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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Driver for voltage controller regulators
4 *
5 * Copyright (C) 2017 Google, Inc.
6 */
7
8#include <linux/delay.h>
9#include <linux/err.h>
10#include <linux/init.h>
11#include <linux/module.h>
12#include <linux/of.h>
13#include <linux/of_device.h>
14#include <linux/regulator/driver.h>
15#include <linux/regulator/of_regulator.h>
16#include <linux/sort.h>
17
18struct vctrl_voltage_range {
19 int min_uV;
20 int max_uV;
21};
22
23struct vctrl_voltage_ranges {
24 struct vctrl_voltage_range ctrl;
25 struct vctrl_voltage_range out;
26};
27
28struct vctrl_voltage_table {
29 int ctrl;
30 int out;
31 int ovp_min_sel;
32};
33
34struct vctrl_data {
35 struct regulator_dev *rdev;
36 struct regulator_desc desc;
37 struct regulator *ctrl_reg;
38 bool enabled;
39 unsigned int min_slew_down_rate;
40 unsigned int ovp_threshold;
41 struct vctrl_voltage_ranges vrange;
42 struct vctrl_voltage_table *vtable;
43 unsigned int sel;
44};
45
46static int vctrl_calc_ctrl_voltage(struct vctrl_data *vctrl, int out_uV)
47{
48 struct vctrl_voltage_range *ctrl = &vctrl->vrange.ctrl;
49 struct vctrl_voltage_range *out = &vctrl->vrange.out;
50
51 return ctrl->min_uV +
52 DIV_ROUND_CLOSEST_ULL((s64)(out_uV - out->min_uV) *
53 (ctrl->max_uV - ctrl->min_uV),
54 out->max_uV - out->min_uV);
55}
56
57static int vctrl_calc_output_voltage(struct vctrl_data *vctrl, int ctrl_uV)
58{
59 struct vctrl_voltage_range *ctrl = &vctrl->vrange.ctrl;
60 struct vctrl_voltage_range *out = &vctrl->vrange.out;
61
62 if (ctrl_uV < 0) {
63 pr_err("vctrl: failed to get control voltage\n");
64 return ctrl_uV;
65 }
66
67 if (ctrl_uV < ctrl->min_uV)
68 return out->min_uV;
69
70 if (ctrl_uV > ctrl->max_uV)
71 return out->max_uV;
72
73 return out->min_uV +
74 DIV_ROUND_CLOSEST_ULL((s64)(ctrl_uV - ctrl->min_uV) *
75 (out->max_uV - out->min_uV),
76 ctrl->max_uV - ctrl->min_uV);
77}
78
79static int vctrl_get_voltage(struct regulator_dev *rdev)
80{
81 struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
82 int ctrl_uV = regulator_get_voltage(vctrl->ctrl_reg);
83
84 return vctrl_calc_output_voltage(vctrl, ctrl_uV);
85}
86
87static int vctrl_set_voltage(struct regulator_dev *rdev,
88 int req_min_uV, int req_max_uV,
89 unsigned int *selector)
90{
91 struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
92 struct regulator *ctrl_reg = vctrl->ctrl_reg;
93 int orig_ctrl_uV = regulator_get_voltage(ctrl_reg);
94 int uV = vctrl_calc_output_voltage(vctrl, orig_ctrl_uV);
95 int ret;
96
97 if (req_min_uV >= uV || !vctrl->ovp_threshold)
98 /* voltage rising or no OVP */
99 return regulator_set_voltage(
100 ctrl_reg,
101 vctrl_calc_ctrl_voltage(vctrl, req_min_uV),
102 vctrl_calc_ctrl_voltage(vctrl, req_max_uV));
103
104 while (uV > req_min_uV) {
105 int max_drop_uV = (uV * vctrl->ovp_threshold) / 100;
106 int next_uV;
107 int next_ctrl_uV;
108 int delay;
109
110 /* Make sure no infinite loop even in crazy cases */
111 if (max_drop_uV == 0)
112 max_drop_uV = 1;
113
114 next_uV = max_t(int, req_min_uV, uV - max_drop_uV);
115 next_ctrl_uV = vctrl_calc_ctrl_voltage(vctrl, next_uV);
116
117 ret = regulator_set_voltage(ctrl_reg,
118 next_ctrl_uV,
119 next_ctrl_uV);
120 if (ret)
121 goto err;
122
123 delay = DIV_ROUND_UP(uV - next_uV, vctrl->min_slew_down_rate);
124 usleep_range(delay, delay + DIV_ROUND_UP(delay, 10));
125
126 uV = next_uV;
127 }
128
129 return 0;
130
131err:
132 /* Try to go back to original voltage */
133 regulator_set_voltage(ctrl_reg, orig_ctrl_uV, orig_ctrl_uV);
