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Linux/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                 .owner = THIS_MODULE,
118                 .of_match_table = kirkwood_thermal_id_table,
119         },
120 };
121 
122 module_platform_driver(kirkwood_thermal_driver);
123 
124 MODULE_AUTHOR("Nobuhiro Iwamatsu <iwamatsu@nigauri.org>");
125 MODULE_DESCRIPTION("kirkwood thermal driver");
126 MODULE_LICENSE("GPL");
127 

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