mcp3021.c 4.9 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * mcp3021.c - driver for Microchip MCP3021 and MCP3221
  4. *
  5. * Copyright (C) 2008-2009, 2012 Freescale Semiconductor, Inc.
  6. * Author: Mingkai Hu <[email protected]>
  7. * Reworked by Sven Schuchmann <[email protected]>
  8. * DT support added by Clemens Gruber <[email protected]>
  9. *
  10. * This driver exports the value of analog input voltage to sysfs, the
  11. * voltage unit is mV. Through the sysfs interface, lm-sensors tool
  12. * can also display the input voltage.
  13. */
  14. #include <linux/kernel.h>
  15. #include <linux/module.h>
  16. #include <linux/hwmon.h>
  17. #include <linux/slab.h>
  18. #include <linux/i2c.h>
  19. #include <linux/err.h>
  20. #include <linux/device.h>
  21. #include <linux/of.h>
  22. #include <linux/of_device.h>
  23. /* Vdd / reference voltage in millivolt */
  24. #define MCP3021_VDD_REF_MAX 5500
  25. #define MCP3021_VDD_REF_MIN 2700
  26. #define MCP3021_VDD_REF_DEFAULT 3300
  27. /* output format */
  28. #define MCP3021_SAR_SHIFT 2
  29. #define MCP3021_SAR_MASK 0x3ff
  30. #define MCP3021_OUTPUT_RES 10 /* 10-bit resolution */
  31. #define MCP3221_SAR_SHIFT 0
  32. #define MCP3221_SAR_MASK 0xfff
  33. #define MCP3221_OUTPUT_RES 12 /* 12-bit resolution */
  34. enum chips {
  35. mcp3021,
  36. mcp3221
  37. };
  38. /*
  39. * Client data (each client gets its own)
  40. */
  41. struct mcp3021_data {
  42. struct i2c_client *client;
  43. u32 vdd; /* supply and reference voltage in millivolt */
  44. u16 sar_shift;
  45. u16 sar_mask;
  46. u8 output_res;
  47. };
  48. static inline u16 volts_from_reg(struct mcp3021_data *data, u16 val)
  49. {
  50. return DIV_ROUND_CLOSEST(data->vdd * val, 1 << data->output_res);
  51. }
  52. static int mcp3021_read(struct device *dev, enum hwmon_sensor_types type,
  53. u32 attr, int channel, long *val)
  54. {
  55. struct mcp3021_data *data = dev_get_drvdata(dev);
  56. struct i2c_client *client = data->client;
  57. __be16 buf;
  58. u16 reg;
  59. int ret;
  60. if (type != hwmon_in)
  61. return -EOPNOTSUPP;
  62. ret = i2c_master_recv(client, (char *)&buf, 2);
  63. if (ret < 0)
  64. return ret;
  65. if (ret != 2)
  66. return -EIO;
  67. /* The output code of the MCP3021 is transmitted with MSB first. */
  68. reg = be16_to_cpu(buf);
  69. /*
  70. * The ten-bit output code is composed of the lower 4-bit of the
  71. * first byte and the upper 6-bit of the second byte.
  72. */
  73. reg = (reg >> data->sar_shift) & data->sar_mask;
  74. *val = volts_from_reg(data, reg);
  75. return 0;
  76. }
  77. static umode_t mcp3021_is_visible(const void *_data,
  78. enum hwmon_sensor_types type,
  79. u32 attr, int channel)
  80. {
  81. if (type != hwmon_in)
  82. return 0;
  83. if (attr != hwmon_in_input)
  84. return 0;
  85. return 0444;
  86. }
  87. static const struct hwmon_channel_info *mcp3021_info[] = {
  88. HWMON_CHANNEL_INFO(in, HWMON_I_INPUT),
  89. NULL
  90. };
  91. static const struct hwmon_ops mcp3021_hwmon_ops = {
  92. .is_visible = mcp3021_is_visible,
  93. .read = mcp3021_read,
  94. };
  95. static const struct hwmon_chip_info mcp3021_chip_info = {
  96. .ops = &mcp3021_hwmon_ops,
  97. .info = mcp3021_info,
  98. };
  99. static const struct i2c_device_id mcp3021_id[];
  100. static int mcp3021_probe(struct i2c_client *client)
  101. {
  102. struct mcp3021_data *data = NULL;
  103. struct device_node *np = client->dev.of_node;
  104. struct device *hwmon_dev;
  105. if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
  106. return -ENODEV;
  107. data = devm_kzalloc(&client->dev, sizeof(struct mcp3021_data),
  108. GFP_KERNEL);
  109. if (!data)
  110. return -ENOMEM;
  111. i2c_set_clientdata(client, data);
  112. if (np) {
  113. if (!of_property_read_u32(np, "reference-voltage-microvolt",
  114. &data->vdd))
  115. data->vdd /= 1000;
  116. else
  117. data->vdd = MCP3021_VDD_REF_DEFAULT;
  118. } else {
  119. u32 *pdata = dev_get_platdata(&client->dev);
  120. if (pdata)
  121. data->vdd = *pdata;
  122. else
  123. data->vdd = MCP3021_VDD_REF_DEFAULT;
  124. }
  125. switch (i2c_match_id(mcp3021_id, client)->driver_data) {
  126. case mcp3021:
  127. data->sar_shift = MCP3021_SAR_SHIFT;
  128. data->sar_mask = MCP3021_SAR_MASK;
  129. data->output_res = MCP3021_OUTPUT_RES;
  130. break;
  131. case mcp3221:
  132. data->sar_shift = MCP3221_SAR_SHIFT;
  133. data->sar_mask = MCP3221_SAR_MASK;
  134. data->output_res = MCP3221_OUTPUT_RES;
  135. break;
  136. }
  137. data->client = client;
  138. if (data->vdd > MCP3021_VDD_REF_MAX || data->vdd < MCP3021_VDD_REF_MIN)
  139. return -EINVAL;
  140. hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
  141. client->name,
  142. data,
  143. &mcp3021_chip_info,
  144. NULL);
  145. return PTR_ERR_OR_ZERO(hwmon_dev);
  146. }
  147. static const struct i2c_device_id mcp3021_id[] = {
  148. { "mcp3021", mcp3021 },
  149. { "mcp3221", mcp3221 },
  150. { }
  151. };
  152. MODULE_DEVICE_TABLE(i2c, mcp3021_id);
  153. #ifdef CONFIG_OF
  154. static const struct of_device_id of_mcp3021_match[] = {
  155. { .compatible = "microchip,mcp3021", .data = (void *)mcp3021 },
  156. { .compatible = "microchip,mcp3221", .data = (void *)mcp3221 },
  157. { }
  158. };
  159. MODULE_DEVICE_TABLE(of, of_mcp3021_match);
  160. #endif
  161. static struct i2c_driver mcp3021_driver = {
  162. .driver = {
  163. .name = "mcp3021",
  164. .of_match_table = of_match_ptr(of_mcp3021_match),
  165. },
  166. .probe_new = mcp3021_probe,
  167. .id_table = mcp3021_id,
  168. };
  169. module_i2c_driver(mcp3021_driver);
  170. MODULE_AUTHOR("Mingkai Hu <[email protected]>");
  171. MODULE_DESCRIPTION("Microchip MCP3021/MCP3221 driver");
  172. MODULE_LICENSE("GPL");