n",
126 __func__, policy->cpu, result);
131 atomic_inc_return(&freq_table_users);
133 /* FIXME: what's the actual transition time? */
134 result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
140 clk_put(policy->clk);
144 static int omap_cpu_exit(struct cpufreq_policy *policy)
147 clk_put(policy->clk);
151 static struct cpufreq_driver omap_driver = {
152 .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
153 .verify = cpufreq_generic_frequency_table_verify,
154 .target_index = omap_target,
155 .get = cpufreq_generic_get,
156 .init = omap_cpu_init,
157 .exit = omap_cpu_exit,
159 .attr = cpufreq_generic_attr,
162 static int omap_cpufreq_probe(struct platform_device *pdev)
164 mpu_dev = get_cpu_device(0);
166 pr_warning("%s: unable to get the mpu device\n", __func__);
170 mpu_reg = regulator_get(mpu_dev, "vcc");
171 if (IS_ERR(mpu_reg)) {
172 pr_warning("%s: unable to get MPU regulator\n", __func__);
176 * Ensure physical regulator is present.
177 * (e.g. could be dummy regulator.)
179 if (regulator_get_voltage(mpu_reg) < 0) {
180 pr_warn("%s: physical regulator not present for MPU\n",
182 regulator_put(mpu_reg);
187 return cpufreq_register_driver(&omap_driver);
190 static int omap_cpufreq_remove(struct platform_device *pdev)
192 return cpufreq_unregister_driver(&omap_driver);
195 static struct platform_driver omap_cpufreq_platdrv = {
197 .name = "omap-cpufreq",
199 .probe = omap_cpufreq_probe,
200 .remove = omap_cpufreq_remove,
202 module_platform_driver(omap_cpufreq_platdrv);
204 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
205 MODULE_LICENSE("GPL");