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/acpi.h>
 10#include <linux/hwmon.h>
 11#include <linux/hwmon-sysfs.h>
 12#include <linux/kernel.h>
 13#include <linux/module.h>
 14#include <linux/spi/spi.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
 25struct max31722_data {
 26	struct device *hwmon_dev;
 27	struct spi_device *spi_device;
 28	u8 mode;
 29};
 30
 31static 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
 50static 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 sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32);
 61}
 62
 63static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0);
 64
 65static struct attribute *max31722_attrs[] = {
 66	&sensor_dev_attr_temp1_input.dev_attr.attr,
 67	NULL,
 68};
 69
 70ATTRIBUTE_GROUPS(max31722);
 71
 72static 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
104static int max31722_remove(struct spi_device *spi)
105{
106	struct max31722_data *data = spi_get_drvdata(spi);
107
108	hwmon_device_unregister(data->hwmon_dev);
109
110	return max31722_set_mode(data, MAX31722_MODE_STANDBY);
111}
112
113static int __maybe_unused max31722_suspend(struct device *dev)
114{
115	struct spi_device *spi_device = to_spi_device(dev);
116	struct max31722_data *data = spi_get_drvdata(spi_device);
117
118	return max31722_set_mode(data, MAX31722_MODE_STANDBY);
119}
120
121static int __maybe_unused max31722_resume(struct device *dev)
122{
123	struct spi_device *spi_device = to_spi_device(dev);
124	struct max31722_data *data = spi_get_drvdata(spi_device);
125
126	return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
127}
128
129static SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
130
131static const struct spi_device_id max31722_spi_id[] = {
132	{"max31722", 0},
133	{"max31723", 0},
134	{}
135};
136
137static const struct acpi_device_id __maybe_unused max31722_acpi_id[] = {
138	{"MAX31722", 0},
139	{"MAX31723", 0},
140	{}
141};
142
143MODULE_DEVICE_TABLE(spi, max31722_spi_id);
144
145static struct spi_driver max31722_driver = {
146	.driver = {
147		.name = "max31722",
148		.pm = &max31722_pm_ops,
149		.acpi_match_table = ACPI_PTR(max31722_acpi_id),
150	},
151	.probe =            max31722_probe,
152	.remove =           max31722_remove,
153	.id_table =         max31722_spi_id,
154};
155
156module_spi_driver(max31722_driver);
157
158MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
159MODULE_DESCRIPTION("max31722 sensor driver");
160MODULE_LICENSE("GPL v2");