1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * Voltage regulators coupler for NVIDIA Tegra20 |
4 | * Copyright (C) 2019 GRATE-DRIVER project |
5 | * |
6 | * Voltage constraints borrowed from downstream kernel sources |
7 | * Copyright (C) 2010-2011 NVIDIA Corporation |
8 | */ |
9 | |
10 | #define pr_fmt(fmt) "tegra voltage-coupler: " fmt |
11 | |
12 | #include <linux/init.h> |
13 | #include <linux/kernel.h> |
14 | #include <linux/of.h> |
15 | #include <linux/reboot.h> |
16 | #include <linux/regulator/coupler.h> |
17 | #include <linux/regulator/driver.h> |
18 | #include <linux/regulator/machine.h> |
19 | #include <linux/suspend.h> |
20 | |
21 | #include <soc/tegra/fuse.h> |
22 | #include <soc/tegra/pmc.h> |
23 | |
24 | struct tegra_regulator_coupler { |
25 | struct regulator_coupler coupler; |
26 | struct regulator_dev *core_rdev; |
27 | struct regulator_dev *cpu_rdev; |
28 | struct regulator_dev *rtc_rdev; |
29 | struct notifier_block reboot_notifier; |
30 | struct notifier_block suspend_notifier; |
31 | int core_min_uV, cpu_min_uV; |
32 | bool sys_reboot_mode_req; |
33 | bool sys_reboot_mode; |
34 | bool sys_suspend_mode_req; |
35 | bool sys_suspend_mode; |
36 | }; |
37 | |
38 | static inline struct tegra_regulator_coupler * |
39 | to_tegra_coupler(struct regulator_coupler *coupler) |
40 | { |
41 | return container_of(coupler, struct tegra_regulator_coupler, coupler); |
42 | } |
43 | |
44 | static int tegra20_core_limit(struct tegra_regulator_coupler *tegra, |
45 | struct regulator_dev *core_rdev) |
46 | { |
47 | int core_min_uV = 0; |
48 | int core_max_uV; |
49 | int core_cur_uV; |
50 | int err; |
51 | |
52 | /* |
53 | * Tegra20 SoC has critical DVFS-capable devices that are |
54 | * permanently-active or active at a boot time, like EMC |
55 | * (DRAM controller) or Display controller for example. |
56 | * |
57 | * The voltage of a CORE SoC power domain shall not be dropped below |
58 | * a minimum level, which is determined by device's clock rate. |
59 | * This means that we can't fully allow CORE voltage scaling until |
60 | * the state of all DVFS-critical CORE devices is synced. |
61 | */ |
62 | if (tegra_pmc_core_domain_state_synced() && !tegra->sys_reboot_mode) { |
63 | pr_info_once("voltage state synced\n" ); |
64 | return 0; |
65 | } |
66 | |
67 | if (tegra->core_min_uV > 0) |
68 | return tegra->core_min_uV; |
69 | |
70 | core_cur_uV = regulator_get_voltage_rdev(rdev: core_rdev); |
71 | if (core_cur_uV < 0) |
72 | return core_cur_uV; |
73 | |
74 | core_max_uV = max(core_cur_uV, 1200000); |
75 | |
76 | err = regulator_check_voltage(rdev: core_rdev, min_uV: &core_min_uV, max_uV: &core_max_uV); |
77 | if (err) |
78 | return err; |
79 | |
80 | /* |
81 | * Limit minimum CORE voltage to a value left from bootloader or, |
82 | * if it's unreasonably low value, to the most common 1.2v or to |
83 | * whatever maximum value defined via board's device-tree. |
84 | */ |
85 | tegra->core_min_uV = core_max_uV; |
86 | |
87 | pr_info("core voltage initialized to %duV\n" , tegra->core_min_uV); |
