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Shawn Guo95ceafd2012-09-06 07:09:11 +00001/*
2 * Copyright (C) 2012 Freescale Semiconductor, Inc.
3 *
4 * The OPP code in function cpu0_set_target() is reused from
5 * drivers/cpufreq/omap-cpufreq.c
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/clk.h>
Shawn Guo95ceafd2012-09-06 07:09:11 +000015#include <linux/cpufreq.h>
16#include <linux/err.h>
17#include <linux/module.h>
18#include <linux/of.h>
19#include <linux/opp.h>
Shawn Guo5553f9e2013-01-30 14:27:49 +000020#include <linux/platform_device.h>
Shawn Guo95ceafd2012-09-06 07:09:11 +000021#include <linux/regulator/consumer.h>
22#include <linux/slab.h>
23
24static unsigned int transition_latency;
25static unsigned int voltage_tolerance; /* in percentage */
26
27static struct device *cpu_dev;
28static struct clk *cpu_clk;
29static struct regulator *cpu_reg;
30static struct cpufreq_frequency_table *freq_table;
31
32static int cpu0_verify_speed(struct cpufreq_policy *policy)
33{
34 return cpufreq_frequency_table_verify(policy, freq_table);
35}
36
37static unsigned int cpu0_get_speed(unsigned int cpu)
38{
39 return clk_get_rate(cpu_clk) / 1000;
40}
41
42static int cpu0_set_target(struct cpufreq_policy *policy,
43 unsigned int target_freq, unsigned int relation)
44{
45 struct cpufreq_freqs freqs;
46 struct opp *opp;
47 unsigned long freq_Hz, volt = 0, volt_old = 0, tol = 0;
48 unsigned int index, cpu;
49 int ret;
50
51 ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
52 relation, &index);
53 if (ret) {
54 pr_err("failed to match target freqency %d: %d\n",
55 target_freq, ret);
56 return ret;
57 }
58
59 freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
60 if (freq_Hz < 0)
61 freq_Hz = freq_table[index].frequency * 1000;
62 freqs.new = freq_Hz / 1000;
63 freqs.old = clk_get_rate(cpu_clk) / 1000;
64
65 if (freqs.old == freqs.new)
66 return 0;
67
68 for_each_online_cpu(cpu) {
69 freqs.cpu = cpu;
70 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
71 }
72
73 if (cpu_reg) {
Nishanth Menon78e8eb82013-01-18 19:52:33 +000074 rcu_read_lock();
Shawn Guo95ceafd2012-09-06 07:09:11 +000075 opp = opp_find_freq_ceil(cpu_dev, &freq_Hz);
76 if (IS_ERR(opp)) {
Nishanth Menon78e8eb82013-01-18 19:52:33 +000077 rcu_read_unlock();
Shawn Guo95ceafd2012-09-06 07:09:11 +000078 pr_err("failed to find OPP for %ld\n", freq_Hz);
79 return PTR_ERR(opp);
80 }
81 volt = opp_get_voltage(opp);
Nishanth Menon78e8eb82013-01-18 19:52:33 +000082 rcu_read_unlock();
Shawn Guo95ceafd2012-09-06 07:09:11 +000083 tol = volt * voltage_tolerance / 100;
84 volt_old = regulator_get_voltage(cpu_reg);
85 }
86
87 pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
88 freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
89 freqs.new / 1000, volt ? volt / 1000 : -1);
90
91 /* scaling up? scale voltage before frequency */
92 if (cpu_reg && freqs.new > freqs.old) {
93 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
94 if (ret) {
95 pr_err("failed to scale voltage up: %d\n", ret);
96 freqs.new = freqs.old;
97 return ret;
98 }
99 }
100
101 ret = clk_set_rate(cpu_clk, freqs.new * 1000);
102 if (ret) {
103 pr_err("failed to set clock rate: %d\n", ret);
104 if (cpu_reg)
105 regulator_set_voltage_tol(cpu_reg, volt_old, tol);
106 return ret;
107 }
108
109 /* scaling down? scale voltage after frequency */
110 if (cpu_reg && freqs.new < freqs.old) {
111 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
112 if (ret) {
113 pr_err("failed to scale voltage down: %d\n", ret);
114 clk_set_rate(cpu_clk, freqs.old * 1000);
115 freqs.new = freqs.old;
116 return ret;
117 }
118 }
119
120 for_each_online_cpu(cpu) {
121 freqs.cpu = cpu;
122 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
123 }
124
125 return 0;
126}
127
128static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
129{
130 int ret;
131
132 if (policy->cpu != 0)
133 return -EINVAL;
134
135 ret = cpufreq_frequency_table_cpuinfo(policy, freq_table);
136 if (ret) {
137 pr_err("invalid frequency table: %d\n", ret);
138 return ret;
139 }
140
141 policy->cpuinfo.transition_latency = transition_latency;
142 policy->cur = clk_get_rate(cpu_clk) / 1000;
143
144 /*
145 * The driver only supports the SMP configuartion where all processors
146 * share the clock and voltage and clock. Use cpufreq affected_cpus
147 * interface to have all CPUs scaled together.
