1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * System Control and Power Interface (SCMI) based CPUFreq Interface driver
  4 *
  5 * Copyright (C) 2018-2021 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 struct scmi_protocol_handle *ph;
 29static const struct scmi_perf_proto_ops *perf_ops;
 30
 31static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
 32{
 33	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
 34	struct scmi_data *priv = policy->driver_data;
 35	unsigned long rate;
 36	int ret;
 37
 38	ret = perf_ops->freq_get(ph, 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	u64 freq = policy->freq_table[index].frequency;
 54
 55	return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
 56}
 57
 58static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
 59					     unsigned int target_freq)
 60{
 61	struct scmi_data *priv = policy->driver_data;
 62
 63	if (!perf_ops->freq_set(ph, priv->domain_id,
 64				target_freq * 1000, true))
 65		return target_freq;
 66
 67	return 0;
 68}
 69
 70static int
 71scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
 72{
 73	int cpu, domain, tdomain;
 74	struct device *tcpu_dev;
 75
 76	domain = perf_ops->device_domain_id(cpu_dev);
 77	if (domain < 0)
 78		return domain;
 79
 80	for_each_possible_cpu(cpu) {
 81		if (cpu == cpu_dev->id)
 82			continue;
 83
 84		tcpu_dev = get_cpu_device(cpu);
 85		if (!tcpu_dev)
 86			continue;
 87
 88		tdomain = perf_ops->device_domain_id(tcpu_dev);
 89		if (tdomain == domain)
 90			cpumask_set_cpu(cpu, cpumask);
 91	}
 92
 93	return 0;
 94}
 95
 96static int __maybe_unused
 97scmi_get_cpu_power(unsigned long *power, unsigned long *KHz,
 98		   struct device *cpu_dev)
 99{
100	unsigned long Hz;
101	int ret, domain;
102
103	domain = perf_ops->device_domain_id(cpu_dev);
104	if (domain < 0)
105		return domain;
106
107	/* Get the power cost of the performance domain. */
108	Hz = *KHz * 1000;
109	ret = perf_ops->est_power_get(ph, domain, &Hz, power);
110	if (ret)
111		return ret;
112
113	/* The EM framework specifies the frequency in KHz. */
114	*KHz = Hz / 1000;
115
116	return 0;
117}
118
119static int scmi_cpufreq_init(struct cpufreq_policy *policy)
120{
121	int ret, nr_opp;
122	unsigned int latency;
123	struct device *cpu_dev;
124	struct scmi_data *priv;
125	struct cpufreq_frequency_table *freq_table;
126	struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
127	cpumask_var_t opp_shared_cpus;
128	bool power_scale_mw;
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	if (!zalloc_cpumask_var(&opp_shared_cpus, GFP_KERNEL))
137		return -ENOMEM;
138
139	/* Obtain CPUs that share SCMI performance controls */
140	ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
141	if (ret) {
142		dev_warn(cpu_dev, "failed to get sharing cpumask\n");
143		goto out_free_cpumask;
144	}
145
146	/*
147	 * Obtain CPUs that share performance levels.
148	 * The OPP 'sharing cpus' info may come from DT through an empty opp
149	 * table and opp-shared.
150	 */
151	ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, opp_shared_cpus);
152	if (ret || !cpumask_weight(opp_shared_cpus)) {
153		/*
154		 * Either opp-table is not set or no opp-shared was found.
155		 * Use the CPU mask from SCMI to designate CPUs sharing an OPP
156		 * table.
157		 */
158		cpumask_copy(opp_shared_cpus, policy->cpus);
159	}
160
161	 /*
162	  * A previous CPU may have marked OPPs as shared for a few CPUs, based on
163	  * what OPP core provided. If the current CPU is part of those few, then
164	  * there is no need to add OPPs again.
