max5432.c 3.3 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134
  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * Maxim Integrated MAX5432-MAX5435 digital potentiometer driver
  4. * Copyright (C) 2019 Martin Kaiser <martin@kaiser.cx>
  5. *
  6. * Datasheet:
  7. * https://datasheets.maximintegrated.com/en/ds/MAX5432-MAX5435.pdf
  8. */
  9. #include <linux/i2c.h>
  10. #include <linux/iio/iio.h>
  11. #include <linux/limits.h>
  12. #include <linux/module.h>
  13. #include <linux/mod_devicetable.h>
  14. #include <linux/property.h>
  15. /* All chip variants have 32 wiper positions. */
  16. #define MAX5432_MAX_POS 31
  17. #define MAX5432_OHM_50K (50 * 1000)
  18. #define MAX5432_OHM_100K (100 * 1000)
  19. /* Update the volatile (currently active) setting. */
  20. #define MAX5432_CMD_VREG 0x11
  21. struct max5432_data {
  22. struct i2c_client *client;
  23. unsigned long ohm;
  24. };
  25. static const struct iio_chan_spec max5432_channels[] = {
  26. {
  27. .type = IIO_RESISTANCE,
  28. .indexed = 1,
  29. .output = 1,
  30. .channel = 0,
  31. .address = MAX5432_CMD_VREG,
  32. .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  33. .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
  34. }
  35. };
  36. static int max5432_read_raw(struct iio_dev *indio_dev,
  37. struct iio_chan_spec const *chan,
  38. int *val, int *val2, long mask)
  39. {
  40. struct max5432_data *data = iio_priv(indio_dev);
  41. if (mask != IIO_CHAN_INFO_SCALE)
  42. return -EINVAL;
  43. if (unlikely(data->ohm > INT_MAX))
  44. return -ERANGE;
  45. *val = data->ohm;
  46. *val2 = MAX5432_MAX_POS;
  47. return IIO_VAL_FRACTIONAL;
  48. }
  49. static int max5432_write_raw(struct iio_dev *indio_dev,
  50. struct iio_chan_spec const *chan,
  51. int val, int val2, long mask)
  52. {
  53. struct max5432_data *data = iio_priv(indio_dev);
  54. u8 data_byte;
  55. if (mask != IIO_CHAN_INFO_RAW)
  56. return -EINVAL;
  57. if (val < 0 || val > MAX5432_MAX_POS)
  58. return -EINVAL;
  59. if (val2 != 0)
  60. return -EINVAL;
  61. /* Wiper position is in bits D7-D3. (D2-D0 are don't care bits.) */
  62. data_byte = val << 3;
  63. return i2c_smbus_write_byte_data(data->client, chan->address,
  64. data_byte);
  65. }
  66. static const struct iio_info max5432_info = {
  67. .read_raw = max5432_read_raw,
  68. .write_raw = max5432_write_raw,
  69. };
  70. static int max5432_probe(struct i2c_client *client,
  71. const struct i2c_device_id *id)
  72. {
  73. struct device *dev = &client->dev;
  74. struct iio_dev *indio_dev;
  75. struct max5432_data *data;
  76. indio_dev = devm_iio_device_alloc(dev, sizeof(struct max5432_data));
  77. if (!indio_dev)
  78. return -ENOMEM;
  79. i2c_set_clientdata(client, indio_dev);
  80. data = iio_priv(indio_dev);
  81. data->client = client;
  82. data->ohm = (unsigned long)device_get_match_data(dev);
  83. indio_dev->info = &max5432_info;
  84. indio_dev->channels = max5432_channels;
  85. indio_dev->num_channels = ARRAY_SIZE(max5432_channels);
  86. indio_dev->name = client->name;
  87. return devm_iio_device_register(dev, indio_dev);
  88. }
  89. static const struct of_device_id max5432_dt_ids[] = {
  90. { .compatible = "maxim,max5432", .data = (void *)MAX5432_OHM_50K },
  91. { .compatible = "maxim,max5433", .data = (void *)MAX5432_OHM_100K },
  92. { .compatible = "maxim,max5434", .data = (void *)MAX5432_OHM_50K },
  93. { .compatible = "maxim,max5435", .data = (void *)MAX5432_OHM_100K },
  94. { /* sentinel */ }
  95. };
  96. MODULE_DEVICE_TABLE(of, max5432_dt_ids);
  97. static struct i2c_driver max5432_driver = {
  98. .driver = {
  99. .name = "max5432",
  100. .of_match_table = max5432_dt_ids,
  101. },
  102. .probe = max5432_probe,
  103. };
  104. module_i2c_driver(max5432_driver);
  105. MODULE_AUTHOR("Martin Kaiser <martin@kaiser.cx>");
  106. MODULE_DESCRIPTION("max5432-max5435 digital potentiometers");
  107. MODULE_LICENSE("GPL v2");