drivers/iio/dac/ad5592r-base.c

   1 /*
   2  * AD5592R Digital <-> Analog converters driver
   3  *
   4  * Copyright 2014-2016 Analog Devices Inc.
   5  * Author: Paul Cercueil <paul.cercueil@analog.com>
   6  *
   7  * Licensed under the GPL-2.
   8  */
   9
  10 #include <linux/bitops.h>
  11 #include <linux/delay.h>
  12 #include <linux/iio/iio.h>
  13 #include <linux/module.h>
  14 #include <linux/mutex.h>
  15 #include <linux/of.h>
  16 #include <linux/regulator/consumer.h>
  17 #include <linux/gpio/consumer.h>
  18 #include <linux/gpio/driver.h>
  19 #include <linux/gpio.h>
  20 #include <linux/property.h>
  21
  22 #include <dt-bindings/iio/adi,ad5592r.h>
  23
  24 #include "ad5592r-base.h"
  25
  26 static int ad5592r_gpio_get(struct gpio_chip *chip, unsigned offset)
  27 {
  28         struct ad5592r_state *st = gpiochip_get_data(chip);
  29         int ret = 0;
  30         u8 val;
  31
  32         mutex_lock(&st->gpio_lock);
  33
  34         if (st->gpio_out & BIT(offset))
  35                 val = st->gpio_val;
  36         else
  37                 ret = st->ops->gpio_read(st, &val);
  38
  39         mutex_unlock(&st->gpio_lock);
  40
  41         if (ret < 0)
  42                 return ret;
  43
  44         return !!(val & BIT(offset));
  45 }
  46
  47 static void ad5592r_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
  48 {
  49         struct ad5592r_state *st = gpiochip_get_data(chip);
  50
  51         mutex_lock(&st->gpio_lock);
  52
  53         if (value)
  54                 st->gpio_val |= BIT(offset);
  55         else
  56                 st->gpio_val &= ~BIT(offset);
  57
  58         st->ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
  59
  60         mutex_unlock(&st->gpio_lock);
  61 }
  62
  63 static int ad5592r_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
  64 {
  65         struct ad5592r_state *st = gpiochip_get_data(chip);
  66         int ret;
  67
  68         mutex_lock(&st->gpio_lock);
  69
  70         st->gpio_out &= ~BIT(offset);
  71         st->gpio_in |= BIT(offset);
  72
  73         ret = st->ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
  74         if (ret < 0)
  75                 goto err_unlock;
  76
  77         ret = st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
  78
  79 err_unlock:
  80         mutex_unlock(&st->gpio_lock);
  81
  82         return ret;
  83 }
  84
  85 static int ad5592r_gpio_direction_output(struct gpio_chip *chip,
  86                                          unsigned offset, int value)
  87 {
  88         struct ad5592r_state *st = gpiochip_get_data(chip);
  89         int ret;
  90
  91         mutex_lock(&st->gpio_lock);
  92
  93         if (value)
  94                 st->gpio_val |= BIT(offset);
  95         else
  96                 st->gpio_val &= ~BIT(offset);
  97
  98         st->gpio_in &= ~BIT(offset);
  99         st->gpio_out |= BIT(offset);
 100
 101         ret = st->ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
 102         if (ret < 0)
 103                 goto err_unlock;
 104
 105         ret = st->ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
 106         if (ret < 0)
 107                 goto err_unlock;
 108
 109         ret = st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
 110
 111 err_unlock:
 112         mutex_unlock(&st->gpio_lock);
 113
 114         return ret;
 115 }
 116
 117 static int ad5592r_gpio_request(struct gpio_chip *chip, unsigned offset)
 118 {
 119         struct ad5592r_state *st = gpiochip_get_data(chip);
 120
 121         if (!(st->gpio_map & BIT(offset))) {
 122                 dev_err(st->dev, "GPIO %d is reserved by alternate function\n",
 123                         offset);
 124                 return -ENODEV;
 125         }
 126
 127         return 0;
 128 }
 129
 130 static int ad5592r_gpio_init(struct ad5592r_state *st)
 131 {
 132         if (!st->gpio_map)
 133                 return 0;
 134
 135         st->gpiochip.label = dev_name(st->dev);
 136         st->gpiochip.base = -1;
 137         st->gpiochip.ngpio = 8;
