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/platform_device.h>
14 #include <linux/regulator/coupler.h>
15 #include <linux/regulator/driver.h>
16 #include <linux/regulator/of_regulator.h>
17 #include <linux/sort.h>
18 
19 #include "internal.h"
20 
21 struct vctrl_voltage_range {
22 	int min_uV;
23 	int max_uV;
24 };
25 
26 struct vctrl_voltage_ranges {
27 	struct vctrl_voltage_range ctrl;
28 	struct vctrl_voltage_range out;
29 };
30 
31 struct vctrl_voltage_table {
32 	int ctrl;
33 	int out;
34 	int ovp_min_sel;
35 };
36 
37 struct vctrl_data {
38 	struct regulator_dev *rdev;
39 	struct regulator_desc desc;
40 	bool enabled;
41 	unsigned int min_slew_down_rate;
42 	unsigned int ovp_threshold;
43 	struct vctrl_voltage_ranges vrange;
44 	struct vctrl_voltage_table *vtable;
45 	unsigned int sel;
46 };
47 
48 static int vctrl_calc_ctrl_voltage(struct vctrl_data *vctrl, int out_uV)
49 {
50 	struct vctrl_voltage_range *ctrl = &vctrl->vrange.ctrl;
51 	struct vctrl_voltage_range *out = &vctrl->vrange.out;
52 
53 	return ctrl->min_uV +
54 		DIV_ROUND_CLOSEST_ULL((s64)(out_uV - out->min_uV) *
55 				      (ctrl->max_uV - ctrl->min_uV),
56 				      out->max_uV - out->min_uV);
57 }
58 
59 static int vctrl_calc_output_voltage(struct vctrl_data *vctrl, int ctrl_uV)
60 {
61 	struct vctrl_voltage_range *ctrl = &vctrl->vrange.ctrl;
62 	struct vctrl_voltage_range *out = &vctrl->vrange.out;
63 
64 	if (ctrl_uV < 0) {
65 		pr_err("vctrl: failed to get control voltage\n");
66 		return ctrl_uV;
67 	}
68 
69 	if (ctrl_uV < ctrl->min_uV)
70 		return out->min_uV;
71 
72 	if (ctrl_uV > ctrl->max_uV)
73 		return out->max_uV;
74 
75 	return out->min_uV +
76 		DIV_ROUND_CLOSEST_ULL((s64)(ctrl_uV - ctrl->min_uV) *
77 				      (out->max_uV - out->min_uV),
78 				      ctrl->max_uV - ctrl->min_uV);
79 }
80 
81 static int vctrl_get_voltage(struct regulator_dev *rdev)
82 {
83 	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
84 	int ctrl_uV;
85 
86 	if (!rdev->supply)
87 		return -EPROBE_DEFER;
88 
89 	ctrl_uV = regulator_get_voltage_rdev(rdev->supply->rdev);
90 
91 	return vctrl_calc_output_voltage(vctrl, ctrl_uV);
92 }
93 
94 static int vctrl_set_voltage(struct regulator_dev *rdev,
95 			     int req_min_uV, int req_max_uV,
96 			     unsigned int *selector)
97 {
98 	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
99 	int orig_ctrl_uV;
100 	int uV;
101 	int ret;
102 
103 	if (!rdev->supply)
104 		return -EPROBE_DEFER;
105 
106 	orig_ctrl_uV = regulator_get_voltage_rdev(rdev->supply->rdev);
107 	uV = vctrl_calc_output_voltage(vctrl, orig_ctrl_uV);
108 
109 	if (req_min_uV >= uV || !vctrl->ovp_threshold)
110 		/* voltage rising or no OVP */
111 		return regulator_set_voltage_rdev(rdev->supply->rdev,
112 			vctrl_calc_ctrl_voltage(vctrl, req_min_uV),
113 			vctrl_calc_ctrl_voltage(vctrl, req_max_uV),
114 			PM_SUSPEND_ON);
115 
116 	while (uV > req_min_uV) {
117 		int max_drop_uV = (uV * vctrl->ovp_threshold) / 100;
118 		int next_uV;
119 		int next_ctrl_uV;
120 		int delay;
121 
122 		/* Make sure no infinite loop even in crazy cases */
