/drivers/hwmon/lm70.c

http://github.com/mirrors/linux · C · 207 lines · 138 code · 29 blank · 40 comment · 6 complexity · 9bbd6acbc41a4f25a05e24656b2edefc MD5 · raw file

  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * lm70.c
  4. *
  5. * The LM70 is a temperature sensor chip from National Semiconductor (NS).
  6. * Copyright (C) 2006 Kaiwan N Billimoria <kaiwan@designergraphix.com>
  7. *
  8. * The LM70 communicates with a host processor via an SPI/Microwire Bus
  9. * interface. The complete datasheet is available at National's website
  10. * here:
  11. * http://www.national.com/pf/LM/LM70.html
  12. */
  13. #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14. #include <linux/init.h>
  15. #include <linux/module.h>
  16. #include <linux/kernel.h>
  17. #include <linux/device.h>
  18. #include <linux/err.h>
  19. #include <linux/sysfs.h>
  20. #include <linux/hwmon.h>
  21. #include <linux/mutex.h>
  22. #include <linux/mod_devicetable.h>
  23. #include <linux/spi/spi.h>
  24. #include <linux/slab.h>
  25. #include <linux/of_device.h>
  26. #define DRVNAME "lm70"
  27. #define LM70_CHIP_LM70 0 /* original NS LM70 */
  28. #define LM70_CHIP_TMP121 1 /* TI TMP121/TMP123 */
  29. #define LM70_CHIP_LM71 2 /* NS LM71 */
  30. #define LM70_CHIP_LM74 3 /* NS LM74 */
  31. #define LM70_CHIP_TMP122 4 /* TI TMP122/TMP124 */
  32. struct lm70 {
  33. struct spi_device *spi;
  34. struct mutex lock;
  35. unsigned int chip;
  36. };
  37. /* sysfs hook function */
  38. static ssize_t temp1_input_show(struct device *dev,
  39. struct device_attribute *attr, char *buf)
  40. {
  41. struct lm70 *p_lm70 = dev_get_drvdata(dev);
  42. struct spi_device *spi = p_lm70->spi;
  43. int status, val = 0;
  44. u8 rxbuf[2];
  45. s16 raw = 0;
  46. if (mutex_lock_interruptible(&p_lm70->lock))
  47. return -ERESTARTSYS;
  48. /*
  49. * spi_read() requires a DMA-safe buffer; so we use
  50. * spi_write_then_read(), transmitting 0 bytes.
  51. */
  52. status = spi_write_then_read(spi, NULL, 0, &rxbuf[0], 2);
  53. if (status < 0) {
  54. dev_warn(dev, "spi_write_then_read failed with status %d\n",
  55. status);
  56. goto out;
  57. }
  58. raw = (rxbuf[0] << 8) + rxbuf[1];
  59. dev_dbg(dev, "rxbuf[0] : 0x%02x rxbuf[1] : 0x%02x raw=0x%04x\n",
  60. rxbuf[0], rxbuf[1], raw);
  61. /*
  62. * LM70:
  63. * The "raw" temperature read into rxbuf[] is a 16-bit signed 2's
  64. * complement value. Only the MSB 11 bits (1 sign + 10 temperature
  65. * bits) are meaningful; the LSB 5 bits are to be discarded.
  66. * See the datasheet.
  67. *
  68. * Further, each bit represents 0.25 degrees Celsius; so, multiply
  69. * by 0.25. Also multiply by 1000 to represent in millidegrees
  70. * Celsius.
  71. * So it's equivalent to multiplying by 0.25 * 1000 = 250.
  72. *
  73. * LM74 and TMP121/TMP122/TMP123/TMP124:
  74. * 13 bits of 2's complement data, discard LSB 3 bits,
  75. * resolution 0.0625 degrees celsius.
  76. *
  77. * LM71:
  78. * 14 bits of 2's complement data, discard LSB 2 bits,
  79. * resolution 0.0312 degrees celsius.
