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/cpu.h>
 12#include <linux/cpufreq.h>
 13#include <linux/cpumask.h>
 14#include <linux/cpu_cooling.h>
 15#include <linux/export.h>
 16#include <linux/module.h>
 17#include <linux/pm_opp.h>
 18#include <linux/slab.h>
 19#include <linux/scmi_protocol.h>
 20#include <linux/types.h>
 21
 22struct scmi_data {
 23	int domain_id;
 24	struct device *cpu_dev;
 25	struct thermal_cooling_device *cdev;
 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	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	int ret;
 53	struct scmi_data *priv = policy->driver_data;
 54	struct scmi_perf_ops *perf_ops = handle->perf_ops;
 55	u64 freq = policy->freq_table[index].frequency * 1000;
 56
 57	ret = perf_ops->freq_set(handle, priv->domain_id, freq, false);
 58	if (!ret)
 59		arch_set_freq_scale(policy->related_cpus, freq,
 60				    policy->cpuinfo.max_freq);
 61	return ret;
 62}
 63
 64static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
 65					     unsigned int target_freq)
 66{
 67	struct scmi_data *priv = policy->driver_data;
 68	struct scmi_perf_ops *perf_ops = handle->perf_ops;
 69
 70	if (!perf_ops->freq_set(handle, priv->domain_id,
 71				target_freq * 1000, true)) {
 72		arch_set_freq_scale(policy->related_cpus, target_freq,
 73				    policy->cpuinfo.max_freq);
 74		return target_freq;
 75	}
 76
 77	return 0;
 78}
 79
 80static int
 81scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
 82{
 83	int cpu, domain, tdomain;
 84	struct device *tcpu_dev;
 85
 86	domain = handle->perf_ops->device_domain_id(cpu_dev);
 87	if (domain < 0)
 88		return domain;
 89
 90	for_each_possible_cpu(cpu) {
 91		if (cpu == cpu_dev->id)
 92			continue;
 93
 94		tcpu_dev = get_cpu_device(cpu);
 95		if (!tcpu_dev)
 96			continue;
 97
 98		tdomain = handle->perf_ops->device_domain_id(tcpu_dev);
 99		if (tdomain == domain)
100			cpumask_set_cpu(cpu, cpumask);
101	}
102
103	return 0;
104}
105
106static int scmi_cpufreq_init(struct cpufreq_policy *policy)
107{
108	int ret;
109	unsigned int latency;
110	struct device *cpu_dev;
111	struct scmi_data *priv;
112	struct cpufreq_frequency_table *freq_table;
113
114	cpu_dev = get_cpu_device(policy->cpu);
115	if (!cpu_dev) {
116		pr_err("failed to get cpu%d device\n", policy->cpu);
117		return -ENODEV;
118	}
119
120	ret = handle->perf_ops->add_opps_to_device(handle, cpu_dev);
121	if (ret) {
122		dev_warn(cpu_dev, "failed to add opps to the device\n");
123		return ret;
124	}
125
126	ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
127	if (ret) {
128		dev_warn(cpu_dev, "failed to get sharing cpumask\n");
129		return ret;
130	}
131
132	ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
133	if (ret) {
134		dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
135			__func__, ret);
136		return ret;
137	}
138
139	ret = dev_pm_opp_get_opp_count(cpu_dev);
140	if (ret <= 0) {
141		dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
142		ret = -EPROBE_DEFER;
143		goto out_free_opp;
144	}
145
146	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
147	if (!priv) {
148		ret = -ENOMEM;
149		goto out_free_opp;
150	}
151
152	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
153	if (ret) {
154		dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
155		goto out_free_priv;
156	}
157
158	priv->cpu_dev = cpu_dev;
159	priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
160
161	policy->driver_data = priv;
162	policy->freq_table = freq_table;
163
164	/* SCMI allows DVFS request for any domain from any CPU */
165	policy->dvfs_possible_from_any_cpu = true;
166
167	latency = handle->perf_ops->get_transition_latency(handle, cpu_dev);
168	if (!latency)
169		latency = CPUFREQ_ETERNAL;
170
171	policy->cpuinfo.transition_latency = latency;
172
173	policy->fast_switch_possible = true;
174	return 0;
175
176out_free_priv:
177	kfree(priv);
178out_free_opp:
179	dev_pm_opp_cpumask_remove_table(policy->cpus);
180
181	return ret;
182}
183
184static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
185{
186	struct scmi_data *priv = policy->driver_data;
187
188	cpufreq_cooling_unregister(priv->cdev);
189	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
190	kfree(priv);
191	dev_pm_opp_cpumask_remove_table(policy->related_cpus);
192
193	return 0;
194}
195
196static void scmi_cpufreq_ready(struct cpufreq_policy *policy)
197{
198	struct scmi_data *priv = policy->driver_data;
199
200	priv->cdev = of_cpufreq_cooling_register(policy);
201}
202
203static struct cpufreq_driver scmi_cpufreq_driver = {
204	.name	= "scmi",
205	.flags	= CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
206		  CPUFREQ_NEED_INITIAL_FREQ_CHECK,
207	.verify	= cpufreq_generic_frequency_table_verify,
208	.attr	= cpufreq_generic_attr,
209	.target_index	= scmi_cpufreq_set_target,
210	.fast_switch	= scmi_cpufreq_fast_switch,
211	.get	= scmi_cpufreq_get_rate,
212	.init	= scmi_cpufreq_init,
213	.exit	= scmi_cpufreq_exit,
214	.ready	= scmi_cpufreq_ready,
215};
216
217static int scmi_cpufreq_probe(struct scmi_device *sdev)
218{
219	int ret;
220
221	handle = sdev->handle;
222
223	if (!handle || !handle->perf_ops)
224		return -ENODEV;
225
226	ret = cpufreq_register_driver(&scmi_cpufreq_driver);
227	if (ret) {
228		dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n",
229			__func__, ret);
230	}
231
232	return ret;
233}
234
235static void scmi_cpufreq_remove(struct scmi_device *sdev)
236{
237	cpufreq_unregister_driver(&scmi_cpufreq_driver);
238}
239
240static const struct scmi_device_id scmi_id_table[] = {
241	{ SCMI_PROTOCOL_PERF },
242	{ },
243};
244MODULE_DEVICE_TABLE(scmi, scmi_id_table);
245
246static struct scmi_driver scmi_cpufreq_drv = {
247	.name		= "scmi-cpufreq",
248	.probe		= scmi_cpufreq_probe,
249	.remove		= scmi_cpufreq_remove,
250	.id_table	= scmi_id_table,
251};
252module_scmi_driver(scmi_cpufreq_drv);
253
254MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
255MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
256MODULE_LICENSE("GPL v2");