drivers/regulator/pwm-regulator.c

   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
  31         /* regulator descriptor */
  32         struct regulator_desc desc;
  33
  34         /* Regulator ops */
  35         struct regulator_ops ops;
  36
  37         int state;
  38
  39         /* Continuous voltage */
  40         int volt_uV;
  41 };
  42
  43 struct pwm_voltages {
  44         unsigned int uV;
  45         unsigned int dutycycle;
  46 };
  47
  48 /**
  49  * Voltage table call-backs
  50  */
  51 static int pwm_regulator_get_voltage_sel(struct regulator_dev *rdev)
  52 {
  53         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
  54
  55         return drvdata->state;
  56 }
  57
  58 static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev,
  59                                          unsigned selector)
  60 {
  61         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
  62         unsigned int pwm_reg_period;
  63         int dutycycle;
  64         int ret;
  65
  66         pwm_reg_period = pwm_get_period(drvdata->pwm);
  67
  68         dutycycle = (pwm_reg_period *
  69                     drvdata->duty_cycle_table[selector].dutycycle) / 100;
  70
  71         ret = pwm_config(drvdata->pwm, dutycycle, pwm_reg_period);
  72         if (ret) {
  73                 dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
  74                 return ret;
  75         }
  76
  77         drvdata->state = selector;
  78
  79         return 0;
  80 }
  81
  82 static int pwm_regulator_list_voltage(struct regulator_dev *rdev,
  83                                       unsigned selector)
  84 {
  85         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
  86
  87         if (selector >= rdev->desc->n_voltages)
  88                 return -EINVAL;
  89
  90         return drvdata->duty_cycle_table[selector].uV;
  91 }
  92
  93 static int pwm_regulator_enable(struct regulator_dev *dev)
  94 {
  95         struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
  96
  97         return pwm_enable(drvdata->pwm);
  98 }
  99
 100 static int pwm_regulator_disable(struct regulator_dev *dev)
 101 {
 102         struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
 103
 104         pwm_disable(drvdata->pwm);
 105
 106         return 0;
 107 }
 108
 109 static int pwm_regulator_is_enabled(struct regulator_dev *dev)
 110 {
 111         struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
 112
 113         return pwm_is_enabled(drvdata->pwm);
 114 }
 115
 116 static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
 117 {
 118         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
 119
 120         return drvdata->volt_uV;
 121 }
 122
 123 static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
 124                                         int min_uV, int max_uV,
 125                                         unsigned *selector)
 126 {
 127         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
 128         unsigned int ramp_delay = rdev->constraints->ramp_delay;
 129         unsigned int period = pwm_get_period(drvdata->pwm);
 130         unsigned int req_diff = min_uV - rdev->constraints->min_uV;
 131         unsigned int diff;
 132         unsigned int duty_pulse;
 133         u64 req_period;
 134         u32 rem;
 135         int ret;
 136
 137         diff = rdev->constraints->max_uV - rdev->constraints->min_uV;
 138
 139         /* First try to find out if we get the iduty cycle time which is
 140          * factor of PWM period time. If (request_diff_to_min * pwm_period)
 141          * is perfect divided by voltage_range_diff then it is possible to
 142          * get duty cycle time which is factor of PWM period. This will help
 143          * to get output voltage nearer to requested value as there is no
 144          * calculation loss.
 145          */
 146         req_period = req_diff * period;
 147         div_u64_rem(req_period, diff, &rem);
 148         if (!rem) {
 149                 do_div(req_period, diff);
 150                 duty_pulse = (unsigned int)req_period;
 151         } else {
 152                 duty_pulse = (period / 100) * ((req_diff * 100) / diff);
 153         }
 154
 155         ret = pwm_config(drvdata->pwm, duty_pulse, period);
 156         if (ret) {
 157                 dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
 158                 return ret;
 159         }
 160
 161         ret = pwm_enable(drvdata->pwm);
 162         if (ret) {
 163                 dev_err(&rdev->dev, "Failed to enable PWM: %d\n", ret);
 164                 return ret;
 165         }
 166         drvdata->volt_uV = min_uV;
 167
 168         /* Delay required by PWM regulator to settle to the new voltage */
 169         usleep_range(ramp_delay, ramp_delay + 1000);
 170
 171         return 0;
 172 }
 173
 174 static struct regulator_ops pwm_regulator_voltage_table_ops = {
 175         .set_voltage_sel = pwm_regulator_set_voltage_sel,
 176         .get_voltage_sel = pwm_regulator_get_voltage_sel,
 177         .list_voltage    = pwm_regulator_list_voltage,
 178         .map_voltage     = regulator_map_voltage_iterate,
 179         .enable          = pwm_regulator_enable,
 180         .disable         = pwm_regulator_disable,
 181         .is_enabled      = pwm_regulator_is_enabled,
 182 };
 183