 138         st->gpiochip.parent = st->dev;
 139         st->gpiochip.can_sleep = true;
 140         st->gpiochip.direction_input = ad5592r_gpio_direction_input;
 141         st->gpiochip.direction_output = ad5592r_gpio_direction_output;
 142         st->gpiochip.get = ad5592r_gpio_get;
 143         st->gpiochip.set = ad5592r_gpio_set;
 144         st->gpiochip.request = ad5592r_gpio_request;
 145         st->gpiochip.owner = THIS_MODULE;
 146
 147         mutex_init(&st->gpio_lock);
 148
 149         return gpiochip_add_data(&st->gpiochip, st);
 150 }
 151
 152 static void ad5592r_gpio_cleanup(struct ad5592r_state *st)
 153 {
 154         if (st->gpio_map)
 155                 gpiochip_remove(&st->gpiochip);
 156 }
 157
 158 static int ad5592r_reset(struct ad5592r_state *st)
 159 {
 160         struct gpio_desc *gpio;
 161         struct iio_dev *iio_dev = iio_priv_to_dev(st);
 162
 163         gpio = devm_gpiod_get_optional(st->dev, "reset", GPIOD_OUT_LOW);
 164         if (IS_ERR(gpio))
 165                 return PTR_ERR(gpio);
 166
 167         if (gpio) {
 168                 udelay(1);
 169                 gpiod_set_value(gpio, 1);
 170         } else {
 171                 mutex_lock(&iio_dev->mlock);
 172                 /* Writing this magic value resets the device */
 173                 st->ops->reg_write(st, AD5592R_REG_RESET, 0xdac);
 174                 mutex_unlock(&iio_dev->mlock);
 175         }
 176
 177         udelay(250);
 178
 179         return 0;
 180 }
 181
 182 static int ad5592r_get_vref(struct ad5592r_state *st)
 183 {
 184         int ret;
 185
 186         if (st->reg) {
 187                 ret = regulator_get_voltage(st->reg);
 188                 if (ret < 0)
 189                         return ret;
 190
 191                 return ret / 1000;
 192         } else {
 193                 return 2500;
 194         }
 195 }
 196
 197 static int ad5592r_set_channel_modes(struct ad5592r_state *st)
 198 {
 199         const struct ad5592r_rw_ops *ops = st->ops;
 200         int ret;
 201         unsigned i;
 202         struct iio_dev *iio_dev = iio_priv_to_dev(st);
 203         u8 pulldown = 0, tristate = 0, dac = 0, adc = 0;
 204         u16 read_back;
 205
 206         for (i = 0; i < st->num_channels; i++) {
 207                 switch (st->channel_modes[i]) {
 208                 case CH_MODE_DAC:
 209                         dac |= BIT(i);
 210                         break;
 211
 212                 case CH_MODE_ADC:
 213                         adc |= BIT(i);
 214                         break;
 215
 216                 case CH_MODE_DAC_AND_ADC:
 217                         dac |= BIT(i);
 218                         adc |= BIT(i);
 219                         break;
 220
 221                 case CH_MODE_GPIO:
 222                         st->gpio_map |= BIT(i);
 223                         st->gpio_in |= BIT(i); /* Default to input */
 224                         break;
 225
 226                 case CH_MODE_UNUSED:
 227                         /* fall-through */
 228                 default:
 229                         switch (st->channel_offstate[i]) {
 230                         case CH_OFFSTATE_OUT_TRISTATE:
 231                                 tristate |= BIT(i);
 232                                 break;
 233
 234                         case CH_OFFSTATE_OUT_LOW:
 235                                 st->gpio_out |= BIT(i);
 236                                 break;
 237
 238                         case CH_OFFSTATE_OUT_HIGH:
 239                                 st->gpio_out |= BIT(i);
 240                                 st->gpio_val |= BIT(i);
 241                                 break;
 242
 243                         case CH_OFFSTATE_PULLDOWN:
 244                                 /* fall-through */
 245                         default:
 246                                 pulldown |= BIT(i);
 247                                 break;
 248                         }
 249                 }
 250         }
 251
 252         mutex_lock(&iio_dev->mlock);
