1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI 4 * digital thermometer and thermostats. 5 * 6 * Copyright (c) 2016, Intel Corporation. 7 */ 8 9 #include <linux/hwmon.h> 10 #include <linux/hwmon-sysfs.h> 11 #include <linux/kernel.h> 12 #include <linux/module.h> 13 #include <linux/spi/spi.h> 14 #include <linux/sysfs.h> 15 16 #define MAX31722_REG_CFG 0x00 17 #define MAX31722_REG_TEMP_LSB 0x01 18 19 #define MAX31722_MODE_CONTINUOUS 0x00 20 #define MAX31722_MODE_STANDBY 0x01 21 #define MAX31722_MODE_MASK 0xFE 22 #define MAX31722_RESOLUTION_12BIT 0x06 23 #define MAX31722_WRITE_MASK 0x80 24 25 struct max31722_data { 26 struct device *hwmon_dev; 27 struct spi_device *spi_device; 28 u8 mode; 29 }; 30 31 static int max31722_set_mode(struct max31722_data *data, u8 mode) 32 { 33 int ret; 34 struct spi_device *spi = data->spi_device; 35 u8 buf[2] = { 36 MAX31722_REG_CFG | MAX31722_WRITE_MASK, 37 (data->mode & MAX31722_MODE_MASK) | mode 38 }; 39 40 ret = spi_write(spi, &buf, sizeof(buf)); 41 if (ret < 0) { 42 dev_err(&spi->dev, "failed to set sensor mode.\n"); 43 return ret; 44 } 45 data->mode = (data->mode & MAX31722_MODE_MASK) | mode; 46 47 return 0; 48 } 49 50 static ssize_t max31722_temp_show(struct device *dev, 51 struct device_attribute *attr, char *buf) 52 { 53 ssize_t ret; 54 struct max31722_data *data = dev_get_drvdata(dev); 55 56 ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB); 57 if (ret < 0) 58 return ret; 59 /* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */ 60 return sysfs_emit(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32); 61 } 62 63 static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0); 64 65 static struct attribute *max31722_attrs[] = { 66 &sensor_dev_attr_temp1_input.dev_attr.attr, 67 NULL, 68 }; 69 70 ATTRIBUTE_GROUPS(max31722); 71 72 static int max31722_probe(struct spi_device *spi) 73 { 74 int ret; 75 struct max31722_data *data; 76 77 data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL); 78 if (!data) 79 return -ENOMEM; 80 81 spi_set_drvdata(spi, data); 82 data->spi_device = spi; 83 /* 84 * Set SD bit to 0 so we can have continuous measurements. 85 * Set resolution to 12 bits for maximum precision. 86 */ 87 data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT; 88 ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS); 89 if (ret < 0) 90 return ret; 91 92 data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev, 93 spi->modalias, 94 data, 95 max31722_groups); 96 if (IS_ERR(data->hwmon_dev)) { 97 max31722_set_mode(data, MAX31722_MODE_STANDBY); 98 return PTR_ERR(data->hwmon_dev); 99 } 100 101 return 0; 102 } 103 104 static void max31722_remove(struct spi_device *spi) 105 { 106 struct max31722_data *data = spi_get_drvdata(spi); 107 int ret; 108 109 hwmon_device_unregister(data->hwmon_dev); 110 111 ret = max31722_set_mode(data, MAX31722_MODE_STANDBY); 112 if (ret) 113 /* There is nothing we can do about this ... */ 114 dev_warn(&spi->dev, "Failed to put device in stand-by mode\n"); 115 } 116 117 static int max31722_suspend(struct device *dev) 118 { 119 struct spi_device *spi_device = to_spi_device(dev); 120 struct max31722_data *data = spi_get_drvdata(spi_device); 121 122 return max31722_set_mode(data, MAX31722_MODE_STANDBY); 123 } 124 125 static int max31722_resume(struct device *dev) 126 { 127 struct spi_device *spi_device = to_spi_device(dev); 128 struct max31722_data *data = spi_get_drvdata(spi_device); 129 130 return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS); 131 } 132 133 static DEFINE_SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume); 134 135 static const struct spi_device_id max31722_spi_id[] = { 136 {"max31722", 0}, 137 {"max31723", 0}, 138 {} 139 }; 140 MODULE_DEVICE_TABLE(spi, max31722_spi_id); 141 142 static struct spi_driver max31722_driver = { 143 .driver = { 144 .name = "max31722", 145 .pm = pm_sleep_ptr(&max31722_pm_ops), 146 }, 147 .probe = max31722_probe, 148 .remove = max31722_remove, 149 .id_table = max31722_spi_id, 150 }; 151 152 module_spi_driver(max31722_driver); 153 154 MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>"); 155 MODULE_DESCRIPTION("max31722 sensor driver"); 156 MODULE_LICENSE("GPL v2"); 157