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