1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * This is a non-complete driver implementation for the
  4 * HS3001 humidity and temperature sensor and compatibles. It does not include
  5 * the configuration possibilities, where it needs to be set to 'programming mode'
  6 * during power-up.
  7 *
  8 *
  9 * Copyright (C) 2023 SYS TEC electronic AG
 10 * Author: Andre Werner <andre.werner@systec-electronic.com>
 11 */
 12
 13#include <linux/bitfield.h>
 14#include <linux/delay.h>
 15#include <linux/err.h>
 16#include <linux/hwmon.h>
 17#include <linux/i2c.h>
 18#include <linux/init.h>
 19#include <linux/kernel.h>
 20#include <linux/module.h>
 21#include <linux/of_device.h>
 22#include <linux/slab.h>
 23#include <linux/types.h>
 24
 25/* Measurement times */
 26#define HS3001_WAKEUP_TIME	100	/* us */
 27#define HS3001_8BIT_RESOLUTION	550	/* us */
 28#define HS3001_10BIT_RESOLUTION	1310	/* us */
 29#define HS3001_12BIT_RESOLUTION	4500	/* us */
 30#define HS3001_14BIT_RESOLUTION	16900	/* us */
 31
 32#define HS3001_RESPONSE_LENGTH	4
 33
 34#define HS3001_FIXPOINT_ARITH	1000U
 35
 36#define HS3001_MASK_HUMIDITY_0X3FFF	GENMASK(13, 0)
 37#define HS3001_MASK_STATUS_0XC0	GENMASK(7, 6)
 38
 39/* Definitions for Status Bits of A/D Data */
 40#define HS3001_DATA_VALID	0x00	/* Valid Data */
 41#define HS3001_DATA_STALE	0x01	/* Stale Data */
 42
 43struct hs3001_data {
 44	struct i2c_client *client;
 45	struct mutex i2c_lock; /* lock for sending i2c commands */
 46	u32 wait_time;		/* in us */
 47	int temperature;	/* in milli degree */
 48	u32 humidity;		/* in milli % */
 49};
 50
 51static int hs3001_extract_temperature(u16 raw)
 52{
 53	/* fixpoint arithmetic 1 digit */
 54	u32 temp = (raw >> 2) * HS3001_FIXPOINT_ARITH * 165;
 55
 56	temp /= (1 << 14) - 1;
 57
 58	return (int)temp - 40 * HS3001_FIXPOINT_ARITH;
 59}
 60
 61static u32 hs3001_extract_humidity(u16 raw)
 62{
 63	u32 hum = (raw & HS3001_MASK_HUMIDITY_0X3FFF) * HS3001_FIXPOINT_ARITH * 100;
 64
 65	return hum / (1 << 14) - 1;
 66}
 67
 68static int hs3001_data_fetch_command(struct i2c_client *client,
 69				     struct hs3001_data *data)
 70{
 71	int ret;
 72	u8 buf[HS3001_RESPONSE_LENGTH];
 73	u8 hs3001_status;
 74
 75	ret = i2c_master_recv(client, buf, HS3001_RESPONSE_LENGTH);
 76	if (ret != HS3001_RESPONSE_LENGTH) {
 77		ret = ret < 0 ? ret : -EIO;
 78		dev_dbg(&client->dev,
 79			"Error in i2c communication. Error code: %d.\n", ret);
 80		return ret;
 81	}
 82
 83	hs3001_status = FIELD_GET(HS3001_MASK_STATUS_0XC0, buf[0]);
 84	if (hs3001_status == HS3001_DATA_STALE) {
 85		dev_dbg(&client->dev, "Sensor busy.\n");
 86		return -EBUSY;
 87	}
 88	if (hs3001_status != HS3001_DATA_VALID) {
 89		dev_dbg(&client->dev, "Data invalid.\n");
 90		return -EIO;
 91	}
 92
 93	data->humidity =
 94		hs3001_extract_humidity(be16_to_cpup((__be16 *)&buf[0]));
 95	data->temperature =
 96		hs3001_extract_temperature(be16_to_cpup((__be16 *)&buf[2]));
 97
 98	return 0;
 99}
100
101static umode_t hs3001_is_visible(const void *data, enum hwmon_sensor_types type,
102				 u32 attr, int channel)
103{
104	/* Both, humidity and temperature can only be read. */
105	return 0444;
106}
107
108static int hs3001_read(struct device *dev, enum hwmon_sensor_types type,