88 | |
89 | return tegra->core_min_uV; |
90 | } |
91 | |
92 | static int tegra20_core_rtc_max_spread(struct regulator_dev *core_rdev, |
93 | struct regulator_dev *rtc_rdev) |
94 | { |
95 | struct coupling_desc *c_desc = &core_rdev->coupling_desc; |
96 | struct regulator_dev *rdev; |
97 | int max_spread; |
98 | unsigned int i; |
99 | |
100 | for (i = 1; i < c_desc->n_coupled; i++) { |
101 | max_spread = core_rdev->constraints->max_spread[i - 1]; |
102 | rdev = c_desc->coupled_rdevs[i]; |
103 | |
104 | if (rdev == rtc_rdev && max_spread) |
105 | return max_spread; |
106 | } |
107 | |
108 | pr_err_once("rtc-core max-spread is undefined in device-tree\n" ); |
109 | |
110 | return 150000; |
111 | } |
112 | |
113 | static int tegra20_cpu_nominal_uV(void) |
114 | { |
115 | switch (tegra_sku_info.soc_speedo_id) { |
116 | case 0: |
117 | return 1100000; |
118 | case 1: |
119 | return 1025000; |
120 | default: |
121 | return 1125000; |
122 | } |
123 | } |
124 | |
125 | static int tegra20_core_nominal_uV(void) |
126 | { |
127 | switch (tegra_sku_info.soc_speedo_id) { |
128 | default: |
129 | return 1225000; |
130 | case 2: |
131 | return 1300000; |
132 | } |
133 | } |
134 | |
135 | static int tegra20_core_rtc_update(struct tegra_regulator_coupler *tegra, |
136 | struct regulator_dev *core_rdev, |
137 | struct regulator_dev *rtc_rdev, |
138 | int cpu_uV, int cpu_min_uV) |
139 | { |
140 | int core_min_uV, core_max_uV = INT_MAX; |
141 | int rtc_min_uV, rtc_max_uV = INT_MAX; |
142 | int core_target_uV; |
143 | int rtc_target_uV; |
144 | int max_spread; |
145 | int core_uV; |
146 | int rtc_uV; |
147 | int err; |
148 | |
149 | /* |
150 | * RTC and CORE voltages should be no more than 170mV from each other, |
151 | * CPU should be below RTC and CORE by at least 120mV. This applies |
152 | * to all Tegra20 SoC's. |
153 | */ |
154 | max_spread = tegra20_core_rtc_max_spread(core_rdev, rtc_rdev); |
155 | |
156 | /* |
157 | * The core voltage scaling is currently not hooked up in drivers, |
158 | * hence we will limit the minimum core voltage to a reasonable value. |
159 | * This should be good enough for the time being. |
160 | */ |
161 | core_min_uV = tegra20_core_limit(tegra, core_rdev); |
162 | if (core_min_uV < 0) |
163 | return core_min_uV; |
164 | |
165 | err = regulator_check_voltage(rdev: core_rdev, min_uV: &core_min_uV, max_uV: &core_max_uV); |
166 | if (err) |
167 | return err; |
168 | |
169 | err = regulator_check_consumers(rdev: core_rdev, min_uV: &core_min_uV, max_uV: &core_max_uV, |
170 | PM_SUSPEND_ON); |
171 | if (err) |
172 | return err; |
173 | |
174 | /* prepare voltage level for suspend */ |
175 | if (tegra->sys_suspend_mode) |
176 | core_min_uV = clamp(tegra20_core_nominal_uV(), |
177 | core_min_uV, core_max_uV); |
178 | |
179 | core_uV = regulator_get_voltage_rdev(rdev: core_rdev); |
180 | if (core_uV < 0) |
181 | return core_uV; |
182 | |
183 | core_min_uV = max(cpu_min_uV + 125000, core_min_uV); |
184 | if (core_min_uV > core_max_uV) |
