1 /*
2  * Regulator driver for PWM Regulators
3  *
4  * Copyright (C) 2014 - STMicroelectronics Inc.
5  *
6  * Author: Lee Jones <lee.jones@linaro.org>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  */
12 
13 #include <linux/delay.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/err.h>
17 #include <linux/regulator/driver.h>
18 #include <linux/regulator/machine.h>
19 #include <linux/regulator/of_regulator.h>
20 #include <linux/of.h>
21 #include <linux/of_device.h>
22 #include <linux/pwm.h>
23 #include <linux/gpio/consumer.h>
24 
25 struct pwm_continuous_reg_data {
26 	unsigned int min_uV_dutycycle;
27 	unsigned int max_uV_dutycycle;
28 	unsigned int dutycycle_unit;
29 };
30 
31 struct pwm_regulator_data {
32 	/*  Shared */
33 	struct pwm_device *pwm;
34 
35 	/* Voltage table */
36 	struct pwm_voltages *duty_cycle_table;
37 
38 	/* Continuous mode info */
39 	struct pwm_continuous_reg_data continuous;
40 
41 	/* regulator descriptor */
42 	struct regulator_desc desc;
43 
44 	/* Regulator ops */
45 	struct regulator_ops ops;
46 
47 	int state;
48 
49 	/* Enable GPIO */
50 	struct gpio_desc *enb_gpio;
51 };
52 
53 struct pwm_voltages {
54 	unsigned int uV;
55 	unsigned int dutycycle;
56 };
57 
58 /**
59  * Voltage table call-backs
60  */
61 static void pwm_regulator_init_state(struct regulator_dev *rdev)
62 {
63 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
64 	struct pwm_state pwm_state;
65 	unsigned int dutycycle;
66 	int i;
67 
68 	pwm_get_state(drvdata->pwm, &pwm_state);
69 	dutycycle = pwm_get_relative_duty_cycle(&pwm_state, 100);
70 
71 	for (i = 0; i < rdev->desc->n_voltages; i++) {
72 		if (dutycycle == drvdata->duty_cycle_table[i].dutycycle) {
73 			drvdata->state = i;
74 			return;
75 		}
76 	}
77 }
78 
79 static int pwm_regulator_get_voltage_sel(struct regulator_dev *rdev)
80 {
81 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
82 
83 	if (drvdata->state < 0)
84 		pwm_regulator_init_state(rdev);
85 
86 	return drvdata->state;
87 }
88 
89 static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev,
90 					 unsigned selector)
91 {
92 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
93 	struct pwm_state pstate;
94 	int ret;
95 
96 	pwm_init_state(drvdata->pwm, &pstate);
97 	pwm_set_relative_duty_cycle(&pstate,
98 			drvdata->duty_cycle_table[selector].dutycycle, 100);
99 
100 	ret = pwm_apply_state(drvdata->pwm, &pstate);
101 	if (ret) {
102 		dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
103 		return ret;
104 	}
105 
106 	drvdata->state = selector;
107 
108 	return 0;
109 }
110 
111 static int pwm_regulator_list_voltage(struct regulator_dev *rdev,
112 				      unsigned selector)
113 {
114 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
115 
116 	if (selector >= rdev->desc->n_voltages)
117 		return -EINVAL;
118 
119 	return drvdata->duty_cycle_table[selector].uV;
120 }
121 
122 static int pwm_regulator_enable(struct regulator_dev *dev)
123 {
124 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
125 
126 	if (drvdata->enb_gpio)
127 		gpiod_set_value_cansleep(drvdata->enb_gpio, 1);
128 
129 	return pwm_enable(drvdata->pwm);
130 }
131 
132 static int pwm_regulator_disable(struct regulator_dev *dev)
133 {
134 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
135 
136 	pwm_disable(drvdata->pwm);
137 
138 	if (drvdata->enb_gpio)
139 		gpiod_set_value_cansleep(drvdata->enb_gpio, 0);
140 
141 	return 0;
142 }
143 
144 static int pwm_regulator_is_enabled(struct regulator_dev *dev)
145 {
146 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
147 
148 	if (drvdata->enb_gpio && !gpiod_get_value_cansleep(drvdata->enb_gpio))
149 		return false;
150 
151 	return pwm_is_enabled(drvdata->pwm);
152 }
153 
154 static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
155 {
156 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
157 	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
158 	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
159 	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;
160 	int min_uV = rdev->constraints->min_uV;
161 	int max_uV = rdev->constraints->max_uV;
162 	int diff_uV = max_uV - min_uV;
163 	struct pwm_state pstate;
164 	unsigned int diff_duty;
165 	unsigned int voltage;
166 
167 	pwm_get_state(drvdata->pwm, &pstate);
168 
169 	voltage = pwm_get_relative_duty_cycle(&pstate, duty_unit);
170 
171 	/*
172 	 * The dutycycle for min_uV might be greater than the one for max_uV.
173 	 * This is happening when the user needs an inversed polarity, but the
174 	 * PWM device does not support inversing it in hardware.
