1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Lantiq cpu temperature sensor driver 3 * 4 * Copyright (C) 2017 Florian Eckert <fe@dev.tdt.de> 5 */ 6 7 #include <linux/bitops.h> 8 #include <linux/delay.h> 9 #include <linux/hwmon.h> 10 #include <linux/hwmon-sysfs.h> 11 #include <linux/init.h> 12 #include <linux/mod_devicetable.h> 13 #include <linux/module.h> 14 #include <linux/platform_device.h> 15 16 #include <lantiq_soc.h> 17 18 /* gphy1 configuration register contains cpu temperature */ 19 #define CGU_GPHY1_CR 0x0040 20 #define CGU_TEMP_PD BIT(19) 21 22 static void ltq_cputemp_enable(void) 23 { 24 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) | CGU_TEMP_PD, CGU_GPHY1_CR); 25 } 26 27 static void ltq_cputemp_disable(void *data) 28 { 29 ltq_cgu_w32(ltq_cgu_r32(CGU_GPHY1_CR) & ~CGU_TEMP_PD, CGU_GPHY1_CR); 30 } 31 32 static int ltq_read(struct device *dev, enum hwmon_sensor_types type, 33 u32 attr, int channel, long *temp) 34 { 35 int value; 36 37 switch (attr) { 38 case hwmon_temp_input: 39 /* get the temperature including one decimal place */ 40 value = (ltq_cgu_r32(CGU_GPHY1_CR) >> 9) & 0x01FF; 41 value = value * 5; 42 /* range -38 to +154 °C, register value zero is -38.0 °C */ 43 value -= 380; 44 /* scale temp to millidegree */ 45 value = value * 100; 46 break; 47 default: 48 return -EOPNOTSUPP; 49 } 50 51 *temp = value; 52 return 0; 53 } 54 55 static umode_t ltq_is_visible(const void *_data, enum hwmon_sensor_types type, 56 u32 attr, int channel) 57 { 58 if (type != hwmon_temp) 59 return 0; 60 61 switch (attr) { 62 case hwmon_temp_input: 63 return 0444; 64 default: 65 return 0; 66 } 67 } 68 69 static const struct hwmon_channel_info * const ltq_info[] = { 70 HWMON_CHANNEL_INFO(chip, 71 HWMON_C_REGISTER_TZ), 72 HWMON_CHANNEL_INFO(temp, 73 HWMON_T_INPUT), 74 NULL 75 }; 76 77 static const struct hwmon_ops ltq_hwmon_ops = { 78 .is_visible = ltq_is_visible, 79 .read = ltq_read, 80 }; 81 82 static const struct hwmon_chip_info ltq_chip_info = { 83 .ops = <q_hwmon_ops, 84 .info = ltq_info, 85 }; 86 87 static int ltq_cputemp_probe(struct platform_device *pdev) 88 { 89 struct device *hwmon_dev; 90 int err = 0; 91 92 /* available on vr9 v1.2 SoCs only */ 93 if (ltq_soc_type() != SOC_TYPE_VR9_2) 94 return -ENODEV; 95 96 err = devm_add_action(&pdev->dev, ltq_cputemp_disable, NULL); 97 if (err) 98 return err; 99 100 ltq_cputemp_enable(); 101 102 hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, 103 "ltq_cputemp", 104 NULL, 105 <q_chip_info, 106 NULL); 107 108 if (IS_ERR(hwmon_dev)) { 109 dev_err(&pdev->dev, "Failed to register as hwmon device"); 110 return PTR_ERR(hwmon_dev); 111 } 112 113 return 0; 114 } 115 116 const struct of_device_id ltq_cputemp_match[] = { 117 { .compatible = "lantiq,cputemp" }, 118 {}, 119 }; 120 MODULE_DEVICE_TABLE(of, ltq_cputemp_match); 121 122 static struct platform_driver ltq_cputemp_driver = { 123 .probe = ltq_cputemp_probe, 124 .driver = { 125 .name = "ltq-cputemp", 126 .of_match_table = ltq_cputemp_match, 127 }, 128 }; 129 130 module_platform_driver(ltq_cputemp_driver); 131 132 MODULE_AUTHOR("Florian Eckert <fe@dev.tdt.de>"); 133 MODULE_DESCRIPTION("Lantiq cpu temperature sensor driver"); 134 MODULE_LICENSE("GPL"); 135