185 | return -EINVAL; |
186 | |
187 | if (cpu_uV + 120000 > core_uV) |
188 | pr_err("core-cpu voltage constraint violated: %d %d\n" , |
189 | core_uV, cpu_uV + 120000); |
190 | |
191 | rtc_uV = regulator_get_voltage_rdev(rdev: rtc_rdev); |
192 | if (rtc_uV < 0) |
193 | return rtc_uV; |
194 | |
195 | if (cpu_uV + 120000 > rtc_uV) |
196 | pr_err("rtc-cpu voltage constraint violated: %d %d\n" , |
197 | rtc_uV, cpu_uV + 120000); |
198 | |
199 | if (abs(core_uV - rtc_uV) > 170000) |
200 | pr_err("core-rtc voltage constraint violated: %d %d\n" , |
201 | core_uV, rtc_uV); |
202 | |
203 | rtc_min_uV = max(cpu_min_uV + 125000, core_min_uV - max_spread); |
204 | |
205 | err = regulator_check_voltage(rdev: rtc_rdev, min_uV: &rtc_min_uV, max_uV: &rtc_max_uV); |
206 | if (err) |
207 | return err; |
208 | |
209 | while (core_uV != core_min_uV || rtc_uV != rtc_min_uV) { |
210 | if (core_uV < core_min_uV) { |
211 | core_target_uV = min(core_uV + max_spread, core_min_uV); |
212 | core_target_uV = min(rtc_uV + max_spread, core_target_uV); |
213 | } else { |
214 | core_target_uV = max(core_uV - max_spread, core_min_uV); |
215 | core_target_uV = max(rtc_uV - max_spread, core_target_uV); |
216 | } |
217 | |
218 | if (core_uV == core_target_uV) |
219 | goto update_rtc; |
220 | |
221 | err = regulator_set_voltage_rdev(rdev: core_rdev, |
222 | min_uV: core_target_uV, |
223 | max_uV: core_max_uV, |
224 | PM_SUSPEND_ON); |
225 | if (err) |
226 | return err; |
227 | |
228 | core_uV = core_target_uV; |
229 | update_rtc: |
230 | if (rtc_uV < rtc_min_uV) { |
231 | rtc_target_uV = min(rtc_uV + max_spread, rtc_min_uV); |
232 | rtc_target_uV = min(core_uV + max_spread, rtc_target_uV); |
233 | } else { |
234 | rtc_target_uV = max(rtc_uV - max_spread, rtc_min_uV); |
235 | rtc_target_uV = max(core_uV - max_spread, rtc_target_uV); |
236 | } |
237 | |
238 | if (rtc_uV == rtc_target_uV) |
239 | continue; |
240 | |
241 | err = regulator_set_voltage_rdev(rdev: rtc_rdev, |
242 | min_uV: rtc_target_uV, |
243 | max_uV: rtc_max_uV, |
244 | PM_SUSPEND_ON); |
245 | if (err) |
246 | return err; |
247 | |
248 | rtc_uV = rtc_target_uV; |
249 | } |
250 | |
251 | return 0; |
252 | } |
253 | |
254 | static int tegra20_core_voltage_update(struct tegra_regulator_coupler *tegra, |
255 | struct regulator_dev *cpu_rdev, |
256 | struct regulator_dev *core_rdev, |
257 | struct regulator_dev *rtc_rdev) |
258 | { |
259 | int cpu_uV; |
260 | |
261 | cpu_uV = regulator_get_voltage_rdev(rdev: cpu_rdev); |
262 | if (cpu_uV < 0) |
263 | return cpu_uV; |
264 | |
265 | return tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev, |
266 | cpu_uV, cpu_min_uV: cpu_uV); |
267 | } |
268 | |
269 | static int tegra20_cpu_voltage_update(struct tegra_regulator_coupler *tegra, |
270 | struct regulator_dev *cpu_rdev, |
271 | struct regulator_dev *core_rdev, |
272 | struct regulator_dev *rtc_rdev) |
273 | { |
274 | int cpu_min_uV_consumers = 0; |
275 | int cpu_max_uV = INT_MAX; |
276 | int cpu_min_uV = 0; |
277 | int cpu_uV; |
