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 #include <linux/gpio/consumer.h>
  24
  25 struct pwm_regulator_data {
  26         /*  Shared */
  27         struct pwm_device *pwm;
  28
  29         /* Voltage table */
  30         struct pwm_voltages *duty_cycle_table;
  31
  32         /* regulator descriptor */
  33         struct regulator_desc desc;
  34
  35         /* Regulator ops */
  36         struct regulator_ops ops;
  37
  38         int state;
  39
  40         /* Continuous voltage */
  41         int volt_uV;
  42
  43         /* Enable GPIO */
  44         struct gpio_desc *enb_gpio;
  45 };
  46
  47 struct pwm_voltages {
  48         unsigned int uV;
  49         unsigned int dutycycle;
  50 };
  51
  52 /**
  53  * Voltage table call-backs
  54  */
  55 static int pwm_regulator_get_voltage_sel(struct regulator_dev *rdev)
  56 {
  57         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
  58
  59         return drvdata->state;
  60 }
  61
  62 static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev,
  63                                          unsigned selector)
  64 {
  65         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
  66         struct pwm_args pargs;
  67         int dutycycle;
  68         int ret;
  69
  70         pwm_get_args(drvdata->pwm, &pargs);
  71
  72         dutycycle = (pargs.period *
  73                     drvdata->duty_cycle_table[selector].dutycycle) / 100;
  74
  75         ret = pwm_config(drvdata->pwm, dutycycle, pargs.period);
  76         if (ret) {
  77                 dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
  78                 return ret;
  79         }
  80
  81         drvdata->state = selector;
  82
  83         return 0;
  84 }
  85
  86 static int pwm_regulator_list_voltage(struct regulator_dev *rdev,
  87                                       unsigned selector)
  88 {
  89         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
  90
  91         if (selector >= rdev->desc->n_voltages)
  92                 return -EINVAL;
  93
  94         return drvdata->duty_cycle_table[selector].uV;
  95 }
  96
  97 static int pwm_regulator_enable(struct regulator_dev *dev)
  98 {
  99         struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
 100
 101         if (drvdata->enb_gpio)
 102                 gpiod_set_value_cansleep(drvdata->enb_gpio, 1);
 103
 104         return pwm_enable(drvdata->pwm);
 105 }
 106
 107 static int pwm_regulator_disable(struct regulator_dev *dev)
 108 {
 109         struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
 110
 111         pwm_disable(drvdata->pwm);
 112
 113         if (drvdata->enb_gpio)
 114                 gpiod_set_value_cansleep(drvdata->enb_gpio, 0);
 115
 116         return 0;
 117 }
 118
 119 static int pwm_regulator_is_enabled(struct regulator_dev *dev)
 120 {
 121         struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
 122
 123         if (drvdata->enb_gpio && !gpiod_get_value_cansleep(drvdata->enb_gpio))
 124                 return false;
 125
 126         return pwm_is_enabled(drvdata->pwm);
 127 }
 128
 129 static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
 130 {
 131         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
 132
 133         return drvdata->volt_uV;
 134 }
 135
 136 static int pwm_regulator_set_voltage(struct regulator_dev *rdev,
 137                                         int min_uV, int max_uV,
 138                                         unsigned *selector)
 139 {
 140         struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
 141         unsigned int ramp_delay = rdev->constraints->ramp_delay;
 142         struct pwm_args pargs;
 143         unsigned int req_diff = min_uV - rdev->constraints->min_uV;
 144         unsigned int diff;
 145         unsigned int duty_pulse;
 146         u64 req_period;
 147         u32 rem;
 148         int old_uV = pwm_regulator_get_voltage(rdev);
 149         int ret;
 150
 151         pwm_get_args(drvdata->pwm, &pargs);
 152         diff = rdev->constraints->max_uV - rdev->constraints->min_uV;
 153
 154         /* First try to find out if we get the iduty cycle time which is
 155          * factor of PWM period time. If (request_diff_to_min * pwm_period)
 156          * is perfect divided by voltage_range_diff then it is possible to
 157          * get duty cycle time which is factor of PWM period. This will help
 158          * to get output voltage nearer to requested value as there is no
 159          * calculation loss.