 184 static struct regulator_ops pwm_regulator_voltage_continuous_ops = {
 185         .get_voltage = pwm_regulator_get_voltage,
 186         .set_voltage = pwm_regulator_set_voltage,
 187         .enable          = pwm_regulator_enable,
 188         .disable         = pwm_regulator_disable,
 189         .is_enabled      = pwm_regulator_is_enabled,
 190 };
 191
 192 static struct regulator_desc pwm_regulator_desc = {
 193         .name           = "pwm-regulator",
 194         .type           = REGULATOR_VOLTAGE,
 195         .owner          = THIS_MODULE,
 196         .supply_name    = "pwm",
 197 };
 198
 199 static int pwm_regulator_init_table(struct platform_device *pdev,
 200                                     struct pwm_regulator_data *drvdata)
 201 {
 202         struct device_node *np = pdev->dev.of_node;
 203         struct pwm_voltages *duty_cycle_table;
 204         unsigned int length = 0;
 205         int ret;
 206
 207         of_find_property(np, "voltage-table", &length);
 208
 209         if ((length < sizeof(*duty_cycle_table)) ||
 210             (length % sizeof(*duty_cycle_table))) {
 211                 dev_err(&pdev->dev, "voltage-table length(%d) is invalid\n",
 212                         length);
 213                 return -EINVAL;
 214         }
 215
 216         duty_cycle_table = devm_kzalloc(&pdev->dev, length, GFP_KERNEL);
 217         if (!duty_cycle_table)
 218                 return -ENOMEM;
 219
 220         ret = of_property_read_u32_array(np, "voltage-table",
 221                                          (u32 *)duty_cycle_table,
 222                                          length / sizeof(u32));
 223         if (ret) {
 224                 dev_err(&pdev->dev, "Failed to read voltage-table: %d\n", ret);
 225                 return ret;
 226         }
 227
 228         drvdata->duty_cycle_table       = duty_cycle_table;
 229         memcpy(&drvdata->ops, &pwm_regulator_voltage_table_ops,
 230                sizeof(drvdata->ops));
 231         drvdata->desc.ops = &drvdata->ops;
 232         drvdata->desc.n_voltages        = length / sizeof(*duty_cycle_table);
 233
 234         return 0;
 235 }
 236
 237 static int pwm_regulator_init_continuous(struct platform_device *pdev,
 238                                          struct pwm_regulator_data *drvdata)
 239 {
 240         memcpy(&drvdata->ops, &pwm_regulator_voltage_continuous_ops,
 241                sizeof(drvdata->ops));
 242         drvdata->desc.ops = &drvdata->ops;
 243         drvdata->desc.continuous_voltage_range = true;
 244
 245         return 0;
 246 }
 247
 248 static int pwm_regulator_probe(struct platform_device *pdev)
 249 {
 250         const struct regulator_init_data *init_data;
 251         struct pwm_regulator_data *drvdata;
 252         struct regulator_dev *regulator;
 253         struct regulator_config config = { };
 254         struct device_node *np = pdev->dev.of_node;
 255         int ret;
 256
 257         if (!np) {
 258                 dev_err(&pdev->dev, "Device Tree node missing\n");
 259                 return -EINVAL;
 260         }
 261
 262         drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
 263         if (!drvdata)
 264                 return -ENOMEM;
 265
 266         memcpy(&drvdata->desc, &pwm_regulator_desc, sizeof(drvdata->desc));
 267
 268         if (of_find_property(np, "voltage-table", NULL))
 269                 ret = pwm_regulator_init_table(pdev, drvdata);
 270         else
 271                 ret = pwm_regulator_init_continuous(pdev, drvdata);
 272         if (ret)
 273                 return ret;
 274
 275         init_data = of_get_regulator_init_data(&pdev->dev, np,
 276                                                &drvdata->desc);
 277         if (!init_data)
 278                 return -ENOMEM;
 279
 280         config.of_node = np;
 281         config.dev = &pdev->dev;
 282         config.driver_data = drvdata;
 283         config.init_data = init_data;
 284
 285         drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
 286         if (IS_ERR(drvdata->pwm)) {
 287                 ret = PTR_ERR(drvdata->pwm);
 288                 dev_err(&pdev->dev, "Failed to get PWM: %d\n", ret);
 289                 return ret;
 290         }
 291
 292         regulator = devm_regulator_register(&pdev->dev,
 293                                             &drvdata->desc, &config);
 294         if (IS_ERR(regulator)) {
 295                 ret = PTR_ERR(regulator);
 296                 dev_err(&pdev->dev, "Failed to register regulator %s: %d\n",
 297                         drvdata->desc.name, ret);
 298                 return ret;
 299         }
 300
 301         return 0;
 302 }
 303
 304 static const struct of_device_id pwm_of_match[] = {
 305         { .compatible = "pwm-regulator" },
 306         { },
 307 };
 308 MODULE_DEVICE_TABLE(of, pwm_of_match);
 309
 310 static struct platform_driver pwm_regulator_driver = {
 311         .driver = {
 312                 .name           = "pwm-regulator",
 313                 .of_match_table = of_match_ptr(pwm_of_match),
 314         },
 315         .probe = pwm_regulator_probe,
 316 };
 317
 318 module_platform_driver(pwm_regulator_driver);
 319
 320 MODULE_LICENSE("GPL");
 321 MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
 322 MODULE_DESCRIPTION("PWM Regulator Driver");
 323 MODULE_ALIAS("platform:pwm-regulator");