123 		if (max_drop_uV == 0)
124 			max_drop_uV = 1;
125 
126 		next_uV = max_t(int, req_min_uV, uV - max_drop_uV);
127 		next_ctrl_uV = vctrl_calc_ctrl_voltage(vctrl, next_uV);
128 
129 		ret = regulator_set_voltage_rdev(rdev->supply->rdev,
130 					    next_ctrl_uV,
131 					    next_ctrl_uV,
132 					    PM_SUSPEND_ON);
133 		if (ret)
134 			goto err;
135 
136 		delay = DIV_ROUND_UP(uV - next_uV, vctrl->min_slew_down_rate);
137 		usleep_range(delay, delay + DIV_ROUND_UP(delay, 10));
138 
139 		uV = next_uV;
140 	}
141 
142 	return 0;
143 
144 err:
145 	/* Try to go back to original voltage */
146 	regulator_set_voltage_rdev(rdev->supply->rdev, orig_ctrl_uV, orig_ctrl_uV,
147 				   PM_SUSPEND_ON);
148 
149 	return ret;
150 }
151 
152 static int vctrl_get_voltage_sel(struct regulator_dev *rdev)
153 {
154 	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
155 
156 	return vctrl->sel;
157 }
158 
159 static int vctrl_set_voltage_sel(struct regulator_dev *rdev,
160 				 unsigned int selector)
161 {
162 	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
163 	unsigned int orig_sel = vctrl->sel;
164 	int ret;
165 
166 	if (!rdev->supply)
167 		return -EPROBE_DEFER;
168 
169 	if (selector >= rdev->desc->n_voltages)
170 		return -EINVAL;
171 
172 	if (selector >= vctrl->sel || !vctrl->ovp_threshold) {
173 		/* voltage rising or no OVP */
174 		ret = regulator_set_voltage_rdev(rdev->supply->rdev,
175 					    vctrl->vtable[selector].ctrl,
176 					    vctrl->vtable[selector].ctrl,
177 					    PM_SUSPEND_ON);
178 		if (!ret)
179 			vctrl->sel = selector;
180 
181 		return ret;
182 	}
183 
184 	while (vctrl->sel != selector) {
185 		unsigned int next_sel;
186 		int delay;
187 
188 		next_sel = max_t(unsigned int, selector, vctrl->vtable[vctrl->sel].ovp_min_sel);
189 
190 		ret = regulator_set_voltage_rdev(rdev->supply->rdev,
191 					    vctrl->vtable[next_sel].ctrl,
192 					    vctrl->vtable[next_sel].ctrl,
193 					    PM_SUSPEND_ON);
194 		if (ret) {
195 			dev_err(&rdev->dev,
196 				"failed to set control voltage to %duV\n",
197 				vctrl->vtable[next_sel].ctrl);
198 			goto err;
199 		}
200 		vctrl->sel = next_sel;
201 
202 		delay = DIV_ROUND_UP(vctrl->vtable[vctrl->sel].out -
203 				     vctrl->vtable[next_sel].out,
204 				     vctrl->min_slew_down_rate);
205 		usleep_range(delay, delay + DIV_ROUND_UP(delay, 10));
206 	}
207 
208 	return 0;
209 
210 err:
211 	if (vctrl->sel != orig_sel) {
212 		/* Try to go back to original voltage */
213 		if (!regulator_set_voltage_rdev(rdev->supply->rdev,
214 					   vctrl->vtable[orig_sel].ctrl,
215 					   vctrl->vtable[orig_sel].ctrl,
216 					   PM_SUSPEND_ON))
217 			vctrl->sel = orig_sel;
218 		else
219 			dev_warn(&rdev->dev,
220 				 "failed to restore original voltage\n");
221 	}
222 
223 	return ret;
224 }
225 
226 static int vctrl_list_voltage(struct regulator_dev *rdev,
227 			      unsigned int selector)
228 {
229 	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
230 
231 	if (selector >= rdev->desc->n_voltages)
232 		return -EINVAL;
233 
234 	return vctrl->vtable[selector].out;
