tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * System Control and Power Interface (SCPI) based CPUFreq Interface driver
3 *
4 * It provides necessary ops to arm_big_little cpufreq driver.
5 *
6 * Copyright (C) 2015 ARM Ltd.
7 * Sudeep Holla <sudeep.holla@arm.com>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 *
13 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
14 * kind, whether express or implied; without even the implied warranty
15 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 */
18
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/clk.h>
22#include <linux/cpu.h>
23#include <linux/cpufreq.h>
24#include <linux/cpumask.h>
25#include <linux/export.h>
26#include <linux/module.h>
27#include <linux/of_platform.h>
28#include <linux/pm_opp.h>
29#include <linux/scpi_protocol.h>
30#include <linux/slab.h>
31#include <linux/types.h>
32
33struct scpi_data {
34 struct clk *clk;
35 struct device *cpu_dev;
36};
37
38static struct scpi_ops *scpi_ops;
39
40static unsigned int scpi_cpufreq_get_rate(unsigned int cpu)
41{
42 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
43 struct scpi_data *priv = policy->driver_data;
44 unsigned long rate = clk_get_rate(priv->clk);
45
46 return rate / 1000;
47}
48
49static int
50scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
51{
52 unsigned long freq = policy->freq_table[index].frequency;
53 struct scpi_data *priv = policy->driver_data;
54 u64 rate = freq * 1000;
55 int ret;
56
57 ret = clk_set_rate(priv->clk, rate);
58
59 if (ret)
60 return ret;
61
62 if (clk_get_rate(priv->clk) != rate)
63 return -EIO;
64
65 arch_set_freq_scale(policy->related_cpus, freq,
66 policy->cpuinfo.max_freq);
67
68 return 0;
69}
70
71static int
72scpi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
73{
74 int cpu, domain, tdomain;
75 struct device *tcpu_dev;
76
77 domain = scpi_ops->device_domain_id(cpu_dev);
78 if (domain < 0)
79 return domain;
80
81 for_each_possible_cpu(cpu) {
82 if (cpu == cpu_dev->id)
83 continue;
84
85 tcpu_dev = get_cpu_device(cpu);
86 if (!tcpu_dev)
87 continue;
88
89 tdomain = scpi_ops->device_domain_id(tcpu_dev);
90 if (tdomain == domain)
91 cpumask_set_cpu(cpu, cpumask);
92 }
93
94 return 0;
95}
96
97static int scpi_cpufreq_init(struct cpufreq_policy *policy)
98{
99 int ret;
100 unsigned int latency;
101 struct device *cpu_dev;
102 struct scpi_data *priv;
103 struct cpufreq_frequency_table *freq_table;
104
105 cpu_dev = get_cpu_device(policy->cpu);
106 if (!cpu_dev) {
107 pr_err("failed to get cpu%d device\n", policy->cpu);
108 return -ENODEV;
109 }
110
111 ret = scpi_ops->add_opps_to_device(cpu_dev);
112 if (ret) {
113 dev_warn(cpu_dev, "failed to add opps to the device\n");
114 return ret;
115 }
116
117 ret = scpi_get_sharing_cpus(cpu_dev, policy->cpus);
118 if (ret) {
119 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
120 return ret;
121 }
122
123 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
124 if (ret) {
125 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
126 __func__, ret);
127 return ret;
128 }
129
130 ret = dev_pm_opp_get_opp_count(cpu_dev);
131 if (ret <= 0) {
132 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
133 ret = -EPROBE_DEFER;
134 goto out_free_opp;
135 }
136
137 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
138 if (!priv) {
139 ret = -ENOMEM;
140 goto out_free_opp;
141 }
142
143 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
144 if (ret) {
145 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
146 goto out_free_priv;
147 }
148
149 priv->cpu_dev = cpu_dev;
150 priv->clk = clk_get(cpu_dev, NULL);
151 if (IS_ERR(priv->clk)) {
152 dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d\n",
153 __func__, cpu_dev->id);
154 ret = PTR_ERR(priv->clk);
155 goto out_free_cpufreq_table;
156 }
157
158 policy->driver_data = priv;
159 policy->freq_table = freq_table;
160
161 /* scpi allows DVFS request for any domain from any CPU */
162 policy->dvfs_possible_from_any_cpu = true;
163
164 latency = scpi_ops->get_transition_latency(cpu_dev);
165 if (!latency)
166 latency = CPUFREQ_ETERNAL;
167
168 policy->cpuinfo.transition_latency = latency;
169
170 policy->fast_switch_possible = false;
171
172 dev_pm_opp_of_register_em(policy->cpus);
173
174 return 0;
175
176out_free_cpufreq_table:
177 dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
178out_free_priv:
179 kfree(priv);
180out_free_opp:
181 dev_pm_opp_remove_all_dynamic(cpu_dev);
182
183 return ret;
184}
185
186static int scpi_cpufreq_exit(struct cpufreq_policy *policy)
187{
188 struct scpi_data *priv = policy->driver_data;
189
190 clk_put(priv->clk);
191 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
192 dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
193 kfree(priv);
194
195 return 0;
196}
197
198static struct cpufreq_driver scpi_cpufreq_driver = {
199 .name = "scpi-cpufreq",
200 .flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
201 CPUFREQ_NEED_INITIAL_FREQ_CHECK |
202 CPUFREQ_IS_COOLING_DEV,
203 .verify = cpufreq_generic_frequency_table_verify,
204 .attr = cpufreq_generic_attr,
205 .get = scpi_cpufreq_get_rate,
206 .init = scpi_cpufreq_init,
207 .exit = scpi_cpufreq_exit,
208 .target_index = scpi_cpufreq_set_target,
209};
210
211static int scpi_cpufreq_probe(struct platform_device *pdev)
212{
213 int ret;
214
215 scpi_ops = get_scpi_ops();
216 if (!scpi_ops)
217 return -EIO;
218
219 ret = cpufreq_register_driver(&scpi_cpufreq_driver);
220 if (ret)
221 dev_err(&pdev->dev, "%s: registering cpufreq failed, err: %d\n",
222 __func__, ret);
223 return ret;
224}
225
226static int scpi_cpufreq_remove(struct platform_device *pdev)
227{
228 cpufreq_unregister_driver(&scpi_cpufreq_driver);
229 scpi_ops = NULL;
230 return 0;
231}
232
233static struct platform_driver scpi_cpufreq_platdrv = {
234 .driver = {
235 .name = "scpi-cpufreq",
236 },
237 .probe = scpi_cpufreq_probe,
238 .remove = scpi_cpufreq_remove,
239};
240module_platform_driver(scpi_cpufreq_platdrv);
241
242MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
243MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
244MODULE_LICENSE("GPL v2");