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         struct pwm_args pargs;
  63         int dutycycle;
  64         int ret;
  65
  66         pwm_get_args(drvdata->pwm, &pargs);
  67
  68         dutycycle = (pargs.period *
  69                     drvdata->duty_cycle_table[selector].dutycycle) / 100;
  70
  71         ret = pwm_config(drvdata->pwm, dutycycle, pargs.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         struct pwm_args pargs;
 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         pwm_get_args(drvdata->pwm, &pargs);
 138         diff = rdev->constraints->max_uV - rdev->constraints->min_uV;
 139
 140         /* First try to find out if we get the iduty cycle time which is
 141          * factor of PWM period time. If (request_diff_to_min * pwm_period)
 142          * is perfect divided by voltage_range_diff then it is possible to
 143          * get duty cycle time which is factor of PWM period. This will help
 144          * to get output voltage nearer to requested value as there is no
 145          * calculation loss.
 146          */
 147         req_period = req_diff * pargs.period;
 148         div_u64_rem(req_period, diff, &rem);
 149         if (!rem) {
 150                 do_div(req_period, diff);
 151                 duty_pulse = (unsigned int)req_period;
 152         } else {
 153                 duty_pulse = (pargs.period / 100) * ((req_diff * 100) / diff);
 154         }
 155
 156         ret = pwm_config(drvdata->pwm, duty_pulse, pargs.period);
 157         if (ret) {
 158                 dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
 159                 return ret;
 160         }
 161
 162         ret = pwm_enable(drvdata->pwm);
 163         if (ret) {
 164                 dev_err(&rdev->dev, "Failed to enable PWM: %d\n", ret);
 165                 return ret;
 166         }
 167         drvdata->volt_uV = min_uV;
 168
 169         /* Delay required by PWM regulator to settle to the new voltage */
 170         usleep_range(ramp_delay, ramp_delay + 1000);
 171
 172         return 0;
 173 }
 174
 175 static struct regulator_ops pwm_regulator_voltage_table_ops = {
 176         .set_voltage_sel = pwm_regulator_set_voltage_sel,
 177         .get_voltage_sel = pwm_regulator_get_voltage_sel,
 178         .list_voltage    = pwm_regulator_list_voltage,
 179         .map_voltage     = regulator_map_voltage_iterate,
 180         .enable          = pwm_regulator_enable,
 181         .disable         = pwm_regulator_disable,
 182         .is_enabled      = pwm_regulator_is_enabled,
 183 };
 184
 185 static struct regulator_ops pwm_regulator_voltage_continuous_ops = {
 186         .get_voltage = pwm_regulator_get_voltage,
 187         .set_voltage = pwm_regulator_set_voltage,
 188         .enable          = pwm_regulator_enable,
 189         .disable         = pwm_regulator_disable,
 190         .is_enabled      = pwm_regulator_is_enabled,
 191 };
 192
 193 static struct regulator_desc pwm_regulator_desc = {
 194         .name           = "pwm-regulator",
 195         .type           = REGULATOR_VOLTAGE,
 196         .owner          = THIS_MODULE,
 197         .supply_name    = "pwm",
 198 };
 199
 200 static int pwm_regulator_init_table(struct platform_device *pdev,
 201                                     struct pwm_regulator_data *drvdata)
 202 {
 203         struct device_node *np = pdev->dev.of_node;
 204         struct pwm_voltages *duty_cycle_table;
 205         unsigned int length = 0;
 206         int ret;
 207
 208         of_find_property(np, "voltage-table", &length);
 209
 210         if ((length < sizeof(*duty_cycle_table)) ||
 211             (length % sizeof(*duty_cycle_table))) {
 212                 dev_err(&pdev->dev, "voltage-table length(%d) is invalid\n",
 213                         length);
 214                 return -EINVAL;
 215         }
 216
 217         duty_cycle_table = devm_kzalloc(&pdev->dev, length, GFP_KERNEL);
 218         if (!duty_cycle_table)
 219                 return -ENOMEM;
 220
 221         ret = of_property_read_u32_array(np, "voltage-table",
