1// SPDX-License-Identifier: GPL-2.0
2/*
3 * SCMI Powercap support.
4 *
5 * Copyright (C) 2022 ARM Ltd.
6 */
7
8#include <linux/device.h>
9#include <linux/math.h>
10#include <linux/limits.h>
11#include <linux/list.h>
12#include <linux/module.h>
13#include <linux/powercap.h>
14#include <linux/scmi_protocol.h>
15#include <linux/slab.h>
16
17#define to_scmi_powercap_zone(z) \
18 container_of(z, struct scmi_powercap_zone, zone)
19
20static const struct scmi_powercap_proto_ops *powercap_ops;
21
22struct scmi_powercap_zone {
23 bool registered;
24 bool invalid;
25 unsigned int height;
26 struct device *dev;
27 struct scmi_protocol_handle *ph;
28 const struct scmi_powercap_info *info;
29 struct scmi_powercap_zone *spzones;
30 struct powercap_zone zone;
31 struct list_head node;
32};
33
34struct scmi_powercap_root {
35 unsigned int num_zones;
36 struct scmi_powercap_zone *spzones;
37 struct list_head *registered_zones;
38 struct list_head scmi_zones;
39};
40
41static struct powercap_control_type *scmi_top_pcntrl;
42
43static int scmi_powercap_zone_release(struct powercap_zone *pz)
44{
45 return 0;
46}
47
48static int scmi_powercap_get_max_power_range_uw(struct powercap_zone *pz,
49 u64 *max_power_range_uw)
50{
51 *max_power_range_uw = U32_MAX;
52 return 0;
53}
54
55static int scmi_powercap_get_power_uw(struct powercap_zone *pz,
56 u64 *power_uw)
57{
58 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
59 u32 avg_power, pai;
60 int ret;
61
62 if (!spz->info->powercap_monitoring)
63 return -EINVAL;
64
65 ret = powercap_ops->measurements_get(spz->ph, spz->info->id, &avg_power,
66 &pai);
67 if (ret)
68 return ret;
69
70 *power_uw = avg_power;
71 if (spz->info->powercap_scale_mw)
72 *power_uw *= 1000;
73
74 return 0;
75}
76
77static int scmi_powercap_zone_enable_set(struct powercap_zone *pz, bool mode)
78{
79 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
80
81 return powercap_ops->cap_enable_set(spz->ph, spz->info->id, mode);
82}
83
84static int scmi_powercap_zone_enable_get(struct powercap_zone *pz, bool *mode)
85{
86 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
87
88 return powercap_ops->cap_enable_get(spz->ph, spz->info->id, mode);
89}
90
91static const struct powercap_zone_ops zone_ops = {
92 .get_max_power_range_uw = scmi_powercap_get_max_power_range_uw,
93 .get_power_uw = scmi_powercap_get_power_uw,
94 .release = scmi_powercap_zone_release,
95 .set_enable = scmi_powercap_zone_enable_set,
96 .get_enable = scmi_powercap_zone_enable_get,
97};
98
99static void scmi_powercap_normalize_cap(const struct scmi_powercap_zone *spz,
100 u64 power_limit_uw, u32 *norm)
101{
102 bool scale_mw = spz->info->powercap_scale_mw;
103 u64 val;
104
105 val = scale_mw ? DIV_ROUND_UP_ULL(power_limit_uw, 1000) : power_limit_uw;
106 /*
107 * This cast is lossless since here @req_power is certain to be within
108 * the range [min_power_cap, max_power_cap] whose bounds are assured to
109 * be two unsigned 32bits quantities.
