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#include <linux/units.h>
 23
 24struct scmi_data {
 25	int domain_id;
 26	int nr_opp;
 27	struct device *cpu_dev;
 28	cpumask_var_t opp_shared_cpus;
 29};
 30
 31static struct scmi_protocol_handle *ph;
 32static const struct scmi_perf_proto_ops *perf_ops;
 33
 34static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
 35{
 36	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
 37	struct scmi_data *priv = policy->driver_data;
 38	unsigned long rate;
 39	int ret;
 40
 41	ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false);
 42	if (ret)
 43		return 0;
 44	return rate / 1000;
 45}
 46
 47/*
 48 * perf_ops->freq_set is not a synchronous, the actual OPP change will
 49 * happen asynchronously and can get notified if the events are
 50 * subscribed for by the SCMI firmware
 51 */
 52static int
 53scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
 54{
 55	struct scmi_data *priv = policy->driver_data;
 56	u64 freq = policy->freq_table[index].frequency;
 57
 58	return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
 59}
 60
 61static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
 62					     unsigned int target_freq)
 63{
 64	struct scmi_data *priv = policy->driver_data;
 65
 66	if (!perf_ops->freq_set(ph, priv->domain_id,
 67				target_freq * 1000, true))
 68		return target_freq;
 69
 70	return 0;
 71}
 72
 73static int
 74scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
 75{
 76	int cpu, domain, tdomain;
 77	struct device *tcpu_dev;
 78
 79	domain = perf_ops->device_domain_id(cpu_dev);
 80	if (domain < 0)
 81		return domain;
 82
 83	for_each_possible_cpu(cpu) {
 84		if (cpu == cpu_dev->id)
 85			continue;
 86
 87		tcpu_dev = get_cpu_device(cpu);
 88		if (!tcpu_dev)
 89			continue;
 90
 91		tdomain = perf_ops->device_domain_id(tcpu_dev);
 92		if (tdomain == domain)
 93			cpumask_set_cpu(cpu, cpumask);
 94	}
 95
 96	return 0;
 97}
 98
 99static int __maybe_unused
100scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
101		   unsigned long *KHz)
102{
103	enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
104	unsigned long Hz;
105	int ret, domain;
106
107	domain = perf_ops->device_domain_id(cpu_dev);
108	if (domain < 0)
109		return domain;
110
111	/* Get the power cost of the performance domain. */
112	Hz = *KHz * 1000;
113	ret = perf_ops->est_power_get(ph, domain, &Hz, power);
114	if (ret)
115		return ret;
116
117	/* Convert the power to uW if it is mW (ignore bogoW) */
118	if (power_scale == SCMI_POWER_MILLIWATTS)
119		*power *= MICROWATT_PER_MILLIWATT;
120
121	/* The EM framework specifies the frequency in KHz. */
122	*KHz = Hz / 1000;
123
124	return 0;
125}
126
127static int scmi_cpufreq_init(struct cpufreq_policy *policy)
128{
129	int ret, nr_opp;
130	unsigned int latency;
131	struct device *cpu_dev;
132	struct scmi_data *priv;
133	struct cpufreq_frequency_table *freq_table;
134
135	cpu_dev = get_cpu_device(policy->cpu);
136	if (!cpu_dev) {
137		pr_err("failed to get cpu%d device\n", policy->cpu);
138		return -ENODEV;
139	}
140
141	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
142	if (!priv)
143		return -ENOMEM;
144
145	if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) {
146		ret = -ENOMEM;
147		goto out_free_priv;
148	}
149
150	/* Obtain CPUs that share SCMI performance controls */
151	ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
152	if (ret) {
153		dev_warn(cpu_dev, "failed to get sharing cpumask\n");
154		goto out_free_cpumask;
155	}
156
157	/*
158	 * Obtain CPUs that share performance levels.
159	 * The OPP 'sharing cpus' info may come from DT through an empty opp
160	 * table and opp-shared.
161	 */
162	ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
163	if (ret || cpumask_empty(priv->opp_shared_cpus)) {
164		/*
165		 * Either opp-table is not set or no opp-shared was found.
166		 * Use the CPU mask from SCMI to designate CPUs sharing an OPP
167		 * table.
168		 */
169		cpumask_copy(priv->opp_shared_cpus, policy->cpus);
170	}
171
172	 /*
173	  * A previous CPU may have marked OPPs as shared for a few CPUs, based on
174	  * what OPP core provided. If the current CPU is part of those few, then
175	  * there is no need to add OPPs again.
