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