1 /* 2 * max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI 3 * digital thermometer and thermostats. 4 * 5 * Copyright (c) 2016, Intel Corporation. 6 * 7 * This file is subject to the terms and conditions of version 2 of 8 * the GNU General Public License. See the file COPYING in the main 9 * directory of this archive for more details. 10 */ 11 12 #include <linux/acpi.h> 13 #include <linux/hwmon.h> 14 #include <linux/hwmon-sysfs.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/spi/spi.h> 18 19 #define MAX31722_REG_CFG 0x00 20 #define MAX31722_REG_TEMP_LSB 0x01 21 22 #define MAX31722_MODE_CONTINUOUS 0x00 23 #define MAX31722_MODE_STANDBY 0x01 24 #define MAX31722_MODE_MASK 0xFE 25 #define MAX31722_RESOLUTION_12BIT 0x06 26 #define MAX31722_WRITE_MASK 0x80 27 28 struct max31722_data { 29 struct device *hwmon_dev; 30 struct spi_device *spi_device; 31 u8 mode; 32 }; 33 34 static int max31722_set_mode(struct max31722_data *data, u8 mode) 35 { 36 int ret; 37 struct spi_device *spi = data->spi_device; 38 u8 buf[2] = { 39 MAX31722_REG_CFG | MAX31722_WRITE_MASK, 40 (data->mode & MAX31722_MODE_MASK) | mode 41 }; 42 43 ret = spi_write(spi, &buf, sizeof(buf)); 44 if (ret < 0) { 45 dev_err(&spi->dev, "failed to set sensor mode.\n"); 46 return ret; 47 } 48 data->mode = (data->mode & MAX31722_MODE_MASK) | mode; 49 50 return 0; 51 } 52 53 static ssize_t max31722_temp_show(struct device *dev, 54 struct device_attribute *attr, char *buf) 55 { 56 ssize_t ret; 57 struct max31722_data *data = dev_get_drvdata(dev); 58 59 ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB); 60 if (ret < 0) 61 return ret; 62 /* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */ 63 return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32); 64 } 65 66 static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0); 67 68 static struct attribute *max31722_attrs[] = { 69 &sensor_dev_attr_temp1_input.dev_attr.attr, 70 NULL, 71 }; 72 73 ATTRIBUTE_GROUPS(max31722); 74 75 static int max31722_probe(struct spi_device *spi) 76 { 77 int ret; 78 struct max31722_data *data; 79 80 data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL); 81 if (!data) 82 return -ENOMEM; 83 84 spi_set_drvdata(spi, data); 85 data->spi_device = spi; 86 /* 87 * Set SD bit to 0 so we can have continuous measurements. 88 * Set resolution to 12 bits for maximum precision. 89 */ 90 data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT; 91 ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS); 92 if (ret < 0) 93 return ret; 94 95 data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev, 96 spi->modalias, 97 data, 98 max31722_groups); 99 if (IS_ERR(data->hwmon_dev)) { 100 max31722_set_mode(data, MAX31722_MODE_STANDBY); 101 return PTR_ERR(data->hwmon_dev); 102 } 103 104 return 0; 105 } 106 107 static int max31722_remove(struct spi_device *spi) 108 { 109 struct max31722_data *data = spi_get_drvdata(spi); 110 111 hwmon_device_unregister(data->hwmon_dev); 112 113 return max31722_set_mode(data, MAX31722_MODE_STANDBY); 114 } 115 116 static int __maybe_unused 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 __maybe_unused 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 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 }; 139 140 static const struct acpi_device_id __maybe_unused max31722_acpi_id[] = { 141 {"MAX31722", 0}, 142 {"MAX31723", 0}, 143 {} 144 }; 145 146 MODULE_DEVICE_TABLE(spi, max31722_spi_id); 147 148 static struct spi_driver max31722_driver = { 149 .driver = { 150 .name = "max31722", 151 .pm = &max31722_pm_ops, 152 .acpi_match_table = ACPI_PTR(max31722_acpi_id), 153 }, 154 .probe = max31722_probe, 155 .remove = max31722_remove, 156 .id_table = max31722_spi_id, 157 }; 158 159 module_spi_driver(max31722_driver); 160 161 MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>"); 162 MODULE_DESCRIPTION("max31722 sensor driver"); 163 MODULE_LICENSE("GPL v2"); 164