drivers/iio/dac/stm32-dac.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * This file is part of STM32 DAC driver
   4  *
   5  * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
   6  * Authors: Amelie Delaunay <[email protected]>
   7  *          Fabrice Gasnier <[email protected]>
   8  */
   9
  10 #include <linux/bitfield.h>
  11 #include <linux/delay.h>
  12 #include <linux/iio/iio.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/mod_devicetable.h>
  16 #include <linux/of.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/pm_runtime.h>
  19 #include <linux/string_helpers.h>
  20
  21 #include "stm32-dac-core.h"
  22
  23 #define STM32_DAC_CHANNEL_1             1
  24 #define STM32_DAC_CHANNEL_2             2
  25 #define STM32_DAC_IS_CHAN_1(ch)         ((ch) & STM32_DAC_CHANNEL_1)
  26
  27 #define STM32_DAC_AUTO_SUSPEND_DELAY_MS 2000
  28
  29 /**
  30  * struct stm32_dac - private data of DAC driver
  31  * @common:             reference to DAC common data
  32  * @lock:               lock to protect against potential races when reading
  33  *                      and update CR, to keep it in sync with pm_runtime
  34  */
  35 struct stm32_dac {
  36         struct stm32_dac_common *common;
  37         struct mutex            lock;
  38 };
  39
  40 static int stm32_dac_is_enabled(struct iio_dev *indio_dev, int channel)
  41 {
  42         struct stm32_dac *dac = iio_priv(indio_dev);
  43         u32 en, val;
  44         int ret;
  45
  46         ret = regmap_read(dac->common->regmap, STM32_DAC_CR, &val);
  47         if (ret < 0)
  48                 return ret;
  49         if (STM32_DAC_IS_CHAN_1(channel))
  50                 en = FIELD_GET(STM32_DAC_CR_EN1, val);
  51         else
  52                 en = FIELD_GET(STM32_DAC_CR_EN2, val);
  53
  54         return !!en;
  55 }
  56
  57 static int stm32_dac_set_enable_state(struct iio_dev *indio_dev, int ch,
  58                                       bool enable)
  59 {
  60         struct stm32_dac *dac = iio_priv(indio_dev);
  61         struct device *dev = indio_dev->dev.parent;
  62         u32 msk = STM32_DAC_IS_CHAN_1(ch) ? STM32_DAC_CR_EN1 : STM32_DAC_CR_EN2;
  63         u32 en = enable ? msk : 0;
  64         int ret;
  65
  66         /* already enabled / disabled ? */
  67         mutex_lock(&dac->lock);
  68         ret = stm32_dac_is_enabled(indio_dev, ch);
  69         if (ret < 0 || enable == !!ret) {
  70                 mutex_unlock(&dac->lock);
  71                 return ret < 0 ? ret : 0;
  72         }
  73
  74         if (enable) {
  75                 ret = pm_runtime_resume_and_get(dev);
  76                 if (ret < 0) {
  77                         mutex_unlock(&dac->lock);
  78                         return ret;
  79                 }
  80         }
  81
  82         ret = regmap_update_bits(dac->common->regmap, STM32_DAC_CR, msk, en);
  83         mutex_unlock(&dac->lock);
  84         if (ret < 0) {
  85                 dev_err(&indio_dev->dev, "%s failed\n", str_enable_disable(en));
  86                 goto err_put_pm;
  87         }
  88
  89         /*
  90          * When HFSEL is set, it is not allowed to write the DHRx register
  91          * during 8 clock cycles after the ENx bit is set. It is not allowed
  92          * to make software/hardware trigger during this period either.
