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