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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/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
 21struct vctrl_voltage_range {
 22	int min_uV;
 23	int max_uV;
 24};
 25
 26struct vctrl_voltage_ranges {
 27	struct vctrl_voltage_range ctrl;
 28	struct vctrl_voltage_range out;
 29};
 30
 31struct vctrl_voltage_table {
 32	int ctrl;
 33	int out;
 34	int ovp_min_sel;
 35};
 36
 37struct 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
 48static 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
 59static 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
 81static 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
 94static 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
144err:
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
152static 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
159static 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		if (selector >= vctrl->vtable[vctrl->sel].ovp_min_sel)
189			next_sel = selector;
190		else
191			next_sel = vctrl->vtable[vctrl->sel].ovp_min_sel;
192
193		ret = regulator_set_voltage_rdev(rdev->supply->rdev,
194					    vctrl->vtable[next_sel].ctrl,
195					    vctrl->vtable[next_sel].ctrl,
196					    PM_SUSPEND_ON);
197		if (ret) {
198			dev_err(&rdev->dev,
199				"failed to set control voltage to %duV\n",
200				vctrl->vtable[next_sel].ctrl);
201			goto err;
202		}
203		vctrl->sel = next_sel;
204
205		delay = DIV_ROUND_UP(vctrl->vtable[vctrl->sel].out -
206				     vctrl->vtable[next_sel].out,
207				     vctrl->min_slew_down_rate);
208		usleep_range(delay, delay + DIV_ROUND_UP(delay, 10));
209	}
210
211	return 0;
212
213err:
214	if (vctrl->sel != orig_sel) {
215		/* Try to go back to original voltage */
216		if (!regulator_set_voltage_rdev(rdev->supply->rdev,
217					   vctrl->vtable[orig_sel].ctrl,
218					   vctrl->vtable[orig_sel].ctrl,
219					   PM_SUSPEND_ON))
220			vctrl->sel = orig_sel;
221		else
222			dev_warn(&rdev->dev,
223				 "failed to restore original voltage\n");
224	}
225
226	return ret;
227}
228
229static int vctrl_list_voltage(struct regulator_dev *rdev,
230			      unsigned int selector)
231{
232	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
233
234	if (selector >= rdev->desc->n_voltages)
235		return -EINVAL;
236
237	return vctrl->vtable[selector].out;
238}
239
240static int vctrl_parse_dt(struct platform_device *pdev,
241			  struct vctrl_data *vctrl)
242{
243	int ret;
244	struct device_node *np = pdev->dev.of_node;
245	u32 pval;
246	u32 vrange_ctrl[2];
247
248	ret = of_property_read_u32(np, "ovp-threshold-percent", &pval);
249	if (!ret) {
250		vctrl->ovp_threshold = pval;
251		if (vctrl->ovp_threshold > 100) {
252			dev_err(&pdev->dev,
253				"ovp-threshold-percent (%u) > 100\n",
254				vctrl->ovp_threshold);
255			return -EINVAL;
256		}
257	}
258
259	ret = of_property_read_u32(np, "min-slew-down-rate", &pval);
260	if (!ret) {
261		vctrl->min_slew_down_rate = pval;
262
263		/* We use the value as int and as divider; sanity check */
264		if (vctrl->min_slew_down_rate == 0) {
265			dev_err(&pdev->dev,
266				"min-slew-down-rate must not be 0\n");
267			return -EINVAL;
268		} else if (vctrl->min_slew_down_rate > INT_MAX) {
269			dev_err(&pdev->dev, "min-slew-down-rate (%u) too big\n",
270				vctrl->min_slew_down_rate);
271			return -EINVAL;
272		}
273	}
274
275	if (vctrl->ovp_threshold && !vctrl->min_slew_down_rate) {
276		dev_err(&pdev->dev,
277			"ovp-threshold-percent requires min-slew-down-rate\n");
278		return -EINVAL;
279	}
280
281	ret = of_property_read_u32(np, "regulator-min-microvolt", &pval);
282	if (ret) {
283		dev_err(&pdev->dev,
284			"failed to read regulator-min-microvolt: %d\n", ret);
285		return ret;