134
135 return ret;
136}
137
138static int vctrl_get_voltage_sel(struct regulator_dev *rdev)
139{
140 struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
141
142 return vctrl->sel;
143}
144
145static int vctrl_set_voltage_sel(struct regulator_dev *rdev,
146 unsigned int selector)
147{
148 struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
149 struct regulator *ctrl_reg = vctrl->ctrl_reg;
150 unsigned int orig_sel = vctrl->sel;
151 int ret;
152
153 if (selector >= rdev->desc->n_voltages)
154 return -EINVAL;
155
156 if (selector >= vctrl->sel || !vctrl->ovp_threshold) {
157 /* voltage rising or no OVP */
158 ret = regulator_set_voltage(ctrl_reg,
159 vctrl->vtable[selector].ctrl,
160 vctrl->vtable[selector].ctrl);
161 if (!ret)
162 vctrl->sel = selector;
163
164 return ret;
165 }
166
167 while (vctrl->sel != selector) {
168 unsigned int next_sel;
169 int delay;
170
171 if (selector >= vctrl->vtable[vctrl->sel].ovp_min_sel)
172 next_sel = selector;
173 else
174 next_sel = vctrl->vtable[vctrl->sel].ovp_min_sel;
175
176 ret = regulator_set_voltage(ctrl_reg,
177 vctrl->vtable[next_sel].ctrl,
178 vctrl->vtable[next_sel].ctrl);
179 if (ret) {
180 dev_err(&rdev->dev,
181 "failed to set control voltage to %duV\n",
182 vctrl->vtable[next_sel].ctrl);
183 goto err;
184 }
185 vctrl->sel = next_sel;
186
187 delay = DIV_ROUND_UP(vctrl->vtable[vctrl->sel].out -
188 vctrl->vtable[next_sel].out,
189 vctrl->min_slew_down_rate);
190 usleep_range(delay, delay + DIV_ROUND_UP(delay, 10));
191 }
192
193 return 0;
194
195err:
196 if (vctrl->sel != orig_sel) {
197 /* Try to go back to original voltage */
198 if (!regulator_set_voltage(ctrl_reg,
199 vctrl->vtable[orig_sel].ctrl,
200 vctrl->vtable[orig_sel].ctrl))
201 vctrl->sel = orig_sel;
202 else
203 dev_warn(&rdev->dev,
204 "failed to restore original voltage\n");
205 }
206
207 return ret;
208}
209
210static int vctrl_list_voltage(struct regulator_dev *rdev,
211 unsigned int selector)
212{
213 struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
214
215 if (selector >= rdev->desc->n_voltages)
216 return -EINVAL;
217
218 return vctrl->vtable[selector].out;
219}
220
221static int vctrl_parse_dt(struct platform_device *pdev,
222 struct vctrl_data *vctrl)
223{
224 int ret;
225 struct device_node *np = pdev->dev.of_node;
226 u32 pval;
227 u32 vrange_ctrl[2];
228
229 vctrl->ctrl_reg = devm_regulator_get(&pdev->dev, "ctrl");
230 if (IS_ERR(vctrl->ctrl_reg))
231 return PTR_ERR(vctrl->ctrl_reg);
232
233 ret = of_property_read_u32(np, "ovp-threshold-percent", &pval);
234 if (!ret) {
235 vctrl->ovp_threshold = pval;
236 if (vctrl->ovp_threshold > 100) {
237 dev_err(&pdev->dev,
238 "ovp-threshold-percent (%u) > 100\n",
239 vctrl->ovp_threshold);
240 return -EINVAL;
241 }
242 }
243
244 ret = of_property_read_u32(np, "min-slew-down-rate", &pval);
245 if (!ret) {
246 vctrl->min_slew_down_rate = pval;
247
248 /* We use the value as int and as divider; sanity check */
249 if (vctrl->min_slew_down_rate == 0) {
250 dev_err(&pdev->dev,
251 "min-slew-down-rate must not be 0\n");
252 return -EINVAL;
253 } else if (vctrl->min_slew_down_rate > INT_MAX) {
254 dev_err(&pdev->dev, "min-slew-down-rate (%u) too big\n",
255 vctrl->min_slew_down_rate);
256 return -EINVAL;
257 }
258 }
259
260 if (vctrl->ovp_threshold && !vctrl->min_slew_down_rate) {
261 dev_err(&pdev->dev,
262 "ovp-threshold-percent requires min-slew-down-rate\n");
263 return -EINVAL;
264 }
265
266 ret = of_property_read_u32(np, "regulator-min-microvolt", &pval);
267 if (ret) {
268 dev_err(&pdev->dev,