110 */
111 *norm = clamp_t(u32, val, spz->info->min_power_cap,
112 spz->info->max_power_cap);
113 *norm = rounddown(*norm, spz->info->power_cap_step);
114
115 val = (scale_mw) ? *norm * 1000 : *norm;
116 if (power_limit_uw != val)
117 dev_dbg(spz->dev,
118 "Normalized %s:CAP - requested:%llu - normalized:%llu\n",
119 spz->info->name, power_limit_uw, val);
120}
121
122static int scmi_powercap_set_power_limit_uw(struct powercap_zone *pz, int cid,
123 u64 power_uw)
124{
125 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
126 u32 norm_power;
127
128 if (!spz->info->powercap_cap_config)
129 return -EINVAL;
130
131 scmi_powercap_normalize_cap(spz, power_limit_uw: power_uw, norm: &norm_power);
132
133 return powercap_ops->cap_set(spz->ph, spz->info->id, norm_power, false);
134}
135
136static int scmi_powercap_get_power_limit_uw(struct powercap_zone *pz, int cid,
137 u64 *power_limit_uw)
138{
139 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
140 u32 power;
141 int ret;
142
143 ret = powercap_ops->cap_get(spz->ph, spz->info->id, &power);
144 if (ret)
145 return ret;
146
147 *power_limit_uw = power;
148 if (spz->info->powercap_scale_mw)
149 *power_limit_uw *= 1000;
150
151 return 0;
152}
153
154static void scmi_powercap_normalize_time(const struct scmi_powercap_zone *spz,
155 u64 time_us, u32 *norm)
156{
157 /*
158 * This cast is lossless since here @time_us is certain to be within the
159 * range [min_pai, max_pai] whose bounds are assured to be two unsigned
160 * 32bits quantities.
161 */
162 *norm = clamp_t(u32, time_us, spz->info->min_pai, spz->info->max_pai);
163 *norm = rounddown(*norm, spz->info->pai_step);
164
165 if (time_us != *norm)
166 dev_dbg(spz->dev,
167 "Normalized %s:PAI - requested:%llu - normalized:%u\n",
168 spz->info->name, time_us, *norm);
169}
170
171static int scmi_powercap_set_time_window_us(struct powercap_zone *pz, int cid,
172 u64 time_window_us)
173{
174 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
175 u32 norm_pai;
176
177 if (!spz->info->powercap_pai_config)
178 return -EINVAL;
179
180 scmi_powercap_normalize_time(spz, time_us: time_window_us, norm: &norm_pai);
181
182 return powercap_ops->pai_set(spz->ph, spz->info->id, norm_pai);
183}
184
185static int scmi_powercap_get_time_window_us(struct powercap_zone *pz, int cid,
186 u64 *time_window_us)
187{
188 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
189 int ret;
190 u32 pai;
191
192 ret = powercap_ops->pai_get(spz->ph, spz->info->id, &pai);
193 if (ret)
194 return ret;
195
196 *time_window_us = pai;
197
198 return 0;
199}
200
201static int scmi_powercap_get_max_power_uw(struct powercap_zone *pz, int cid,
202 u64 *max_power_uw)
203{
204 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
205
206 *max_power_uw = spz->info->max_power_cap;
207 if (spz->info->powercap_scale_mw)
208 *max_power_uw *= 1000;
209
210 return 0;
211}
212
213static int scmi_powercap_get_min_power_uw(struct powercap_zone *pz, int cid,
214 u64 *min_power_uw)
215{
216 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
217
218 *min_power_uw = spz->info->min_power_cap;
219 if (spz->info->powercap_scale_mw)
220 *min_power_uw *= 1000;
221
222 return 0;
223}
224
225static int scmi_powercap_get_max_time_window_us(struct powercap_zone *pz,
226 int cid, u64 *time_window_us)
227{
228 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
229
230 *time_window_us = spz->info->max_pai;
231
232 return 0;
233}
234
