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\n");
  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 /**
 117  * Continuous voltage call-backs
 118  */
 119 static int pwm_voltage_to_duty_cycle_percentage(struct regulator_dev *rdev, int req_uV)
 120 {
 121         int min_uV = rdev->constraints->min_uV;
 122         int max_uV = rdev->constraints->max_uV;
 123         int diff = max_uV - min_uV;
 124
 125         return ((req_uV * 100) - (min_uV * 100)) / diff;
 126 }
 127
 128 static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
 129 {
 130         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
 131
 132         return drvdata->volt_uV;
 133 }
 134
 135 static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
 136                                         int min_uV, int max_uV,
 137                                         unsigned *selector)
 138 {
 139         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
 140         unsigned int ramp_delay = rdev->constraints->ramp_delay;
 141         unsigned int period = pwm_get_period(drvdata->pwm);
 142         int duty_cycle;
 143         int ret;
 144
 145         duty_cycle = pwm_voltage_to_duty_cycle_percentage(rdev, min_uV);
 146
 147         ret = pwm_config(drvdata->pwm, (period / 100) * duty_cycle, period);
 148         if (ret) {
 149                 dev_err(&rdev->dev, "Failed to configure PWM\n");
 150                 return ret;
 151         }
 152
 153         ret = pwm_enable(drvdata->pwm);
 154         if (ret) {
 155                 dev_err(&rdev->dev, "Failed to enable PWM\n");
 156                 return ret;
 157         }
 158         drvdata->volt_uV = min_uV;
 159
 160         /* Delay required by PWM regulator to settle to the new voltage */
 161         usleep_range(ramp_delay, ramp_delay + 1000);
 162
 163         return 0;
 164 }
 165
 166 static struct regulator_ops pwm_regulator_voltage_table_ops = {
 167         .set_voltage_sel = pwm_regulator_set_voltage_sel,
 168         .get_voltage_sel = pwm_regulator_get_voltage_sel,
 169         .list_voltage    = pwm_regulator_list_voltage,
 170         .map_voltage     = regulator_map_voltage_iterate,
 171         .enable          = pwm_regulator_enable,
 172         .disable         = pwm_regulator_disable,
 173         .is_enabled      = pwm_regulator_is_enabled,
 174 };
 175
 176 static struct regulator_ops pwm_regulator_voltage_continuous_ops = {
 177         .get_voltage = pwm_regulator_get_voltage,
 178         .set_voltage = pwm_regulator_set_voltage,
 179         .enable          = pwm_regulator_enable,
 180         .disable         = pwm_regulator_disable,
 181         .is_enabled      = pwm_regulator_is_enabled,
 182 };
 183
 184 static struct regulator_desc pwm_regulator_desc = {
 185         .name           = "pwm-regulator",
 186         .type           = REGULATOR_VOLTAGE,
 187         .owner          = THIS_MODULE,
 188         .supply_name    = "pwm",
 189 };
 190
 191 static int pwm_regulator_init_table(struct platform_device *pdev,
 192                                     struct pwm_regulator_data *drvdata)
 193 {
 194         struct device_node *np = pdev->dev.of_node;
 195         struct pwm_voltages *duty_cycle_table;
 196         unsigned int length = 0;
 197         int ret;
 198
 199         of_find_property(np, "voltage-table", &length);
 200
 201         if ((length < sizeof(*duty_cycle_table)) ||
 202             (length % sizeof(*duty_cycle_table))) {
 203                 dev_err(&pdev->dev,
 204                         "voltage-table length(%d) is invalid\n",
 205                         length);
 206                 return -EINVAL;
 207         }
 208
 209         duty_cycle_table = devm_kzalloc(&pdev->dev, length, GFP_KERNEL);
 210         if (!duty_cycle_table)
 211                 return -ENOMEM;
 212
 213         ret = of_property_read_u32_array(np, "voltage-table",
 214                                          (u32 *)duty_cycle_table,
 215                                          length / sizeof(u32));
 216         if (ret) {
 217                 dev_err(&pdev->dev, "Failed to read voltage-table\n");
 218                 return ret;
 219         }
 220
 221         drvdata->duty_cycle_table       = duty_cycle_table;
 222         memcpy(&drvdata->ops, &pwm_regulator_voltage_table_ops,
 223                sizeof(drvdata->ops));
 224         drvdata->desc.ops = &drvdata->ops;
 225         drvdata->desc.n_voltages        = length / sizeof(*duty_cycle_table);
 226
 227         return 0;
 228 }
 229
 230 static int pwm_regulator_init_continuous(struct platform_device *pdev,
 231                                          struct pwm_regulator_data *drvdata)
 232 {
 233         memcpy(&drvdata->ops, &pwm_regulator_voltage_continuous_ops,
 234                sizeof(drvdata->ops));
 235         drvdata->desc.ops = &drvdata->ops;
 236         drvdata->desc.continuous_voltage_range = true;
 237
 238         return 0;
 239 }
 240
 241 static int pwm_regulator_probe(struct platform_device *pdev)
 242 {
 243         const struct regulator_init_data *init_data;
 244         struct pwm_regulator_data *drvdata;
 245         struct regulator_dev *regulator;
 246         struct regulator_config config = { };
 247         struct device_node *np = pdev->dev.of_node;
 248         int ret;
 249
 250         if (!np) {
 251                 dev_err(&pdev->dev, "Device Tree node missing\n");
 252                 return -EINVAL;
 253         }
 254
 255         drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
 256         if (!drvdata)
 257                 return -ENOMEM;
 258
 259         memcpy(&drvdata->desc, &pwm_regulator_desc, sizeof(drvdata->desc));
 260
 261         if (of_find_property(np, "voltage-table", NULL))
 262                 ret = pwm_regulator_init_table(pdev, drvdata);
 263         else
 264                 ret = pwm_regulator_init_continuous(pdev, drvdata);
 265         if (ret)
 266                 return ret;
 267
 268         init_data = of_get_regulator_init_data(&pdev->dev, np,
 269                                                &drvdata->desc);
 270         if (!init_data)
 271                 return -ENOMEM;
 272
 273         config.of_node = np;
 274         config.dev = &pdev->dev;
 275         config.driver_data = drvdata;
 276         config.init_data = init_data;
 277
 278         drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
 279         if (IS_ERR(drvdata->pwm)) {
 280                 dev_err(&pdev->dev, "Failed to get PWM\n");
 281                 return PTR_ERR(drvdata->pwm);
 282         }
 283
 284         regulator = devm_regulator_register(&pdev->dev,
 285                                             &drvdata->desc, &config);
 286         if (IS_ERR(regulator)) {
 287                 dev_err(&pdev->dev, "Failed to register regulator %s\n",
 288                         drvdata->desc.name);
 289                 return PTR_ERR(regulator);
 290         }
 291
 292         return 0;
 293 }
 294
 295 static const struct of_device_id pwm_of_match[] = {
 296         { .compatible = "pwm-regulator" },
 297         { },
 298 };
 299 MODULE_DEVICE_TABLE(of, pwm_of_match);
 300
 301 static struct platform_driver pwm_regulator_driver = {
 302         .driver = {
 303                 .name           = "pwm-regulator",
 304                 .of_match_table = of_match_ptr(pwm_of_match),
 305         },
 306         .probe = pwm_regulator_probe,
 307 };
 308
 309 module_platform_driver(pwm_regulator_driver);
 310
 311 MODULE_LICENSE("GPL");
 312 MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
 313 MODULE_DESCRIPTION("PWM Regulator Driver");
 314 MODULE_ALIAS("platform:pwm-regulator");