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 u32 ltq_chip_config[] = { 81 HWMON_C_REGISTER_TZ, 82 0 83 }; 84 85 static const struct hwmon_channel_info ltq_chip = { 86 .type = hwmon_chip, 87 .config = ltq_chip_config, 88 }; 89 90 static const u32 ltq_temp_config[] = { 91 HWMON_T_INPUT, 92 0 93 }; 94 95 static const struct hwmon_channel_info ltq_temp = { 96 .type = hwmon_temp, 97 .config = ltq_temp_config, 98 }; 99 100 static const struct hwmon_channel_info *ltq_info[] = { 101 <q_chip, 102 <q_temp, 103 NULL 104 }; 105 106 static const struct hwmon_ops ltq_hwmon_ops = { 107 .is_visible = ltq_is_visible, 108 .read = ltq_read, 109 }; 110 111 static const struct hwmon_chip_info ltq_chip_info = { 112 .ops = <q_hwmon_ops, 113 .info = ltq_info, 114 }; 115 116 static int ltq_cputemp_probe(struct platform_device *pdev) 117 { 118 struct device *hwmon_dev; 119 int err = 0; 120 121 /* available on vr9 v1.2 SoCs only */ 122 if (ltq_soc_type() != SOC_TYPE_VR9_2) 123 return -ENODEV; 124 125 err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL); 126 if (err) 127 return err; 128 129 ltq_cputemp_enable(); 130 131 hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, 132 "ltq_cputemp", 133 NULL, 134 <q_chip_info, 135 NULL); 136 137 if (IS_ERR(hwmon_dev)) { 138 dev_err(&pdev->dev, "Failed to register as hwmon device"); 139 return PTR_ERR(hwmon_dev); 140 } 141 142 return 0; 143 } 144 145 const struct of_device_id ltq_cputemp_match[] = { 146 { .compatible = "lantiq,cputemp" }, 147 {}, 148 }; 149 MODULE_DEVICE_TABLE(of, ltq_cputemp_match); 150 151 static struct platform_driver ltq_cputemp_driver = { 152 .probe = ltq_cputemp_probe, 153 .driver = { 154 .name = "ltq-cputemp", 155 .of_match_table = ltq_cputemp_match, 156 }, 157 }; 158 159 module_platform_driver(ltq_cputemp_driver); 160 161 MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>"); 162 MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver"); 163 MODULE_LICENSE("GPL"); 164