  93          */
  94         if (en && dac->common->hfsel)
  95                 udelay(1);
  96
  97         if (!enable) {
  98                 pm_runtime_mark_last_busy(dev);
  99                 pm_runtime_put_autosuspend(dev);
 100         }
 101
 102         return 0;
 103
 104 err_put_pm:
 105         if (enable) {
 106                 pm_runtime_mark_last_busy(dev);
 107                 pm_runtime_put_autosuspend(dev);
 108         }
 109
 110         return ret;
 111 }
 112
 113 static int stm32_dac_get_value(struct stm32_dac *dac, int channel, int *val)
 114 {
 115         int ret;
 116
 117         if (STM32_DAC_IS_CHAN_1(channel))
 118                 ret = regmap_read(dac->common->regmap, STM32_DAC_DOR1, val);
 119         else
 120                 ret = regmap_read(dac->common->regmap, STM32_DAC_DOR2, val);
 121
 122         return ret ? ret : IIO_VAL_INT;
 123 }
 124
 125 static int stm32_dac_set_value(struct stm32_dac *dac, int channel, int val)
 126 {
 127         int ret;
 128
 129         if (STM32_DAC_IS_CHAN_1(channel))
 130                 ret = regmap_write(dac->common->regmap, STM32_DAC_DHR12R1, val);
 131         else
 132                 ret = regmap_write(dac->common->regmap, STM32_DAC_DHR12R2, val);
 133
 134         return ret;
 135 }
 136
 137 static int stm32_dac_read_raw(struct iio_dev *indio_dev,
 138                               struct iio_chan_spec const *chan,
 139                               int *val, int *val2, long mask)
 140 {
 141         struct stm32_dac *dac = iio_priv(indio_dev);
 142
 143         switch (mask) {
 144         case IIO_CHAN_INFO_RAW:
 145                 return stm32_dac_get_value(dac, chan->channel, val);
 146         case IIO_CHAN_INFO_SCALE:
 147                 *val = dac->common->vref_mv;
 148                 *val2 = chan->scan_type.realbits;
 149                 return IIO_VAL_FRACTIONAL_LOG2;
 150         default:
 151                 return -EINVAL;
 152         }
 153 }
 154
 155 static int stm32_dac_write_raw(struct iio_dev *indio_dev,
 156                                struct iio_chan_spec const *chan,
 157                                int val, int val2, long mask)
 158 {
 159         struct stm32_dac *dac = iio_priv(indio_dev);
 160
 161         switch (mask) {
 162         case IIO_CHAN_INFO_RAW:
 163                 return stm32_dac_set_value(dac, chan->channel, val);
 164         default:
 165                 return -EINVAL;
 166         }
 167 }
 168
 169 static int stm32_dac_debugfs_reg_access(struct iio_dev *indio_dev,
 170                                         unsigned reg, unsigned writeval,
 171                                         unsigned *readval)
 172 {
 173         struct stm32_dac *dac = iio_priv(indio_dev);
 174
 175         if (!readval)
 176                 return regmap_write(dac->common->regmap, reg, writeval);
 177         else
 178                 return regmap_read(dac->common->regmap, reg, readval);
 179 }
 180
 181 static const struct iio_info stm32_dac_iio_info = {
 182         .read_raw = stm32_dac_read_raw,
 183         .write_raw = stm32_dac_write_raw,
 184         .debugfs_reg_access = stm32_dac_debugfs_reg_access,
 185 };
 186
 187 static const char * const stm32_dac_powerdown_modes[] = {
 188         "three_state",
 189 };
 190
 191 static int stm32_dac_get_powerdown_mode(struct iio_dev *indio_dev,
 192                                         const struct iio_chan_spec *chan)
 193 {
 194         return 0;
 195 }
 196
 197 static int stm32_dac_set_powerdown_mode(struct iio_dev *indio_dev,
 198                                         const struct iio_chan_spec *chan,
 199                                         unsigned int type)
 200 {
 201         return 0;
 202 }
 203
 204 static ssize_t stm32_dac_read_powerdown(struct iio_dev *indio_dev,
 205                                         uintptr_t private,
 206                                         const struct iio_chan_spec *chan,
 207                                         char *buf)
