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 
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;
41 
42 static 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 
105 static 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 
111 static 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 
138 static int omap_cpu_exit(struct cpufreq_policy *policy)
139 {
140 	freq_table_free();
141 	clk_put(policy->clk);
142 	return 0;
143 }
144 
145 static 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 
157 static 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 
185 static int omap_cpufreq_remove(struct platform_device *pdev)
186 {
187 	cpufreq_unregister_driver(&omap_driver);
188 
189 	return 0;
190 }
191 
192 static struct platform_driver omap_cpufreq_platdrv = {
193 	.driver = {
194 		.name	= "omap-cpufreq",
195 	},
196 	.probe		= omap_cpufreq_probe,
197 	.remove		= omap_cpufreq_remove,
198 };
199 module_platform_driver(omap_cpufreq_platdrv);
200 
201 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
202 MODULE_LICENSE("GPL");
203