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
24 struct pwm_regulator_data {
25 /* Shared */
26 struct pwm_device *pwm;
27
28 /* Voltage table */
29 struct pwm_voltages *duty_cycle_table;
30 int state;
31
32 /* Continuous voltage */
33 int volt_uV;
34 };
35
36 struct pwm_voltages {
37 unsigned int uV;
38 unsigned int dutycycle;
39 };
40
41 /**
42 * Voltage table call-backs
43 */
pwm_regulator_get_voltage_sel(struct regulator_dev * rdev)44 static int pwm_regulator_get_voltage_sel(struct regulator_dev *rdev)
45 {
46 struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
47
48 return drvdata->state;
49 }
50
pwm_regulator_set_voltage_sel(struct regulator_dev * rdev,unsigned selector)51 static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev,
52 unsigned selector)
53 {
54 struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
55 unsigned int pwm_reg_period;
56 int dutycycle;
57 int ret;
58
59 pwm_reg_period = pwm_get_period(drvdata->pwm);
60
61 dutycycle = (pwm_reg_period *
62 drvdata->duty_cycle_table[selector].dutycycle) / 100;
63
64 ret = pwm_config(drvdata->pwm, dutycycle, pwm_reg_period);
65 if (ret) {
66 dev_err(&rdev->dev, "Failed to configure PWM\n");
67 return ret;
68 }
69
70 drvdata->state = selector;
71
72 return 0;
73 }
74
pwm_regulator_list_voltage(struct regulator_dev * rdev,unsigned selector)75 static int pwm_regulator_list_voltage(struct regulator_dev *rdev,
76 unsigned selector)
77 {
78 struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
79
80 if (selector >= rdev->desc->n_voltages)
81 return -EINVAL;
82
83 return drvdata->duty_cycle_table[selector].uV;
84 }
85
pwm_regulator_enable(struct regulator_dev * dev)86 static int pwm_regulator_enable(struct regulator_dev *dev)
87 {
88 struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
89
90 return pwm_enable(drvdata->pwm);
91 }
92
pwm_regulator_disable(struct regulator_dev * dev)93 static int pwm_regulator_disable(struct regulator_dev *dev)
94 {
95 struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
96
97 pwm_disable(drvdata->pwm);
98
99 return 0;
100 }
101
pwm_regulator_is_enabled(struct regulator_dev * dev)102 static int pwm_regulator_is_enabled(struct regulator_dev *dev)
103 {
104 struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
105
106 return pwm_is_enabled(drvdata->pwm);
107 }
108
109 /**
110 * Continuous voltage call-backs
111 */
pwm_voltage_to_duty_cycle_percentage(struct regulator_dev * rdev,int req_uV)112 static int pwm_voltage_to_duty_cycle_percentage(struct regulator_dev *rdev, int req_uV)
113 {
114 int min_uV = rdev->constraints->min_uV;
115 int max_uV = rdev->constraints->max_uV;
116 int diff = max_uV - min_uV;
117
118 return 100 - (((req_uV * 100) - (min_uV * 100)) / diff);
119 }
120
pwm_regulator_get_voltage(struct regulator_dev * rdev)121 static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
122 {
123 struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
124
125 return drvdata->volt_uV;
126 }
127
pwm_regulator_set_voltage(struct regulator_dev * rdev,int min_uV,int max_uV,unsigned * selector)128 static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
129 int min_uV, int max_uV,
130 unsigned *selector)
131 {
132 struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
133 unsigned int ramp_delay = rdev->constraints->ramp_delay;
134 unsigned int period = pwm_get_period(drvdata->pwm);
135 int duty_cycle;
136 int ret;
137
138 duty_cycle = pwm_voltage_to_duty_cycle_percentage(rdev, min_uV);
139
140 ret = pwm_config(drvdata->pwm, (period / 100) * duty_cycle, period);
141 if (ret) {
142 dev_err(&rdev->dev, "Failed to configure PWM\n");
143 return ret;
144 }
145
146 ret = pwm_enable(drvdata->pwm);
147 if (ret) {
148 dev_err(&rdev->dev, "Failed to enable PWM\n");
149 return ret;
150 }
151 drvdata->volt_uV = min_uV;
152
153 /* Delay required by PWM regulator to settle to the new voltage */
154 usleep_range(ramp_delay, ramp_delay + 1000);
155
156 return 0;
157 }
158
159 static struct regulator_ops pwm_regulator_voltage_table_ops = {
160 .set_voltage_sel = pwm_regulator_set_voltage_sel,
161 .get_voltage_sel = pwm_regulator_get_voltage_sel,
162 .list_voltage = pwm_regulator_list_voltage,
163 .map_voltage = regulator_map_voltage_iterate,
