1/*
  2 *  CPU frequency scaling for OMAP using OPP information
  3 *
  4 *  Copyright (C) 2005 Nokia Corporation
  5 *  Written by Tony Lindgren <tony@atomide.com>
  6 *
  7 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
  8 *
  9 * Copyright (C) 2007-2011 Texas Instruments, Inc.
 10 * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar
 11 *
 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.
 15 */
 16
 17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 18
 19#include <linux/types.h>
 20#include <linux/kernel.h>
 21#include <linux/sched.h>
 22#include <linux/cpufreq.h>
 23#include <linux/delay.h>
 24#include <linux/init.h>
 25#include <linux/err.h>
 26#include <linux/clk.h>
 27#include <linux/io.h>
 28#include <linux/pm_opp.h>
 29#include <linux/cpu.h>
 30#include <linux/module.h>
 31#include <linux/platform_device.h>
 32#include <linux/regulator/consumer.h>
 33
 34#include <asm/smp_plat.h>
 35#include <asm/cpu.h>
 36
 37/* OPP tolerance in percentage */
 38#define	OPP_TOLERANCE	4
 39
 40static struct cpufreq_frequency_table *freq_table;
 41static atomic_t freq_table_users = ATOMIC_INIT(0);
 42static struct device *mpu_dev;
 43static struct regulator *mpu_reg;
 44
 45static int omap_target(struct cpufreq_policy *policy, unsigned int index)
 46{
 47	int r, ret;
 48	struct dev_pm_opp *opp;
 49	unsigned long freq, volt = 0, volt_old = 0, tol = 0;
 50	unsigned int old_freq, new_freq;
 51
 52	old_freq = policy->cur;
 53	new_freq = freq_table[index].frequency;
 54
 55	freq = new_freq * 1000;
 56	ret = clk_round_rate(policy->clk, freq);
 57	if (ret < 0) {
 58		dev_warn(mpu_dev,
 59			 "CPUfreq: Cannot find matching frequency for %lu\n",
 60			 freq);
 61		return ret;
 62	}
 63	freq = ret;
 64
 65	if (mpu_reg) {
 66		opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
 67		if (IS_ERR(opp)) {
 68			dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
 69				__func__, new_freq);
 70			return -EINVAL;
 71		}
 72		volt = dev_pm_opp_get_voltage(opp);
 73		dev_pm_opp_put(opp);
 74		tol = volt * OPP_TOLERANCE / 100;
 75		volt_old = regulator_get_voltage(mpu_reg);
 76	}
 77
 78	dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n", 
 79		old_freq / 1000, volt_old ? volt_old / 1000 : -1,
 80		new_freq / 1000, volt ? volt / 1000 : -1);
 81
 82	/* scaling up?  scale voltage before frequency */
 83	if (mpu_reg && (new_freq > old_freq)) {
 84		r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
 85		if (r < 0) {
 86			dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
 87				 __func__);
 88			return r;
 89		}
 90	}
 91
 92	ret = clk_set_rate(policy->clk, new_freq * 1000);
 93
 94	/* scaling down?  scale voltage after frequency */
 95	if (mpu_reg && (new_freq < old_freq)) {
 96		r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
 97		if (r < 0) {
 98			dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
 99				 __func__);
100			clk_set_rate(policy->clk, old_freq * 1000);
101			return r;
102		}
103	}
104
105	return ret;
106}
107
108static inline void freq_table_free(void)
109{
110	if (atomic_dec_and_test(&freq_table_users))
111		dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
112}
113
114static int omap_cpu_init(struct cpufreq_policy *policy)
115{
116	int result;
117
118	policy->clk = clk_get(NULL, "cpufreq_ck");
119	if (IS_ERR(policy->clk))
120		return PTR_ERR(policy->clk);
121
122	if (!freq_table) {
123		result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
124		if (result) {
125			dev_err(mpu_dev,
126				"%s: cpu%d: failed creating freq table[%d]\n",
127				__func__, policy->cpu, result);
128			goto fail;
129		}
130	}
131
132	atomic_inc_return(&freq_table_users);
133
134	/* FIXME: what's the actual transition time? */
135	result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
136	if (!result)
137		return 0;
138
139	freq_table_free();
140fail:
141	clk_put(policy->clk);
142	return result;
143}
144
145static int omap_cpu_exit(struct cpufreq_policy *policy)
146{
147	freq_table_free();
148	clk_put(policy->clk);
149	return 0;
150}
151
152static struct cpufreq_driver omap_driver = {
153	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
154	.verify		= cpufreq_generic_frequency_table_verify,
155	.target_index	= omap_target,
156	.get		= cpufreq_generic_get,
157	.init		= omap_cpu_init,
158	.exit		= omap_cpu_exit,
159	.name		= "omap",
160	.attr		= cpufreq_generic_attr,
161};
162
163static int omap_cpufreq_probe(struct platform_device *pdev)
164{
165	mpu_dev = get_cpu_device(0);
166	if (!mpu_dev) {
167		pr_warn("%s: unable to get the MPU device\n", __func__);
168		return -EINVAL;
169	}
170
171	mpu_reg = regulator_get(mpu_dev, "vcc");
172	if (IS_ERR(mpu_reg)) {
173		pr_warn("%s: unable to get MPU regulator\n", __func__);
174		mpu_reg = NULL;
175	} else {
176		/* 
177		 * Ensure physical regulator is present.
178		 * (e.g. could be dummy regulator.)
179		 */
180		if (regulator_get_voltage(mpu_reg) < 0) {
181			pr_warn("%s: physical regulator not present for MPU\n",
182				__func__);
183			regulator_put(mpu_reg);
184			mpu_reg = NULL;
185		}
186	}
187
188	return cpufreq_register_driver(&omap_driver);
189}
190
191static int omap_cpufreq_remove(struct platform_device *pdev)
192{
193	return cpufreq_unregister_driver(&omap_driver);
194}
195
196static struct platform_driver omap_cpufreq_platdrv = {
197	.driver = {
198		.name	= "omap-cpufreq",
199	},
200	.probe		= omap_cpufreq_probe,
201	.remove		= omap_cpufreq_remove,
202};
203module_platform_driver(omap_cpufreq_platdrv);
204
205MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
206MODULE_LICENSE("GPL");