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