165	  */
166	nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
167	if (nr_opp <= 0) {
168		ret = perf_ops->device_opps_add(ph, cpu_dev);
169		if (ret) {
170			dev_warn(cpu_dev, "failed to add opps to the device\n");
171			goto out_free_cpumask;
172		}
173
174		nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
175		if (nr_opp <= 0) {
176			dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
177				__func__, nr_opp);
178
179			ret = -ENODEV;
180			goto out_free_opp;
181		}
182
183		ret = dev_pm_opp_set_sharing_cpus(cpu_dev, opp_shared_cpus);
184		if (ret) {
185			dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
186				__func__, ret);
187
188			goto out_free_opp;
189		}
190
191		power_scale_mw = perf_ops->power_scale_mw_get(ph);
192		em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb,
193					    opp_shared_cpus, power_scale_mw);
194	}
195
196	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
197	if (!priv) {
198		ret = -ENOMEM;
199		goto out_free_opp;
200	}
201
202	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
203	if (ret) {
204		dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
205		goto out_free_priv;
206	}
207
208	priv->cpu_dev = cpu_dev;
209	priv->domain_id = perf_ops->device_domain_id(cpu_dev);
210
211	policy->driver_data = priv;
212	policy->freq_table = freq_table;
213
214	/* SCMI allows DVFS request for any domain from any CPU */
215	policy->dvfs_possible_from_any_cpu = true;
216
217	latency = perf_ops->transition_latency_get(ph, cpu_dev);
218	if (!latency)
219		latency = CPUFREQ_ETERNAL;
220
221	policy->cpuinfo.transition_latency = latency;
222
223	policy->fast_switch_possible =
224		perf_ops->fast_switch_possible(ph, cpu_dev);
225
226	free_cpumask_var(opp_shared_cpus);
227	return 0;
228
229out_free_priv:
230	kfree(priv);
231
232out_free_opp:
233	dev_pm_opp_remove_all_dynamic(cpu_dev);
234
235out_free_cpumask:
236	free_cpumask_var(opp_shared_cpus);
237
238	return ret;
239}
240
241static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
242{
243	struct scmi_data *priv = policy->driver_data;
244
245	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
246	dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
247	kfree(priv);
248
249	return 0;
250}
251
252static struct cpufreq_driver scmi_cpufreq_driver = {
253	.name	= "scmi",
254	.flags	= CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
255		  CPUFREQ_NEED_INITIAL_FREQ_CHECK |
256		  CPUFREQ_IS_COOLING_DEV,
257	.verify	= cpufreq_generic_frequency_table_verify,
258	.attr	= cpufreq_generic_attr,
259	.target_index	= scmi_cpufreq_set_target,
260	.fast_switch	= scmi_cpufreq_fast_switch,
261	.get	= scmi_cpufreq_get_rate,
262	.init	= scmi_cpufreq_init,
263	.exit	= scmi_cpufreq_exit,
264};
265
266static int scmi_cpufreq_probe(struct scmi_device *sdev)
267{
268	int ret;
269	struct device *dev = &sdev->dev;
270	const struct scmi_handle *handle;
271
272	handle = sdev->handle;
273
274	if (!handle)
275		return -ENODEV;
276
277	perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
278	if (IS_ERR(perf_ops))
279		return PTR_ERR(perf_ops);
280
281#ifdef CONFIG_COMMON_CLK
282	/* dummy clock provider as needed by OPP if clocks property is used */
283	if (of_find_property(dev->of_node, "#clock-cells", NULL))
284		devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
285#endif
286
287	ret = cpufreq_register_driver(&scmi_cpufreq_driver);
288	if (ret) {
289		dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
290			__func__, ret);
291	}
292
293	return ret;
294}
295
296static void scmi_cpufreq_remove(struct scmi_device *sdev)
297{
298	cpufreq_unregister_driver(&scmi_cpufreq_driver);
299}
300
301static const struct scmi_device_id scmi_id_table[] = {
302	{ SCMI_PROTOCOL_PERF, "cpufreq" },
303	{ },
304};
305MODULE_DEVICE_TABLE(scmi, scmi_id_table);
306
307static struct scmi_driver scmi_cpufreq_drv = {
308	.name		= "scmi-cpufreq",
309	.probe		= scmi_cpufreq_probe,
310	.remove		= scmi_cpufreq_remove,
311	.id_table	= scmi_id_table,
312};
313module_scmi_driver(scmi_cpufreq_drv);
314
315MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
316MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
317MODULE_LICENSE("GPL v2");