235static int scmi_powercap_get_min_time_window_us(struct powercap_zone *pz,
236 int cid, u64 *time_window_us)
237{
238 struct scmi_powercap_zone *spz = to_scmi_powercap_zone(pz);
239
240 *time_window_us = (u64)spz->info->min_pai;
241
242 return 0;
243}
244
245static const char *scmi_powercap_get_name(struct powercap_zone *pz, int cid)
246{
247 return "SCMI power-cap";
248}
249
250static const struct powercap_zone_constraint_ops constraint_ops = {
251 .set_power_limit_uw = scmi_powercap_set_power_limit_uw,
252 .get_power_limit_uw = scmi_powercap_get_power_limit_uw,
253 .set_time_window_us = scmi_powercap_set_time_window_us,
254 .get_time_window_us = scmi_powercap_get_time_window_us,
255 .get_max_power_uw = scmi_powercap_get_max_power_uw,
256 .get_min_power_uw = scmi_powercap_get_min_power_uw,
257 .get_max_time_window_us = scmi_powercap_get_max_time_window_us,
258 .get_min_time_window_us = scmi_powercap_get_min_time_window_us,
259 .get_name = scmi_powercap_get_name,
260};
261
262static void scmi_powercap_unregister_all_zones(struct scmi_powercap_root *pr)
263{
264 int i;
265
266 /* Un-register children zones first starting from the leaves */
267 for (i = pr->num_zones - 1; i >= 0; i--) {
268 if (!list_empty(head: &pr->registered_zones[i])) {
269 struct scmi_powercap_zone *spz;
270
271 list_for_each_entry(spz, &pr->registered_zones[i], node)
272 powercap_unregister_zone(control_type: scmi_top_pcntrl,
273 power_zone: &spz->zone);
274 }
275 }
276}
277
278static inline unsigned int
279scmi_powercap_get_zone_height(struct scmi_powercap_zone *spz)
280{
281 if (spz->info->parent_id == SCMI_POWERCAP_ROOT_ZONE_ID)
282 return 0;
283
284 return spz->spzones[spz->info->parent_id].height + 1;
285}
286
287static inline struct scmi_powercap_zone *
288scmi_powercap_get_parent_zone(struct scmi_powercap_zone *spz)
289{
290 if (spz->info->parent_id == SCMI_POWERCAP_ROOT_ZONE_ID)
291 return NULL;
292
293 return &spz->spzones[spz->info->parent_id];
294}
295
296static int scmi_powercap_register_zone(struct scmi_powercap_root *pr,
297 struct scmi_powercap_zone *spz,
298 struct scmi_powercap_zone *parent)
299{
300 int ret = 0;
301 struct powercap_zone *z;
302
303 if (spz->invalid) {
304 list_del(entry: &spz->node);
305 return -EINVAL;
306 }
307
308 z = powercap_register_zone(power_zone: &spz->zone, control_type: scmi_top_pcntrl, name: spz->info->name,
309 parent: parent ? &parent->zone : NULL,
310 ops: &zone_ops, nr_constraints: 1, const_ops: &constraint_ops);
311 if (!IS_ERR(ptr: z)) {
312 spz->height = scmi_powercap_get_zone_height(spz);
313 spz->registered = true;
314 list_move(list: &spz->node, head: &pr->registered_zones[spz->height]);
315 dev_dbg(spz->dev, "Registered node %s - parent %s - height:%d\n",
316 spz->info->name, parent ? parent->info->name : "ROOT",
317 spz->height);
318 } else {
319 list_del(entry: &spz->node);
320 ret = PTR_ERR(ptr: z);
321 dev_err(spz->dev,
322 "Error registering node:%s - parent:%s - h:%d - ret:%d\n",
323 spz->info->name,
324 parent ? parent->info->name : "ROOT",
325 spz->height, ret);
326 }
327
328 return ret;
329}
330
331/**
332 * scmi_zones_register- Register SCMI powercap zones starting from parent zones
333 *
334 * @dev: A reference to the SCMI device
335 * @pr: A reference to the root powercap zones descriptors
336 *
337 * When registering SCMI powercap zones with the powercap framework we should
338 * take care to always register zones starting from the root ones and to
339 * deregister starting from the leaves.