176	  */
177	nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
178	if (nr_opp <= 0) {
179		ret = perf_ops->device_opps_add(ph, cpu_dev);
180		if (ret) {
181			dev_warn(cpu_dev, "failed to add opps to the device\n");
182			goto out_free_cpumask;
183		}
184
185		nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
186		if (nr_opp <= 0) {
187			dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
188				__func__, nr_opp);
189
190			ret = -ENODEV;
191			goto out_free_opp;
192		}
193
194		ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
195		if (ret) {
196			dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
197				__func__, ret);
198
199			goto out_free_opp;
200		}
201
202		priv->nr_opp = nr_opp;
203	}
204
205	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
206	if (ret) {
207		dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
208		goto out_free_opp;
209	}
210
211	priv->cpu_dev = cpu_dev;
212	priv->domain_id = perf_ops->device_domain_id(cpu_dev);
213
214	policy->driver_data = priv;
215	policy->freq_table = freq_table;
216
217	/* SCMI allows DVFS request for any domain from any CPU */
218	policy->dvfs_possible_from_any_cpu = true;
219
220	latency = perf_ops->transition_latency_get(ph, cpu_dev);
221	if (!latency)
222		latency = CPUFREQ_ETERNAL;
223
224	policy->cpuinfo.transition_latency = latency;
225
226	policy->fast_switch_possible =
227		perf_ops->fast_switch_possible(ph, cpu_dev);
228
229	return 0;
230
231out_free_opp:
232	dev_pm_opp_remove_all_dynamic(cpu_dev);
233
234out_free_cpumask:
235	free_cpumask_var(priv->opp_shared_cpus);
236
237out_free_priv:
238	kfree(priv);
239
240	return ret;
241}
242
243static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
244{
245	struct scmi_data *priv = policy->driver_data;
246
247	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
248	dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
249	free_cpumask_var(priv->opp_shared_cpus);
250	kfree(priv);
251
252	return 0;
253}
254
255static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
256{
257	struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
258	enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
259	struct scmi_data *priv = policy->driver_data;
260	bool em_power_scale = false;
261
262	/*
263	 * This callback will be called for each policy, but we don't need to
264	 * register with EM every time. Despite not being part of the same
265	 * policy, some CPUs may still share their perf-domains, and a CPU from
266	 * another policy may already have registered with EM on behalf of CPUs
267	 * of this policy.
268	 */
269	if (!priv->nr_opp)
270		return;
271
272	if (power_scale == SCMI_POWER_MILLIWATTS
273	    || power_scale == SCMI_POWER_MICROWATTS)
274		em_power_scale = true;
275
276	em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
277				    &em_cb, priv->opp_shared_cpus,
278				    em_power_scale);
279}
280
281static struct cpufreq_driver scmi_cpufreq_driver = {
282	.name	= "scmi",
283	.flags	= CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
284		  CPUFREQ_NEED_INITIAL_FREQ_CHECK |
285		  CPUFREQ_IS_COOLING_DEV,
286	.verify	= cpufreq_generic_frequency_table_verify,
287	.attr	= cpufreq_generic_attr,
288	.target_index	= scmi_cpufreq_set_target,
289	.fast_switch	= scmi_cpufreq_fast_switch,
290	.get	= scmi_cpufreq_get_rate,
291	.init	= scmi_cpufreq_init,
292	.exit	= scmi_cpufreq_exit,
293	.register_em	= scmi_cpufreq_register_em,
294};
295
296static int scmi_cpufreq_probe(struct scmi_device *sdev)
297{
298	int ret;
299	struct device *dev = &sdev->dev;
300	const struct scmi_handle *handle;
301
302	handle = sdev->handle;
303
304	if (!handle)
305		return -ENODEV;
306
307	perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
308	if (IS_ERR(perf_ops))
309		return PTR_ERR(perf_ops);
310
311#ifdef CONFIG_COMMON_CLK
312	/* dummy clock provider as needed by OPP if clocks property is used */
313	if (of_find_property(dev->of_node, "#clock-cells", NULL))
314		devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
315#endif
316
317	ret = cpufreq_register_driver(&scmi_cpufreq_driver);
318	if (ret) {
319		dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
320			__func__, ret);
321	}
322
323	return ret;
324}
325
326static void scmi_cpufreq_remove(struct scmi_device *sdev)
327{
328	cpufreq_unregister_driver(&scmi_cpufreq_driver);
329}
330
331static const struct scmi_device_id scmi_id_table[] = {
332	{ SCMI_PROTOCOL_PERF, "cpufreq" },
333	{ },
334};
335MODULE_DEVICE_TABLE(scmi, scmi_id_table);
336
337static struct scmi_driver scmi_cpufreq_drv = {
338	.name		= "scmi-cpufreq",
339	.probe		= scmi_cpufreq_probe,
340	.remove		= scmi_cpufreq_remove,
341	.id_table	= scmi_id_table,
342};
343module_scmi_driver(scmi_cpufreq_drv);
344
345MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
346MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
347MODULE_LICENSE("GPL v2");