 222                                          (u32 *)duty_cycle_table,
 223                                          length / sizeof(u32));
 224         if (ret) {
 225                 dev_err(&pdev->dev, "Failed to read voltage-table: %d\n", ret);
 226                 return ret;
 227         }
 228
 229         drvdata->duty_cycle_table       = duty_cycle_table;
 230         memcpy(&drvdata->ops, &pwm_regulator_voltage_table_ops,
 231                sizeof(drvdata->ops));
 232         drvdata->desc.ops = &drvdata->ops;
 233         drvdata->desc.n_voltages        = length / sizeof(*duty_cycle_table);
 234
 235         return 0;
 236 }
 237
 238 static int pwm_regulator_init_continuous(struct platform_device *pdev,
 239                                          struct pwm_regulator_data *drvdata)
 240 {
 241         memcpy(&drvdata->ops, &pwm_regulator_voltage_continuous_ops,
 242                sizeof(drvdata->ops));
 243         drvdata->desc.ops = &drvdata->ops;
 244         drvdata->desc.continuous_voltage_range = true;
 245
 246         return 0;
 247 }
 248
 249 static int pwm_regulator_probe(struct platform_device *pdev)
 250 {
 251         const struct regulator_init_data *init_data;
 252         struct pwm_regulator_data *drvdata;
 253         struct regulator_dev *regulator;
 254         struct regulator_config config = { };
 255         struct device_node *np = pdev->dev.of_node;
 256         int ret;
 257
 258         if (!np) {
 259                 dev_err(&pdev->dev, "Device Tree node missing\n");
 260                 return -EINVAL;
 261         }
 262
 263         drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
 264         if (!drvdata)
 265                 return -ENOMEM;
 266
 267         memcpy(&drvdata->desc, &pwm_regulator_desc, sizeof(drvdata->desc));
 268
 269         if (of_find_property(np, "voltage-table", NULL))
 270                 ret = pwm_regulator_init_table(pdev, drvdata);
 271         else
 272                 ret = pwm_regulator_init_continuous(pdev, drvdata);
 273         if (ret)
 274                 return ret;
 275
 276         init_data = of_get_regulator_init_data(&pdev->dev, np,
 277                                                &drvdata->desc);
 278         if (!init_data)
 279                 return -ENOMEM;
 280
 281         config.of_node = np;
 282         config.dev = &pdev->dev;
 283         config.driver_data = drvdata;
 284         config.init_data = init_data;
 285
 286         drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
 287         if (IS_ERR(drvdata->pwm)) {
 288                 ret = PTR_ERR(drvdata->pwm);
 289                 dev_err(&pdev->dev, "Failed to get PWM: %d\n", ret);
 290                 return ret;
 291         }
 292
 293         /*
 294          * FIXME: pwm_apply_args() should be removed when switching to the
 295          * atomic PWM API.
 296          */
 297         pwm_apply_args(drvdata->pwm);
 298
 299         regulator = devm_regulator_register(&pdev->dev,
 300                                             &drvdata->desc, &config);
 301         if (IS_ERR(regulator)) {
 302                 ret = PTR_ERR(regulator);
 303                 dev_err(&pdev->dev, "Failed to register regulator %s: %d\n",
 304                         drvdata->desc.name, ret);
 305                 return ret;
 306         }
 307
 308         return 0;
 309 }
 310
 311 static const struct of_device_id pwm_of_match[] = {
 312         { .compatible = "pwm-regulator" },
 313         { },
 314 };
 315 MODULE_DEVICE_TABLE(of, pwm_of_match);
 316
 317 static struct platform_driver pwm_regulator_driver = {
 318         .driver = {
 319                 .name           = "pwm-regulator",
 320                 .of_match_table = of_match_ptr(pwm_of_match),
 321         },
 322         .probe = pwm_regulator_probe,
 323 };
 324
 325 module_platform_driver(pwm_regulator_driver);
 326
 327 MODULE_LICENSE("GPL");
 328 MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
 329 MODULE_DESCRIPTION("PWM Regulator Driver");
 330 MODULE_ALIAS("platform:pwm-regulator");