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,
55 unsigned int target_freq,
56 unsigned int relation)
60 struct cpufreq_freqs freqs;
61 struct dev_pm_opp *opp;
62 unsigned long freq, volt = 0, volt_old = 0, tol = 0;
65 dev_err(mpu_dev, "%s: cpu%d: no freq table!\n", __func__,
70 ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
73 dev_dbg(mpu_dev, "%s: cpu%d: no freq match for %d(ret=%d)\n",
74 __func__, policy->cpu, target_freq, ret);
77 freqs.new = freq_table[i].frequency;
79 dev_err(mpu_dev, "%s: cpu%d: no match for freq %d\n", __func__,
80 policy->cpu, target_freq);
84 freqs.old = omap_getspeed(policy->cpu);
86 if (freqs.old == freqs.new && policy->cur == freqs.new)
89 freq = freqs.new * 1000;
90 ret = clk_round_rate(mpu_clk, freq);
91 if (IS_ERR_VALUE(ret)) {
93 "CPUfreq: Cannot find matching frequency for %lu\n",
101 opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
104 dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
105 __func__, freqs.new);
108 volt = dev_pm_opp_get_voltage(opp);
110 tol = volt * OPP_TOLERANCE / 100;
111 volt_old = regulator_get_voltage(mpu_reg);
114 dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
115 freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
116 freqs.new / 1000, volt ? volt / 1000 : -1);
119 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
121 /* scaling up? scale voltage before frequency */
122 if (mpu_reg && (freqs.new > freqs.old)) {
123 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
125 dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
127 freqs.new = freqs.old;
132 ret = clk_set_rate(mpu_clk, freqs.new * 1000);
134 /* scaling down? scale voltage after frequency */
135 if (mpu_reg && (freqs.new < freqs.old)) {
136 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
138 dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
140 ret = clk_set_rate(mpu_clk, freqs.old * 1000);
141 freqs.new = freqs.old;
146 freqs.new = omap_getspeed(policy->cpu);
150 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
155 static inline void freq_table_free(void)
157 if (atomic_dec_and_test(&freq_table_users))
158 dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
161 static int omap_cpu_init(struct cpufreq_policy *policy)
165 mpu_clk = clk_get(NULL, "cpufreq_ck");
167 return PTR_ERR(mpu_clk);
170 result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
173 "%s: cpu%d: failed creating freq table[%d]\n",
174 __func__, policy->cpu, result);
179 atomic_inc_return(&freq_table_users);
181 /* FIXME: what's the actual transition time? */
182 result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
192 static int omap_cpu_exit(struct cpufreq_policy *policy)
194 cpufreq_frequency_table_put_attr(policy->cpu);
200 static struct cpufreq_driver omap_driver = {
201 .flags = CPUFREQ_STICKY,
202 .verify = cpufreq_generic_frequency_table_verify,
203 .target = omap_target,
204 .get = omap_getspeed,
205 .init = omap_cpu_init,
206 .exit = omap_cpu_exit,
208 .attr = cpufreq_generic_attr,
211 static int omap_cpufreq_probe(struct platform_device *pdev)
213 mpu_dev = get_cpu_device(0);
215 pr_warning("%s: unable to get the mpu device\n", __func__);
219 mpu_reg = regulator_get(mpu_dev, "vcc");
220 if (IS_ERR(mpu_reg)) {
221 pr_warning("%s: unable to get MPU regulator\n", __func__);
225 * Ensure physical regulator is present.
226 * (e.g. could be dummy regulator.)
228 if (regulator_get_voltage(mpu_reg) < 0) {
229 pr_warn("%s: physical regulator not present for MPU\n",
231 regulator_put(mpu_reg);
236 return cpufreq_register_driver(&omap_driver);
239 static int omap_cpufreq_remove(struct platform_device *pdev)
241 return cpufreq_unregister_driver(&omap_driver);
244 static struct platform_driver omap_cpufreq_platdrv = {
246 .name = "omap-cpufreq",
247 .owner = THIS_MODULE,
249 .probe = omap_cpufreq_probe,
250 .remove = omap_cpufreq_remove,
252 module_platform_driver(omap_cpufreq_platdrv);
254 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
255 MODULE_LICENSE("GPL");