1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  CPU frequency scaling for OMAP using OPP information
  4 *
  5 *  Copyright (C) 2005 Nokia Corporation
  6 *  Written by Tony Lindgren <tony@atomide.com>
  7 *
  8 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
  9 *
 10 * Copyright (C) 2007-2011 Texas Instruments, Inc.
 11 * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar
 12 */
 13
 14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 15
 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>
 24#include <linux/io.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>
 30
 31/* OPP tolerance in percentage */
 32#define	OPP_TOLERANCE	4
 33
 34static struct cpufreq_frequency_table *freq_table;
 35static atomic_t freq_table_users = ATOMIC_INIT(0);
 36static struct device *mpu_dev;
 37static struct regulator *mpu_reg;
 38
 39static int omap_target(struct cpufreq_policy *policy, unsigned int index)
 40{
 41	int r, ret;
 42	struct dev_pm_opp *opp;
 43	unsigned long freq, volt = 0, volt_old = 0, tol = 0;
 44	unsigned int old_freq, new_freq;
 45
 46	old_freq = policy->cur;
 47	new_freq = freq_table[index].frequency;
 48
 49	freq = new_freq * 1000;
 50	ret = clk_round_rate(policy->clk, freq);
 51	if (ret < 0) {
 52		dev_warn(mpu_dev,
 53			 "CPUfreq: Cannot find matching frequency for %lu\n",
 54			 freq);
 55		return ret;
 56	}
 57	freq = ret;
 58
 59	if (mpu_reg) {
 60		opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
 61		if (IS_ERR(opp)) {
 62			dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
 63				__func__, new_freq);
 64			return -EINVAL;
 65		}
 66		volt = dev_pm_opp_get_voltage(opp);
 67		dev_pm_opp_put(opp);
 68		tol = volt * OPP_TOLERANCE / 100;
 69		volt_old = regulator_get_voltage(mpu_reg);
 70	}
 71
 72	dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n", 
 73		old_freq / 1000, volt_old ? volt_old / 1000 : -1,
 74		new_freq / 1000, volt ? volt / 1000 : -1);
 75
 76	/* scaling up?  scale voltage before frequency */
 77	if (mpu_reg && (new_freq > old_freq)) {
 78		r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
 79		if (r < 0) {
 80			dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
 81				 __func__);
 82			return r;
 83		}
 84	}
 85
 86	ret = clk_set_rate(policy->clk, new_freq * 1000);
 87
 88	/* scaling down?  scale voltage after frequency */
 89	if (mpu_reg && (new_freq < old_freq)) {
 90		r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
 91		if (r < 0) {
 92			dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
 93				 __func__);
 94			clk_set_rate(policy->clk, old_freq * 1000);
 95			return r;
 96		}
 97	}
 98
 99	return ret;
100}
101
102static inline void freq_table_free(void)
103{
104	if (atomic_dec_and_test(&freq_table_users))
105		dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
106}
107
108static int omap_cpu_init(struct cpufreq_policy *policy)
109{
110	int result;
111
112	policy->clk = clk_get(NULL, "cpufreq_ck");
113	if (IS_ERR(policy->clk))
114		return PTR_ERR(policy->clk);
115
116	if (!freq_table) {
117		result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
118		if (result) {
119			dev_err(mpu_dev,
120				"%s: cpu%d: failed creating freq table[%d]\n",
121				__func__, policy->cpu, result);
122			clk_put(policy->clk);
123			return result;
124		}
125	}
126
127	atomic_inc_return(&freq_table_users);
128
129	/* FIXME: what's the actual transition time? */
130	cpufreq_generic_init(policy, freq_table, 300 * 1000);
131
132	return 0;
133}
134
135static void omap_cpu_exit(struct cpufreq_policy *policy)
136{
137	freq_table_free();
138	clk_put(policy->clk);
139}
140
141static struct cpufreq_driver omap_driver = {
142	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
143	.verify		= cpufreq_generic_frequency_table_verify,
144	.target_index	= omap_target,
145	.get		= cpufreq_generic_get,
146	.init		= omap_cpu_init,
147	.exit		= omap_cpu_exit,
148	.register_em	= cpufreq_register_em_with_opp,
149	.name		= "omap",
150	.attr		= cpufreq_generic_attr,
151};
152
153static int omap_cpufreq_probe(struct platform_device *pdev)
154{
155	mpu_dev = get_cpu_device(0);
156	if (!mpu_dev) {
157		pr_warn("%s: unable to get the MPU device\n", __func__);
158		return -EINVAL;
159	}
160
161	mpu_reg = regulator_get(mpu_dev, "vcc");
162	if (IS_ERR(mpu_reg)) {
163		pr_warn("%s: unable to get MPU regulator\n", __func__);
164		mpu_reg = NULL;
165	} else {
166		/* 
167		 * Ensure physical regulator is present.
168		 * (e.g. could be dummy regulator.)
169		 */
170		if (regulator_get_voltage(mpu_reg) < 0) {
171			pr_warn("%s: physical regulator not present for MPU\n",
172				__func__);
173			regulator_put(mpu_reg);
174			mpu_reg = NULL;
175		}
176	}
177
178	return cpufreq_register_driver(&omap_driver);
179}
180
181static void omap_cpufreq_remove(struct platform_device *pdev)
182{
183	cpufreq_unregister_driver(&omap_driver);
184}
185
186static struct platform_driver omap_cpufreq_platdrv = {
187	.driver = {
188		.name	= "omap-cpufreq",
189	},
190	.probe		= omap_cpufreq_probe,
191	.remove		= omap_cpufreq_remove,
192};
193module_platform_driver(omap_cpufreq_platdrv);
194
195MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
196MODULE_LICENSE("GPL");