drivers/thermal/kirkwood_thermal.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Kirkwood thermal sensor driver
   4  *
   5  * Copyright (C) 2012 Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
   6  */
   7 #include <linux/device.h>
   8 #include <linux/err.h>
   9 #include <linux/io.h>
  10 #include <linux/kernel.h>
  11 #include <linux/of.h>
  12 #include <linux/module.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/thermal.h>
  15
  16 #define KIRKWOOD_THERMAL_VALID_OFFSET   9
  17 #define KIRKWOOD_THERMAL_VALID_MASK     0x1
  18 #define KIRKWOOD_THERMAL_TEMP_OFFSET    10
  19 #define KIRKWOOD_THERMAL_TEMP_MASK      0x1FF
  20
  21 /* Kirkwood Thermal Sensor Dev Structure */
  22 struct kirkwood_thermal_priv {
  23         void __iomem *sensor;
  24 };
  25
  26 static int kirkwood_get_temp(struct thermal_zone_device *thermal,
  27                           int *temp)
  28 {
  29         unsigned long reg;
  30         struct kirkwood_thermal_priv *priv = thermal->devdata;
  31
  32         reg = readl_relaxed(priv->sensor);
  33
  34         /* Valid check */
  35         if (!((reg >> KIRKWOOD_THERMAL_VALID_OFFSET) &
  36             KIRKWOOD_THERMAL_VALID_MASK)) {
  37                 dev_err(&thermal->device,
  38                         "Temperature sensor reading not valid\n");
  39                 return -EIO;
  40         }
  41
  42         /*
  43          * Calculate temperature. According to Marvell internal
  44          * documentation the formula for this is:
  45          * Celsius = (322-reg)/1.3625
  46          */
  47         reg = (reg >> KIRKWOOD_THERMAL_TEMP_OFFSET) &
  48                 KIRKWOOD_THERMAL_TEMP_MASK;
  49         *temp = ((3220000000UL - (10000000UL * reg)) / 13625);
  50
  51         return 0;
  52 }
  53
  54 static struct thermal_zone_device_ops ops = {
  55         .get_temp = kirkwood_get_temp,
  56 };
  57
  58 static const struct of_device_id kirkwood_thermal_id_table[] = {
  59         { .compatible = "marvell,kirkwood-thermal" },
  60         {}
  61 };
  62
  63 static int kirkwood_thermal_probe(struct platform_device *pdev)
  64 {
  65         struct thermal_zone_device *thermal = NULL;
  66         struct kirkwood_thermal_priv *priv;
  67         struct resource *res;
  68
  69         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  70         if (!priv)
  71                 return -ENOMEM;
  72
  73         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  74         priv->sensor = devm_ioremap_resource(&pdev->dev, res);
  75         if (IS_ERR(priv->sensor))
  76                 return PTR_ERR(priv->sensor);
  77
  78         thermal = thermal_zone_device_register("kirkwood_thermal", 0, 0,
  79                                                priv, &ops, NULL, 0, 0);
  80         if (IS_ERR(thermal)) {
  81                 dev_err(&pdev->dev,
  82                         "Failed to register thermal zone device\n");
  83                 return PTR_ERR(thermal);
  84         }
  85
  86         platform_set_drvdata(pdev, thermal);
  87
  88         return 0;
  89 }
  90
  91 static int kirkwood_thermal_exit(struct platform_device *pdev)
  92 {
  93         struct thermal_zone_device *kirkwood_thermal =
  94                 platform_get_drvdata(pdev);
  95
  96         thermal_zone_device_unregister(kirkwood_thermal);
  97
  98         return 0;
  99 }
 100
 101 MODULE_DEVICE_TABLE(of, kirkwood_thermal_id_table);
 102
 103 static struct platform_driver kirkwood_thermal_driver = {
 104         .probe = kirkwood_thermal_probe,
 105         .remove = kirkwood_thermal_exit,
 106         .driver = {
 107                 .name = "kirkwood_thermal",
 108                 .of_match_table = kirkwood_thermal_id_table,
 109         },
 110 };
 111
 112 module_platform_driver(kirkwood_thermal_driver);
 113
 114 MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
 115 MODULE_DESCRIPTION("kirkwood thermal driver");
 116 MODULE_LICENSE("GPL");