drivers/thermal/kirkwood_thermal.c

   1 /*
   2  * Kirkwood thermal sensor driver
   3  *
   4  * Copyright (C) 2012 Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   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  */
  16 #include <linux/device.h>
  17 #include <linux/err.h>
  18 #include <linux/io.h>
  19 #include <linux/kernel.h>
  20 #include <linux/of.h>
  21 #include <linux/module.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/thermal.h>
  24
  25 #define KIRKWOOD_THERMAL_VALID_OFFSET   9
  26 #define KIRKWOOD_THERMAL_VALID_MASK     0x1
  27 #define KIRKWOOD_THERMAL_TEMP_OFFSET    10
  28 #define KIRKWOOD_THERMAL_TEMP_MASK      0x1FF
  29
  30 /* Kirkwood Thermal Sensor Dev Structure */
  31 struct kirkwood_thermal_priv {
  32         void __iomem *sensor;
  33 };
  34
  35 static int kirkwood_get_temp(struct thermal_zone_device *thermal,
  36                           unsigned long *temp)
  37 {
  38         unsigned long reg;
  39         struct kirkwood_thermal_priv *priv = thermal->devdata;
  40
  41         reg = readl_relaxed(priv->sensor);
  42
  43         /* Valid check */
  44         if (!((reg >> KIRKWOOD_THERMAL_VALID_OFFSET) &
  45             KIRKWOOD_THERMAL_VALID_MASK)) {
  46                 dev_err(&thermal->device,
  47                         "Temperature sensor reading not valid\n");
  48                 return -EIO;
  49         }
  50
  51         /*
  52          * Calculate temperature. According to Marvell internal
  53          * documentation the formula for this is:
  54          * Celsius = (322-reg)/1.3625
  55          */
  56         reg = (reg >> KIRKWOOD_THERMAL_TEMP_OFFSET) &
  57                 KIRKWOOD_THERMAL_TEMP_MASK;
  58         *temp = ((3220000000UL - (10000000UL * reg)) / 13625);
  59
  60         return 0;
  61 }
  62
  63 static struct thermal_zone_device_ops ops = {
  64         .get_temp = kirkwood_get_temp,
  65 };
  66
  67 static const struct of_device_id kirkwood_thermal_id_table[] = {
  68         { .compatible = "marvell,kirkwood-thermal" },
  69         {}
  70 };
  71
  72 static int kirkwood_thermal_probe(struct platform_device *pdev)
  73 {
  74         struct thermal_zone_device *thermal = NULL;
  75         struct kirkwood_thermal_priv *priv;
  76         struct resource *res;
  77
  78         priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
  79         if (!priv)
  80                 return -ENOMEM;
  81
  82         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  83         priv->sensor = devm_ioremap_resource(&pdev->dev, res);
  84         if (IS_ERR(priv->sensor))
  85                 return PTR_ERR(priv->sensor);
  86
  87         thermal = thermal_zone_device_register("kirkwood_thermal", 0, 0,
  88                                                priv, &ops, NULL, 0, 0);
  89         if (IS_ERR(thermal)) {
  90                 dev_err(&pdev->dev,
  91                         "Failed to register thermal zone device\n");
  92                 return PTR_ERR(thermal);
  93         }
  94
  95         platform_set_drvdata(pdev, thermal);
  96
  97         return 0;
  98 }
  99
 100 static int kirkwood_thermal_exit(struct platform_device *pdev)
 101 {
 102         struct thermal_zone_device *kirkwood_thermal =
 103                 platform_get_drvdata(pdev);
 104
 105         thermal_zone_device_unregister(kirkwood_thermal);
 106
 107         return 0;
 108 }
 109
 110 MODULE_DEVICE_TABLE(of, kirkwood_thermal_id_table);
 111
 112 static struct platform_driver kirkwood_thermal_driver = {
 113         .probe = kirkwood_thermal_probe,
 114         .remove = kirkwood_thermal_exit,
 115         .driver = {
 116                 .name = "kirkwood_thermal",
 117                 .of_match_table = kirkwood_thermal_id_table,
 118         },
 119 };
 120
 121 module_platform_driver(kirkwood_thermal_driver);
 122
 123 MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
 124 MODULE_DESCRIPTION("kirkwood thermal driver");
 125 MODULE_LICENSE("GPL");