1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * System Control and Power Interface (SCPI) based CPUFreq Interface driver
4 *
5 * Copyright (C) 2015 ARM Ltd.
6 * Sudeep Holla <sudeep.holla@arm.com>
7 */
8
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11 #include <linux/clk.h>
12 #include <linux/cpu.h>
13 #include <linux/cpufreq.h>
14 #include <linux/cpumask.h>
15 #include <linux/export.h>
16 #include <linux/module.h>
17 #include <linux/platform_device.h>
18 #include <linux/pm_opp.h>
19 #include <linux/scpi_protocol.h>
20 #include <linux/slab.h>
21 #include <linux/types.h>
22
23 struct scpi_data {
24 struct clk *clk;
25 struct device *cpu_dev;
26 };
27
28 static struct scpi_ops *scpi_ops;
29
scpi_cpufreq_get_rate(unsigned int cpu)30 static unsigned int scpi_cpufreq_get_rate(unsigned int cpu)
31 {
32 struct cpufreq_policy *policy;
33 struct scpi_data *priv;
34 unsigned long rate;
35
36 policy = cpufreq_cpu_get_raw(cpu);
37 if (unlikely(!policy))
38 return 0;
39
40 priv = policy->driver_data;
41 rate = clk_get_rate(priv->clk);
42
43 return rate / 1000;
44 }
45
46 static int
scpi_cpufreq_set_target(struct cpufreq_policy * policy,unsigned int index)47 scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
48 {
49 unsigned long freq_khz = policy->freq_table[index].frequency;
50 struct scpi_data *priv = policy->driver_data;
51 unsigned long rate = freq_khz * 1000;
52 int ret;
53
54 ret = clk_set_rate(priv->clk, rate);
55
56 if (ret)
57 return ret;
58
59 if (clk_get_rate(priv->clk) / 1000 != freq_khz)
60 return -EIO;
61
62 return 0;
63 }
64
65 static int
scpi_get_sharing_cpus(struct device * cpu_dev,struct cpumask * cpumask)66 scpi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
67 {
68 int cpu, domain, tdomain;
69 struct device *tcpu_dev;
70
71 domain = scpi_ops->device_domain_id(cpu_dev);
72 if (domain < 0)
73 return domain;
74
75 for_each_present_cpu(cpu) {
76 if (cpu == cpu_dev->id)
77 continue;
78
79 tcpu_dev = get_cpu_device(cpu);
80 if (!tcpu_dev)
81 continue;
82
83 tdomain = scpi_ops->device_domain_id(tcpu_dev);
84 if (tdomain == domain)
85 cpumask_set_cpu(cpu, cpumask);
86 }
87
88 return 0;
89 }
90
scpi_cpufreq_init(struct cpufreq_policy * policy)91 static int scpi_cpufreq_init(struct cpufreq_policy *policy)
92 {
93 int ret;
94 unsigned int latency;
95 struct device *cpu_dev;
96 struct scpi_data *priv;
97 struct cpufreq_frequency_table *freq_table;
98
99 cpu_dev = get_cpu_device(policy->cpu);
100 if (!cpu_dev) {
101 pr_err("failed to get cpu%d device\n", policy->cpu);
102 return -ENODEV;
103 }
104
105 ret = scpi_ops->add_opps_to_device(cpu_dev);
106 if (ret) {
107 dev_warn(cpu_dev, "failed to add opps to the device\n");
108 return ret;
109 }
110
111 ret = scpi_get_sharing_cpus(cpu_dev, policy->cpus);
112 if (ret) {
113 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
114 return ret;
115 }
116
117 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
118 if (ret) {
119 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
120 __func__, ret);
121 return ret;
122 }
123
124 ret = dev_pm_opp_get_opp_count(cpu_dev);
125 if (ret <= 0) {
126 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
127 ret = -EPROBE_DEFER;
128 goto out_free_opp;
129 }
130
131 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
132 if (!priv) {
133 ret = -ENOMEM;
134 goto out_free_opp;
135 }
136
137 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
138 if (ret) {
139 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
140 goto out_free_priv;
141 }
142
143 priv->cpu_dev = cpu_dev;
144 priv->clk = clk_get(cpu_dev, NULL);
145 if (IS_ERR(priv->clk)) {
146 dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d\n",
147 __func__, cpu_dev->id);
148 ret = PTR_ERR(priv->clk);
149 goto out_free_cpufreq_table;
150 }
151
152 policy->driver_data = priv;
153 policy->freq_table = freq_table;
154
155 /* scpi allows DVFS request for any domain from any CPU */
156 policy->dvfs_possible_from_any_cpu = true;
157
158 latency = scpi_ops->get_transition_latency(cpu_dev);
159 if (!latency)
160 latency = CPUFREQ_ETERNAL;
161
162 policy->cpuinfo.transition_latency = latency;
163
164 policy->fast_switch_possible = false;
165
166 return 0;
167
168 out_free_cpufreq_table:
169 dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
170 out_free_priv:
171 kfree(priv);
172 out_free_opp:
173 dev_pm_opp_remove_all_dynamic(cpu_dev);
174
175 return ret;
176 }
177
scpi_cpufreq_exit(struct cpufreq_policy * policy)178 static void scpi_cpufreq_exit(struct cpufreq_policy *policy)
179 {
180 struct scpi_data *priv = policy->driver_data;
181
182 clk_put(priv->clk);
183 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
184 dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
185 kfree(priv);
186 }
187
188 static struct cpufreq_driver scpi_cpufreq_driver = {
189 .name = "scpi-cpufreq",
190 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
191 CPUFREQ_NEED_INITIAL_FREQ_CHECK |
192 CPUFREQ_IS_COOLING_DEV,
193 .verify = cpufreq_generic_frequency_table_verify,
194 .get = scpi_cpufreq_get_rate,
195 .init = scpi_cpufreq_init,
196 .exit = scpi_cpufreq_exit,
197 .target_index = scpi_cpufreq_set_target,
198 .register_em = cpufreq_register_em_with_opp,
199 };
200
scpi_cpufreq_probe(struct platform_device * pdev)201 static int scpi_cpufreq_probe(struct platform_device *pdev)
202 {
203 int ret;
204
205 scpi_ops = get_scpi_ops();
206 if (!scpi_ops)
207 return -EIO;
208
209 ret = cpufreq_register_driver(&scpi_cpufreq_driver);
210 if (ret)
211 dev_err(&pdev->dev, "%s: registering cpufreq failed, err: %d\n",
212 __func__, ret);
213 return ret;
214 }
215
scpi_cpufreq_remove(struct platform_device * pdev)216 static void scpi_cpufreq_remove(struct platform_device *pdev)
217 {
218 cpufreq_unregister_driver(&scpi_cpufreq_driver);
219 scpi_ops = NULL;
220 }
221
222 static struct platform_driver scpi_cpufreq_platdrv = {
223 .driver = {
224 .name = "scpi-cpufreq",
225 },
226 .probe = scpi_cpufreq_probe,
227 .remove = scpi_cpufreq_remove,
228 };
229 module_platform_driver(scpi_cpufreq_platdrv);
230
231 MODULE_ALIAS("platform:scpi-cpufreq");
232 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
233 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
234 MODULE_LICENSE("GPL v2");
235