 253
 254         /* Pull down unused pins to GND */
 255         ret = ops->reg_write(st, AD5592R_REG_PULLDOWN, pulldown);
 256         if (ret)
 257                 goto err_unlock;
 258
 259         ret = ops->reg_write(st, AD5592R_REG_TRISTATE, tristate);
 260         if (ret)
 261                 goto err_unlock;
 262
 263         /* Configure pins that we use */
 264         ret = ops->reg_write(st, AD5592R_REG_DAC_EN, dac);
 265         if (ret)
 266                 goto err_unlock;
 267
 268         ret = ops->reg_write(st, AD5592R_REG_ADC_EN, adc);
 269         if (ret)
 270                 goto err_unlock;
 271
 272         ret = ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
 273         if (ret)
 274                 goto err_unlock;
 275
 276         ret = ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
 277         if (ret)
 278                 goto err_unlock;
 279
 280         ret = ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
 281         if (ret)
 282                 goto err_unlock;
 283
 284         /* Verify that we can read back at least one register */
 285         ret = ops->reg_read(st, AD5592R_REG_ADC_EN, &read_back);
 286         if (!ret && (read_back & 0xff) != adc)
 287                 ret = -EIO;
 288
 289 err_unlock:
 290         mutex_unlock(&iio_dev->mlock);
 291         return ret;
 292 }
 293
 294 static int ad5592r_reset_channel_modes(struct ad5592r_state *st)
 295 {
 296         int i;
 297
 298         for (i = 0; i < ARRAY_SIZE(st->channel_modes); i++)
 299                 st->channel_modes[i] = CH_MODE_UNUSED;
 300
 301         return ad5592r_set_channel_modes(st);
 302 }
 303
 304 static int ad5592r_write_raw(struct iio_dev *iio_dev,
 305         struct iio_chan_spec const *chan, int val, int val2, long mask)
 306 {
 307         struct ad5592r_state *st = iio_priv(iio_dev);
 308         int ret;
 309
 310         switch (mask) {
 311         case IIO_CHAN_INFO_RAW:
 312
 313                 if (val >= (1 << chan->scan_type.realbits) || val < 0)
 314                         return -EINVAL;
 315
 316                 if (!chan->output)
 317                         return -EINVAL;
 318
 319                 mutex_lock(&iio_dev->mlock);
 320                 ret = st->ops->write_dac(st, chan->channel, val);
 321                 if (!ret)
 322                         st->cached_dac[chan->channel] = val;
 323                 mutex_unlock(&iio_dev->mlock);
 324                 return ret;
 325         case IIO_CHAN_INFO_SCALE:
 326                 if (chan->type == IIO_VOLTAGE) {
 327                         bool gain;
 328
 329                         if (val == st->scale_avail[0][0] &&
 330                                 val2 == st->scale_avail[0][1])
 331                                 gain = false;
 332                         else if (val == st->scale_avail[1][0] &&
 333                                  val2 == st->scale_avail[1][1])
 334                                 gain = true;
 335                         else
 336                                 return -EINVAL;
 337
 338                         mutex_lock(&iio_dev->mlock);
 339
 340                         ret = st->ops->reg_read(st, AD5592R_REG_CTRL,
 341                                                 &st->cached_gp_ctrl);
 342                         if (ret < 0) {
 343                                 mutex_unlock(&iio_dev->mlock);
 344                                 return ret;
 345                         }
 346
 347                         if (chan->output) {
 348                                 if (gain)
 349                                         st->cached_gp_ctrl |=
 350                                                 AD5592R_REG_CTRL_DAC_RANGE;
 351                                 else
 352                                         st->cached_gp_ctrl &=
 353                                                 ~AD5592R_REG_CTRL_DAC_RANGE;
 354                         } else {
 355                                 if (gain)
 356                                         st->cached_gp_ctrl |=
