drivers/hwmon/ltq-cputemp.c

   1 /* Lantiq cpu temperature sensor driver
   2  *
   3  * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version
   9  *
  10  * This program is distributed in the hope that it will be useful
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, see <http://www.gnu.org/licenses/>
  17  */
  18
  19 #include <linux/bitops.h>
  20 #include <linux/delay.h>
  21 #include <linux/hwmon.h>
  22 #include <linux/hwmon-sysfs.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/of_device.h>
  26
  27 #include <lantiq_soc.h>
  28
  29 /* gphy1 configuration register contains cpu temperature */
  30 #define CGU_GPHY1_CR   0x0040
  31 #define CGU_TEMP_PD    BIT(19)
  32
  33 static void ltq_cputemp_enable(void)
  34 {
  35         ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR);
  36 }
  37
  38 static void ltq_cputemp_disable(void *data)
  39 {
  40         ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR);
  41 }
  42
  43 static int ltq_read(struct device *dev, enum hwmon_sensor_types type,
  44                     u32 attr, int channel, long *temp)
  45 {
  46         int value;
  47
  48         switch (attr) {
  49         case hwmon_temp_input:
  50                 /* get the temperature including one decimal place */
  51                 value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF;
  52                 value = value * 5;
  53                 /* range -38 to +154 °C, register value zero is -38.0 °C */
  54                 value -= 380;
  55                 /* scale temp to millidegree */
  56                 value = value * 100;
  57                 break;
  58         default:
  59                 return -EOPNOTSUPP;
  60         }
  61
  62         *temp = value;
  63         return 0;
  64 }
  65
  66 static umode_t ltq_is_visible(const void *_data, enum hwmon_sensor_types type,
  67                               u32 attr, int channel)
  68 {
  69         if (type != hwmon_temp)
  70                 return 0;
  71
  72         switch (attr) {
  73         case hwmon_temp_input:
  74                 return 0444;
  75         default:
  76                 return 0;
  77         }
  78 }
  79
  80 static const u32 ltq_chip_config[] = {
  81         HWMON_C_REGISTER_TZ,
  82         0
  83 };
  84
  85 static const struct hwmon_channel_info ltq_chip = {
  86         .type = hwmon_chip,
  87         .config = ltq_chip_config,
  88 };
  89
  90 static const u32 ltq_temp_config[] = {
  91         HWMON_T_INPUT,
  92         0
  93 };
  94
  95 static const struct hwmon_channel_info ltq_temp = {
  96         .type = hwmon_temp,
  97         .config = ltq_temp_config,
  98 };
  99
 100 static const struct hwmon_channel_info *ltq_info[] = {
 101         &ltq_chip,
 102         &ltq_temp,
 103         NULL
 104 };
 105
 106 static const struct hwmon_ops ltq_hwmon_ops = {
 107         .is_visible = ltq_is_visible,
 108         .read = ltq_read,
 109 };
 110
 111 static const struct hwmon_chip_info ltq_chip_info = {
 112         .ops = &ltq_hwmon_ops,
 113         .info = ltq_info,
 114 };
 115
 116 static int ltq_cputemp_probe(struct platform_device *pdev)
 117 {
 118         struct device *hwmon_dev;
 119         int err = 0;
 120
 121         /* available on vr9 v1.2 SoCs only */
 122         if (ltq_soc_type() != SOC_TYPE_VR9_2)
 123                 return -ENODEV;
 124
 125         err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL);
 126         if (err)
 127                 return err;
 128
 129         ltq_cputemp_enable();
 130
 131         hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
 132                                                          "ltq_cputemp",
 133                                                          NULL,
 134                                                          &ltq_chip_info,
 135                                                          NULL);
 136
 137         if (IS_ERR(hwmon_dev)) {
 138                 dev_err(&pdev->dev, "Failed to register as hwmon device");
 139                 return PTR_ERR(hwmon_dev);
 140         }
 141
 142         return 0;
 143 }
 144
 145 const struct of_device_id ltq_cputemp_match[] = {
 146         { .compatible = "lantiq,cputemp" },
 147         {},
 148 };
 149 MODULE_DEVICE_TABLE(of, ltq_cputemp_match);
 150
 151 static struct platform_driver ltq_cputemp_driver = {
 152         .probe = ltq_cputemp_probe,
 153         .driver = {
 154                 .name = "ltq-cputemp",
 155                 .of_match_table = ltq_cputemp_match,
 156         },
 157 };
 158
 159 module_platform_driver(ltq_cputemp_driver);
 160
 161 MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>");
 162 MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver");
 163 MODULE_LICENSE("GPL");