235 }
236 
237 static int vctrl_parse_dt(struct platform_device *pdev,
238 			  struct vctrl_data *vctrl)
239 {
240 	int ret;
241 	struct device_node *np = pdev->dev.of_node;
242 	u32 pval;
243 	u32 vrange_ctrl[2];
244 
245 	ret = of_property_read_u32(np, "ovp-threshold-percent", &pval);
246 	if (!ret) {
247 		vctrl->ovp_threshold = pval;
248 		if (vctrl->ovp_threshold > 100) {
249 			dev_err(&pdev->dev,
250 				"ovp-threshold-percent (%u) > 100\n",
251 				vctrl->ovp_threshold);
252 			return -EINVAL;
253 		}
254 	}
255 
256 	ret = of_property_read_u32(np, "min-slew-down-rate", &pval);
257 	if (!ret) {
258 		vctrl->min_slew_down_rate = pval;
259 
260 		/* We use the value as int and as divider; sanity check */
261 		if (vctrl->min_slew_down_rate == 0) {
262 			dev_err(&pdev->dev,
263 				"min-slew-down-rate must not be 0\n");
264 			return -EINVAL;
265 		} else if (vctrl->min_slew_down_rate > INT_MAX) {
266 			dev_err(&pdev->dev, "min-slew-down-rate (%u) too big\n",
267 				vctrl->min_slew_down_rate);
268 			return -EINVAL;
269 		}
270 	}
271 
272 	if (vctrl->ovp_threshold && !vctrl->min_slew_down_rate) {
273 		dev_err(&pdev->dev,
274 			"ovp-threshold-percent requires min-slew-down-rate\n");
275 		return -EINVAL;
276 	}
277 
278 	ret = of_property_read_u32(np, "regulator-min-microvolt", &pval);
279 	if (ret) {
280 		dev_err(&pdev->dev,
281 			"failed to read regulator-min-microvolt: %d\n", ret);
282 		return ret;
283 	}
284 	vctrl->vrange.out.min_uV = pval;
285 
286 	ret = of_property_read_u32(np, "regulator-max-microvolt", &pval);
287 	if (ret) {
288 		dev_err(&pdev->dev,
289 			"failed to read regulator-max-microvolt: %d\n", ret);
290 		return ret;
291 	}
292 	vctrl->vrange.out.max_uV = pval;
293 
294 	ret = of_property_read_u32_array(np, "ctrl-voltage-range", vrange_ctrl,
295 					 2);
296 	if (ret) {
297 		dev_err(&pdev->dev, "failed to read ctrl-voltage-range: %d\n",
298 			ret);
299 		return ret;
300 	}
301 
302 	if (vrange_ctrl[0] >= vrange_ctrl[1]) {
303 		dev_err(&pdev->dev, "ctrl-voltage-range is invalid: %d-%d\n",
304 			vrange_ctrl[0], vrange_ctrl[1]);
305 		return -EINVAL;
306 	}
307 
308 	vctrl->vrange.ctrl.min_uV = vrange_ctrl[0];
309 	vctrl->vrange.ctrl.max_uV = vrange_ctrl[1];
310 
311 	return 0;
312 }
313 
314 static int vctrl_cmp_ctrl_uV(const void *a, const void *b)
315 {
316 	const struct vctrl_voltage_table *at = a;
317 	const struct vctrl_voltage_table *bt = b;
318 
319 	return at->ctrl - bt->ctrl;
320 }
321 
322 static int vctrl_init_vtable(struct platform_device *pdev,
323 			     struct regulator *ctrl_reg)
324 {
325 	struct vctrl_data *vctrl = platform_get_drvdata(pdev);
326 	struct regulator_desc *rdesc = &vctrl->desc;
327 	struct vctrl_voltage_range *vrange_ctrl = &vctrl->vrange.ctrl;
328 	int n_voltages;
329 	int ctrl_uV;
330 	int i, idx_vt;
331 
332 	n_voltages = regulator_count_voltages(ctrl_reg);
333 
334 	rdesc->n_voltages = n_voltages;
335 
336 	/* determine number of steps within the range of the vctrl regulator */
337 	for (i = 0; i < n_voltages; i++) {
338 		ctrl_uV = regulator_list_voltage(ctrl_reg, i);