286	}
287	vctrl->vrange.out.min_uV = pval;
288
289	ret = of_property_read_u32(np, "regulator-max-microvolt", &pval);
290	if (ret) {
291		dev_err(&pdev->dev,
292			"failed to read regulator-max-microvolt: %d\n", ret);
293		return ret;
294	}
295	vctrl->vrange.out.max_uV = pval;
296
297	ret = of_property_read_u32_array(np, "ctrl-voltage-range", vrange_ctrl,
298					 2);
299	if (ret) {
300		dev_err(&pdev->dev, "failed to read ctrl-voltage-range: %d\n",
301			ret);
302		return ret;
303	}
304
305	if (vrange_ctrl[0] >= vrange_ctrl[1]) {
306		dev_err(&pdev->dev, "ctrl-voltage-range is invalid: %d-%d\n",
307			vrange_ctrl[0], vrange_ctrl[1]);
308		return -EINVAL;
309	}
310
311	vctrl->vrange.ctrl.min_uV = vrange_ctrl[0];
312	vctrl->vrange.ctrl.max_uV = vrange_ctrl[1];
313
314	return 0;
315}
316
317static int vctrl_cmp_ctrl_uV(const void *a, const void *b)
318{
319	const struct vctrl_voltage_table *at = a;
320	const struct vctrl_voltage_table *bt = b;
321
322	return at->ctrl - bt->ctrl;
323}
324
325static int vctrl_init_vtable(struct platform_device *pdev,
326			     struct regulator *ctrl_reg)
327{
328	struct vctrl_data *vctrl = platform_get_drvdata(pdev);
329	struct regulator_desc *rdesc = &vctrl->desc;
330	struct vctrl_voltage_range *vrange_ctrl = &vctrl->vrange.ctrl;
331	int n_voltages;
332	int ctrl_uV;
333	int i, idx_vt;
334
335	n_voltages = regulator_count_voltages(ctrl_reg);
336
337	rdesc->n_voltages = n_voltages;
338
339	/* determine number of steps within the range of the vctrl regulator */
340	for (i = 0; i < n_voltages; i++) {
341		ctrl_uV = regulator_list_voltage(ctrl_reg, i);
342
343		if (ctrl_uV < vrange_ctrl->min_uV ||
344		    ctrl_uV > vrange_ctrl->max_uV)
345			rdesc->n_voltages--;
346	}
347
348	if (rdesc->n_voltages == 0) {
349		dev_err(&pdev->dev, "invalid configuration\n");
350		return -EINVAL;
351	}
352
353	vctrl->vtable = devm_kcalloc(&pdev->dev, rdesc->n_voltages,
354				     sizeof(struct vctrl_voltage_table),
355				     GFP_KERNEL);
356	if (!vctrl->vtable)
357		return -ENOMEM;
358
359	/* create mapping control <=> output voltage */
360	for (i = 0, idx_vt = 0; i < n_voltages; i++) {
361		ctrl_uV = regulator_list_voltage(ctrl_reg, i);
362
363		if (ctrl_uV < vrange_ctrl->min_uV ||
364		    ctrl_uV > vrange_ctrl->max_uV)
365			continue;
366
367		vctrl->vtable[idx_vt].ctrl = ctrl_uV;
368		vctrl->vtable[idx_vt].out =
369			vctrl_calc_output_voltage(vctrl, ctrl_uV);
370		idx_vt++;
371	}
372
373	/* we rely on the table to be ordered by ascending voltage */
374	sort(vctrl->vtable, rdesc->n_voltages,
375	     sizeof(struct vctrl_voltage_table), vctrl_cmp_ctrl_uV,
376	     NULL);
377
378	/* pre-calculate OVP-safe downward transitions */
379	for (i = rdesc->n_voltages - 1; i > 0; i--) {
380		int j;
381		int ovp_min_uV = (vctrl->vtable[i].out *
382				  (100 - vctrl->ovp_threshold)) / 100;
383
384		for (j = 0; j < i; j++) {
385			if (vctrl->vtable[j].out >= ovp_min_uV) {
386				vctrl->vtable[i].ovp_min_sel = j;
387				break;
388			}
389		}
390
391		if (j == i) {
392			dev_warn(&pdev->dev, "switching down from %duV may cause OVP shutdown\n",
393				vctrl->vtable[i].out);
394			/* use next lowest voltage */
395			vctrl->vtable[i].ovp_min_sel = i - 1;
396		}
397	}
398
399	return 0;
400}
401
402static int vctrl_enable(struct regulator_dev *rdev)
403{
404	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
405
406	vctrl->enabled = true;
407
408	return 0;
409}
410
411static int vctrl_disable(struct regulator_dev *rdev)
412{
413	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
414
415	vctrl->enabled = false;
416
417	return 0;
418}
419
420static int vctrl_is_enabled(struct regulator_dev *rdev)
421{
422	struct vctrl_data *vctrl = rdev_get_drvdata(rdev);
423
