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
 24struct max31722_data {
 25	struct device *hwmon_dev;
 26	struct spi_device *spi_device;
 27	u8 mode;
 28};
 29
 30static 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
 49static 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
 62static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0);
 63
 64static struct attribute *max31722_attrs[] = {
 65	&sensor_dev_attr_temp1_input.dev_attr.attr,
 66	NULL,
 67};
 68
 69ATTRIBUTE_GROUPS(max31722);
 70
 71static 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
103static 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
116static 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
124static 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
132static DEFINE_SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
133
134static const struct spi_device_id max31722_spi_id[] = {
135	{"max31722", 0},
136	{"max31723", 0},
137	{}
138};
139MODULE_DEVICE_TABLE(spi, max31722_spi_id);
140
141static 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
151module_spi_driver(max31722_driver);
152
153MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
154MODULE_DESCRIPTION("max31722 sensor driver");
155MODULE_LICENSE("GPL v2");