269 "failed to read regulator-min-microvolt: %d\n", ret);
270 return ret;
271 }
272 vctrl->vrange.out.min_uV = pval;
273
274 ret = of_property_read_u32(np, "regulator-max-microvolt", &pval);
275 if (ret) {
276 dev_err(&pdev->dev,
277 "failed to read regulator-max-microvolt: %d\n", ret);
278 return ret;
279 }
280 vctrl->vrange.out.max_uV = pval;
281
282 ret = of_property_read_u32_array(np, "ctrl-voltage-range", vrange_ctrl,
283 2);
284 if (ret) {
285 dev_err(&pdev->dev, "failed to read ctrl-voltage-range: %d\n",
286 ret);
287 return ret;
288 }
289
290 if (vrange_ctrl[0] >= vrange_ctrl[1]) {
291 dev_err(&pdev->dev, "ctrl-voltage-range is invalid: %d-%d\n",
292 vrange_ctrl[0], vrange_ctrl[1]);
293 return -EINVAL;
294 }
295
296 vctrl->vrange.ctrl.min_uV = vrange_ctrl[0];
297 vctrl->vrange.ctrl.max_uV = vrange_ctrl[1];
298
299 return 0;
300}
301
302static int vctrl_cmp_ctrl_uV(const void *a, const void *b)
303{
304 const struct vctrl_voltage_table *at = a;
305 const struct vctrl_voltage_table *bt = b;
306
307 return at->ctrl - bt->ctrl;
308}
309
310static int vctrl_init_vtable(struct platform_device *pdev)
311{
312 struct vctrl_data *vctrl = platform_get_drvdata(pdev);
313 struct regulator_desc *rdesc = &vctrl->desc;
314 struct regulator *ctrl_reg = vctrl->ctrl_reg;
315 struct vctrl_voltage_range *vrange_ctrl = &vctrl->vrange.ctrl;
316 int n_voltages;
317 int ctrl_uV;
318 int i, idx_vt;
319
320 n_voltages = regulator_count_voltages(ctrl_reg);
321
322 rdesc->n_voltages = n_voltages;
323
324 /* determine number of steps within the range of the vctrl regulator */
325 for (i = 0; i < n_voltages; i++) {
326 ctrl_uV = regulator_list_voltage(ctrl_reg, i);
327
328 if (ctrl_uV < vrange_ctrl->min_uV ||
329 ctrl_uV > vrange_ctrl->max_uV)
330 rdesc->n_voltages--;
331 }
332
333 if (rdesc->n_voltages == 0) {
334 dev_err(&pdev->dev, "invalid configuration\n");
335 return -EINVAL;
336 }
337
338 vctrl->vtable = devm_kcalloc(&pdev->dev, rdesc->n_voltages,
339 sizeof(struct vctrl_voltage_table),
340 GFP_KERNEL);
341 if (!vctrl->vtable)
342 return -ENOMEM;
343
344 /* create mapping control <=> output voltage */
345 for (i = 0, idx_vt = 0; i < n_voltages; i++) {
346 ctrl_uV = regulator_list_voltage(ctrl_reg, i);
347
348 if (ctrl_uV < vrange_ctrl->min_uV ||
349 ctrl_uV > vrange_ctrl->max_uV)
350 continue;
351
352 vctrl->vtable[idx_vt].ctrl = ctrl_uV;
353 vctrl->vtable[idx_vt].out =
354 vctrl_calc_output_voltage(vctrl, ctrl_uV);
355 idx_vt++;
356 }
357
358 /* we rely on the table to be ordered by ascending voltage */
359 sort(vctrl->vtable, rdesc->n_voltages,
360 sizeof(struct vctrl_voltage_table), vctrl_cmp_ctrl_uV,
361 NULL);
362
363 /* pre-calculate OVP-safe downward transitions */
364 for (i = rdesc->n_voltages - 1; i > 0; i--) {
365 int j;
366 int ovp_min_uV = (vctrl->vtable[i].out *
367 (100 - vctrl->ovp_threshold)) / 100;
368
369 for (j = 0; j < i; j++) {
370 if (vctrl->vtable[j].out >= ovp_min_uV) {
371 vctrl->vtable[i].ovp_min_sel = j;
372 break;
373 }
374 }
375
376 if (j == i) {
377 dev_warn(&pdev->dev, "switching down from %duV may cause OVP shutdown\n",
378 vctrl->vtable[i].out);
379 /* use next lowest voltage */
380 vctrl->vtable[i].ovp_min_sel = i - 1;
381 }
382 }
383
384 return 0;
385}
386
387static int vctrl_enable(struct regulator_dev *rdev)
388{
389 struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
390 int ret = regulator_enable(vctrl->ctrl_reg);
391
392 if (!ret)
393 vctrl->enabled = true;
394
395 return ret;
396}
397
398static int vctrl_disable(struct regulator_dev *rdev)
399{
400 struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