 357                                                 AD5592R_REG_CTRL_ADC_RANGE;
 358                                 else
 359                                         st->cached_gp_ctrl &=
 360                                                 ~AD5592R_REG_CTRL_ADC_RANGE;
 361                         }
 362
 363                         ret = st->ops->reg_write(st, AD5592R_REG_CTRL,
 364                                                  st->cached_gp_ctrl);
 365                         mutex_unlock(&iio_dev->mlock);
 366
 367                         return ret;
 368                 }
 369                 break;
 370         default:
 371                 return -EINVAL;
 372         }
 373
 374         return 0;
 375 }
 376
 377 static int ad5592r_read_raw(struct iio_dev *iio_dev,
 378                            struct iio_chan_spec const *chan,
 379                            int *val, int *val2, long m)
 380 {
 381         struct ad5592r_state *st = iio_priv(iio_dev);
 382         u16 read_val;
 383         int ret;
 384
 385         switch (m) {
 386         case IIO_CHAN_INFO_RAW:
 387                 mutex_lock(&iio_dev->mlock);
 388
 389                 if (!chan->output) {
 390                         ret = st->ops->read_adc(st, chan->channel, &read_val);
 391                         if (ret)
 392                                 goto unlock;
 393
 394                         if ((read_val >> 12 & 0x7) != (chan->channel & 0x7)) {
 395                                 dev_err(st->dev, "Error while reading channel %u\n",
 396                                                 chan->channel);
 397                                 ret = -EIO;
 398                                 goto unlock;
 399                         }
 400
 401                         read_val &= GENMASK(11, 0);
 402
 403                 } else {
 404                         read_val = st->cached_dac[chan->channel];
 405                 }
 406
 407                 dev_dbg(st->dev, "Channel %u read: 0x%04hX\n",
 408                                 chan->channel, read_val);
 409
 410                 *val = (int) read_val;
 411                 ret = IIO_VAL_INT;
 412                 break;
 413         case IIO_CHAN_INFO_SCALE:
 414                 *val = ad5592r_get_vref(st);
 415
 416                 if (chan->type == IIO_TEMP) {
 417                         s64 tmp = *val * (3767897513LL / 25LL);
 418                         *val = div_s64_rem(tmp, 1000000000LL, val2);
 419
 420                         ret = IIO_VAL_INT_PLUS_MICRO;
 421                 } else {
 422                         int mult;
 423
 424                         mutex_lock(&iio_dev->mlock);
 425
 426                         if (chan->output)
 427                                 mult = !!(st->cached_gp_ctrl &
 428                                         AD5592R_REG_CTRL_DAC_RANGE);
 429                         else
 430                                 mult = !!(st->cached_gp_ctrl &
 431                                         AD5592R_REG_CTRL_ADC_RANGE);
 432
 433                         *val *= ++mult;
 434
 435                         *val2 = chan->scan_type.realbits;
 436                         ret = IIO_VAL_FRACTIONAL_LOG2;
 437                 }
 438                 break;
 439         case IIO_CHAN_INFO_OFFSET:
 440                 ret = ad5592r_get_vref(st);
 441
 442                 mutex_lock(&iio_dev->mlock);
 443
 444                 if (st->cached_gp_ctrl & AD5592R_REG_CTRL_ADC_RANGE)
 445                         *val = (-34365 * 25) / ret;
 446                 else
 447                         *val = (-75365 * 25) / ret;
 448                 ret =  IIO_VAL_INT;
 449                 break;
 450         default:
 451                 ret = -EINVAL;
 452         }
 453
 454 unlock:
 455         mutex_unlock(&iio_dev->mlock);
 456         return ret;
 457 }
 458
 459 static int ad5592r_write_raw_get_fmt(struct iio_dev *indio_dev,
 460                                  struct iio_chan_spec const *chan, long mask)
 461 {
 462         switch (mask) {