278 | int err; |
279 | |
280 | err = regulator_check_voltage(rdev: cpu_rdev, min_uV: &cpu_min_uV, max_uV: &cpu_max_uV); |
281 | if (err) |
282 | return err; |
283 | |
284 | err = regulator_check_consumers(rdev: cpu_rdev, min_uV: &cpu_min_uV, max_uV: &cpu_max_uV, |
285 | PM_SUSPEND_ON); |
286 | if (err) |
287 | return err; |
288 | |
289 | err = regulator_check_consumers(rdev: cpu_rdev, min_uV: &cpu_min_uV_consumers, |
290 | max_uV: &cpu_max_uV, PM_SUSPEND_ON); |
291 | if (err) |
292 | return err; |
293 | |
294 | cpu_uV = regulator_get_voltage_rdev(rdev: cpu_rdev); |
295 | if (cpu_uV < 0) |
296 | return cpu_uV; |
297 | |
298 | /* store boot voltage level */ |
299 | if (!tegra->cpu_min_uV) |
300 | tegra->cpu_min_uV = cpu_uV; |
301 | |
302 | /* |
303 | * CPU's regulator may not have any consumers, hence the voltage |
304 | * must not be changed in that case because CPU simply won't |
305 | * survive the voltage drop if it's running on a higher frequency. |
306 | */ |
307 | if (!cpu_min_uV_consumers) |
308 | cpu_min_uV = cpu_uV; |
309 | |
310 | /* restore boot voltage level */ |
311 | if (tegra->sys_reboot_mode) |
312 | cpu_min_uV = max(cpu_min_uV, tegra->cpu_min_uV); |
313 | |
314 | /* prepare voltage level for suspend */ |
315 | if (tegra->sys_suspend_mode) |
316 | cpu_min_uV = clamp(tegra20_cpu_nominal_uV(), |
317 | cpu_min_uV, cpu_max_uV); |
318 | |
319 | if (cpu_min_uV > cpu_uV) { |
320 | err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev, |
321 | cpu_uV, cpu_min_uV); |
322 | if (err) |
323 | return err; |
324 | |
325 | err = regulator_set_voltage_rdev(rdev: cpu_rdev, min_uV: cpu_min_uV, |
326 | max_uV: cpu_max_uV, PM_SUSPEND_ON); |
327 | if (err) |
328 | return err; |
329 | } else if (cpu_min_uV < cpu_uV) { |
330 | err = regulator_set_voltage_rdev(rdev: cpu_rdev, min_uV: cpu_min_uV, |
331 | max_uV: cpu_max_uV, PM_SUSPEND_ON); |
332 | if (err) |
333 | return err; |
334 | |
335 | err = tegra20_core_rtc_update(tegra, core_rdev, rtc_rdev, |
336 | cpu_uV, cpu_min_uV); |
337 | if (err) |
338 | return err; |
339 | } |
340 | |
341 | return 0; |
342 | } |
343 | |
344 | static int tegra20_regulator_balance_voltage(struct regulator_coupler *coupler, |
345 | struct regulator_dev *rdev, |
346 | suspend_state_t state) |
347 | { |
348 | struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler); |
349 | struct regulator_dev *core_rdev = tegra->core_rdev; |
350 | struct regulator_dev *cpu_rdev = tegra->cpu_rdev; |
351 | struct regulator_dev *rtc_rdev = tegra->rtc_rdev; |
352 | |
353 | if ((core_rdev != rdev && cpu_rdev != rdev && rtc_rdev != rdev) || |
354 | state != PM_SUSPEND_ON) { |
355 | pr_err("regulators are not coupled properly\n" ); |
356 | return -EINVAL; |
357 | } |
358 | |
359 | tegra->sys_reboot_mode = READ_ONCE(tegra->sys_reboot_mode_req); |
360 | tegra->sys_suspend_mode = READ_ONCE(tegra->sys_suspend_mode_req); |
361 | |
362 | if (rdev == cpu_rdev) |
363 | return tegra20_cpu_voltage_update(tegra, cpu_rdev, |
364 | core_rdev, rtc_rdev); |
365 | |