 160          */
 161         req_period = req_diff * pargs.period;
 162         div_u64_rem(req_period, diff, &rem);
 163         if (!rem) {
 164                 do_div(req_period, diff);
 165                 duty_pulse = (unsigned int)req_period;
 166         } else {
 167                 duty_pulse = (pargs.period / 100) * ((req_diff * 100) / diff);
 168         }
 169
 170         ret = pwm_config(drvdata->pwm, duty_pulse, pargs.period);
 171         if (ret) {
 172                 dev_err(&rdev->dev, "Failed to configure PWM: %d\n", ret);
 173                 return ret;
 174         }
 175
 176         drvdata->volt_uV = min_uV;
 177
 178         if ((ramp_delay == 0) || !pwm_regulator_is_enabled(rdev))
 179                 return 0;
 180
 181         /* Ramp delay is in uV/uS. Adjust to uS and delay */
 182         ramp_delay = DIV_ROUND_UP(abs(min_uV - old_uV), ramp_delay);
 183         usleep_range(ramp_delay, ramp_delay + DIV_ROUND_UP(ramp_delay, 10));
 184
 185         return 0;
 186 }
 187
 188 static struct regulator_ops pwm_regulator_voltage_table_ops = {
 189         .set_voltage_sel = pwm_regulator_set_voltage_sel,
 190         .get_voltage_sel = pwm_regulator_get_voltage_sel,
 191         .list_voltage    = pwm_regulator_list_voltage,
 192         .map_voltage     = regulator_map_voltage_iterate,
 193         .enable          = pwm_regulator_enable,
 194         .disable         = pwm_regulator_disable,
 195         .is_enabled      = pwm_regulator_is_enabled,
 196 };
 197
 198 static struct regulator_ops pwm_regulator_voltage_continuous_ops = {
 199         .get_voltage = pwm_regulator_get_voltage,
 200         .set_voltage = pwm_regulator_set_voltage,
 201         .enable          = pwm_regulator_enable,
 202         .disable         = pwm_regulator_disable,
 203         .is_enabled      = pwm_regulator_is_enabled,
 204 };
 205
 206 static struct regulator_desc pwm_regulator_desc = {
 207         .name           = "pwm-regulator",
 208         .type           = REGULATOR_VOLTAGE,
 209         .owner          = THIS_MODULE,
 210         .supply_name    = "pwm",
 211 };
 212
 213 static int pwm_regulator_init_table(struct platform_device *pdev,
 214                                     struct pwm_regulator_data *drvdata)
 215 {
 216         struct device_node *np = pdev->dev.of_node;
 217         struct pwm_voltages *duty_cycle_table;
 218         unsigned int length = 0;
 219         int ret;
 220
 221         of_find_property(np, "voltage-table", &length);
 222
 223         if ((length < sizeof(*duty_cycle_table)) ||
 224             (length % sizeof(*duty_cycle_table))) {
 225                 dev_err(&pdev->dev, "voltage-table length(%d) is invalid\n",
 226                         length);
 227                 return -EINVAL;
 228         }
 229
 230         duty_cycle_table = devm_kzalloc(&pdev->dev, length, GFP_KERNEL);
 231         if (!duty_cycle_table)
 232                 return -ENOMEM;
 233
 234         ret = of_property_read_u32_array(np, "voltage-table",
 235                                          (u32 *)duty_cycle_table,
 236                                          length / sizeof(u32));
 237         if (ret) {
 238                 dev_err(&pdev->dev, "Failed to read voltage-table: %d\n", ret);
 239                 return ret;
 240         }
 241
 242         drvdata->duty_cycle_table       = duty_cycle_table;
 243         memcpy(&drvdata->ops, &pwm_regulator_voltage_table_ops,
 244                sizeof(drvdata->ops));
 245         drvdata->desc.ops = &drvdata->ops;
 246         drvdata->desc.n_voltages        = length / sizeof(*duty_cycle_table);
 247
 248         return 0;
 249 }
 250
 251 static int pwm_regulator_init_continuous(struct platform_device *pdev,
 252                                          struct pwm_regulator_data *drvdata)
 253 {
