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_zone_device_priv(thermal);
  31
  32         reg = readl_relaxed(priv->sensor);
  33
  34         /* Valid check */
  35         if (!((reg >> KIRKWOOD_THERMAL_VALID_OFFSET) &
  36             KIRKWOOD_THERMAL_VALID_MASK))
  37                 return -EIO;
  38
  39         /*
  40          * Calculate temperature. According to Marvell internal
  41          * documentation the formula for this is:
  42          * Celsius = (322-reg)/1.3625
  43          */
  44         reg = (reg >> KIRKWOOD_THERMAL_TEMP_OFFSET) &
  45                 KIRKWOOD_THERMAL_TEMP_MASK;
  46         *temp = ((3220000000UL - (10000000UL * reg)) / 13625);
  47
  48         return 0;
  49 }
  50
  51 static struct thermal_zone_device_ops ops = {
  52         .get_temp = kirkwood_get_temp,
  53 };
  54
  55 static const struct of_device_id kirkwood_thermal_id_table[] = {
  56         { .compatible = "marvell,kirkwood-thermal" },
  57         {}
  58 };
  59
  60 static int kirkwood_thermal_probe(struct platform_device *pdev)
  61 {
  62         struct thermal_zone_device *thermal = NULL;
  63         struct kirkwood_thermal_priv *priv;
  64         int ret;
  65
  66         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  67         if (!priv)
  68                 return -ENOMEM;
  69
  70         priv->sensor = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
  71         if (IS_ERR(priv->sensor))
  72                 return PTR_ERR(priv->sensor);
  73
  74         thermal = thermal_tripless_zone_device_register("kirkwood_thermal",
  75                                                         priv, &ops, NULL);
  76         if (IS_ERR(thermal)) {
  77                 dev_err(&pdev->dev,
  78                         "Failed to register thermal zone device\n");
  79                 return PTR_ERR(thermal);
  80         }
  81         ret = thermal_zone_device_enable(thermal);
  82         if (ret) {
  83                 thermal_zone_device_unregister(thermal);
  84                 dev_err(&pdev->dev, "Failed to enable thermal zone device\n");
  85                 return ret;
  86         }
  87
  88         platform_set_drvdata(pdev, thermal);
  89
  90         return 0;
  91 }
  92
  93 static void kirkwood_thermal_exit(struct platform_device *pdev)
  94 {
  95         struct thermal_zone_device *kirkwood_thermal =
  96                 platform_get_drvdata(pdev);
  97
  98         thermal_zone_device_unregister(kirkwood_thermal);
  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");