1// SPDX-License-Identifier: GPL-2.0
2/*
3 * System Control and Power Interface (SCMI) based CPUFreq Interface driver
4 *
5 * Copyright (C) 2018 ARM Ltd.
6 * Sudeep Holla <sudeep.holla@arm.com>
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <linux/clk-provider.h>
12#include <linux/cpu.h>
13#include <linux/cpufreq.h>
14#include <linux/cpumask.h>
15#include <linux/energy_model.h>
16#include <linux/export.h>
17#include <linux/module.h>
18#include <linux/pm_opp.h>
19#include <linux/slab.h>
20#include <linux/scmi_protocol.h>
21#include <linux/types.h>
22
23struct scmi_data {
24	int domain_id;
25	struct device *cpu_dev;
26};
27
28static const struct scmi_handle *handle;
29
30static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
31{
32	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
33	const struct scmi_perf_ops *perf_ops = handle->perf_ops;
34	struct scmi_data *priv = policy->driver_data;
35	unsigned long rate;
36	int ret;
37
38	ret = perf_ops->freq_get(handle, priv->domain_id, &rate, false);
39	if (ret)
40		return 0;
41	return rate / 1000;
42}
43
44/*
45 * perf_ops->freq_set is not a synchronous, the actual OPP change will
46 * happen asynchronously and can get notified if the events are
47 * subscribed for by the SCMI firmware
48 */
49static int
50scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
51{
52	struct scmi_data *priv = policy->driver_data;
53	const struct scmi_perf_ops *perf_ops = handle->perf_ops;
54	u64 freq = policy->freq_table[index].frequency;
55
56	return perf_ops->freq_set(handle, priv->domain_id, freq * 1000, false);
57}
58
59static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
60					     unsigned int target_freq)
61{
62	struct scmi_data *priv = policy->driver_data;
63	const struct scmi_perf_ops *perf_ops = handle->perf_ops;
64
65	if (!perf_ops->freq_set(handle, priv->domain_id,
66				target_freq * 1000, true))
67		return target_freq;
68
69	return 0;
70}
71
72static int
73scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
74{
75	int cpu, domain, tdomain;
76	struct device *tcpu_dev;
77
78	domain = handle->perf_ops->device_domain_id(cpu_dev);
79	if (domain < 0)
80		return domain;
81
82	for_each_possible_cpu(cpu) {
83		if (cpu == cpu_dev->id)
84			continue;
85
86		tcpu_dev = get_cpu_device(cpu);
87		if (!tcpu_dev)
88			continue;
89
90		tdomain = handle->perf_ops->device_domain_id(tcpu_dev);
91		if (tdomain == domain)
92			cpumask_set_cpu(cpu, cpumask);
93	}
94
95	return 0;
96}
97
98static int __maybe_unused
99scmi_get_cpu_power(unsigned long *power, unsigned long *KHz,
100		   struct device *cpu_dev)
101{
102	unsigned long Hz;
103	int ret, domain;
104
105	domain = handle->perf_ops->device_domain_id(cpu_dev);
106	if (domain < 0)
107		return domain;
108
109	/* Get the power cost of the performance domain. */
110	Hz = *KHz * 1000;
111	ret = handle->perf_ops->est_power_get(handle, domain, &Hz, power);
112	if (ret)
113		return ret;
114
115	/* The EM framework specifies the frequency in KHz. */
116	*KHz = Hz / 1000;
117
118	return 0;
119}
120
121static int scmi_cpufreq_init(struct cpufreq_policy *policy)
122{
123	int ret, nr_opp;
124	unsigned int latency;
125	struct device *cpu_dev;
126	struct scmi_data *priv;
127	struct cpufreq_frequency_table *freq_table;
128	struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
129
130	cpu_dev = get_cpu_device(policy->cpu);
131	if (!cpu_dev) {
132		pr_err("failed to get cpu%d device\n", policy->cpu);
133		return -ENODEV;
134	}
135
136	ret = handle->perf_ops->device_opps_add(handle, cpu_dev);
137	if (ret) {
138		dev_warn(cpu_dev, "failed to add opps to the device\n");
139		return ret;
140	}
141
142	ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
143	if (ret) {
