2 * Copyright (C) 2012 Freescale Semiconductor, Inc.
4 * The OPP code in function cpu0_set_target() is reused from
5 * drivers/cpufreq/omap-cpufreq.c
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.
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 #include <linux/clk.h>
15 #include <linux/cpu.h>
16 #include <linux/cpufreq.h>
17 #include <linux/err.h>
18 #include <linux/module.h>
20 #include <linux/opp.h>
21 #include <linux/platform_device.h>
22 #include <linux/regulator/consumer.h>
23 #include <linux/slab.h>
25 static unsigned int transition_latency;
26 static unsigned int voltage_tolerance; /* in percentage */
28 static struct device *cpu_dev;
29 static struct clk *cpu_clk;
30 static struct regulator *cpu_reg;
31 static struct cpufreq_frequency_table *freq_table;
33 static unsigned int cpu0_get_speed(unsigned int cpu)
35 return clk_get_rate(cpu_clk) / 1000;
38 static int cpu0_set_target(struct cpufreq_policy *policy,
39 unsigned int target_freq, unsigned int relation)
41 struct cpufreq_freqs freqs;
43 unsigned long volt = 0, volt_old = 0, tol = 0;
44 long freq_Hz, freq_exact;
48 ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
51 pr_err("failed to match target freqency %d: %d\n",
56 freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
58 freq_Hz = freq_table[index].frequency * 1000;
60 freqs.new = freq_Hz / 1000;
61 freqs.old = clk_get_rate(cpu_clk) / 1000;
63 if (freqs.old == freqs.new)
66 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
68 if (!IS_ERR(cpu_reg)) {
70 opp = opp_find_freq_ceil(cpu_dev, &freq_Hz);
73 pr_err("failed to find OPP for %ld\n", freq_Hz);
74 freqs.new = freqs.old;
78 volt = opp_get_voltage(opp);
80 tol = volt * voltage_tolerance / 100;
81 volt_old = regulator_get_voltage(cpu_reg);
84 pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
85 freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
86 freqs.new / 1000, volt ? volt / 1000 : -1);
88 /* scaling up? scale voltage before frequency */
89 if (!IS_ERR(cpu_reg) && freqs.new > freqs.old) {
90 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
92 pr_err("failed to scale voltage up: %d\n", ret);
93 freqs.new = freqs.old;
98 ret = clk_set_rate(cpu_clk, freq_exact);
100 pr_err("failed to set clock rate: %d\n", ret);
101 if (!IS_ERR(cpu_reg))
102 regulator_set_voltage_tol(cpu_reg, volt_old, tol);
103 freqs.new = freqs.old;
107 /* scaling down? scale voltage after frequency */
108 if (!IS_ERR(cpu_reg) && freqs.new < freqs.old) {
109 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
111 pr_err("failed to scale voltage down: %d\n", ret);
112 clk_set_rate(cpu_clk, freqs.old * 1000);
113 freqs.new = freqs.old;
118 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
123 static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
127 ret = cpufreq_table_validate_and_show(policy, freq_table);
129 pr_err("invalid frequency table: %d\n", ret);
133 policy->cpuinfo.transition_latency = transition_latency;
136 * The driver only supports the SMP configuartion where all processors
137 * share the clock and voltage and clock. Use cpufreq affected_cpus
138 * interface to have all CPUs scaled together.
140 cpumask_setall(policy->cpus);
145 static struct cpufreq_driver cpu0_cpufreq_driver = {
146 .flags = CPUFREQ_STICKY,
147 .verify = cpufreq_generic_frequency_table_verify,
148 .target = cpu0_set_target,
149 .get = cpu0_get_speed,
150 .init = cpu0_cpufreq_init,
151 .exit = cpufreq_generic_exit,
152 .name = "generic_cpu0",
153 .attr = cpufreq_generic_attr,
156 static int cpu0_cpufreq_probe(struct platform_device *pdev)
158 struct device_node *np;
161 cpu_dev = get_cpu_device(0);
163 pr_err("failed to get cpu0 device\n");
167 np = of_node_get(cpu_dev->of_node);
169 pr_err("failed to find cpu0 node\n");
173 cpu_reg = devm_regulator_get_optional(cpu_dev, "cpu0");
174 if (IS_ERR(cpu_reg)) {
176 * If cpu0 regulator supply node is present, but regulator is
177 * not yet registered, we should try defering probe.
179 if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
180 dev_err(cpu_dev, "cpu0 regulator not ready, retry\n");
184 pr_warn("failed to get cpu0 regulator: %ld\n",
188 cpu_clk = devm_clk_get(cpu_dev, NULL);
189 if (IS_ERR(cpu_clk)) {
190 ret = PTR_ERR(cpu_clk);
191 pr_err("failed to get cpu0 clock: %d\n", ret);
195 ret = of_init_opp_table(cpu_dev);
197 pr_err("failed to init OPP table: %d\n", ret);
201 ret = opp_init_cpufreq_table(cpu_dev, &freq_table);
203 pr_err("failed to init cpufreq table: %d\n", ret);
207 of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
209 if (of_property_read_u32(np, "clock-latency", &transition_latency))
210 transition_latency = CPUFREQ_ETERNAL;
214 unsigned long min_uV, max_uV;
218 * OPP is maintained in order of increasing frequency, and
219 * freq_table initialised from OPP is therefore sorted in the
222 for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
225 opp = opp_find_freq_exact(cpu_dev,
226 freq_table[0].frequency * 1000, true);
227 min_uV = opp_get_voltage(opp);
228 opp = opp_find_freq_exact(cpu_dev,
229 freq_table[i-1].frequency * 1000, true);
230 max_uV = opp_get_voltage(opp);
232 ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
234 transition_latency += ret * 1000;
237 ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
239 pr_err("failed register driver: %d\n", ret);
247 opp_free_cpufreq_table(cpu_dev, &freq_table);
253 static int cpu0_cpufreq_remove(struct platform_device *pdev)
255 cpufreq_unregister_driver(&cpu0_cpufreq_driver);
256 opp_free_cpufreq_table(cpu_dev, &freq_table);
261 static struct platform_driver cpu0_cpufreq_platdrv = {
263 .name = "cpufreq-cpu0",
264 .owner = THIS_MODULE,
266 .probe = cpu0_cpufreq_probe,
267 .remove = cpu0_cpufreq_remove,
269 module_platform_driver(cpu0_cpufreq_platdrv);
271 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
272 MODULE_DESCRIPTION("Generic CPU0 cpufreq driver");
273 MODULE_LICENSE("GPL");