drivers/iio/counter/stm32-lptimer-cnt.c

   1 /*
   2  * STM32 Low-Power Timer Encoder and Counter driver
   3  *
   4  * Copyright (C) STMicroelectronics 2017
   5  *
   6  * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
   7  *
   8  * Inspired by 104-quad-8 and stm32-timer-trigger drivers.
   9  *
  10  * License terms:  GNU General Public License (GPL), version 2
  11  */
  12
  13 #include <linux/bitfield.h>
  14 #include <linux/iio/iio.h>
  15 #include <linux/mfd/stm32-lptimer.h>
  16 #include <linux/module.h>
  17 #include <linux/platform_device.h>
  18
  19 struct stm32_lptim_cnt {
  20         struct device *dev;
  21         struct regmap *regmap;
  22         struct clk *clk;
  23         u32 preset;
  24         u32 polarity;
  25         u32 quadrature_mode;
  26 };
  27
  28 static int stm32_lptim_is_enabled(struct stm32_lptim_cnt *priv)
  29 {
  30         u32 val;
  31         int ret;
  32
  33         ret = regmap_read(priv->regmap, STM32_LPTIM_CR, &val);
  34         if (ret)
  35                 return ret;
  36
  37         return FIELD_GET(STM32_LPTIM_ENABLE, val);
  38 }
  39
  40 static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,
  41                                         int enable)
  42 {
  43         int ret;
  44         u32 val;
  45
  46         val = FIELD_PREP(STM32_LPTIM_ENABLE, enable);
  47         ret = regmap_write(priv->regmap, STM32_LPTIM_CR, val);
  48         if (ret)
  49                 return ret;
  50
  51         if (!enable) {
  52                 clk_disable(priv->clk);
  53                 return 0;
  54         }
  55
  56         /* LP timer must be enabled before writing CMP & ARR */
  57         ret = regmap_write(priv->regmap, STM32_LPTIM_ARR, priv->preset);
  58         if (ret)
  59                 return ret;
  60
  61         ret = regmap_write(priv->regmap, STM32_LPTIM_CMP, 0);
  62         if (ret)
  63                 return ret;
  64
  65         /* ensure CMP & ARR registers are properly written */
  66         ret = regmap_read_poll_timeout(priv->regmap, STM32_LPTIM_ISR, val,
  67                                        (val & STM32_LPTIM_CMPOK_ARROK),
  68                                        100, 1000);
  69         if (ret)
  70                 return ret;
  71
  72         ret = regmap_write(priv->regmap, STM32_LPTIM_ICR,
  73                            STM32_LPTIM_CMPOKCF_ARROKCF);
  74         if (ret)
  75                 return ret;
  76
  77         ret = clk_enable(priv->clk);
  78         if (ret) {
  79                 regmap_write(priv->regmap, STM32_LPTIM_CR, 0);
  80                 return ret;
  81         }
  82
  83         /* Start LP timer in continuous mode */
  84         return regmap_update_bits(priv->regmap, STM32_LPTIM_CR,
  85                                   STM32_LPTIM_CNTSTRT, STM32_LPTIM_CNTSTRT);
  86 }
  87
  88 static int stm32_lptim_setup(struct stm32_lptim_cnt *priv, int enable)
  89 {
  90         u32 mask = STM32_LPTIM_ENC | STM32_LPTIM_COUNTMODE |
  91                    STM32_LPTIM_CKPOL | STM32_LPTIM_PRESC;
  92         u32 val;
  93
  94         /* Setup LP timer encoder/counter and polarity, without prescaler */
  95         if (priv->quadrature_mode)
  96                 val = enable ? STM32_LPTIM_ENC : 0;
  97         else
  98                 val = enable ? STM32_LPTIM_COUNTMODE : 0;
  99         val |= FIELD_PREP(STM32_LPTIM_CKPOL, enable ? priv->polarity : 0);
 100
 101         return regmap_update_bits(priv->regmap, STM32_LPTIM_CFGR, mask, val);
 102 }
 103
 104 static int stm32_lptim_write_raw(struct iio_dev *indio_dev,
 105                                  struct iio_chan_spec const *chan,
 106                                  int val, int val2, long mask)
 107 {
 108         struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
 109         int ret;
 110
 111         switch (mask) {
 112         case IIO_CHAN_INFO_ENABLE:
 113                 if (val < 0 || val > 1)
 114                         return -EINVAL;
 115
 116                 /* Check nobody uses the timer, or already disabled/enabled */
 117                 ret = stm32_lptim_is_enabled(priv);
 118                 if ((ret < 0) || (!ret && !val))
 119                         return ret;
 120                 if (val && ret)
 121                         return -EBUSY;
 122
 123                 ret = stm32_lptim_setup(priv, val);
 124                 if (ret)
 125                         return ret;
 126                 return stm32_lptim_set_enable_state(priv, val);
 127
 128         default:
 129                 return -EINVAL;
 130         }
 131 }
 132
 133 static int stm32_lptim_read_raw(struct iio_dev *indio_dev,
 134                                 struct iio_chan_spec const *chan,
