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 int *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"); 126