164 .enable = pwm_regulator_enable,
165 .disable = pwm_regulator_disable,
166 .is_enabled = pwm_regulator_is_enabled,
167 };
168
169 static struct regulator_ops pwm_regulator_voltage_continuous_ops = {
170 .get_voltage = pwm_regulator_get_voltage,
171 .set_voltage = pwm_regulator_set_voltage,
172 .enable = pwm_regulator_enable,
173 .disable = pwm_regulator_disable,
174 .is_enabled = pwm_regulator_is_enabled,
175 };
176
177 static struct regulator_desc pwm_regulator_desc = {
178 .name = "pwm-regulator",
179 .type = REGULATOR_VOLTAGE,
180 .owner = THIS_MODULE,
181 .supply_name = "pwm",
182 };
183
pwm_regulator_init_table(struct platform_device * pdev,struct pwm_regulator_data * drvdata)184 static int pwm_regulator_init_table(struct platform_device *pdev,
185 struct pwm_regulator_data *drvdata)
186 {
187 struct device_node *np = pdev->dev.of_node;
188 struct pwm_voltages *duty_cycle_table;
189 unsigned int length = 0;
190 int ret;
191
192 of_find_property(np, "voltage-table", &length);
193
194 if ((length < sizeof(*duty_cycle_table)) ||
195 (length % sizeof(*duty_cycle_table))) {
196 dev_err(&pdev->dev,
197 "voltage-table length(%d) is invalid\n",
198 length);
199 return -EINVAL;
200 }
201
202 duty_cycle_table = devm_kzalloc(&pdev->dev, length, GFP_KERNEL);
203 if (!duty_cycle_table)
204 return -ENOMEM;
205
206 ret = of_property_read_u32_array(np, "voltage-table",
207 (u32 *)duty_cycle_table,
208 length / sizeof(u32));
209 if (ret) {
210 dev_err(&pdev->dev, "Failed to read voltage-table\n");
211 return ret;
212 }
213
214 drvdata->duty_cycle_table = duty_cycle_table;
215 pwm_regulator_desc.ops = &pwm_regulator_voltage_table_ops;
216 pwm_regulator_desc.n_voltages = length / sizeof(*duty_cycle_table);
217
218 return 0;
219 }
220
pwm_regulator_init_continuous(struct platform_device * pdev,struct pwm_regulator_data * drvdata)221 static int pwm_regulator_init_continuous(struct platform_device *pdev,
222 struct pwm_regulator_data *drvdata)
223 {
224 pwm_regulator_desc.ops = &pwm_regulator_voltage_continuous_ops;
225 pwm_regulator_desc.continuous_voltage_range = true;
226
227 return 0;
228 }
229
pwm_regulator_probe(struct platform_device * pdev)230 static int pwm_regulator_probe(struct platform_device *pdev)
231 {
232 const struct regulator_init_data *init_data;
233 struct pwm_regulator_data *drvdata;
234 struct regulator_dev *regulator;
235 struct regulator_config config = { };
236 struct device_node *np = pdev->dev.of_node;
237 int ret;
238
239 if (!np) {
240 dev_err(&pdev->dev, "Device Tree node missing\n");
241 return -EINVAL;
242 }
243
244 drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
245 if (!drvdata)
246 return -ENOMEM;
247
248 if (of_find_property(np, "voltage-table", NULL))
249 ret = pwm_regulator_init_table(pdev, drvdata);
250 else
251 ret = pwm_regulator_init_continuous(pdev, drvdata);
252 if (ret)
253 return ret;
254
255 init_data = of_get_regulator_init_data(&pdev->dev, np,
256 &pwm_regulator_desc);
257 if (!init_data)
258 return -ENOMEM;
259
260 config.of_node = np;
261 config.dev = &pdev->dev;
262 config.driver_data = drvdata;
263 config.init_data = init_data;
264
265 drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
266 if (IS_ERR(drvdata->pwm)) {
267 dev_err(&pdev->dev, "Failed to get PWM\n");
268 return PTR_ERR(drvdata->pwm);
269 }
270
271 regulator = devm_regulator_register(&pdev->dev,
272 &pwm_regulator_desc, &config);
273 if (IS_ERR(regulator)) {
274 dev_err(&pdev->dev, "Failed to register regulator %s\n",
275 pwm_regulator_desc.name);
276 return PTR_ERR(regulator);
277 }
278
279 return 0;
280 }
281
282 static const struct of_device_id pwm_of_match[] = {
283 { .compatible = "pwm-regulator" },
284 { },
285 };
286 MODULE_DEVICE_TABLE(of, pwm_of_match);
287
288 static struct platform_driver pwm_regulator_driver = {
289 .driver = {
290 .name = "pwm-regulator",
291 .of_match_table = of_match_ptr(pwm_of_match),
292 },
293 .probe = pwm_regulator_probe,
294 };
295
296 module_platform_driver(pwm_regulator_driver);
297
298 MODULE_LICENSE("GPL");
299 MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
300 MODULE_DESCRIPTION("PWM Regulator Driver");
301 MODULE_ALIAS("platform:pwm-regulator");
302