 135                                 int *val, int *val2, long mask)
 136 {
 137         struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
 138         u32 dat;
 139         int ret;
 140
 141         switch (mask) {
 142         case IIO_CHAN_INFO_RAW:
 143                 ret = regmap_read(priv->regmap, STM32_LPTIM_CNT, &dat);
 144                 if (ret)
 145                         return ret;
 146                 *val = dat;
 147                 return IIO_VAL_INT;
 148
 149         case IIO_CHAN_INFO_ENABLE:
 150                 ret = stm32_lptim_is_enabled(priv);
 151                 if (ret < 0)
 152                         return ret;
 153                 *val = ret;
 154                 return IIO_VAL_INT;
 155
 156         case IIO_CHAN_INFO_SCALE:
 157                 /* Non-quadrature mode: scale = 1 */
 158                 *val = 1;
 159                 *val2 = 0;
 160                 if (priv->quadrature_mode) {
 161                         /*
 162                          * Quadrature encoder mode:
 163                          * - both edges, quarter cycle, scale is 0.25
 164                          * - either rising/falling edge scale is 0.5
 165                          */
 166                         if (priv->polarity > 1)
 167                                 *val2 = 2;
 168                         else
 169                                 *val2 = 1;
 170                 }
 171                 return IIO_VAL_FRACTIONAL_LOG2;
 172
 173         default:
 174                 return -EINVAL;
 175         }
 176 }
 177
 178 static const struct iio_info stm32_lptim_cnt_iio_info = {
 179         .read_raw = stm32_lptim_read_raw,
 180         .write_raw = stm32_lptim_write_raw,
 181         .driver_module = THIS_MODULE,
 182 };
 183
 184 static const char *const stm32_lptim_quadrature_modes[] = {
 185         "non-quadrature",
 186         "quadrature",
 187 };
 188
 189 static int stm32_lptim_get_quadrature_mode(struct iio_dev *indio_dev,
 190                                            const struct iio_chan_spec *chan)
 191 {
 192         struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
 193
 194         return priv->quadrature_mode;
 195 }
 196
 197 static int stm32_lptim_set_quadrature_mode(struct iio_dev *indio_dev,
 198                                            const struct iio_chan_spec *chan,
 199                                            unsigned int type)
 200 {
 201         struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
 202
 203         if (stm32_lptim_is_enabled(priv))
 204                 return -EBUSY;
 205
 206         priv->quadrature_mode = type;
 207
 208         return 0;
 209 }
 210
 211 static const struct iio_enum stm32_lptim_quadrature_mode_en = {
 212         .items = stm32_lptim_quadrature_modes,
 213         .num_items = ARRAY_SIZE(stm32_lptim_quadrature_modes),
 214         .get = stm32_lptim_get_quadrature_mode,
 215         .set = stm32_lptim_set_quadrature_mode,
 216 };
 217
 218 static const char * const stm32_lptim_cnt_polarity[] = {
 219         "rising-edge", "falling-edge", "both-edges",
 220 };
 221
 222 static int stm32_lptim_cnt_get_polarity(struct iio_dev *indio_dev,
 223                                         const struct iio_chan_spec *chan)
 224 {
 225         struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
 226
 227         return priv->polarity;
 228 }
 229
 230 static int stm32_lptim_cnt_set_polarity(struct iio_dev *indio_dev,
 231                                         const struct iio_chan_spec *chan,
 232                                         unsigned int type)
 233 {
 234         struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
 235
 236         if (stm32_lptim_is_enabled(priv))
 237                 return -EBUSY;
 238
 239         priv->polarity = type;
 240
 241         return 0;
 242 }
 243
 244 static const struct iio_enum stm32_lptim_cnt_polarity_en = {
 245         .items = stm32_lptim_cnt_polarity,
 246         .num_items = ARRAY_SIZE(stm32_lptim_cnt_polarity),
 247         .get = stm32_lptim_cnt_get_polarity,
 248         .set = stm32_lptim_cnt_set_polarity,
 249 };
 250
 251 static ssize_t stm32_lptim_cnt_get_preset(struct iio_dev *indio_dev,
 252                                           uintptr_t private,
 253                                           const struct iio_chan_spec *chan,
 254                                           char *buf)
 255 {
 256         struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
 257
 258         return snprintf(buf, PAGE_SIZE, "%u\n", priv->preset);
 259 }
 260
 261 static ssize_t stm32_lptim_cnt_set_preset(struct iio_dev *indio_dev,