339 
340 		if (ctrl_uV < vrange_ctrl->min_uV ||
341 		    ctrl_uV > vrange_ctrl->max_uV)
342 			rdesc->n_voltages--;
343 	}
344 
345 	if (rdesc->n_voltages == 0) {
346 		dev_err(&pdev->dev, "invalid configuration\n");
347 		return -EINVAL;
348 	}
349 
350 	vctrl->vtable = devm_kcalloc(&pdev->dev, rdesc->n_voltages,
351 				     sizeof(struct vctrl_voltage_table),
352 				     GFP_KERNEL);
353 	if (!vctrl->vtable)
354 		return -ENOMEM;
355 
356 	/* create mapping control <=> output voltage */
357 	for (i = 0, idx_vt = 0; i < n_voltages; i++) {
358 		ctrl_uV = regulator_list_voltage(ctrl_reg, i);
359 
360 		if (ctrl_uV < vrange_ctrl->min_uV ||
361 		    ctrl_uV > vrange_ctrl->max_uV)
362 			continue;
363 
364 		vctrl->vtable[idx_vt].ctrl = ctrl_uV;
365 		vctrl->vtable[idx_vt].out =
366 			vctrl_calc_output_voltage(vctrl, ctrl_uV);
367 		idx_vt++;
368 	}
369 
370 	/* we rely on the table to be ordered by ascending voltage */
371 	sort(vctrl->vtable, rdesc->n_voltages,
372 	     sizeof(struct vctrl_voltage_table), vctrl_cmp_ctrl_uV,
373 	     NULL);
374 
375 	/* pre-calculate OVP-safe downward transitions */
376 	for (i = rdesc->n_voltages - 1; i > 0; i--) {
377 		int j;
378 		int ovp_min_uV = (vctrl->vtable[i].out *
379 				  (100 - vctrl->ovp_threshold)) / 100;
380 
381 		for (j = 0; j < i; j++) {
382 			if (vctrl->vtable[j].out >= ovp_min_uV) {
383 				vctrl->vtable[i].ovp_min_sel = j;
384 				break;
385 			}
386 		}
387 
388 		if (j == i) {
389 			dev_warn(&pdev->dev, "switching down from %duV may cause OVP shutdown\n",
390 				vctrl->vtable[i].out);
391 			/* use next lowest voltage */
392 			vctrl->vtable[i].ovp_min_sel = i - 1;
393 		}
394 	}
395 
396 	return 0;
397 }
398 
399 static int vctrl_enable(struct regulator_dev *rdev)
400 {
401 	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
402 
403 	vctrl->enabled = true;
404 
405 	return 0;
406 }
407 
408 static int vctrl_disable(struct regulator_dev *rdev)
409 {
410 	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
411 
412 	vctrl->enabled = false;
413 
414 	return 0;
415 }
416 
417 static int vctrl_is_enabled(struct regulator_dev *rdev)
418 {
419 	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
420 
421 	return vctrl->enabled;
422 }
423 
424 static const struct regulator_ops vctrl_ops_cont = {
425 	.enable		  = vctrl_enable,
426 	.disable	  = vctrl_disable,
427 	.is_enabled	  = vctrl_is_enabled,
428 	.get_voltage	  = vctrl_get_voltage,
429 	.set_voltage	  = vctrl_set_voltage,
430 };
431 
432 static const struct regulator_ops vctrl_ops_non_cont = {
433 	.enable		  = vctrl_enable,
434 	.disable	  = vctrl_disable,
435 	.is_enabled	  = vctrl_is_enabled,
436 	.set_voltage_sel = vctrl_set_voltage_sel,
437 	.get_voltage_sel = vctrl_get_voltage_sel,
438 	.list_voltage    = vctrl_list_voltage,
439 	.map_voltage     = regulator_map_voltage_iterate,
440 };
441 
442 static int vctrl_probe(struct platform_device *pdev)
443 {
444 	struct device_node *np = pdev->dev.of_node;
445 	struct vctrl_data *vctrl;
446 	const struct regulator_init_data *init_data;