175 	 */
176 	if (max_uV_duty < min_uV_duty) {
177 		voltage = min_uV_duty - voltage;
178 		diff_duty = min_uV_duty - max_uV_duty;
179 	} else {
180 		voltage = voltage - min_uV_duty;
181 		diff_duty = max_uV_duty - min_uV_duty;
182 	}
183 
184 	voltage = DIV_ROUND_CLOSEST_ULL((u64)voltage * diff_uV, diff_duty);
185 
186 	return voltage + min_uV;
187 }
188 
189 static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
190 				     int req_min_uV, int req_max_uV,
191 				     unsigned int *selector)
192 {
193 	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
194 	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
195 	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
196 	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;
197 	unsigned int ramp_delay = rdev->constraints->ramp_delay;
198 	int min_uV = rdev->constraints->min_uV;
199 	int max_uV = rdev->constraints->max_uV;
200 	int diff_uV = max_uV - min_uV;
201 	struct pwm_state pstate;
202 	int old_uV = pwm_regulator_get_voltage(rdev);
203 	unsigned int diff_duty;
204 	unsigned int dutycycle;
205 	int ret;
206 
207 	pwm_init_state(drvdata->pwm, &pstate);
208 
209 	/*
210 	 * The dutycycle for min_uV might be greater than the one for max_uV.
211 	 * This is happening when the user needs an inversed polarity, but the
212 	 * PWM device does not support inversing it in hardware.
213 	 */
214 	if (max_uV_duty < min_uV_duty)
215 		diff_duty = min_uV_duty - max_uV_duty;
216 	else
217 		diff_duty = max_uV_duty - min_uV_duty;
218 
219 	dutycycle = DIV_ROUND_CLOSEST_ULL((u64)(req_min_uV - min_uV) *
220 					  diff_duty,
221 					  diff_uV);
222 
223 	if (max_uV_duty < min_uV_duty)
224 		dutycycle = min_uV_duty - dutycycle;
225 	else
226 		dutycycle = min_uV_duty + dutycycle;
227 
228 	pwm_set_relative_duty_cycle(&pstate, dutycycle, duty_unit);
229 
230 	ret = pwm_apply_state(drvdata->pwm, &pstate);
231 	if (ret) {
232 		dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
233 		return ret;
234 	}
235 
236 	if ((ramp_delay == 0) || !pwm_regulator_is_enabled(rdev))
237 		return 0;
238 
239 	/* Ramp delay is in uV/uS. Adjust to uS and delay */
240 	ramp_delay = DIV_ROUND_UP(abs(req_min_uV - old_uV), ramp_delay);
241 	usleep_range(ramp_delay, ramp_delay + DIV_ROUND_UP(ramp_delay, 10));
242 
243 	return 0;
244 }
245 
246 static struct regulator_ops pwm_regulator_voltage_table_ops = {
247 	.set_voltage_sel = pwm_regulator_set_voltage_sel,
248 	.get_voltage_sel = pwm_regulator_get_voltage_sel,
249 	.list_voltage    = pwm_regulator_list_voltage,
250 	.map_voltage     = regulator_map_voltage_iterate,
251 	.enable          = pwm_regulator_enable,
252 	.disable         = pwm_regulator_disable,
253 	.is_enabled      = pwm_regulator_is_enabled,
254 };
255 
256 static struct regulator_ops pwm_regulator_voltage_continuous_ops = {
257 	.get_voltage = pwm_regulator_get_voltage,
258 	.set_voltage = pwm_regulator_set_voltage,
259 	.enable          = pwm_regulator_enable,
260 	.disable         = pwm_regulator_disable,
261 	.is_enabled      = pwm_regulator_is_enabled,
262 };
263 
264 static struct regulator_desc pwm_regulator_desc = {
265 	.name		= "pwm-regulator",
266 	.type		= REGULATOR_VOLTAGE,
267 	.owner		= THIS_MODULE,
268 	.supply_name    = "pwm",
269 };
270 
271 static int pwm_regulator_init_table(struct platform_device *pdev,
272 				    struct pwm_regulator_data *drvdata)
273 {
274 	struct device_node *np = pdev->dev.of_node;
275 	struct pwm_voltages *duty_cycle_table;
276 	unsigned int length = 0;
277 	int ret;
278 
279 	of_find_property(np, "voltage-table", &length);
280 
281 	if ((length < sizeof(*duty_cycle_table)) ||
282 	    (length % sizeof(*duty_cycle_table))) {
283 		dev_err(&pdev->dev, "voltage-table length(%d) is invalid\n",
284 			length);
285 		return -EINVAL;
286 	}
287 
288 	duty_cycle_table = devm_kzalloc(&pdev->dev, length, GFP_KERNEL);
289 	if (!duty_cycle_table)
290 		return -ENOMEM;
291 
292 	ret = of_property_read_u32_array(np, "voltage-table",
293 					 (u32 *)duty_cycle_table,
294 					 length / sizeof(u32));
295 	if (ret) {
296 		dev_err(&pdev->dev, "Failed to read voltage-table: %d\n", ret);