 262                                           uintptr_t private,
 263                                           const struct iio_chan_spec *chan,
 264                                           const char *buf, size_t len)
 265 {
 266         struct stm32_lptim_cnt *priv = iio_priv(indio_dev);
 267         int ret;
 268
 269         if (stm32_lptim_is_enabled(priv))
 270                 return -EBUSY;
 271
 272         ret = kstrtouint(buf, 0, &priv->preset);
 273         if (ret)
 274                 return ret;
 275
 276         if (priv->preset > STM32_LPTIM_MAX_ARR)
 277                 return -EINVAL;
 278
 279         return len;
 280 }
 281
 282 /* LP timer with encoder */
 283 static const struct iio_chan_spec_ext_info stm32_lptim_enc_ext_info[] = {
 284         {
 285                 .name = "preset",
 286                 .shared = IIO_SEPARATE,
 287                 .read = stm32_lptim_cnt_get_preset,
 288                 .write = stm32_lptim_cnt_set_preset,
 289         },
 290         IIO_ENUM("polarity", IIO_SEPARATE, &stm32_lptim_cnt_polarity_en),
 291         IIO_ENUM_AVAILABLE("polarity", &stm32_lptim_cnt_polarity_en),
 292         IIO_ENUM("quadrature_mode", IIO_SEPARATE,
 293                  &stm32_lptim_quadrature_mode_en),
 294         IIO_ENUM_AVAILABLE("quadrature_mode", &stm32_lptim_quadrature_mode_en),
 295         {}
 296 };
 297
 298 static const struct iio_chan_spec stm32_lptim_enc_channels = {
 299         .type = IIO_COUNT,
 300         .channel = 0,
 301         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 302                               BIT(IIO_CHAN_INFO_ENABLE) |
 303                               BIT(IIO_CHAN_INFO_SCALE),
 304         .ext_info = stm32_lptim_enc_ext_info,
 305         .indexed = 1,
 306 };
 307
 308 /* LP timer without encoder (counter only) */
 309 static const struct iio_chan_spec_ext_info stm32_lptim_cnt_ext_info[] = {
 310         {
 311                 .name = "preset",
 312                 .shared = IIO_SEPARATE,
 313                 .read = stm32_lptim_cnt_get_preset,
 314                 .write = stm32_lptim_cnt_set_preset,
 315         },
 316         IIO_ENUM("polarity", IIO_SEPARATE, &stm32_lptim_cnt_polarity_en),
 317         IIO_ENUM_AVAILABLE("polarity", &stm32_lptim_cnt_polarity_en),
 318         {}
 319 };
 320
 321 static const struct iio_chan_spec stm32_lptim_cnt_channels = {
 322         .type = IIO_COUNT,
 323         .channel = 0,
 324         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 325                               BIT(IIO_CHAN_INFO_ENABLE) |
 326                               BIT(IIO_CHAN_INFO_SCALE),
 327         .ext_info = stm32_lptim_cnt_ext_info,
 328         .indexed = 1,
 329 };
 330
 331 static int stm32_lptim_cnt_probe(struct platform_device *pdev)
 332 {
 333         struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent);
 334         struct stm32_lptim_cnt *priv;
 335         struct iio_dev *indio_dev;
 336
 337         if (IS_ERR_OR_NULL(ddata))
 338                 return -EINVAL;
 339
 340         indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
 341         if (!indio_dev)
 342                 return -ENOMEM;
 343
 344         priv = iio_priv(indio_dev);
 345         priv->dev = &pdev->dev;
 346         priv->regmap = ddata->regmap;
 347         priv->clk = ddata->clk;
 348         priv->preset = STM32_LPTIM_MAX_ARR;
 349
 350         indio_dev->name = dev_name(&pdev->dev);
 351         indio_dev->dev.parent = &pdev->dev;
 352         indio_dev->dev.of_node = pdev->dev.of_node;
 353         indio_dev->info = &stm32_lptim_cnt_iio_info;
 354         if (ddata->has_encoder)
 355                 indio_dev->channels = &stm32_lptim_enc_channels;
 356         else
 357                 indio_dev->channels = &stm32_lptim_cnt_channels;
 358         indio_dev->num_channels = 1;
 359
 360         platform_set_drvdata(pdev, priv);
 361
 362         return devm_iio_device_register(&pdev->dev, indio_dev);
 363 }
 364
 365 static const struct of_device_id stm32_lptim_cnt_of_match[] = {
 366         { .compatible = "st,stm32-lptimer-counter", },
 367         {},
 368 };
 369 MODULE_DEVICE_TABLE(of, stm32_lptim_cnt_of_match);
 370
 371 static struct platform_driver stm32_lptim_cnt_driver = {
 372         .probe = stm32_lptim_cnt_probe,
 373         .driver = {
 374                 .name = "stm32-lptimer-counter",
 375                 .of_match_table = stm32_lptim_cnt_of_match,
 376         },
 377 };
 378 module_platform_driver(stm32_lptim_cnt_driver);
 379
 380 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
 381 MODULE_ALIAS("platform:stm32-lptimer-counter");
 382 MODULE_DESCRIPTION("STMicroelectronics STM32 LPTIM counter driver");
 383 MODULE_LICENSE("GPL v2");