148 */
Shawn Guo95ceafd2012-09-06 07:09:11 +0000149 cpumask_setall(policy->cpus);
150
151 cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
152
153 return 0;
154}
155
156static int cpu0_cpufreq_exit(struct cpufreq_policy *policy)
157{
158 cpufreq_frequency_table_put_attr(policy->cpu);
159
160 return 0;
161}
162
163static struct freq_attr *cpu0_cpufreq_attr[] = {
164 &cpufreq_freq_attr_scaling_available_freqs,
165 NULL,
166};
167
168static struct cpufreq_driver cpu0_cpufreq_driver = {
169 .flags = CPUFREQ_STICKY,
170 .verify = cpu0_verify_speed,
171 .target = cpu0_set_target,
172 .get = cpu0_get_speed,
173 .init = cpu0_cpufreq_init,
174 .exit = cpu0_cpufreq_exit,
175 .name = "generic_cpu0",
176 .attr = cpu0_cpufreq_attr,
177};
178
Shawn Guo5553f9e2013-01-30 14:27:49 +0000179static int cpu0_cpufreq_probe(struct platform_device *pdev)
Shawn Guo95ceafd2012-09-06 07:09:11 +0000180{
181 struct device_node *np;
182 int ret;
183
Mark Langsdorf6754f552013-01-28 16:13:15 +0000184 for_each_child_of_node(of_find_node_by_path("/cpus"), np) {
185 if (of_get_property(np, "operating-points", NULL))
186 break;
187 }
188
Shawn Guo95ceafd2012-09-06 07:09:11 +0000189 if (!np) {
190 pr_err("failed to find cpu0 node\n");
191 return -ENOENT;
192 }
193
Shawn Guo5553f9e2013-01-30 14:27:49 +0000194 cpu_dev = &pdev->dev;
Shawn Guo95ceafd2012-09-06 07:09:11 +0000195 cpu_dev->of_node = np;
196
Shawn Guo5553f9e2013-01-30 14:27:49 +0000197 cpu_clk = devm_clk_get(cpu_dev, NULL);
Shawn Guo95ceafd2012-09-06 07:09:11 +0000198 if (IS_ERR(cpu_clk)) {
199 ret = PTR_ERR(cpu_clk);
200 pr_err("failed to get cpu0 clock: %d\n", ret);
201 goto out_put_node;
202 }
203
Shawn Guo5553f9e2013-01-30 14:27:49 +0000204 cpu_reg = devm_regulator_get(cpu_dev, "cpu0");
Shawn Guo95ceafd2012-09-06 07:09:11 +0000205 if (IS_ERR(cpu_reg)) {
206 pr_warn("failed to get cpu0 regulator\n");
207 cpu_reg = NULL;
208 }
209
210 ret = of_init_opp_table(cpu_dev);
211 if (ret) {
212 pr_err("failed to init OPP table: %d\n", ret);
213 goto out_put_node;
214 }
215
216 ret = opp_init_cpufreq_table(cpu_dev, &freq_table);
217 if (ret) {
218 pr_err("failed to init cpufreq table: %d\n", ret);
219 goto out_put_node;
220 }
221
222 of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
223
224 if (of_property_read_u32(np, "clock-latency", &transition_latency))
225 transition_latency = CPUFREQ_ETERNAL;
226
227 if (cpu_reg) {
228 struct opp *opp;
229 unsigned long min_uV, max_uV;
230 int i;
231
232 /*
233 * OPP is maintained in order of increasing frequency, and
234 * freq_table initialised from OPP is therefore sorted in the
235 * same order.
236 */
237 for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
238 ;
Nishanth Menon78e8eb82013-01-18 19:52:33 +0000239 rcu_read_lock();
Shawn Guo95ceafd2012-09-06 07:09:11 +0000240 opp = opp_find_freq_exact(cpu_dev,
241 freq_table[0].frequency * 1000, true);
242 min_uV = opp_get_voltage(opp);
243 opp = opp_find_freq_exact(cpu_dev,
244 freq_table[i-1].frequency * 1000, true);
245 max_uV = opp_get_voltage(opp);
Nishanth Menon78e8eb82013-01-18 19:52:33 +0000246 rcu_read_unlock();
Shawn Guo95ceafd2012-09-06 07:09:11 +0000247 ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
248 if (ret > 0)
249 transition_latency += ret * 1000;
250 }
251
252 ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
253 if (ret) {
254 pr_err("failed register driver: %d\n", ret);
255 goto out_free_table;
256 }
257
258 of_node_put(np);
259 return 0;
260
261out_free_table:
262 opp_free_cpufreq_table(cpu_dev, &freq_table);
263out_put_node:
264 of_node_put(np);
265 return ret;
266}
Shawn Guo5553f9e2013-01-30 14:27:49 +0000267
268static int cpu0_cpufreq_remove(struct platform_device *pdev)
269{
270 cpufreq_unregister_driver(&cpu0_cpufreq_driver);
271 opp_free_cpufreq_table(cpu_dev, &freq_table);
272
273 return 0;
274}
275
276static struct platform_driver cpu0_cpufreq_platdrv = {
277 .driver = {
278 .name = "cpufreq-cpu0",
279 .owner = THIS_MODULE,
280 },
281 .probe = cpu0_cpufreq_probe,
282 .remove = cpu0_cpufreq_remove,
283};
284module_platform_driver(cpu0_cpufreq_platdrv);
Shawn Guo95ceafd2012-09-06 07:09:11 +0000285
286MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
287MODULE_DESCRIPTION("Generic CPU0 cpufreq driver");
288MODULE_LICENSE("GPL");