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// SPDX-License-Identifier: GPL-2.0
/*
* Sensirion SPS30 particulate matter sensor driver
*
* Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
*
* I2C slave address: 0x69
*/
#include <asm/unaligned.h>
#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/kernel.h>
#include <linux/module.h>
#define SPS30_CRC8_POLYNOMIAL 0x31
/* max number of bytes needed to store PM measurements or serial string */
#define SPS30_MAX_READ_SIZE 48
/* sensor measures reliably up to 3000 ug / m3 */
#define SPS30_MAX_PM 3000
/* minimum and maximum self cleaning periods in seconds */
#define SPS30_AUTO_CLEANING_PERIOD_MIN 0
#define SPS30_AUTO_CLEANING_PERIOD_MAX 604800
/* SPS30 commands */
#define SPS30_START_MEAS 0x0010
#define SPS30_STOP_MEAS 0x0104
#define SPS30_RESET 0xd304
#define SPS30_READ_DATA_READY_FLAG 0x0202
#define SPS30_READ_DATA 0x0300
#define SPS30_READ_SERIAL 0xd033
#define SPS30_START_FAN_CLEANING 0x5607
#define SPS30_AUTO_CLEANING_PERIOD 0x8004
/* not a sensor command per se, used only to distinguish write from read */
#define SPS30_READ_AUTO_CLEANING_PERIOD 0x8005
enum {
PM1,
PM2P5,
PM4,
PM10,
};
enum {
RESET,
MEASURING,
};
struct sps30_state {
struct i2c_client *client;
/*
* Guards against concurrent access to sensor registers.
* Must be held whenever sequence of commands is to be executed.
*/
struct mutex lock;
int state;
};
DECLARE_CRC8_TABLE(sps30_crc8_table);
static int sps30_write_then_read(struct sps30_state *state, u8 *txbuf,
int txsize, u8 *rxbuf, int rxsize)
{
int ret;
/*
* Sensor does not support repeated start so instead of
* sending two i2c messages in a row we just send one by one.
*/
ret = i2c_master_send(state->client, txbuf, txsize);
if (ret != txsize)
return ret < 0 ? ret : -EIO;
if (!rxbuf)
return 0;
ret = i2c_master_recv(state->client, rxbuf, rxsize);
if (ret != rxsize)
return ret < 0 ? ret : -EIO;
return 0;
}
static int sps30_do_cmd(struct sps30_state *state, u16 cmd, u8 *data, int size)
{
/*
* Internally sensor stores measurements in a following manner:
*
* PM1: upper two bytes, crc8, lower two bytes, crc8
* PM2P5: upper two bytes, crc8, lower two bytes, crc8
* PM4: upper two bytes, crc8, lower two bytes, crc8
* PM10: upper two bytes, crc8, lower two bytes, crc8
*
* What follows next are number concentration measurements and
* typical particle size measurement which we omit.
*/
u8 buf[SPS30_MAX_READ_SIZE] = { cmd >> 8, cmd };
int i, ret = 0;
switch (cmd) {
case SPS30_START_MEAS:
buf[2] = 0x03;
buf[3] = 0x00;
buf[4] = crc8(sps30_crc8_table, &buf[2], 2, CRC8_INIT_VALUE);
ret = sps30_write_then_read(state, buf, 5, NULL, 0);
break;
case SPS30_STOP_MEAS:
case SPS30_RESET:
case SPS30_START_FAN_CLEANING:
ret = sps30_write_then_read(state, buf, 2, NULL, 0);
break;
case SPS30_READ_AUTO_CLEANING_PERIOD:
buf[0] = SPS30_AUTO_CLEANING_PERIOD >> 8;
buf[1] = (u8)SPS30_AUTO_CLEANING_PERIOD;
/* fall through */
case SPS30_READ_DATA_READY_FLAG:
case SPS30_READ_DATA:
case SPS30_READ_SERIAL:
/* every two data bytes are checksummed */
size += size / 2;
ret = sps30_write_then_read(state, buf, 2, buf, size);
break;
case SPS30_AUTO_CLEANING_PERIOD:
buf[2] = data[0];
buf[3] = data[1];
buf[4] = crc8(sps30_crc8_table, &buf[2], 2, CRC8_INIT_VALUE);
buf[5] = data[2];
buf[6] = data[3];
buf[7] = crc8(sps30_crc8_table, &buf[5], 2, CRC8_INIT_VALUE);
ret = sps30_write_then_read(state, buf, 8, NULL, 0);
break;
}
if (ret)
return ret;
/* validate received data and strip off crc bytes */
for (i = 0; i < size; i += 3) {
u8 crc = crc8(sps30_crc8_table, &buf[i], 2, CRC8_INIT_VALUE);
if (crc != buf[i + 2]) {
dev_err(&state->client->dev,
"data integrity check failed\n");
return -EIO;
}
*data++ = buf[i];
*data++ = buf[i + 1];
}
return 0;
}
static s32 sps30_float_to_int_clamped(const u8 *fp)
{
int val = get_unaligned_be32(fp);
int mantissa = val & GENMASK(22, 0);
/* this is fine since passed float is always non-negative */
int exp = val >> 23;
int fraction, shift;
/* special case 0 */
if (!exp && !mantissa)
return 0;
exp -= 127;
if (exp < 0) {
/* return values ranging from 1 to 99 */
return ((((1 << 23) + mantissa) * 100) >> 23) >> (-exp);
}
/* return values ranging from 100 to 300000 */
shift = 23 - exp;
val = (1 << exp) + (mantissa >> shift);
if (val >= SPS30_MAX_PM)
return SPS30_MAX_PM * 100;
fraction = mantissa & GENMASK(shift - 1, 0);
return val * 100 + ((fraction * 100) >> shift);
}
static int sps30_do_meas(struct sps30_state *state, s32 *data, int size)
{
int i, ret, tries = 5;
u8 tmp[16];
if (state->state == RESET) {
ret = sps30_do_cmd(state, SPS30_START_MEAS, NULL, 0);
if (ret)
return ret;
state->state = MEASURING;
}
while (tries--) {
ret = sps30_do_cmd(state, SPS30_READ_DATA_READY_FLAG, tmp, 2);
if (ret)
return -EIO;
/* new measurements ready to be read */
if (tmp[1] == 1)
break;
msleep_interruptible(300);
}
if (tries == -1)
return -ETIMEDOUT;
ret = sps30_do_cmd(state, SPS30_READ_DATA, tmp, sizeof(int) * size);
if (ret)
return ret;
for (i = 0; i < size; i++)
data[i] = sps30_float_to_int_clamped(&tmp[4 * i]);
return 0;
}
static irqreturn_t sps30_trigger_handler(int irq, void *p)
{
struct iio_poll_func *pf = p;
struct iio_dev *indio_dev = pf->indio_dev;
struct sps30_state *state = iio_priv(indio_dev);
int ret;
s32 data[4 + 2]; /* PM1, PM2P5, PM4, PM10, timestamp */
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