g760a.c 5.3 KB

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  1. // SPDX-License-Identifier: GPL-2.0-or-later
  2. /*
  3. * g760a - Driver for the Global Mixed-mode Technology Inc. G760A
  4. * fan speed PWM controller chip
  5. *
  6. * Copyright (C) 2007 Herbert Valerio Riedel <hvr@gnu.org>
  7. *
  8. * Complete datasheet is available at GMT's website:
  9. * http://www.gmt.com.tw/product/datasheet/EDS-760A.pdf
  10. */
  11. #include <linux/module.h>
  12. #include <linux/init.h>
  13. #include <linux/slab.h>
  14. #include <linux/jiffies.h>
  15. #include <linux/i2c.h>
  16. #include <linux/hwmon.h>
  17. #include <linux/hwmon-sysfs.h>
  18. #include <linux/err.h>
  19. #include <linux/mutex.h>
  20. #include <linux/sysfs.h>
  21. enum g760a_regs {
  22. G760A_REG_SET_CNT = 0x00,
  23. G760A_REG_ACT_CNT = 0x01,
  24. G760A_REG_FAN_STA = 0x02
  25. };
  26. #define G760A_REG_FAN_STA_RPM_OFF 0x1 /* +/-20% off */
  27. #define G760A_REG_FAN_STA_RPM_LOW 0x2 /* below 1920rpm */
  28. /* register data is read (and cached) at most once per second */
  29. #define G760A_UPDATE_INTERVAL (HZ)
  30. struct g760a_data {
  31. struct i2c_client *client;
  32. struct mutex update_lock;
  33. /* board specific parameters */
  34. u32 clk; /* default 32kHz */
  35. u16 fan_div; /* default P=2 */
  36. /* g760a register cache */
  37. unsigned int valid:1;
  38. unsigned long last_updated; /* In jiffies */
  39. u8 set_cnt; /* PWM (period) count number; 0xff stops fan */
  40. u8 act_cnt; /* formula: cnt = (CLK * 30)/(rpm * P) */
  41. u8 fan_sta; /* bit 0: set when actual fan speed more than 20%
  42. * outside requested fan speed
  43. * bit 1: set when fan speed below 1920 rpm
  44. */
  45. };
  46. #define G760A_DEFAULT_CLK 32768
  47. #define G760A_DEFAULT_FAN_DIV 2
  48. #define PWM_FROM_CNT(cnt) (0xff-(cnt))
  49. #define PWM_TO_CNT(pwm) (0xff-(pwm))
  50. static inline unsigned int rpm_from_cnt(u8 val, u32 clk, u16 div)
  51. {
  52. return ((val == 0x00) ? 0 : ((clk*30)/(val*div)));
  53. }
  54. /* read/write wrappers */
  55. static int g760a_read_value(struct i2c_client *client, enum g760a_regs reg)
  56. {
  57. return i2c_smbus_read_byte_data(client, reg);
  58. }
  59. static int g760a_write_value(struct i2c_client *client, enum g760a_regs reg,
  60. u16 value)
  61. {
  62. return i2c_smbus_write_byte_data(client, reg, value);
  63. }
  64. /*
  65. * sysfs attributes
  66. */
  67. static struct g760a_data *g760a_update_client(struct device *dev)
  68. {
  69. struct g760a_data *data = dev_get_drvdata(dev);
  70. struct i2c_client *client = data->client;
  71. mutex_lock(&data->update_lock);
  72. if (time_after(jiffies, data->last_updated + G760A_UPDATE_INTERVAL)
  73. || !data->valid) {
  74. dev_dbg(&client->dev, "Starting g760a update\n");
  75. data->set_cnt = g760a_read_value(client, G760A_REG_SET_CNT);
  76. data->act_cnt = g760a_read_value(client, G760A_REG_ACT_CNT);
  77. data->fan_sta = g760a_read_value(client, G760A_REG_FAN_STA);
  78. data->last_updated = jiffies;
  79. data->valid = 1;
  80. }
  81. mutex_unlock(&data->update_lock);
  82. return data;