144		dev_warn(cpu_dev, "failed to get sharing cpumask\n");
145		return ret;
146	}
147
148	ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
149	if (ret) {
150		dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
151			__func__, ret);
152		return ret;
153	}
154
155	nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
156	if (nr_opp <= 0) {
157		dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
158		ret = -EPROBE_DEFER;
159		goto out_free_opp;
160	}
161
162	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
163	if (!priv) {
164		ret = -ENOMEM;
165		goto out_free_opp;
166	}
167
168	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
169	if (ret) {
170		dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
171		goto out_free_priv;
172	}
173
174	priv->cpu_dev = cpu_dev;
175	priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
176
177	policy->driver_data = priv;
178	policy->freq_table = freq_table;
179
180	/* SCMI allows DVFS request for any domain from any CPU */
181	policy->dvfs_possible_from_any_cpu = true;
182
183	latency = handle->perf_ops->transition_latency_get(handle, cpu_dev);
184	if (!latency)
185		latency = CPUFREQ_ETERNAL;
186
187	policy->cpuinfo.transition_latency = latency;
188
189	policy->fast_switch_possible =
190		handle->perf_ops->fast_switch_possible(handle, cpu_dev);
191
192	em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus);
193
194	return 0;
195
196out_free_priv:
197	kfree(priv);
198out_free_opp:
199	dev_pm_opp_remove_all_dynamic(cpu_dev);
200
201	return ret;
202}
203
204static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
205{
206	struct scmi_data *priv = policy->driver_data;
207
208	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
209	dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
210	kfree(priv);
211
212	return 0;
213}
214
215static struct cpufreq_driver scmi_cpufreq_driver = {
216	.name	= "scmi",
217	.flags	= CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
218		  CPUFREQ_NEED_INITIAL_FREQ_CHECK |
219		  CPUFREQ_IS_COOLING_DEV,
220	.verify	= cpufreq_generic_frequency_table_verify,
221	.attr	= cpufreq_generic_attr,
222	.target_index	= scmi_cpufreq_set_target,
223	.fast_switch	= scmi_cpufreq_fast_switch,
224	.get	= scmi_cpufreq_get_rate,
225	.init	= scmi_cpufreq_init,
226	.exit	= scmi_cpufreq_exit,
227};
228
229static int scmi_cpufreq_probe(struct scmi_device *sdev)
230{
231	int ret;
232	struct device *dev = &sdev->dev;
233
234	handle = sdev->handle;
235
236	if (!handle || !handle->perf_ops)
237		return -ENODEV;
238
239#ifdef CONFIG_COMMON_CLK
240	/* dummy clock provider as needed by OPP if clocks property is used */
241	if (of_property_present(dev->of_node, "#clock-cells")) {
242		ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
243		if (ret)
244			return dev_err_probe(dev, ret, "%s: registering clock provider failed\n", __func__);
245	}
246#endif
247
248	ret = cpufreq_register_driver(&scmi_cpufreq_driver);
249	if (ret) {
250		dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
251			__func__, ret);
252	}
253
254	return ret;
255}
256
257static void scmi_cpufreq_remove(struct scmi_device *sdev)
258{
259	cpufreq_unregister_driver(&scmi_cpufreq_driver);
260}
261
262static const struct scmi_device_id scmi_id_table[] = {
263	{ SCMI_PROTOCOL_PERF, "cpufreq" },
264	{ },
265};
266MODULE_DEVICE_TABLE(scmi, scmi_id_table);
267
268static struct scmi_driver scmi_cpufreq_drv = {
269	.name		= "scmi-cpufreq",
270	.probe		= scmi_cpufreq_probe,
271	.remove		= scmi_cpufreq_remove,
272	.id_table	= scmi_id_table,
273};
274module_scmi_driver(scmi_cpufreq_drv);
275
276MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
277MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
278MODULE_LICENSE("GPL v2");
279