drivers/hwmon/ltq-cputemp.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Lantiq cpu temperature sensor driver
   3  *
   4  * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de>
   5  */
   6
   7 #include <linux/bitops.h>
   8 #include <linux/delay.h>
   9 #include <linux/hwmon.h>
  10 #include <linux/hwmon-sysfs.h>
  11 #include <linux/init.h>
  12 #include <linux/mod_devicetable.h>
  13 #include <linux/module.h>
  14 #include <linux/platform_device.h>
  15
  16 #include <lantiq_soc.h>
  17
  18 /* gphy1 configuration register contains cpu temperature */
  19 #define CGU_GPHY1_CR   0x0040
  20 #define CGU_TEMP_PD    BIT(19)
  21
  22 static void ltq_cputemp_enable(void)
  23 {
  24         ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
  25 }
  26
  27 static void ltq_cputemp_disable(void *data)
  28 {
  29         ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);
  30 }
  31
  32 static int ltq_read(struct device *dev, enum hwmon_sensor_types type,
  33                     u32 attr, int channel, long *temp)
  34 {
  35         int value;
  36
  37         switch (attr) {
  38         case hwmon_temp_input:
  39                 /* get the temperature including one decimal place */
  40                 value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
  41                 value = value * 5;
  42                 /* range -38 to +154 °C, register value zero is -38.0 °C */
  43                 value -= 380;
  44                 /* scale temp to millidegree */
  45                 value = value * 100;
  46                 break;
  47         default:
  48                 return -EOPNOTSUPP;
  49         }
  50
  51         *temp = value;
  52         return 0;
  53 }
  54
  55 static umode_t ltq_is_visible(const void *_data, enum hwmon_sensor_types type,
  56                               u32 attr, int channel)
  57 {
  58         if (type != hwmon_temp)
  59                 return 0;
  60
  61         switch (attr) {
  62         case hwmon_temp_input:
  63                 return 0444;
  64         default:
  65                 return 0;
  66         }
  67 }
  68
  69 static const struct hwmon_channel_info * const ltq_info[] = {
  70         HWMON_CHANNEL_INFO(chip,
  71                            HWMON_C_REGISTER_TZ),
  72         HWMON_CHANNEL_INFO(temp,
  73                            HWMON_T_INPUT),
  74         NULL
  75 };
  76
  77 static const struct hwmon_ops ltq_hwmon_ops = {
  78         .is_visible = ltq_is_visible,
  79         .read = ltq_read,
  80 };
  81
  82 static const struct hwmon_chip_info ltq_chip_info = {
  83         .ops = &ltq_hwmon_ops,
  84         .info = ltq_info,
  85 };
  86
  87 static int ltq_cputemp_probe(struct platform_device *pdev)
  88 {
  89         struct device *hwmon_dev;
  90         int err = 0;
  91
  92         /* available on vr9 v1.2 SoCs only */
  93         if (ltq_soc_type() != SOC_TYPE_VR9_2)
  94                 return -ENODEV;
  95
  96         err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL);
  97         if (err)
  98                 return err;
  99
 100         ltq_cputemp_enable();
 101
 102         hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
 103                                                          "ltq_cputemp",
 104                                                          NULL,
 105                                                          &ltq_chip_info,
 106                                                          NULL);
 107
 108         if (IS_ERR(hwmon_dev)) {
 109                 dev_err(&pdev->dev, "Failed to register as hwmon device");
 110                 return PTR_ERR(hwmon_dev);
 111         }
 112
 113         return 0;
 114 }
 115
 116 const struct of_device_id ltq_cputemp_match[] = {
 117         { .compatible = "lantiq,cputemp" },
 118         {},
 119 };
 120 MODULE_DEVICE_TABLE(of, ltq_cputemp_match);
 121
 122 static struct platform_driver ltq_cputemp_driver = {
 123         .probe = ltq_cputemp_probe,
 124         .driver = {
 125                 .name = "ltq-cputemp",
 126                 .of_match_table = ltq_cputemp_match,
 127         },
 128 };
 129
 130 module_platform_driver(ltq_cputemp_driver);
 131
 132 MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
 133 MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
 134 MODULE_LICENSE("GPL");