1 /* Lantiq cpu temperature sensor driver 2 * 3 * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de> 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version 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 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, see <http://www.gnu.org/licenses/> 17 */ 18 19 #include <linux/bitops.h> 20 #include <linux/delay.h> 21 #include <linux/hwmon.h> 22 #include <linux/hwmon-sysfs.h> 23 #include <linux/init.h> 24 #include <linux/module.h> 25 #include <linux/of_device.h> 26 27 #include <lantiq_soc.h> 28 29 /* gphy1 configuration register contains cpu temperature */ 30 #define CGU_GPHY1_CR 0x0040 31 #define CGU_TEMP_PD BIT(19) 32 33 static void ltq_cputemp_enable(void) 34 { 35 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR); 36 } 37 38 static void ltq_cputemp_disable(void *data) 39 { 40 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR); 41 } 42 43 static int ltq_read(struct device *dev, enum hwmon_sensor_types type, 44 u32 attr, int channel, long *temp) 45 { 46 int value; 47 48 switch (attr) { 49 case hwmon_temp_input: 50 /* get the temperature including one decimal place */ 51 value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF; 52 value = value * 5; 53 /* range -38 to +154 °C, register value zero is -38.0 °C */ 54 value -= 380; 55 /* scale temp to millidegree */ 56 value = value * 100; 57 break; 58 default: 59 return -EOPNOTSUPP; 60 } 61 62 *temp = value; 63 return 0; 64 } 65 66 static umode_t ltq_is_visible(const void *_data, enum hwmon_sensor_types type, 67 u32 attr, int channel) 68 { 69 if (type != hwmon_temp) 70 return 0; 71 72 switch (attr) { 73 case hwmon_temp_input: 74 return 0444; 75 default: 76 return 0; 77 } 78 } 79 80 static const struct hwmon_channel_info *ltq_info[] = { 81 HWMON_CHANNEL_INFO(chip, 82 HWMON_C_REGISTER_TZ), 83 HWMON_CHANNEL_INFO(temp, 84 HWMON_T_INPUT), 85 NULL 86 }; 87 88 static const struct hwmon_ops ltq_hwmon_ops = { 89 .is_visible = ltq_is_visible, 90 .read = ltq_read, 91 }; 92 93 static const struct hwmon_chip_info ltq_chip_info = { 94 .ops = <q_hwmon_ops, 95 .info = ltq_info, 96 }; 97 98 static int ltq_cputemp_probe(struct platform_device *pdev) 99 { 100 struct device *hwmon_dev; 101 int err = 0; 102 103 /* available on vr9 v1.2 SoCs only */ 104 if (ltq_soc_type() != SOC_TYPE_VR9_2) 105 return -ENODEV; 106 107 err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL); 108 if (err) 109 return err; 110 111 ltq_cputemp_enable(); 112 113 hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, 114 "ltq_cputemp", 115 NULL, 116 <q_chip_info, 117 NULL); 118 119 if (IS_ERR(hwmon_dev)) { 120 dev_err(&pdev->dev, "Failed to register as hwmon device"); 121 return PTR_ERR(hwmon_dev); 122 } 123 124 return 0; 125 } 126 127 const struct of_device_id ltq_cputemp_match[] = { 128 { .compatible = "lantiq,cputemp" }, 129 {}, 130 }; 131 MODULE_DEVICE_TABLE(of, ltq_cputemp_match); 132 133 static struct platform_driver ltq_cputemp_driver = { 134 .probe = ltq_cputemp_probe, 135 .driver = { 136 .name = "ltq-cputemp", 137 .of_match_table = ltq_cputemp_match, 138 }, 139 }; 140 141 module_platform_driver(ltq_cputemp_driver); 142 143 MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>"); 144 MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver"); 145 MODULE_LICENSE("GPL"); 146