  83. }
  84. static ssize_t fan1_input_show(struct device *dev,
  85. struct device_attribute *da, char *buf)
  86. {
  87. struct g760a_data *data = g760a_update_client(dev);
  88. unsigned int rpm = 0;
  89. mutex_lock(&data->update_lock);
  90. if (!(data->fan_sta & G760A_REG_FAN_STA_RPM_LOW))
  91. rpm = rpm_from_cnt(data->act_cnt, data->clk, data->fan_div);
  92. mutex_unlock(&data->update_lock);
  93. return sprintf(buf, "%d\n", rpm);
  94. }
  95. static ssize_t fan1_alarm_show(struct device *dev,
  96. struct device_attribute *da, char *buf)
  97. {
  98. struct g760a_data *data = g760a_update_client(dev);
  99. int fan_alarm = (data->fan_sta & G760A_REG_FAN_STA_RPM_OFF) ? 1 : 0;
  100. return sprintf(buf, "%d\n", fan_alarm);
  101. }
  102. static ssize_t pwm1_show(struct device *dev, struct device_attribute *da,
  103. char *buf)
  104. {
  105. struct g760a_data *data = g760a_update_client(dev);
  106. return sprintf(buf, "%d\n", PWM_FROM_CNT(data->set_cnt));
  107. }
  108. static ssize_t pwm1_store(struct device *dev, struct device_attribute *da,
  109. const char *buf, size_t count)
  110. {
  111. struct g760a_data *data = g760a_update_client(dev);
  112. struct i2c_client *client = data->client;
  113. unsigned long val;
  114. if (kstrtoul(buf, 10, &val))
  115. return -EINVAL;
  116. mutex_lock(&data->update_lock);
  117. data->set_cnt = PWM_TO_CNT(clamp_val(val, 0, 255));
  118. g760a_write_value(client, G760A_REG_SET_CNT, data->set_cnt);
  119. mutex_unlock(&data->update_lock);
  120. return count;
  121. }
  122. static DEVICE_ATTR_RW(pwm1);
  123. static DEVICE_ATTR_RO(fan1_input);
  124. static DEVICE_ATTR_RO(fan1_alarm);
  125. static struct attribute *g760a_attrs[] = {
  126. &dev_attr_pwm1.attr,
  127. &dev_attr_fan1_input.attr,
  128. &dev_attr_fan1_alarm.attr,
  129. NULL
  130. };
  131. ATTRIBUTE_GROUPS(g760a);
  132. /*
  133. * new-style driver model code
  134. */
  135. static int g760a_probe(struct i2c_client *client)
  136. {
  137. struct device *dev = &client->dev;
  138. struct g760a_data *data;
  139. struct device *hwmon_dev;
  140. if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
  141. return -EIO;
  142. data = devm_kzalloc(dev, sizeof(struct g760a_data), GFP_KERNEL);
  143. if (!data)
  144. return -ENOMEM;
  145. data->client = client;
  146. mutex_init(&data->update_lock);
  147. /* setup default configuration for now */
  148. data->fan_div = G760A_DEFAULT_FAN_DIV;
  149. data->clk = G760A_DEFAULT_CLK;
  150. hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
  151. data,
  152. g760a_groups);
  153. return PTR_ERR_OR_ZERO(hwmon_dev);
  154. }
  155. static const struct i2c_device_id g760a_id[] = {
  156. { "g760a", 0 },
  157. { }
  158. };
  159. MODULE_DEVICE_TABLE(i2c, g760a_id);
  160. static struct i2c_driver g760a_driver = {
  161. .driver = {
  162. .name = "g760a",
  163. },
  164. .probe_new = g760a_probe,
  165. .id_table = g760a_id,
  166. };
  167. module_i2c_driver(g760a_driver);
  168. MODULE_AUTHOR("Herbert Valerio Riedel <hvr@gnu.org>");
  169. MODULE_DESCRIPTION("GMT G760A driver");
  170. MODULE_LICENSE("GPL");