xref: /openbmc/linux/drivers/iio/chemical/sps30_i2c.c (revision 1ac731c529cd4d6adbce134754b51ff7d822b145)
1  // SPDX-License-Identifier: GPL-2.0
2  /*
3   * Sensirion SPS30 particulate matter sensor i2c driver
4   *
5   * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
6   *
7   * I2C slave address: 0x69
8   */
9  #include <asm/unaligned.h>
10  #include <linux/crc8.h>
11  #include <linux/delay.h>
12  #include <linux/device.h>
13  #include <linux/errno.h>
14  #include <linux/i2c.h>
15  #include <linux/mod_devicetable.h>
16  #include <linux/module.h>
17  #include <linux/types.h>
18  
19  #include "sps30.h"
20  
21  #define SPS30_I2C_CRC8_POLYNOMIAL 0x31
22  /* max number of bytes needed to store PM measurements or serial string */
23  #define SPS30_I2C_MAX_BUF_SIZE 48
24  
25  DECLARE_CRC8_TABLE(sps30_i2c_crc8_table);
26  
27  #define SPS30_I2C_START_MEAS 0x0010
28  #define SPS30_I2C_STOP_MEAS 0x0104
29  #define SPS30_I2C_READ_MEAS 0x0300
30  #define SPS30_I2C_MEAS_READY 0x0202
31  #define SPS30_I2C_RESET 0xd304
32  #define SPS30_I2C_CLEAN_FAN 0x5607
33  #define SPS30_I2C_PERIOD 0x8004
34  #define SPS30_I2C_READ_SERIAL 0xd033
35  #define SPS30_I2C_READ_VERSION 0xd100
36  
sps30_i2c_xfer(struct sps30_state * state,unsigned char * txbuf,size_t txsize,unsigned char * rxbuf,size_t rxsize)37  static int sps30_i2c_xfer(struct sps30_state *state, unsigned char *txbuf, size_t txsize,
38  			  unsigned char *rxbuf, size_t rxsize)
39  {
40  	struct i2c_client *client = to_i2c_client(state->dev);
41  	int ret;
42  
43  	/*
44  	 * Sensor does not support repeated start so instead of
45  	 * sending two i2c messages in a row we just send one by one.
46  	 */
47  	ret = i2c_master_send(client, txbuf, txsize);
48  	if (ret < 0)
49  		return ret;
50  	if (ret != txsize)
51  		return -EIO;
52  
53  	if (!rxsize)
54  		return 0;
55  
56  	ret = i2c_master_recv(client, rxbuf, rxsize);
57  	if (ret < 0)
58  		return ret;
59  	if (ret != rxsize)
60  		return -EIO;
61  
62  	return 0;
63  }
64  
sps30_i2c_command(struct sps30_state * state,u16 cmd,void * arg,size_t arg_size,void * rsp,size_t rsp_size)65  static int sps30_i2c_command(struct sps30_state *state, u16 cmd, void *arg, size_t arg_size,
66  			     void *rsp, size_t rsp_size)
67  {
68  	/*
69  	 * Internally sensor stores measurements in a following manner:
70  	 *
71  	 * PM1:   upper two bytes, crc8, lower two bytes, crc8
72  	 * PM2P5: upper two bytes, crc8, lower two bytes, crc8
73  	 * PM4:   upper two bytes, crc8, lower two bytes, crc8
74  	 * PM10:  upper two bytes, crc8, lower two bytes, crc8
75  	 *
76  	 * What follows next are number concentration measurements and
77  	 * typical particle size measurement which we omit.
78  	 */
79  	unsigned char buf[SPS30_I2C_MAX_BUF_SIZE];
80  	unsigned char *tmp;
81  	unsigned char crc;
82  	size_t i;
83  	int ret;
84  
85  	put_unaligned_be16(cmd, buf);
86  	i = 2;
87  
88  	if (rsp) {
89  		/* each two bytes are followed by a crc8 */
90  		rsp_size += rsp_size / 2;
91  	} else {
92  		tmp = arg;
93  
94  		while (arg_size) {
95  			buf[i] = *tmp++;
96  			buf[i + 1] = *tmp++;
97  			buf[i + 2] = crc8(sps30_i2c_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
98  			arg_size -= 2;
99  			i += 3;
100  		}
101  	}
102  
103  	ret = sps30_i2c_xfer(state, buf, i, buf, rsp_size);
104  	if (ret)
105  		return ret;
106  
107  	/* validate received data and strip off crc bytes */
108  	tmp = rsp;
109  	for (i = 0; i < rsp_size; i += 3) {
110  		crc = crc8(sps30_i2c_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
111  		if (crc != buf[i + 2]) {
112  			dev_err(state->dev, "data integrity check failed\n");
113  			return -EIO;
114  		}
115  
116  		*tmp++ = buf[i];
117  		*tmp++ = buf[i + 1];
118  	}
119  
120  	return 0;
121  }
122  
sps30_i2c_start_meas(struct sps30_state * state)123  static int sps30_i2c_start_meas(struct sps30_state *state)
124  {
125  	/* request BE IEEE754 formatted data */
126  	unsigned char buf[] = { 0x03, 0x00 };
127  
128  	return sps30_i2c_command(state, SPS30_I2C_START_MEAS, buf, sizeof(buf), NULL, 0);
129  }
130  
sps30_i2c_stop_meas(struct sps30_state * state)131  static int sps30_i2c_stop_meas(struct sps30_state *state)
132  {
133  	return sps30_i2c_command(state, SPS30_I2C_STOP_MEAS, NULL, 0, NULL, 0);
134  }
135  
sps30_i2c_reset(struct sps30_state * state)136  static int sps30_i2c_reset(struct sps30_state *state)
137  {
138  	int ret;
139  
140  	ret = sps30_i2c_command(state, SPS30_I2C_RESET, NULL, 0, NULL, 0);
141  	msleep(500);
142  	/*
143  	 * Power-on-reset causes sensor to produce some glitch on i2c bus and
144  	 * some controllers end up in error state. Recover simply by placing
145  	 * some data on the bus, for example STOP_MEAS command, which
146  	 * is NOP in this case.