 463         case IIO_CHAN_INFO_SCALE:
 464                 return IIO_VAL_INT_PLUS_NANO;
 465
 466         default:
 467                 return IIO_VAL_INT_PLUS_MICRO;
 468         }
 469
 470         return -EINVAL;
 471 }
 472
 473 static const struct iio_info ad5592r_info = {
 474         .read_raw = ad5592r_read_raw,
 475         .write_raw = ad5592r_write_raw,
 476         .write_raw_get_fmt = ad5592r_write_raw_get_fmt,
 477         .driver_module = THIS_MODULE,
 478 };
 479
 480 static ssize_t ad5592r_show_scale_available(struct iio_dev *iio_dev,
 481                                            uintptr_t private,
 482                                            const struct iio_chan_spec *chan,
 483                                            char *buf)
 484 {
 485         struct ad5592r_state *st = iio_priv(iio_dev);
 486
 487         return sprintf(buf, "%d.%09u %d.%09u\n",
 488                 st->scale_avail[0][0], st->scale_avail[0][1],
 489                 st->scale_avail[1][0], st->scale_avail[1][1]);
 490 }
 491
 492 static struct iio_chan_spec_ext_info ad5592r_ext_info[] = {
 493         {
 494          .name = "scale_available",
 495          .read = ad5592r_show_scale_available,
 496          .shared = true,
 497          },
 498         {},
 499 };
 500
 501 static void ad5592r_setup_channel(struct iio_dev *iio_dev,
 502                 struct iio_chan_spec *chan, bool output, unsigned id)
 503 {
 504         chan->type = IIO_VOLTAGE;
 505         chan->indexed = 1;
 506         chan->output = output;
 507         chan->channel = id;
 508         chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
 509         chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
 510         chan->scan_type.sign = 'u';
 511         chan->scan_type.realbits = 12;
 512         chan->scan_type.storagebits = 16;
 513         chan->ext_info = ad5592r_ext_info;
 514 }
 515
 516 static int ad5592r_alloc_channels(struct ad5592r_state *st)
 517 {
 518         unsigned i, curr_channel = 0,
 519                  num_channels = st->num_channels;
 520         struct iio_dev *iio_dev = iio_priv_to_dev(st);
 521         struct iio_chan_spec *channels;
 522         struct fwnode_handle *child;
 523         u32 reg, tmp;
 524         int ret;
 525
 526         device_for_each_child_node(st->dev, child) {
 527                 ret = fwnode_property_read_u32(child, "reg", &reg);
 528                 if (ret || reg > ARRAY_SIZE(st->channel_modes))
 529                         continue;
 530
 531                 ret = fwnode_property_read_u32(child, "adi,mode", &tmp);
 532                 if (!ret)
 533                         st->channel_modes[reg] = tmp;
 534
 535                 fwnode_property_read_u32(child, "adi,off-state", &tmp);
 536                 if (!ret)
 537                         st->channel_offstate[reg] = tmp;
 538         }
 539
 540         channels = devm_kzalloc(st->dev,
 541                         (1 + 2 * num_channels) * sizeof(*channels), GFP_KERNEL);
 542         if (!channels)
 543                 return -ENOMEM;
 544
 545         for (i = 0; i < num_channels; i++) {
 546                 switch (st->channel_modes[i]) {
 547                 case CH_MODE_DAC:
 548                         ad5592r_setup_channel(iio_dev, &channels[curr_channel],
 549                                         true, i);
 550                         curr_channel++;
 551                         break;
 552
 553                 case CH_MODE_ADC:
 554                         ad5592r_setup_channel(iio_dev, &channels[curr_channel],
 555                                         false, i);
 556                         curr_channel++;
 557                         break;
 558
 559                 case CH_MODE_DAC_AND_ADC:
 560                         ad5592r_setup_channel(iio_dev, &channels[curr_channel],
 561                                         true, i);
 562                         curr_channel++;
 563                         ad5592r_setup_channel(iio_dev, &channels[curr_channel],
 564                                         false, i);