340 *
341 * Unfortunately we cannot assume that the array of available SCMI powercap
342 * zones provided by the SCMI platform firmware is built to comply with such
343 * requirement.
344 *
345 * This function, given the set of SCMI powercap zones to register, takes care
346 * to walk the SCMI powercap zones trees up to the root registering any
347 * unregistered parent zone before registering the child zones; at the same
348 * time each registered-zone height in such a tree is accounted for and each
349 * zone, once registered, is stored in the @registered_zones array that is
350 * indexed by zone height: this way will be trivial, at unregister time, to walk
351 * the @registered_zones array backward and unregister all the zones starting
352 * from the leaves, removing children zones before parents.
353 *
354 * While doing this, we prune away any zone marked as invalid (like the ones
355 * sporting an SCMI abstract power scale) as long as they are positioned as
356 * leaves in the SCMI powercap zones hierarchy: any non-leaf invalid zone causes
357 * the entire process to fail since we cannot assume the correctness of an SCMI
358 * powercap zones hierarchy if some of the internal nodes are missing.
359 *
360 * Note that the array of SCMI powercap zones as returned by the SCMI platform
361 * is known to be sane, i.e. zones relationships have been validated at the
362 * protocol layer.
363 *
364 * Return: 0 on Success
365 */
366static int scmi_zones_register(struct device *dev,
367 struct scmi_powercap_root *pr)
368{
369 int ret = 0;
370 unsigned int sp = 0, reg_zones = 0;
371 struct scmi_powercap_zone *spz, **zones_stack;
372
373 zones_stack = kcalloc(pr->num_zones, sizeof(spz), GFP_KERNEL);
374 if (!zones_stack)
375 return -ENOMEM;
376
377 spz = list_first_entry_or_null(&pr->scmi_zones,
378 struct scmi_powercap_zone, node);
379 while (spz) {
380 struct scmi_powercap_zone *parent;
381
382 parent = scmi_powercap_get_parent_zone(spz);
383 if (parent && !parent->registered) {
384 zones_stack[sp++] = spz;
385 spz = parent;
386 } else {
387 ret = scmi_powercap_register_zone(pr, spz, parent);
388 if (!ret) {
389 reg_zones++;
390 } else if (sp) {
391 /* Failed to register a non-leaf zone.
392 * Bail-out.
393 */
394 dev_err(dev,
395 "Failed to register non-leaf zone - ret:%d\n",
396 ret);
397 scmi_powercap_unregister_all_zones(pr);
398 reg_zones = 0;
399 goto out;
400 }
401 /* Pick next zone to process */
402 if (sp)
403 spz = zones_stack[--sp];
404 else
405 spz = list_first_entry_or_null(&pr->scmi_zones,
406 struct scmi_powercap_zone,
407 node);
408 }
409 }
410
411out:
412 kfree(objp: zones_stack);
413 dev_info(dev, "Registered %d SCMI Powercap domains !\n", reg_zones);
414
415 return ret;
416}
417
418static int scmi_powercap_probe(struct scmi_device *sdev)
419{
420 int ret, i;
421 struct scmi_powercap_root *pr;
422 struct scmi_powercap_zone *spz;
423 struct scmi_protocol_handle *ph;
424 struct device *dev = &sdev->dev;
425
426 if (!sdev->handle)
427 return -ENODEV;
428
429 powercap_ops = sdev->handle->devm_protocol_get(sdev,
430 SCMI_PROTOCOL_POWERCAP,
431 &ph);
432 if (IS_ERR(ptr: powercap_ops))
433 return PTR_ERR(ptr: powercap_ops);
434
435 pr = devm_kzalloc(dev, size: sizeof(*pr), GFP_KERNEL);
436 if (!pr)
437 return -ENOMEM;
438
439 ret = powercap_ops->num_domains_get(ph);
440 if (ret < 0) {
441 dev_err(dev, "number of powercap domains not found\n");
442 return ret;
443 }
444 pr->num_zones = ret;
445
446 pr->spzones = devm_kcalloc(dev, n: pr->num_zones,
447 size: sizeof(*pr->spzones), GFP_KERNEL);
448 if (!pr->spzones)
449 return -ENOMEM;
450
451 /* Allocate for worst possible scenario of maximum tree height. */
452 pr->registered_zones = devm_kcalloc(dev, n: pr->num_zones,
453 size: sizeof(*pr->registered_zones),
454 GFP_KERNEL);
455 if (!pr->registered_zones)
456 return -ENOMEM;
457
458 INIT_LIST_HEAD(list: &pr->scmi_zones);
459
460 for (i = 0, spz = pr->spzones; i < pr->num_zones; i++, spz++) {
461 /*
462 * Powercap domains are validate by the protocol layer, i.e.
