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
34 static struct cpufreq_frequency_table *freq_table;
35 static atomic_t freq_table_users = ATOMIC_INIT(0);
36 static struct device *mpu_dev;
37 static struct regulator *mpu_reg;
38
omap_target(struct cpufreq_policy * policy,unsigned int index)39 static 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
freq_table_free(void)102 static 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
omap_cpu_init(struct cpufreq_policy * policy)108 static 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
omap_cpu_exit(struct cpufreq_policy * policy)135 static void omap_cpu_exit(struct cpufreq_policy *policy)
136 {
137 freq_table_free();
138 clk_put(policy->clk);
139 }
140
141 static 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
omap_cpufreq_probe(struct platform_device * pdev)153 static 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
omap_cpufreq_remove(struct platform_device * pdev)181 static void omap_cpufreq_remove(struct platform_device *pdev)
182 {
183 cpufreq_unregister_driver(&omap_driver);
184 }
185
186 static struct platform_driver omap_cpufreq_platdrv = {
187 .driver = {
188 .name = "omap-cpufreq",
189 },
190 .probe = omap_cpufreq_probe,
191 .remove_new = omap_cpufreq_remove,
192 };
193 module_platform_driver(omap_cpufreq_platdrv);
194
195 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
196 MODULE_LICENSE("GPL");
197