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