109		       u32 attr, int channel, long *val)
110{
111	struct hs3001_data *data = dev_get_drvdata(dev);
112	struct i2c_client *client = data->client;
113	int ret;
114
115	mutex_lock(&data->i2c_lock);
116	ret = i2c_master_send(client, NULL, 0);
117	if (ret < 0) {
118		mutex_unlock(&data->i2c_lock);
119		return ret;
120	}
121
122	/*
123	 * Sensor needs some time to process measurement depending on
124	 * resolution (ref. datasheet)
125	 */
126	fsleep(data->wait_time);
127
128	ret = hs3001_data_fetch_command(client, data);
129	mutex_unlock(&data->i2c_lock);
130
131	if (ret < 0)
132		return ret;
133
134	switch (type) {
135	case hwmon_temp:
136		switch (attr) {
137		case hwmon_temp_input:
138			*val = data->temperature;
139			break;
140		default:
141			return -EINVAL;
142		}
143		break;
144	case hwmon_humidity:
145		switch (attr) {
146		case hwmon_humidity_input:
147			*val = data->humidity;
148			break;
149		default:
150			return -EINVAL;
151		}
152		break;
153	default:
154		return -EINVAL;
155	}
156
157	return 0;
158}
159
160static const struct hwmon_channel_info *hs3001_info[] = {
161	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
162	HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT),
163	NULL
164};
165
166static const struct hwmon_ops hs3001_hwmon_ops = {
167	.is_visible = hs3001_is_visible,
168	.read = hs3001_read,
169};
170
171static const struct hwmon_chip_info hs3001_chip_info = {
172	.ops = &hs3001_hwmon_ops,
173	.info = hs3001_info,
174};
175
176/* device ID table */
177static const struct i2c_device_id hs3001_ids[] = {
178	{ "hs3001", 0 },
179	{ },
180};
181
182MODULE_DEVICE_TABLE(i2c, hs3001_ids);
183
184static const struct of_device_id hs3001_of_match[] = {
185	{.compatible = "renesas,hs3001"},
186	{ },
187};
188
189MODULE_DEVICE_TABLE(of, hs3001_of_match);
190
191static int hs3001_probe(struct i2c_client *client)
192{
193	struct hs3001_data *data;
194	struct device *hwmon_dev;
195	struct device *dev = &client->dev;
196
197	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
198		return -EOPNOTSUPP;
199
200	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
201	if (!data)
202		return -ENOMEM;
203
204	data->client = client;
205
206	/*
207	 * Measurement time = wake-up time + measurement time temperature
208	 * + measurement time humidity. This is currently static, because
209	 * enabling programming mode is not supported, yet.
210	 */
211	data->wait_time = (HS3001_WAKEUP_TIME + HS3001_14BIT_RESOLUTION +
212			   HS3001_14BIT_RESOLUTION);
213
214	mutex_init(&data->i2c_lock);
215
216	hwmon_dev = devm_hwmon_device_register_with_info(dev,
217							 client->name,
218							 data,
219							 &hs3001_chip_info,
220							 NULL);
221
222	if (IS_ERR(hwmon_dev))
223		return dev_err_probe(dev, PTR_ERR(hwmon_dev),
224				     "Unable to register hwmon device.\n");
225
226	return 0;
227}
228
229static struct i2c_driver hs3001_i2c_driver = {
230	.driver = {
231		   .name = "hs3001",
232		   .of_match_table = hs3001_of_match,
233	},
234	.probe = hs3001_probe,
235	.id_table = hs3001_ids,
236};
237
238module_i2c_driver(hs3001_i2c_driver);
239
240MODULE_AUTHOR("Andre Werner <andre.werner@systec-electronic.com>");
241MODULE_DESCRIPTION("HS3001 humidity and temperature sensor base driver");
242MODULE_LICENSE("GPL");