147  	 */
148  	sps30_i2c_stop_meas(state);
149  
150  	return ret;
151  }
152  
sps30_i2c_meas_ready(struct sps30_state * state)153  static bool sps30_i2c_meas_ready(struct sps30_state *state)
154  {
155  	unsigned char buf[2];
156  	int ret;
157  
158  	ret = sps30_i2c_command(state, SPS30_I2C_MEAS_READY, NULL, 0, buf, sizeof(buf));
159  	if (ret)
160  		return false;
161  
162  	return buf[1];
163  }
164  
sps30_i2c_read_meas(struct sps30_state * state,__be32 * meas,size_t num)165  static int sps30_i2c_read_meas(struct sps30_state *state, __be32 *meas, size_t num)
166  {
167  	/* measurements are ready within a second */
168  	if (msleep_interruptible(1000))
169  		return -EINTR;
170  
171  	if (!sps30_i2c_meas_ready(state))
172  		return -ETIMEDOUT;
173  
174  	return sps30_i2c_command(state, SPS30_I2C_READ_MEAS, NULL, 0, meas, sizeof(num) * num);
175  }
176  
sps30_i2c_clean_fan(struct sps30_state * state)177  static int sps30_i2c_clean_fan(struct sps30_state *state)
178  {
179  	return sps30_i2c_command(state, SPS30_I2C_CLEAN_FAN, NULL, 0, NULL, 0);
180  }
181  
sps30_i2c_read_cleaning_period(struct sps30_state * state,__be32 * period)182  static int sps30_i2c_read_cleaning_period(struct sps30_state *state, __be32 *period)
183  {
184  	return sps30_i2c_command(state, SPS30_I2C_PERIOD, NULL, 0, period, sizeof(*period));
185  }
186  
sps30_i2c_write_cleaning_period(struct sps30_state * state,__be32 period)187  static int sps30_i2c_write_cleaning_period(struct sps30_state *state, __be32 period)
188  {
189  	return sps30_i2c_command(state, SPS30_I2C_PERIOD, &period, sizeof(period), NULL, 0);
190  }
191  
sps30_i2c_show_info(struct sps30_state * state)192  static int sps30_i2c_show_info(struct sps30_state *state)
193  {
194  	/* extra nul just in case */
195  	unsigned char buf[32 + 1] = { 0x00 };
196  	int ret;
197  
198  	ret = sps30_i2c_command(state, SPS30_I2C_READ_SERIAL, NULL, 0, buf, sizeof(buf) - 1);
199  	if (ret)
200  		return ret;
201  
202  	dev_info(state->dev, "serial number: %s\n", buf);
203  
204  	ret = sps30_i2c_command(state, SPS30_I2C_READ_VERSION, NULL, 0, buf, 2);
205  	if (ret)
206  		return ret;
207  
208  	dev_info(state->dev, "fw version: %u.%u\n", buf[0], buf[1]);
209  
210  	return 0;
211  }
212  
213  static const struct sps30_ops sps30_i2c_ops = {
214  	.start_meas = sps30_i2c_start_meas,
215  	.stop_meas = sps30_i2c_stop_meas,
216  	.read_meas = sps30_i2c_read_meas,
217  	.reset = sps30_i2c_reset,
218  	.clean_fan = sps30_i2c_clean_fan,
219  	.read_cleaning_period = sps30_i2c_read_cleaning_period,
220  	.write_cleaning_period = sps30_i2c_write_cleaning_period,
221  	.show_info = sps30_i2c_show_info,
222  };
223  
sps30_i2c_probe(struct i2c_client * client)224  static int sps30_i2c_probe(struct i2c_client *client)
225  {
226  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
227  		return -EOPNOTSUPP;
228  
229  	crc8_populate_msb(sps30_i2c_crc8_table, SPS30_I2C_CRC8_POLYNOMIAL);
230  
231  	return sps30_probe(&client->dev, client->name, NULL, &sps30_i2c_ops);
232  }
233  
234  static const struct i2c_device_id sps30_i2c_id[] = {
235  	{ "sps30" },
236  	{ }
237  };
238  MODULE_DEVICE_TABLE(i2c, sps30_i2c_id);
239  
240  static const struct of_device_id sps30_i2c_of_match[] = {
241  	{ .compatible = "sensirion,sps30" },
242  	{ }
243  };
244  MODULE_DEVICE_TABLE(of, sps30_i2c_of_match);
245  
246  static struct i2c_driver sps30_i2c_driver = {
247  	.driver = {
248  		.name = KBUILD_MODNAME,
249  		.of_match_table = sps30_i2c_of_match,
250  	},
251  	.id_table = sps30_i2c_id,
252  	.probe = sps30_i2c_probe,
253  };
254  module_i2c_driver(sps30_i2c_driver);
255  
256  MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
257  MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor i2c driver");
258  MODULE_LICENSE("GPL v2");
259  MODULE_IMPORT_NS(IIO_SPS30);
260