  80. */
  81. switch (p_lm70->chip) {
  82. case LM70_CHIP_LM70:
  83. val = ((int)raw / 32) * 250;
  84. break;
  85. case LM70_CHIP_TMP121:
  86. case LM70_CHIP_TMP122:
  87. case LM70_CHIP_LM74:
  88. val = ((int)raw / 8) * 625 / 10;
  89. break;
  90. case LM70_CHIP_LM71:
  91. val = ((int)raw / 4) * 3125 / 100;
  92. break;
  93. }
  94. status = sprintf(buf, "%d\n", val); /* millidegrees Celsius */
  95. out:
  96. mutex_unlock(&p_lm70->lock);
  97. return status;
  98. }
  99. static DEVICE_ATTR_RO(temp1_input);
  100. static struct attribute *lm70_attrs[] = {
  101. &dev_attr_temp1_input.attr,
  102. NULL
  103. };
  104. ATTRIBUTE_GROUPS(lm70);
  105. /*----------------------------------------------------------------------*/
  106. #ifdef CONFIG_OF
  107. static const struct of_device_id lm70_of_ids[] = {
  108. {
  109. .compatible = "ti,lm70",
  110. .data = (void *) LM70_CHIP_LM70,
  111. },
  112. {
  113. .compatible = "ti,tmp121",
  114. .data = (void *) LM70_CHIP_TMP121,
  115. },
  116. {
  117. .compatible = "ti,tmp122",
  118. .data = (void *) LM70_CHIP_TMP122,
  119. },
  120. {
  121. .compatible = "ti,lm71",
  122. .data = (void *) LM70_CHIP_LM71,
  123. },
  124. {
  125. .compatible = "ti,lm74",
  126. .data = (void *) LM70_CHIP_LM74,
  127. },
  128. {},
  129. };
  130. MODULE_DEVICE_TABLE(of, lm70_of_ids);
  131. #endif
  132. static int lm70_probe(struct spi_device *spi)
  133. {
  134. const struct of_device_id *match;
  135. struct device *hwmon_dev;
  136. struct lm70 *p_lm70;
  137. int chip;
  138. match = of_match_device(lm70_of_ids, &spi->dev);
  139. if (match)
  140. chip = (int)(uintptr_t)match->data;
  141. else
  142. chip = spi_get_device_id(spi)->driver_data;
  143. /* signaling is SPI_MODE_0 */
  144. if (spi->mode & (SPI_CPOL | SPI_CPHA))
  145. return -EINVAL;
  146. /* NOTE: we assume 8-bit words, and convert to 16 bits manually */
  147. p_lm70 = devm_kzalloc(&spi->dev, sizeof(*p_lm70), GFP_KERNEL);
  148. if (!p_lm70)
  149. return -ENOMEM;
  150. mutex_init(&p_lm70->lock);
  151. p_lm70->chip = chip;
  152. p_lm70->spi = spi;
  153. hwmon_dev = devm_hwmon_device_register_with_groups(&spi->dev,
  154. spi->modalias,
  155. p_lm70, lm70_groups);
  156. return PTR_ERR_OR_ZERO(hwmon_dev);
  157. }
  158. static const struct spi_device_id lm70_ids[] = {
  159. { "lm70", LM70_CHIP_LM70 },
  160. { "tmp121", LM70_CHIP_TMP121 },
  161. { "tmp122", LM70_CHIP_TMP122 },
  162. { "lm71", LM70_CHIP_LM71 },
  163. { "lm74", LM70_CHIP_LM74 },
  164. { },
  165. };
  166. MODULE_DEVICE_TABLE(spi, lm70_ids);
  167. static struct spi_driver lm70_driver = {
  168. .driver = {
  169. .name = "lm70",
  170. .of_match_table = of_match_ptr(lm70_of_ids),
  171. },
  172. .id_table = lm70_ids,
  173. .probe = lm70_probe,
  174. };
  175. module_spi_driver(lm70_driver);
  176. MODULE_AUTHOR("Kaiwan N Billimoria");
  177. MODULE_DESCRIPTION("NS LM70 and compatibles Linux driver");
  178. MODULE_LICENSE("GPL");