366 | if (rdev == core_rdev) |
367 | return tegra20_core_voltage_update(tegra, cpu_rdev, |
368 | core_rdev, rtc_rdev); |
369 | |
370 | pr_err("changing %s voltage not permitted\n" , rdev_get_name(rtc_rdev)); |
371 | |
372 | return -EPERM; |
373 | } |
374 | |
375 | static int tegra20_regulator_prepare_suspend(struct tegra_regulator_coupler *tegra, |
376 | bool sys_suspend_mode) |
377 | { |
378 | int err; |
379 | |
380 | if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev) |
381 | return 0; |
382 | |
383 | /* |
384 | * All power domains are enabled early during resume from suspend |
385 | * by GENPD core. Domains like VENC may require a higher voltage |
386 | * when enabled during resume from suspend. This also prepares |
387 | * hardware for resuming from LP0. |
388 | */ |
389 | |
390 | WRITE_ONCE(tegra->sys_suspend_mode_req, sys_suspend_mode); |
391 | |
392 | err = regulator_sync_voltage_rdev(rdev: tegra->cpu_rdev); |
393 | if (err) |
394 | return err; |
395 | |
396 | err = regulator_sync_voltage_rdev(rdev: tegra->core_rdev); |
397 | if (err) |
398 | return err; |
399 | |
400 | return 0; |
401 | } |
402 | |
403 | static int tegra20_regulator_suspend(struct notifier_block *notifier, |
404 | unsigned long mode, void *arg) |
405 | { |
406 | struct tegra_regulator_coupler *tegra; |
407 | int ret = 0; |
408 | |
409 | tegra = container_of(notifier, struct tegra_regulator_coupler, |
410 | suspend_notifier); |
411 | |
412 | switch (mode) { |
413 | case PM_HIBERNATION_PREPARE: |
414 | case PM_RESTORE_PREPARE: |
415 | case PM_SUSPEND_PREPARE: |
416 | ret = tegra20_regulator_prepare_suspend(tegra, sys_suspend_mode: true); |
417 | break; |
418 | |
419 | case PM_POST_HIBERNATION: |
420 | case PM_POST_RESTORE: |
421 | case PM_POST_SUSPEND: |
422 | ret = tegra20_regulator_prepare_suspend(tegra, sys_suspend_mode: false); |
423 | break; |
424 | } |
425 | |
426 | if (ret) |
427 | pr_err("failed to prepare regulators: %d\n" , ret); |
428 | |
429 | return notifier_from_errno(err: ret); |
430 | } |
431 | |
432 | static int tegra20_regulator_prepare_reboot(struct tegra_regulator_coupler *tegra, |
433 | bool sys_reboot_mode) |
434 | { |
435 | int err; |
436 | |
437 | if (!tegra->core_rdev || !tegra->rtc_rdev || !tegra->cpu_rdev) |
438 | return 0; |
439 | |
440 | WRITE_ONCE(tegra->sys_reboot_mode_req, true); |
441 | |
442 | /* |
443 | * Some devices use CPU soft-reboot method and in this case we |
444 | * should ensure that voltages are sane for the reboot by restoring |
445 | * the minimum boot levels. |
446 | */ |
447 | err = regulator_sync_voltage_rdev(rdev: tegra->cpu_rdev); |
448 | if (err) |
449 | return err; |
450 | |
451 | err = regulator_sync_voltage_rdev(rdev: tegra->core_rdev); |
452 | if (err) |
453 | return err; |
454 | |
455 | WRITE_ONCE(tegra->sys_reboot_mode_req, sys_reboot_mode); |
456 | |
457 | return 0; |
458 | } |
459 | |
460 | static int tegra20_regulator_reboot(struct notifier_block *notifier, |
461 | unsigned long event, void *cmd) |
462 | { |
463 | struct tegra_regulator_coupler *tegra; |