 565                         curr_channel++;
 566                         break;
 567
 568                 default:
 569                         continue;
 570                 }
 571         }
 572
 573         channels[curr_channel].type = IIO_TEMP;
 574         channels[curr_channel].channel = 8;
 575         channels[curr_channel].info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 576                                    BIT(IIO_CHAN_INFO_SCALE) |
 577                                    BIT(IIO_CHAN_INFO_OFFSET);
 578         curr_channel++;
 579
 580         iio_dev->num_channels = curr_channel;
 581         iio_dev->channels = channels;
 582
 583         return 0;
 584 }
 585
 586 static void ad5592r_init_scales(struct ad5592r_state *st, int vref_mV)
 587 {
 588         s64 tmp = (s64)vref_mV * 1000000000LL >> 12;
 589
 590         st->scale_avail[0][0] =
 591                 div_s64_rem(tmp, 1000000000LL, &st->scale_avail[0][1]);
 592         st->scale_avail[1][0] =
 593                 div_s64_rem(tmp * 2, 1000000000LL, &st->scale_avail[1][1]);
 594 }
 595
 596 int ad5592r_probe(struct device *dev, const char *name,
 597                 const struct ad5592r_rw_ops *ops)
 598 {
 599         struct iio_dev *iio_dev;
 600         struct ad5592r_state *st;
 601         int ret;
 602
 603         iio_dev = devm_iio_device_alloc(dev, sizeof(*st));
 604         if (!iio_dev)
 605                 return -ENOMEM;
 606
 607         st = iio_priv(iio_dev);
 608         st->dev = dev;
 609         st->ops = ops;
 610         st->num_channels = 8;
 611         dev_set_drvdata(dev, iio_dev);
 612
 613         st->reg = devm_regulator_get_optional(dev, "vref");
 614         if (IS_ERR(st->reg)) {
 615                 if ((PTR_ERR(st->reg) != -ENODEV) && dev->of_node)
 616                         return PTR_ERR(st->reg);
 617
 618                 st->reg = NULL;
 619         } else {
 620                 ret = regulator_enable(st->reg);
 621                 if (ret)
 622                         return ret;
 623         }
 624
 625         iio_dev->dev.parent = dev;
 626         iio_dev->name = name;
 627         iio_dev->info = &ad5592r_info;
 628         iio_dev->modes = INDIO_DIRECT_MODE;
 629
 630         ad5592r_init_scales(st, ad5592r_get_vref(st));
 631
 632         ret = ad5592r_reset(st);
 633         if (ret)
 634                 goto error_disable_reg;
 635
 636         ret = ops->reg_write(st, AD5592R_REG_PD,
 637                      (st->reg == NULL) ? AD5592R_REG_PD_EN_REF : 0);
 638         if (ret)
 639                 goto error_disable_reg;
 640
 641         ret = ad5592r_alloc_channels(st);
 642         if (ret)
 643                 goto error_disable_reg;
 644
 645         ret = ad5592r_set_channel_modes(st);
 646         if (ret)
 647                 goto error_reset_ch_modes;
 648
 649         ret = iio_device_register(iio_dev);
 650         if (ret)
 651                 goto error_reset_ch_modes;
 652
 653         ret = ad5592r_gpio_init(st);
 654         if (ret)
 655                 goto error_dev_unregister;
 656
 657         return 0;
 658
 659 error_dev_unregister:
 660         iio_device_unregister(iio_dev);
 661
 662 error_reset_ch_modes:
 663         ad5592r_reset_channel_modes(st);
 664
 665 error_disable_reg:
 666         if (st->reg)
 667                 regulator_disable(st->reg);
 668
 669         return ret;
 670 }
 671 EXPORT_SYMBOL_GPL(ad5592r_probe);
 672
 673 int ad5592r_remove(struct device *dev)
 674 {
 675         struct iio_dev *iio_dev = dev_get_drvdata(dev);
 676         struct ad5592r_state *st = iio_priv(iio_dev);
 677
 678         iio_device_unregister(iio_dev);
 679         ad5592r_reset_channel_modes(st);
 680         ad5592r_gpio_cleanup(st);
 681
 682         if (st->reg)
 683                 regulator_disable(st->reg);
 684
 685         return 0;
 686 }
 687 EXPORT_SYMBOL_GPL(ad5592r_remove);
 688
 689 MODULE_AUTHOR("Paul Cercueil <paul.cercueil@analog.com>");
 690 MODULE_DESCRIPTION("Analog Devices AD5592R multi-channel converters");
 691 MODULE_LICENSE("GPL v2");