1 /*
2 * CPU frequency scaling for OMAP using OPP information
3 *
4 * Copyright (C) 2005 Nokia Corporation
5 * Written by Tony Lindgren <tony@atomide.com>
6 *
7 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
8 *
9 * Copyright (C) 2007-2011 Texas Instruments, Inc.
10 * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2 as
14 * published by the Free Software Foundation.
15 */
16
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19 #include <linux/types.h>
20 #include <linux/kernel.h>
21 #include <linux/sched.h>
22 #include <linux/cpufreq.h>
23 #include <linux/delay.h>
24 #include <linux/init.h>
25 #include <linux/err.h>
26 #include <linux/clk.h>
27 #include <linux/io.h>
28 #include <linux/pm_opp.h>
29 #include <linux/cpu.h>
30 #include <linux/module.h>
31 #include <linux/platform_device.h>
32 #include <linux/regulator/consumer.h>
33
34 #include <asm/smp_plat.h>
35 #include <asm/cpu.h>
36
37 /* OPP tolerance in percentage */
38 #define OPP_TOLERANCE 4
39
40 static struct cpufreq_frequency_table *freq_table;
41 static atomic_t freq_table_users = ATOMIC_INIT(0);
42 static struct device *mpu_dev;
43 static struct regulator *mpu_reg;
44
omap_target(struct cpufreq_policy * policy,unsigned int index)45 static int omap_target(struct cpufreq_policy *policy, unsigned int index)
46 {
47 int r, ret;
48 struct dev_pm_opp *opp;
49 unsigned long freq, volt = 0, volt_old = 0, tol = 0;
50 unsigned int old_freq, new_freq;
51
52 old_freq = policy->cur;
53 new_freq = freq_table[index].frequency;
54
55 freq = new_freq * 1000;
56 ret = clk_round_rate(policy->clk, freq);
57 if (ret < 0) {
58 dev_warn(mpu_dev,
59 "CPUfreq: Cannot find matching frequency for %lu\n",
60 freq);
61 return ret;
62 }
63 freq = ret;
64
65 if (mpu_reg) {
66 opp = dev_pm_opp_find_freq_ceil(mpu_dev, &freq);
67 if (IS_ERR(opp)) {
68 dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n",
69 __func__, new_freq);
70 return -EINVAL;
71 }
72 volt = dev_pm_opp_get_voltage(opp);
73 dev_pm_opp_put(opp);
74 tol = volt * OPP_TOLERANCE / 100;
75 volt_old = regulator_get_voltage(mpu_reg);
76 }
77
78 dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n",
79 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
80 new_freq / 1000, volt ? volt / 1000 : -1);
81
82 /* scaling up? scale voltage before frequency */
83 if (mpu_reg && (new_freq > old_freq)) {
84 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
85 if (r < 0) {
86 dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
87 __func__);
88 return r;
89 }
90 }
91
92 ret = clk_set_rate(policy->clk, new_freq * 1000);
93
94 /* scaling down? scale voltage after frequency */
95 if (mpu_reg && (new_freq < old_freq)) {
96 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol);
97 if (r < 0) {
98 dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
99 __func__);
100 clk_set_rate(policy->clk, old_freq * 1000);
101 return r;
102 }
103 }
104
105 return ret;
106 }
107
freq_table_free(void)108 static inline void freq_table_free(void)
109 {
110 if (atomic_dec_and_test(&freq_table_users))
111 dev_pm_opp_free_cpufreq_table(mpu_dev, &freq_table);
112 }
113
omap_cpu_init(struct cpufreq_policy * policy)114 static int omap_cpu_init(struct cpufreq_policy *policy)
115 {
116 int result;
117
118 policy->clk = clk_get(NULL, "cpufreq_ck");
119 if (IS_ERR(policy->clk))
120 return PTR_ERR(policy->clk);
121
122 if (!freq_table) {
123 result = dev_pm_opp_init_cpufreq_table(mpu_dev, &freq_table);
124 if (result) {
125 dev_err(mpu_dev,
126 "%s: cpu%d: failed creating freq table[%d]\n",
127 __func__, policy->cpu, result);
128 goto fail;
129 }
130 }
131
132 atomic_inc_return(&freq_table_users);
133
134 /* FIXME: what's the actual transition time? */
135 result = cpufreq_generic_init(policy, freq_table, 300 * 1000);
136 if (!result)
137 return 0;
138
139 freq_table_free();
140 fail:
141 clk_put(policy->clk);
142 return result;
143 }
144
omap_cpu_exit(struct cpufreq_policy * policy)145 static int omap_cpu_exit(struct cpufreq_policy *policy)
146 {
147 freq_table_free();
148 clk_put(policy->clk);
149 return 0;
150 }
151
152 static struct cpufreq_driver omap_driver = {
153 .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
154 .verify = cpufreq_generic_frequency_table_verify,
155 .target_index = omap_target,
156 .get = cpufreq_generic_get,
157 .init = omap_cpu_init,
158 .exit = omap_cpu_exit,
159 .name = "omap",
160 .attr = cpufreq_generic_attr,
161 };
162
omap_cpufreq_probe(struct platform_device * pdev)163 static int omap_cpufreq_probe(struct platform_device *pdev)
164 {
165 mpu_dev = get_cpu_device(0);
166 if (!mpu_dev) {
167 pr_warn("%s: unable to get the MPU device\n", __func__);
168 return -EINVAL;
169 }
170
171 mpu_reg = regulator_get(mpu_dev, "vcc");
172 if (IS_ERR(mpu_reg)) {
173 pr_warn("%s: unable to get MPU regulator\n", __func__);
174 mpu_reg = NULL;
175 } else {
176 /*
177 * Ensure physical regulator is present.
178 * (e.g. could be dummy regulator.)
179 */
180 if (regulator_get_voltage(mpu_reg) < 0) {
181 pr_warn("%s: physical regulator not present for MPU\n",
182 __func__);
183 regulator_put(mpu_reg);
184 mpu_reg = NULL;
185 }
186 }
187
188 return cpufreq_register_driver(&omap_driver);
189 }
190
omap_cpufreq_remove(struct platform_device * pdev)191 static int omap_cpufreq_remove(struct platform_device *pdev)
192 {
193 return cpufreq_unregister_driver(&omap_driver);
194 }
195
196 static struct platform_driver omap_cpufreq_platdrv = {
197 .driver = {
198 .name = "omap-cpufreq",
199 },
200 .probe = omap_cpufreq_probe,
201 .remove = omap_cpufreq_remove,
202 };
203 module_platform_driver(omap_cpufreq_platdrv);
204
205 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
206 MODULE_LICENSE("GPL");
207