 208 {
 209         int ret = stm32_dac_is_enabled(indio_dev, chan->channel);
 210
 211         if (ret < 0)
 212                 return ret;
 213
 214         return sysfs_emit(buf, "%d\n", ret ? 0 : 1);
 215 }
 216
 217 static ssize_t stm32_dac_write_powerdown(struct iio_dev *indio_dev,
 218                                          uintptr_t private,
 219                                          const struct iio_chan_spec *chan,
 220                                          const char *buf, size_t len)
 221 {
 222         bool powerdown;
 223         int ret;
 224
 225         ret = kstrtobool(buf, &powerdown);
 226         if (ret)
 227                 return ret;
 228
 229         ret = stm32_dac_set_enable_state(indio_dev, chan->channel, !powerdown);
 230         if (ret)
 231                 return ret;
 232
 233         return len;
 234 }
 235
 236 static const struct iio_enum stm32_dac_powerdown_mode_en = {
 237         .items = stm32_dac_powerdown_modes,
 238         .num_items = ARRAY_SIZE(stm32_dac_powerdown_modes),
 239         .get = stm32_dac_get_powerdown_mode,
 240         .set = stm32_dac_set_powerdown_mode,
 241 };
 242
 243 static const struct iio_chan_spec_ext_info stm32_dac_ext_info[] = {
 244         {
 245                 .name = "powerdown",
 246                 .read = stm32_dac_read_powerdown,
 247                 .write = stm32_dac_write_powerdown,
 248                 .shared = IIO_SEPARATE,
 249         },
 250         IIO_ENUM("powerdown_mode", IIO_SEPARATE, &stm32_dac_powerdown_mode_en),
 251         IIO_ENUM_AVAILABLE("powerdown_mode", IIO_SHARED_BY_TYPE, &stm32_dac_powerdown_mode_en),
 252         {},
 253 };
 254
 255 #define STM32_DAC_CHANNEL(chan, name) {                 \
 256         .type = IIO_VOLTAGE,                            \
 257         .indexed = 1,                                   \
 258         .output = 1,                                    \
 259         .channel = chan,                                \
 260         .info_mask_separate =                           \
 261                 BIT(IIO_CHAN_INFO_RAW) |                \
 262                 BIT(IIO_CHAN_INFO_SCALE),               \
 263         /* scan_index is always 0 as num_channels is 1 */ \
 264         .scan_type = {                                  \
 265                 .sign = 'u',                            \
 266                 .realbits = 12,                         \
 267                 .storagebits = 16,                      \
 268         },                                              \
 269         .datasheet_name = name,                         \
 270         .ext_info = stm32_dac_ext_info                  \
 271 }
 272
 273 static const struct iio_chan_spec stm32_dac_channels[] = {
 274         STM32_DAC_CHANNEL(STM32_DAC_CHANNEL_1, "out1"),
 275         STM32_DAC_CHANNEL(STM32_DAC_CHANNEL_2, "out2"),
 276 };
 277
 278 static int stm32_dac_chan_of_init(struct iio_dev *indio_dev)
 279 {
 280         struct device_node *np = indio_dev->dev.of_node;
 281         unsigned int i;
 282         u32 channel;
 283         int ret;
 284
 285         ret = of_property_read_u32(np, "reg", &channel);
 286         if (ret) {
 287                 dev_err(&indio_dev->dev, "Failed to read reg property\n");
 288                 return ret;
 289         }
 290
 291         for (i = 0; i < ARRAY_SIZE(stm32_dac_channels); i++) {
 292                 if (stm32_dac_channels[i].channel == channel)
 293                         break;
 294         }
 295         if (i >= ARRAY_SIZE(stm32_dac_channels)) {
 296                 dev_err(&indio_dev->dev, "Invalid reg property\n");
 297                 return -EINVAL;
 298         }
 299
 300         indio_dev->channels = &stm32_dac_channels[i];
 301         /*
 302          * Expose only one channel here, as they can be used independently,
 303          * with separate trigger. Then separate IIO devices are instantiated
 304          * to manage this.
