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
omap_target(struct cpufreq_policy * policy,unsigned int index)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
freq_table_free(void)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
omap_cpu_init(struct cpufreq_policy * policy)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 dev_pm_opp_of_register_em(policy->cpus);
135
136 return 0;
137 }
138
omap_cpu_exit(struct cpufreq_policy * policy)139 static int omap_cpu_exit(struct cpufreq_policy *policy)
140 {
141 freq_table_free();
142 clk_put(policy->clk);
143 return 0;
144 }
145
146 static struct cpufreq_driver omap_driver = {
147 .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
148 .verify = cpufreq_generic_frequency_table_verify,
149 .target_index = omap_target,
150 .get = cpufreq_generic_get,
151 .init = omap_cpu_init,
152 .exit = omap_cpu_exit,
153 .name = "omap",
154 .attr = cpufreq_generic_attr,
155 };
156
omap_cpufreq_probe(struct platform_device * pdev)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
omap_cpufreq_remove(struct platform_device * pdev)185 static int omap_cpufreq_remove(struct platform_device *pdev)
186 {
187 return cpufreq_unregister_driver(&omap_driver);
188 }
189
190 static struct platform_driver omap_cpufreq_platdrv = {
191 .driver = {
192 .name = "omap-cpufreq",
193 },
194 .probe = omap_cpufreq_probe,
195 .remove = omap_cpufreq_remove,
196 };
197 module_platform_driver(omap_cpufreq_platdrv);
198
199 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
200 MODULE_LICENSE("GPL");
201