297 		return ret;
298 	}
299 
300 	drvdata->state			= -EINVAL;
301 	drvdata->duty_cycle_table	= duty_cycle_table;
302 	memcpy(&drvdata->ops, &pwm_regulator_voltage_table_ops,
303 	       sizeof(drvdata->ops));
304 	drvdata->desc.ops = &drvdata->ops;
305 	drvdata->desc.n_voltages	= length / sizeof(*duty_cycle_table);
306 
307 	return 0;
308 }
309 
310 static int pwm_regulator_init_continuous(struct platform_device *pdev,
311 					 struct pwm_regulator_data *drvdata)
312 {
313 	u32 dutycycle_range[2] = { 0, 100 };
314 	u32 dutycycle_unit = 100;
315 
316 	memcpy(&drvdata->ops, &pwm_regulator_voltage_continuous_ops,
317 	       sizeof(drvdata->ops));
318 	drvdata->desc.ops = &drvdata->ops;
319 	drvdata->desc.continuous_voltage_range = true;
320 
321 	of_property_read_u32_array(pdev->dev.of_node,
322 				   "pwm-dutycycle-range",
323 				   dutycycle_range, 2);
324 	of_property_read_u32(pdev->dev.of_node, "pwm-dutycycle-unit",
325 			     &dutycycle_unit);
326 
327 	if (dutycycle_range[0] > dutycycle_unit ||
328 	    dutycycle_range[1] > dutycycle_unit)
329 		return -EINVAL;
330 
331 	drvdata->continuous.dutycycle_unit = dutycycle_unit;
332 	drvdata->continuous.min_uV_dutycycle = dutycycle_range[0];
333 	drvdata->continuous.max_uV_dutycycle = dutycycle_range[1];
334 
335 	return 0;
336 }
337 
338 static int pwm_regulator_probe(struct platform_device *pdev)
339 {
340 	const struct regulator_init_data *init_data;
341 	struct pwm_regulator_data *drvdata;
342 	struct regulator_dev *regulator;
343 	struct regulator_config config = { };
344 	struct device_node *np = pdev->dev.of_node;
345 	enum gpiod_flags gpio_flags;
346 	int ret;
347 
348 	if (!np) {
349 		dev_err(&pdev->dev, "Device Tree node missing\n");
350 		return -EINVAL;
351 	}
352 
353 	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
354 	if (!drvdata)
355 		return -ENOMEM;
356 
357 	memcpy(&drvdata->desc, &pwm_regulator_desc, sizeof(drvdata->desc));
358 
359 	if (of_find_property(np, "voltage-table", NULL))
360 		ret = pwm_regulator_init_table(pdev, drvdata);
361 	else
362 		ret = pwm_regulator_init_continuous(pdev, drvdata);
363 	if (ret)
364 		return ret;
365 
366 	init_data = of_get_regulator_init_data(&pdev->dev, np,
367 					       &drvdata->desc);
368 	if (!init_data)
369 		return -ENOMEM;
370 
371 	config.of_node = np;
372 	config.dev = &pdev->dev;
373 	config.driver_data = drvdata;
374 	config.init_data = init_data;
375 
376 	drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
377 	if (IS_ERR(drvdata->pwm)) {
378 		ret = PTR_ERR(drvdata->pwm);
379 		dev_err(&pdev->dev, "Failed to get PWM: %d\n", ret);
380 		return ret;
381 	}
382 
383 	if (init_data->constraints.boot_on || init_data->constraints.always_on)
384 		gpio_flags = GPIOD_OUT_HIGH;
385 	else
386 		gpio_flags = GPIOD_OUT_LOW;
387 	drvdata->enb_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
388 						    gpio_flags);
389 	if (IS_ERR(drvdata->enb_gpio)) {
390 		ret = PTR_ERR(drvdata->enb_gpio);
391 		dev_err(&pdev->dev, "Failed to get enable GPIO: %d\n", ret);
392 		return ret;
393 	}
394 
395 	ret = pwm_adjust_config(drvdata->pwm);
396 	if (ret)
397 		return ret;
398 
399 	regulator = devm_regulator_register(&pdev->dev,
400 					    &drvdata->desc, &config);
401 	if (IS_ERR(regulator)) {
402 		ret = PTR_ERR(regulator);
403 		dev_err(&pdev->dev, "Failed to register regulator %s: %d\n",
404 			drvdata->desc.name, ret);
405 		return ret;
406 	}
407 
408 	return 0;
409 }
410 
411 static const struct of_device_id pwm_of_match[] = {
412 	{ .compatible = "pwm-regulator" },
413 	{ },
414 };
415 MODULE_DEVICE_TABLE(of, pwm_of_match);
416 
417 static struct platform_driver pwm_regulator_driver = {
418 	.driver = {
419 		.name		= "pwm-regulator",
420 		.of_match_table = of_match_ptr(pwm_of_match),
421 	},
422 	.probe = pwm_regulator_probe,
423 };
424 
425 module_platform_driver(pwm_regulator_driver);
426 
427 MODULE_LICENSE("GPL");
428 MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
429 MODULE_DESCRIPTION("PWM Regulator Driver");
430 MODULE_ALIAS("platform:pwm-regulator");
431