401 int ret = regulator_disable(vctrl->ctrl_reg);
402
403 if (!ret)
404 vctrl->enabled = false;
405
406 return ret;
407}
408
409static int vctrl_is_enabled(struct regulator_dev *rdev)
410{
411 struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
412
413 return vctrl->enabled;
414}
415
416static const struct regulator_ops vctrl_ops_cont = {
417 .enable = vctrl_enable,
418 .disable = vctrl_disable,
419 .is_enabled = vctrl_is_enabled,
420 .get_voltage = vctrl_get_voltage,
421 .set_voltage = vctrl_set_voltage,
422};
423
424static const struct regulator_ops vctrl_ops_non_cont = {
425 .enable = vctrl_enable,
426 .disable = vctrl_disable,
427 .is_enabled = vctrl_is_enabled,
428 .set_voltage_sel = vctrl_set_voltage_sel,
429 .get_voltage_sel = vctrl_get_voltage_sel,
430 .list_voltage = vctrl_list_voltage,
431 .map_voltage = regulator_map_voltage_iterate,
432};
433
434static int vctrl_probe(struct platform_device *pdev)
435{
436 struct device_node *np = pdev->dev.of_node;
437 struct vctrl_data *vctrl;
438 const struct regulator_init_data *init_data;
439 struct regulator_desc *rdesc;
440 struct regulator_config cfg = { };
441 struct vctrl_voltage_range *vrange_ctrl;
442 int ctrl_uV;
443 int ret;
444
445 vctrl = devm_kzalloc(&pdev->dev, sizeof(struct vctrl_data),
446 GFP_KERNEL);
447 if (!vctrl)
448 return -ENOMEM;
449
450 platform_set_drvdata(pdev, vctrl);
451
452 ret = vctrl_parse_dt(pdev, vctrl);
453 if (ret)
454 return ret;
455
456 vrange_ctrl = &vctrl->vrange.ctrl;
457
458 rdesc = &vctrl->desc;
459 rdesc->name = "vctrl";
460 rdesc->type = REGULATOR_VOLTAGE;
461 rdesc->owner = THIS_MODULE;
462
463 if ((regulator_get_linear_step(vctrl->ctrl_reg) == 1) ||
464 (regulator_count_voltages(vctrl->ctrl_reg) == -EINVAL)) {
465 rdesc->continuous_voltage_range = true;
466 rdesc->ops = &vctrl_ops_cont;
467 } else {
468 rdesc->ops = &vctrl_ops_non_cont;
469 }
470
471 init_data = of_get_regulator_init_data(&pdev->dev, np, rdesc);
472 if (!init_data)
473 return -ENOMEM;
474
475 cfg.of_node = np;
476 cfg.dev = &pdev->dev;
477 cfg.driver_data = vctrl;
478 cfg.init_data = init_data;
479
480 if (!rdesc->continuous_voltage_range) {
481 ret = vctrl_init_vtable(pdev);
482 if (ret)
483 return ret;
484
485 ctrl_uV = regulator_get_voltage(vctrl->ctrl_reg);
486 if (ctrl_uV < 0) {
487 dev_err(&pdev->dev, "failed to get control voltage\n");
488 return ctrl_uV;
489 }
490
491 /* determine current voltage selector from control voltage */
492 if (ctrl_uV < vrange_ctrl->min_uV) {
493 vctrl->sel = 0;
494 } else if (ctrl_uV > vrange_ctrl->max_uV) {
495 vctrl->sel = rdesc->n_voltages - 1;
496 } else {
497 int i;
498
499 for (i = 0; i < rdesc->n_voltages; i++) {
500 if (ctrl_uV == vctrl->vtable[i].ctrl) {
501 vctrl->sel = i;
502 break;
503 }
504 }
505 }
506 }
507
508 vctrl->rdev = devm_regulator_register(&pdev->dev, rdesc, &cfg);
509 if (IS_ERR(vctrl->rdev)) {
510 ret = PTR_ERR(vctrl->rdev);
511 dev_err(&pdev->dev, "failed to register regulator: %d\n", ret);
512 return ret;
513 }
514
515 return 0;
516}
517
518static const struct of_device_id vctrl_of_match[] = {
519 { .compatible = "vctrl-regulator", },
520 {},
521};
522MODULE_DEVICE_TABLE(of, vctrl_of_match);
523
524static struct platform_driver vctrl_driver = {
525 .probe = vctrl_probe,
526 .driver = {
527 .name = "vctrl-regulator",
528 .of_match_table = of_match_ptr(vctrl_of_match),
529 },
530};
531
532module_platform_driver(vctrl_driver);
533
534MODULE_DESCRIPTION("Voltage Controlled Regulator Driver");
535MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
536MODULE_LICENSE("GPL v2");