464 | int ret; |
465 | |
466 | if (event != SYS_RESTART) |
467 | return NOTIFY_DONE; |
468 | |
469 | tegra = container_of(notifier, struct tegra_regulator_coupler, |
470 | reboot_notifier); |
471 | |
472 | ret = tegra20_regulator_prepare_reboot(tegra, sys_reboot_mode: true); |
473 | |
474 | return notifier_from_errno(err: ret); |
475 | } |
476 | |
477 | static int tegra20_regulator_attach(struct regulator_coupler *coupler, |
478 | struct regulator_dev *rdev) |
479 | { |
480 | struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler); |
481 | struct device_node *np = rdev->dev.of_node; |
482 | |
483 | if (of_property_read_bool(np, propname: "nvidia,tegra-core-regulator" ) && |
484 | !tegra->core_rdev) { |
485 | tegra->core_rdev = rdev; |
486 | return 0; |
487 | } |
488 | |
489 | if (of_property_read_bool(np, propname: "nvidia,tegra-rtc-regulator" ) && |
490 | !tegra->rtc_rdev) { |
491 | tegra->rtc_rdev = rdev; |
492 | return 0; |
493 | } |
494 | |
495 | if (of_property_read_bool(np, propname: "nvidia,tegra-cpu-regulator" ) && |
496 | !tegra->cpu_rdev) { |
497 | tegra->cpu_rdev = rdev; |
498 | return 0; |
499 | } |
500 | |
501 | return -EINVAL; |
502 | } |
503 | |
504 | static int tegra20_regulator_detach(struct regulator_coupler *coupler, |
505 | struct regulator_dev *rdev) |
506 | { |
507 | struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler); |
508 | |
509 | /* |
510 | * We don't expect regulators to be decoupled during reboot, |
511 | * this may race with the reboot handler and shouldn't ever |
512 | * happen in practice. |
513 | */ |
514 | if (WARN_ON_ONCE(system_state > SYSTEM_RUNNING)) |
515 | return -EPERM; |
516 | |
517 | if (tegra->core_rdev == rdev) { |
518 | tegra->core_rdev = NULL; |
519 | return 0; |
520 | } |
521 | |
522 | if (tegra->rtc_rdev == rdev) { |
523 | tegra->rtc_rdev = NULL; |
524 | return 0; |
525 | } |
526 | |
527 | if (tegra->cpu_rdev == rdev) { |
528 | tegra->cpu_rdev = NULL; |
529 | return 0; |
530 | } |
531 | |
532 | return -EINVAL; |
533 | } |
534 | |
535 | static struct tegra_regulator_coupler tegra20_coupler = { |
536 | .coupler = { |
537 | .attach_regulator = tegra20_regulator_attach, |
538 | .detach_regulator = tegra20_regulator_detach, |
539 | .balance_voltage = tegra20_regulator_balance_voltage, |
540 | }, |
541 | .reboot_notifier.notifier_call = tegra20_regulator_reboot, |
542 | .suspend_notifier.notifier_call = tegra20_regulator_suspend, |
543 | }; |
544 | |
545 | static int __init tegra_regulator_coupler_init(void) |
546 | { |
547 | int err; |
548 | |
549 | if (!of_machine_is_compatible(compat: "nvidia,tegra20" )) |
550 | return 0; |
551 | |
552 | err = register_reboot_notifier(&tegra20_coupler.reboot_notifier); |
553 | WARN_ON(err); |
554 | |
555 | err = register_pm_notifier(nb: &tegra20_coupler.suspend_notifier); |
556 | WARN_ON(err); |
557 | |
558 | return regulator_coupler_register(coupler: &tegra20_coupler.coupler); |
559 | } |
560 | arch_initcall(tegra_regulator_coupler_init); |
561 | |