drivers/iio/chemical/sps30_i2c.c

   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
  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
  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
 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
 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
 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
 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
 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
 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
 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
 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
 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
 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);