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/pm_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 int cpu0_verify_speed(struct cpufreq_policy *policy)
35 return cpufreq_frequency_table_verify(policy, freq_table);
38 static unsigned int cpu0_get_speed(unsigned int cpu)
40 return clk_get_rate(cpu_clk) / 1000;
43 static int cpu0_set_target(struct cpufreq_policy *policy,
44 unsigned int target_freq, unsigned int relation)
46 struct cpufreq_freqs freqs;
47 struct dev_pm_opp *opp;
48 unsigned long volt = 0, volt_old = 0, tol = 0;
49 long freq_Hz, freq_exact;
53 ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
56 pr_err("failed to match target freqency %d: %d\n",
61 freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
63 freq_Hz = freq_table[index].frequency * 1000;
65 freqs.new = freq_Hz / 1000;
66 freqs.old = clk_get_rate(cpu_clk) / 1000;
68 if (freqs.old == freqs.new)
71 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
73 if (!IS_ERR(cpu_reg)) {
75 opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_Hz);
78 pr_err("failed to find OPP for %ld\n", freq_Hz);
79 freqs.new = freqs.old;
83 volt = dev_pm_opp_get_voltage(opp);
85 tol = volt * voltage_tolerance / 100;
86 volt_old = regulator_get_voltage(cpu_reg);
89 pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
90 freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
91 freqs.new / 1000, volt ? volt / 1000 : -1);
93 /* scaling up? scale voltage before frequency */
94 if (!IS_ERR(cpu_reg) && freqs.new > freqs.old) {
95 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
97 pr_err("failed to scale voltage up: %d\n", ret);
98 freqs.new = freqs.old;
103 ret = clk_set_rate(cpu_clk, freq_exact);
105 pr_err("failed to set clock rate: %d\n", ret);
106 if (!IS_ERR(cpu_reg))
107 regulator_set_voltage_tol(cpu_reg, volt_old, tol);
108 freqs.new = freqs.old;
112 /* scaling down? scale voltage after frequency */
113 if (!IS_ERR(cpu_reg) && freqs.new < freqs.old) {
114 ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
116 pr_err("failed to scale voltage down: %d\n", ret);
117 clk_set_rate(cpu_clk, freqs.old * 1000);
118 freqs.new = freqs.old;
123 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
128 static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
132 ret = cpufreq_frequency_table_cpuinfo(policy, freq_table);
134 pr_err("invalid frequency table: %d\n", ret);
138 policy->cpuinfo.transition_latency = transition_latency;
139 policy->cur = clk_get_rate(cpu_clk) / 1000;
142 * The driver only supports the SMP configuartion where all processors
143 * share the clock and voltage and clock. Use cpufreq affected_cpus
144 * interface to have all CPUs scaled together.
146 cpumask_setall(policy->cpus);
148 cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
153 static int cpu0_cpufreq_exit(struct cpufreq_policy *policy)
155 cpufreq_frequency_table_put_attr(policy->cpu);
160 static struct freq_attr *cpu0_cpufreq_attr[] = {
161 &cpufreq_freq_attr_scaling_available_freqs,
165 static struct cpufreq_driver cpu0_cpufreq_driver = {
166 .flags = CPUFREQ_STICKY,
167 .verify = cpu0_verify_speed,
168 .target = cpu0_set_target,
169 .get = cpu0_get_speed,
170 .init = cpu0_cpufreq_init,
171 .exit = cpu0_cpufreq_exit,
172 .name = "generic_cpu0",
173 .attr = cpu0_cpufreq_attr,
176 static int cpu0_cpufreq_probe(struct platform_device *pdev)
178 struct device_node *np;
181 cpu_dev = get_cpu_device(0);
183 pr_err("failed to get cpu0 device\n");
187 np = of_node_get(cpu_dev->of_node);
189 pr_err("failed to find cpu0 node\n");
193 cpu_reg = devm_regulator_get_optional(cpu_dev, "cpu0");
194 if (IS_ERR(cpu_reg)) {
196 * If cpu0 regulator supply node is present, but regulator is
197 * not yet registered, we should try defering probe.
199 if (PTR_ERR(cpu_reg) == -EPROBE_DEFER) {
200 dev_err(cpu_dev, "cpu0 regulator not ready, retry\n");
204 pr_warn("failed to get cpu0 regulator: %ld\n",
208 cpu_clk = devm_clk_get(cpu_dev, NULL);
209 if (IS_ERR(cpu_clk)) {
210 ret = PTR_ERR(cpu_clk);
211 pr_err("failed to get cpu0 clock: %d\n", ret);
215 ret = of_init_opp_table(cpu_dev);
217 pr_err("failed to init OPP table: %d\n", ret);
221 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
223 pr_err("failed to init cpufreq table: %d\n", ret);
227 of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
229 if (of_property_read_u32(np, "clock-latency", &transition_latency))
230 transition_latency = CPUFREQ_ETERNAL;
232 if (!IS_ERR(cpu_reg)) {
233 struct dev_pm_opp *opp;
234 unsigned long min_uV, max_uV;
238 * OPP is maintained in order of increasing frequency, and
239 * freq_table initialised from OPP is therefore sorted in the
242 for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
245 opp = dev_pm_opp_find_freq_exact(cpu_dev,
246 freq_table[0].frequency * 1000, true);
247 min_uV = dev_pm_opp_get_voltage(opp);
248 opp = dev_pm_opp_find_freq_exact(cpu_dev,
249 freq_table[i-1].frequency * 1000, true);
250 max_uV = dev_pm_opp_get_voltage(opp);
252 ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
254 transition_latency += ret * 1000;
257 ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
259 pr_err("failed register driver: %d\n", ret);
267 dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
273 static int cpu0_cpufreq_remove(struct platform_device *pdev)
275 cpufreq_unregister_driver(&cpu0_cpufreq_driver);
276 dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
281 static struct platform_driver cpu0_cpufreq_platdrv = {
283 .name = "cpufreq-cpu0",
284 .owner = THIS_MODULE,
286 .probe = cpu0_cpufreq_probe,
287 .remove = cpu0_cpufreq_remove,
289 module_platform_driver(cpu0_cpufreq_platdrv);
291 MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
292 MODULE_DESCRIPTION("Generic CPU0 cpufreq driver");
293 MODULE_LICENSE("GPL");