447 	struct regulator_desc *rdesc;
448 	struct regulator_config cfg = { };
449 	struct vctrl_voltage_range *vrange_ctrl;
450 	struct regulator *ctrl_reg;
451 	int ctrl_uV;
452 	int ret;
453 
454 	vctrl = devm_kzalloc(&pdev->dev, sizeof(struct vctrl_data),
455 			     GFP_KERNEL);
456 	if (!vctrl)
457 		return -ENOMEM;
458 
459 	platform_set_drvdata(pdev, vctrl);
460 
461 	ret = vctrl_parse_dt(pdev, vctrl);
462 	if (ret)
463 		return ret;
464 
465 	ctrl_reg = devm_regulator_get(&pdev->dev, "ctrl");
466 	if (IS_ERR(ctrl_reg))
467 		return PTR_ERR(ctrl_reg);
468 
469 	vrange_ctrl = &vctrl->vrange.ctrl;
470 
471 	rdesc = &vctrl->desc;
472 	rdesc->name = "vctrl";
473 	rdesc->type = REGULATOR_VOLTAGE;
474 	rdesc->owner = THIS_MODULE;
475 	rdesc->supply_name = "ctrl";
476 
477 	if ((regulator_get_linear_step(ctrl_reg) == 1) ||
478 	    (regulator_count_voltages(ctrl_reg) == -EINVAL)) {
479 		rdesc->continuous_voltage_range = true;
480 		rdesc->ops = &vctrl_ops_cont;
481 	} else {
482 		rdesc->ops = &vctrl_ops_non_cont;
483 	}
484 
485 	init_data = of_get_regulator_init_data(&pdev->dev, np, rdesc);
486 	if (!init_data)
487 		return -ENOMEM;
488 
489 	cfg.of_node = np;
490 	cfg.dev = &pdev->dev;
491 	cfg.driver_data = vctrl;
492 	cfg.init_data = init_data;
493 
494 	if (!rdesc->continuous_voltage_range) {
495 		ret = vctrl_init_vtable(pdev, ctrl_reg);
496 		if (ret)
497 			return ret;
498 
499 		/* Use locked consumer API when not in regulator framework */
500 		ctrl_uV = regulator_get_voltage(ctrl_reg);
501 		if (ctrl_uV < 0) {
502 			dev_err(&pdev->dev, "failed to get control voltage\n");
503 			return ctrl_uV;
504 		}
505 
506 		/* determine current voltage selector from control voltage */
507 		if (ctrl_uV < vrange_ctrl->min_uV) {
508 			vctrl->sel = 0;
509 		} else if (ctrl_uV > vrange_ctrl->max_uV) {
510 			vctrl->sel = rdesc->n_voltages - 1;
511 		} else {
512 			int i;
513 
514 			for (i = 0; i < rdesc->n_voltages; i++) {
515 				if (ctrl_uV == vctrl->vtable[i].ctrl) {
516 					vctrl->sel = i;
517 					break;
518 				}
519 			}
520 		}
521 	}
522 
523 	/* Drop ctrl-supply here in favor of regulator core managed supply */
524 	devm_regulator_put(ctrl_reg);
525 
526 	vctrl->rdev = devm_regulator_register(&pdev->dev, rdesc, &cfg);
527 	if (IS_ERR(vctrl->rdev)) {
528 		ret = PTR_ERR(vctrl->rdev);
529 		dev_err(&pdev->dev, "failed to register regulator: %d\n", ret);
530 		return ret;
531 	}
532 
533 	return 0;
534 }
535 
536 static const struct of_device_id vctrl_of_match[] = {
537 	{ .compatible = "vctrl-regulator", },
538 	{},
539 };
540 MODULE_DEVICE_TABLE(of, vctrl_of_match);
541 
542 static struct platform_driver vctrl_driver = {
543 	.probe		= vctrl_probe,
544 	.driver		= {
545 		.name		= "vctrl-regulator",
546 		.probe_type	= PROBE_PREFER_ASYNCHRONOUS,
547 		.of_match_table = of_match_ptr(vctrl_of_match),
548 	},
549 };
550 
551 module_platform_driver(vctrl_driver);
552 
553 MODULE_DESCRIPTION("Voltage Controlled Regulator Driver");
554 MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
555 MODULE_LICENSE("GPL v2");
556