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");
156