 254         memcpy(&drvdata->ops, &pwm_regulator_voltage_continuous_ops,
 255                sizeof(drvdata->ops));
 256         drvdata->desc.ops = &drvdata->ops;
 257         drvdata->desc.continuous_voltage_range = true;
 258
 259         return 0;
 260 }
 261
 262 static int pwm_regulator_probe(struct platform_device *pdev)
 263 {
 264         const struct regulator_init_data *init_data;
 265         struct pwm_regulator_data *drvdata;
 266         struct regulator_dev *regulator;
 267         struct regulator_config config = { };
 268         struct device_node *np = pdev->dev.of_node;
 269         enum gpiod_flags gpio_flags;
 270         int ret;
 271
 272         if (!np) {
 273                 dev_err(&pdev->dev, "Device Tree node missing\n");
 274                 return -EINVAL;
 275         }
 276
 277         drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
 278         if (!drvdata)
 279                 return -ENOMEM;
 280
 281         memcpy(&drvdata->desc, &pwm_regulator_desc, sizeof(drvdata->desc));
 282
 283         if (of_find_property(np, "voltage-table", NULL))
 284                 ret = pwm_regulator_init_table(pdev, drvdata);
 285         else
 286                 ret = pwm_regulator_init_continuous(pdev, drvdata);
 287         if (ret)
 288                 return ret;
 289
 290         init_data = of_get_regulator_init_data(&pdev->dev, np,
 291                                                &drvdata->desc);
 292         if (!init_data)
 293                 return -ENOMEM;
 294
 295         config.of_node = np;
 296         config.dev = &pdev->dev;
 297         config.driver_data = drvdata;
 298         config.init_data = init_data;
 299
 300         drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
 301         if (IS_ERR(drvdata->pwm)) {
 302                 ret = PTR_ERR(drvdata->pwm);
 303                 dev_err(&pdev->dev, "Failed to get PWM: %d\n", ret);
 304                 return ret;
 305         }
 306
 307         if (init_data->constraints.boot_on || init_data->constraints.always_on)
 308                 gpio_flags = GPIOD_OUT_HIGH;
 309         else
 310                 gpio_flags = GPIOD_OUT_LOW;
 311         drvdata->enb_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
 312                                                     gpio_flags);
 313         if (IS_ERR(drvdata->enb_gpio)) {
 314                 ret = PTR_ERR(drvdata->enb_gpio);
 315                 dev_err(&pdev->dev, "Failed to get enable GPIO: %d\n", ret);
 316                 return ret;
 317         }
 318
 319         /*
 320          * FIXME: pwm_apply_args() should be removed when switching to the
 321          * atomic PWM API.
 322          */
 323         pwm_apply_args(drvdata->pwm);
 324
 325         regulator = devm_regulator_register(&pdev->dev,
 326                                             &drvdata->desc, &config);
 327         if (IS_ERR(regulator)) {
 328                 ret = PTR_ERR(regulator);
 329                 dev_err(&pdev->dev, "Failed to register regulator %s: %d\n",
 330                         drvdata->desc.name, ret);
 331                 return ret;
 332         }
 333
 334         return 0;
 335 }
 336
 337 static const struct of_device_id pwm_of_match[] = {
 338         { .compatible = "pwm-regulator" },
 339         { },
 340 };
 341 MODULE_DEVICE_TABLE(of, pwm_of_match);
 342
 343 static struct platform_driver pwm_regulator_driver = {
 344         .driver = {
 345                 .name           = "pwm-regulator",
 346                 .of_match_table = of_match_ptr(pwm_of_match),
 347         },
 348         .probe = pwm_regulator_probe,
 349 };
 350
 351 module_platform_driver(pwm_regulator_driver);
 352
 353 MODULE_LICENSE("GPL");
 354 MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
 355 MODULE_DESCRIPTION("PWM Regulator Driver");
 356 MODULE_ALIAS("platform:pwm-regulator");