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_show_temp(struct device *dev, 54 struct device_attribute *attr, 55 char *buf) 56 { 57 ssize_t ret; 58 struct max31722_data *data = dev_get_drvdata(dev); 59 60 ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB); 61 if (ret < 0) 62 return ret; 63 /* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */ 64 return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32); 65 } 66 67 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, 68 max31722_show_temp, NULL, 0); 69 70 static struct attribute *max31722_attrs[] = { 71 &sensor_dev_attr_temp1_input.dev_attr.attr, 72 NULL, 73 }; 74 75 ATTRIBUTE_GROUPS(max31722); 76 77 static int max31722_probe(struct spi_device *spi) 78 { 79 int ret; 80 struct max31722_data *data; 81 82 data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL); 83 if (!data) 84 return -ENOMEM; 85 86 spi_set_drvdata(spi, data); 87 data->spi_device = spi; 88 /* 89 * Set SD bit to 0 so we can have continuous measurements. 90 * Set resolution to 12 bits for maximum precision. 91 */ 92 data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT; 93 ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS); 94 if (ret < 0) 95 return ret; 96 97 data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev, 98 spi->modalias, 99 data, 100 max31722_groups); 101 if (IS_ERR(data->hwmon_dev)) { 102 max31722_set_mode(data, MAX31722_MODE_STANDBY); 103 return PTR_ERR(data->hwmon_dev); 104 } 105 106 return 0; 107 } 108 109 static int max31722_remove(struct spi_device *spi) 110 { 111 struct max31722_data *data = spi_get_drvdata(spi); 112 113 hwmon_device_unregister(data->hwmon_dev); 114 115 return max31722_set_mode(data, MAX31722_MODE_STANDBY); 116 } 117 118 static int __maybe_unused max31722_suspend(struct device *dev) 119 { 120 struct spi_device *spi_device = to_spi_device(dev); 121 struct max31722_data *data = spi_get_drvdata(spi_device); 122 123 return max31722_set_mode(data, MAX31722_MODE_STANDBY); 124 } 125 126 static int __maybe_unused max31722_resume(struct device *dev) 127 { 128 struct spi_device *spi_device = to_spi_device(dev); 129 struct max31722_data *data = spi_get_drvdata(spi_device); 130 131 return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS); 132 } 133 134 static SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume); 135 136 static const struct spi_device_id max31722_spi_id[] = { 137 {"max31722", 0}, 138 {"max31723", 0}, 139 {} 140 }; 141 142 static const struct acpi_device_id __maybe_unused max31722_acpi_id[] = { 143 {"MAX31722", 0}, 144 {"MAX31723", 0}, 145 {} 146 }; 147 148 MODULE_DEVICE_TABLE(spi, max31722_spi_id); 149 150 static struct spi_driver max31722_driver = { 151 .driver = { 152 .name = "max31722", 153 .pm = &max31722_pm_ops, 154 .acpi_match_table = ACPI_PTR(max31722_acpi_id), 155 }, 156 .probe = max31722_probe, 157 .remove = max31722_remove, 158 .id_table = max31722_spi_id, 159 }; 160 161 module_spi_driver(max31722_driver); 162 163 MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>"); 164 MODULE_DESCRIPTION("max31722 sensor driver"); 165 MODULE_LICENSE("GPL v2"); 166