463 * when only non-NULL domains are returned here, whose
464 * parent_id is assured to point to another valid domain.
465 */
466 spz->info = powercap_ops->info_get(ph, i);
467
468 spz->dev = dev;
469 spz->ph = ph;
470 spz->spzones = pr->spzones;
471 INIT_LIST_HEAD(list: &spz->node);
472 INIT_LIST_HEAD(list: &pr->registered_zones[i]);
473
474 list_add_tail(new: &spz->node, head: &pr->scmi_zones);
475 /*
476 * Forcibly skip powercap domains using an abstract scale.
477 * Note that only leaves domains can be skipped, so this could
478 * lead later to a global failure.
479 */
480 if (!spz->info->powercap_scale_uw &&
481 !spz->info->powercap_scale_mw) {
482 dev_warn(dev,
483 "Abstract power scale not supported. Skip %s.\n",
484 spz->info->name);
485 spz->invalid = true;
486 continue;
487 }
488 }
489
490 /*
491 * Scan array of retrieved SCMI powercap domains and register them
492 * recursively starting from the root domains.
493 */
494 ret = scmi_zones_register(dev, pr);
495 if (ret)
496 return ret;
497
498 dev_set_drvdata(dev, data: pr);
499
500 return ret;
501}
502
503static void scmi_powercap_remove(struct scmi_device *sdev)
504{
505 struct device *dev = &sdev->dev;
506 struct scmi_powercap_root *pr = dev_get_drvdata(dev);
507
508 scmi_powercap_unregister_all_zones(pr);
509}
510
511static const struct scmi_device_id scmi_id_table[] = {
512 { SCMI_PROTOCOL_POWERCAP, "powercap" },
513 { },
514};
515MODULE_DEVICE_TABLE(scmi, scmi_id_table);
516
517static struct scmi_driver scmi_powercap_driver = {
518 .name = "scmi-powercap",
519 .probe = scmi_powercap_probe,
520 .remove = scmi_powercap_remove,
521 .id_table = scmi_id_table,
522};
523
524static int __init scmi_powercap_init(void)
525{
526 int ret;
527
528 scmi_top_pcntrl = powercap_register_control_type(NULL, name: "arm-scmi", NULL);
529 if (IS_ERR(ptr: scmi_top_pcntrl))
530 return PTR_ERR(ptr: scmi_top_pcntrl);
531
532 ret = scmi_register(&scmi_powercap_driver);
533 if (ret)
534 powercap_unregister_control_type(instance: scmi_top_pcntrl);
535
536 return ret;
537}
538module_init(scmi_powercap_init);
539
540static void __exit scmi_powercap_exit(void)
541{
542 scmi_unregister(&scmi_powercap_driver);
543
544 powercap_unregister_control_type(instance: scmi_top_pcntrl);
545}
546module_exit(scmi_powercap_exit);
547
548MODULE_AUTHOR("Cristian Marussi <cristian.marussi@arm.com>");
549MODULE_DESCRIPTION("ARM SCMI Powercap driver");
550MODULE_LICENSE("GPL");
551

source code of linux/drivers/powercap/arm_scmi_powercap.c