 305          */
 306         indio_dev->num_channels = 1;
 307
 308         return 0;
 309 };
 310
 311 static int stm32_dac_probe(struct platform_device *pdev)
 312 {
 313         struct device_node *np = pdev->dev.of_node;
 314         struct device *dev = &pdev->dev;
 315         struct iio_dev *indio_dev;
 316         struct stm32_dac *dac;
 317         int ret;
 318
 319         if (!np)
 320                 return -ENODEV;
 321
 322         indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac));
 323         if (!indio_dev)
 324                 return -ENOMEM;
 325         platform_set_drvdata(pdev, indio_dev);
 326
 327         dac = iio_priv(indio_dev);
 328         dac->common = dev_get_drvdata(pdev->dev.parent);
 329         indio_dev->name = dev_name(&pdev->dev);
 330         indio_dev->dev.of_node = pdev->dev.of_node;
 331         indio_dev->info = &stm32_dac_iio_info;
 332         indio_dev->modes = INDIO_DIRECT_MODE;
 333
 334         mutex_init(&dac->lock);
 335
 336         ret = stm32_dac_chan_of_init(indio_dev);
 337         if (ret < 0)
 338                 return ret;
 339
 340         /* Get stm32-dac-core PM online */
 341         pm_runtime_get_noresume(dev);
 342         pm_runtime_set_active(dev);
 343         pm_runtime_set_autosuspend_delay(dev, STM32_DAC_AUTO_SUSPEND_DELAY_MS);
 344         pm_runtime_use_autosuspend(dev);
 345         pm_runtime_enable(dev);
 346
 347         ret = iio_device_register(indio_dev);
 348         if (ret)
 349                 goto err_pm_put;
 350
 351         pm_runtime_mark_last_busy(dev);
 352         pm_runtime_put_autosuspend(dev);
 353
 354         return 0;
 355
 356 err_pm_put:
 357         pm_runtime_disable(dev);
 358         pm_runtime_set_suspended(dev);
 359         pm_runtime_put_noidle(dev);
 360
 361         return ret;
 362 }
 363
 364 static int stm32_dac_remove(struct platform_device *pdev)
 365 {
 366         struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 367
 368         pm_runtime_get_sync(&pdev->dev);
 369         iio_device_unregister(indio_dev);
 370         pm_runtime_disable(&pdev->dev);
 371         pm_runtime_set_suspended(&pdev->dev);
 372         pm_runtime_put_noidle(&pdev->dev);
 373
 374         return 0;
 375 }
 376
 377 static int stm32_dac_suspend(struct device *dev)
 378 {
 379         struct iio_dev *indio_dev = dev_get_drvdata(dev);
 380         int channel = indio_dev->channels[0].channel;
 381         int ret;
 382
 383         /* Ensure DAC is disabled before suspend */
 384         ret = stm32_dac_is_enabled(indio_dev, channel);
 385         if (ret)
 386                 return ret < 0 ? ret : -EBUSY;
 387
 388         return pm_runtime_force_suspend(dev);
 389 }
 390
 391 static DEFINE_SIMPLE_DEV_PM_OPS(stm32_dac_pm_ops, stm32_dac_suspend,
 392                                 pm_runtime_force_resume);
 393
 394 static const struct of_device_id stm32_dac_of_match[] = {
 395         { .compatible = "st,stm32-dac", },
 396         {},
 397 };
 398 MODULE_DEVICE_TABLE(of, stm32_dac_of_match);
 399
 400 static struct platform_driver stm32_dac_driver = {
 401         .probe = stm32_dac_probe,
 402         .remove = stm32_dac_remove,
 403         .driver = {
 404                 .name = "stm32-dac",
 405                 .of_match_table = stm32_dac_of_match,
 406                 .pm = pm_sleep_ptr(&stm32_dac_pm_ops),
 407         },
 408 };
 409 module_platform_driver(stm32_dac_driver);
 410
 411 MODULE_ALIAS("platform:stm32-dac");
 412 MODULE_AUTHOR("Amelie Delaunay <[email protected]>");
 413 MODULE_DESCRIPTION("STMicroelectronics STM32 DAC driver");
 414 MODULE_LICENSE("GPL v2");