424	return vctrl->enabled;
425}
426
427static const struct regulator_ops vctrl_ops_cont = {
428	.enable		  = vctrl_enable,
429	.disable	  = vctrl_disable,
430	.is_enabled	  = vctrl_is_enabled,
431	.get_voltage	  = vctrl_get_voltage,
432	.set_voltage	  = vctrl_set_voltage,
433};
434
435static const struct regulator_ops vctrl_ops_non_cont = {
436	.enable		  = vctrl_enable,
437	.disable	  = vctrl_disable,
438	.is_enabled	  = vctrl_is_enabled,
439	.set_voltage_sel = vctrl_set_voltage_sel,
440	.get_voltage_sel = vctrl_get_voltage_sel,
441	.list_voltage    = vctrl_list_voltage,
442	.map_voltage     = regulator_map_voltage_iterate,
443};
444
445static int vctrl_probe(struct platform_device *pdev)
446{
447	struct device_node *np = pdev->dev.of_node;
448	struct vctrl_data *vctrl;
449	const struct regulator_init_data *init_data;
450	struct regulator_desc *rdesc;
451	struct regulator_config cfg = { };
452	struct vctrl_voltage_range *vrange_ctrl;
453	struct regulator *ctrl_reg;
454	int ctrl_uV;
455	int ret;
456
457	vctrl = devm_kzalloc(&pdev->dev, sizeof(struct vctrl_data),
458			     GFP_KERNEL);
459	if (!vctrl)
460		return -ENOMEM;
461
462	platform_set_drvdata(pdev, vctrl);
463
464	ret = vctrl_parse_dt(pdev, vctrl);
465	if (ret)
466		return ret;
467
468	ctrl_reg = devm_regulator_get(&pdev->dev, "ctrl");
469	if (IS_ERR(ctrl_reg))
470		return PTR_ERR(ctrl_reg);
471
472	vrange_ctrl = &vctrl->vrange.ctrl;
473
474	rdesc = &vctrl->desc;
475	rdesc->name = "vctrl";
476	rdesc->type = REGULATOR_VOLTAGE;
477	rdesc->owner = THIS_MODULE;
478	rdesc->supply_name = "ctrl";
479
480	if ((regulator_get_linear_step(ctrl_reg) == 1) ||
481	    (regulator_count_voltages(ctrl_reg) == -EINVAL)) {
482		rdesc->continuous_voltage_range = true;
483		rdesc->ops = &vctrl_ops_cont;
484	} else {
485		rdesc->ops = &vctrl_ops_non_cont;
486	}
487
488	init_data = of_get_regulator_init_data(&pdev->dev, np, rdesc);
489	if (!init_data)
490		return -ENOMEM;
491
492	cfg.of_node = np;
493	cfg.dev = &pdev->dev;
494	cfg.driver_data = vctrl;
495	cfg.init_data = init_data;
496
497	if (!rdesc->continuous_voltage_range) {
498		ret = vctrl_init_vtable(pdev, ctrl_reg);
499		if (ret)
500			return ret;
501
502		/* Use locked consumer API when not in regulator framework */
503		ctrl_uV = regulator_get_voltage(ctrl_reg);
504		if (ctrl_uV < 0) {
505			dev_err(&pdev->dev, "failed to get control voltage\n");
506			return ctrl_uV;
507		}
508
509		/* determine current voltage selector from control voltage */
510		if (ctrl_uV < vrange_ctrl->min_uV) {
511			vctrl->sel = 0;
512		} else if (ctrl_uV > vrange_ctrl->max_uV) {
513			vctrl->sel = rdesc->n_voltages - 1;
514		} else {
515			int i;
516
517			for (i = 0; i < rdesc->n_voltages; i++) {
518				if (ctrl_uV == vctrl->vtable[i].ctrl) {
519					vctrl->sel = i;
520					break;
521				}
522			}
523		}
524	}
525
526	/* Drop ctrl-supply here in favor of regulator core managed supply */
527	devm_regulator_put(ctrl_reg);
528
529	vctrl->rdev = devm_regulator_register(&pdev->dev, rdesc, &cfg);
530	if (IS_ERR(vctrl->rdev)) {
531		ret = PTR_ERR(vctrl->rdev);
532		dev_err(&pdev->dev, "failed to register regulator: %d\n", ret);
533		return ret;
534	}
535
536	return 0;
537}
538
539static const struct of_device_id vctrl_of_match[] = {
540	{ .compatible = "vctrl-regulator", },
541	{},
542};
543MODULE_DEVICE_TABLE(of, vctrl_of_match);
544
545static struct platform_driver vctrl_driver = {
546	.probe		= vctrl_probe,
547	.driver		= {
548		.name		= "vctrl-regulator",
549		.of_match_table = of_match_ptr(vctrl_of_match),
550	},
551};
552
553module_platform_driver(vctrl_driver);
554
555MODULE_DESCRIPTION("Voltage Controlled Regulator Driver");
556MODULE_AUTHOR("Matthias Kaehlcke <mka@chromium.org>");
557MODULE_LICENSE("GPL v2");