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/*
* Sensirion SPS30 particulate matter sensor serial driver
*
* Copyright (c) 2021 Tomasz Duszynski <tomasz.duszynski@octakon.com>
*/
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/iio/iio.h>
#include <linux/minmax.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/serdev.h>
#include <linux/types.h>
#include "sps30.h"
#define SPS30_SERIAL_DEV_NAME "sps30"
#define SPS30_SERIAL_SOF_EOF 0x7e
#define SPS30_SERIAL_TIMEOUT msecs_to_jiffies(20)
#define SPS30_SERIAL_MAX_BUF_SIZE 263
#define SPS30_SERIAL_ESCAPE_CHAR 0x7d
#define SPS30_SERIAL_FRAME_MIN_SIZE 7
#define SPS30_SERIAL_FRAME_ADR_OFFSET 1
#define SPS30_SERIAL_FRAME_CMD_OFFSET 2
#define SPS30_SERIAL_FRAME_MOSI_LEN_OFFSET 3
#define SPS30_SERIAL_FRAME_MISO_STATE_OFFSET 3
#define SPS30_SERIAL_FRAME_MISO_LEN_OFFSET 4
#define SPS30_SERIAL_FRAME_MISO_DATA_OFFSET 5
#define SPS30_SERIAL_START_MEAS 0x00
#define SPS30_SERIAL_STOP_MEAS 0x01
#define SPS30_SERIAL_READ_MEAS 0x03
#define SPS30_SERIAL_RESET 0xd3
#define SPS30_SERIAL_CLEAN_FAN 0x56
#define SPS30_SERIAL_PERIOD 0x80
#define SPS30_SERIAL_DEV_INFO 0xd0
#define SPS30_SERIAL_READ_VERSION 0xd1
struct sps30_serial_priv {
struct completion new_frame;
unsigned char buf[SPS30_SERIAL_MAX_BUF_SIZE];
size_t num;
bool escaped;
bool done;
};
static int sps30_serial_xfer(struct sps30_state *state, const unsigned char *buf, size_t size)
{
struct serdev_device *serdev = to_serdev_device(state->dev);
struct sps30_serial_priv *priv = state->priv;
int ret;
priv->num = 0;
priv->escaped = false;
priv->done = false;
ret = serdev_device_write(serdev, buf, size, SPS30_SERIAL_TIMEOUT);
if (ret < 0)
return ret;
if (ret != size)
return -EIO;
ret = wait_for_completion_interruptible_timeout(&priv->new_frame, SPS30_SERIAL_TIMEOUT);
if (ret < 0)
return ret;
if (!ret)
return -ETIMEDOUT;
return 0;
}
static const struct {
unsigned char byte;
unsigned char byte2;
} sps30_serial_bytes[] = {
{ 0x11, 0x31 },
{ 0x13, 0x33 },
{ 0x7e, 0x5e },
{ 0x7d, 0x5d },
};
static int sps30_serial_put_byte(unsigned char *buf, unsigned char byte)
{
int i;
for (i = 0; i < ARRAY_SIZE(sps30_serial_bytes); i++) {
if (sps30_serial_bytes[i].byte != byte)
continue;
buf[0] = SPS30_SERIAL_ESCAPE_CHAR;
buf[1] = sps30_serial_bytes[i].byte2;
return 2;
}
buf[0] = byte;
return 1;
}
static char sps30_serial_get_byte(bool escaped, unsigned char byte2)
{
int i;
if (!escaped)
return byte2;
for (i = 0; i < ARRAY_SIZE(sps30_serial_bytes); i++) {
if (sps30_serial_bytes[i].byte2 != byte2)
continue;
return sps30_serial_bytes[i].byte;
}
return 0;
}
static unsigned char sps30_serial_calc_chksum(const unsigned char *buf, size_t num)
{
unsigned int chksum = 0;
size_t i;
for (i = 0; i < num; i++)
chksum += buf[i];
return ~chksum;
}
static int sps30_serial_prep_frame(unsigned char *buf, unsigned char cmd,
const unsigned char *arg, size_t arg_size)
{
unsigned char chksum;
int num = 0;
size_t i;
buf[num++] = SPS30_SERIAL_SOF_EOF;
buf[num++] = 0;
num += sps30_serial_put_byte(buf + num, cmd);
num += sps30_serial_put_byte(buf + num, arg_size);
for (i = 0; i < arg_size; i++)
num += sps30_serial_put_byte(buf + num, arg[i]);
/* SOF isn't checksummed */
chksum = sps30_serial_calc_chksum(buf + 1, num - 1);
num += sps30_serial_put_byte(buf + num, chksum);
buf[num++] = SPS30_SERIAL_SOF_EOF;
return num;
}
static bool sps30_serial_frame_valid(struct sps30_state *state, const unsigned char *buf)
{
struct sps30_serial_priv *priv = state->priv;
unsigned char chksum;
if ((priv->num < SPS30_SERIAL_FRAME_MIN_SIZE) ||
(priv->num != SPS30_SERIAL_FRAME_MIN_SIZE +
priv->buf[SPS30_SERIAL_FRAME_MISO_LEN_OFFSET])) {
dev_err(state->dev, "frame has invalid number of bytes\n");
return false;
}
if ((priv->buf[SPS30_SERIAL_FRAME_ADR_OFFSET] != buf[SPS30_SERIAL_FRAME_ADR_OFFSET]) ||
(priv->buf[SPS30_SERIAL_FRAME_CMD_OFFSET] != buf[SPS30_SERIAL_FRAME_CMD_OFFSET])) {
dev_err(state->dev, "frame has wrong ADR and CMD bytes\n");
return false;
}
if (priv->buf[SPS30_SERIAL_FRAME_MISO_STATE_OFFSET]) {
dev_err(state->dev, "frame with non-zero state received (0x%02x)\n",
priv->buf[SPS30_SERIAL_FRAME_MISO_STATE_OFFSET]);
return false;
}
/* SOF, checksum and EOF are not checksummed */
chksum = sps30_serial_calc_chksum(priv->buf + 1, priv->num - 3);
if (priv->buf[priv->num - 2] != chksum) {
dev_err(state->dev, "frame integrity check failed\n");
return false;
}
return true;
}
static int sps30_serial_command(struct sps30_state *state, unsigned char cmd,
const void *arg, size_t arg_size, void *rsp, size_t rsp_size)
{
struct sps30_serial_priv *priv = state->priv;
unsigned char buf[SPS30_SERIAL_MAX_BUF_SIZE];
int ret, size;
size = sps30_serial_prep_frame(buf, cmd, arg, arg_size);
ret = sps30_serial_xfer(state, buf, size);
if (ret)
return ret;
if (!sps30_serial_frame_valid(state, buf))
return -EIO;
if (rsp) {
rsp_size = min_t(size_t, priv->buf[SPS30_SERIAL_FRAME_MISO_LEN_OFFSET], rsp_size);
memcpy(rsp, &priv->buf[SPS30_SERIAL_FRAME_MISO_DATA_OFFSET], rsp_size);
}
return rsp_size;
}
static int sps30_serial_receive_buf(struct serdev_device *serdev,
const unsigned char *buf, size_t size)
{
struct iio_dev *indio_dev = dev_get_drvdata(&serdev->dev);
struct sps30_serial_priv *priv;
struct sps30_state *state;
unsigned char byte;
size_t i;
if (!indio_dev)
return 0;
state = iio_priv(indio_dev);
priv = state->priv;
/* just in case device put some unexpected data on the bus */
if (priv->done)
return size;
/* wait for the start of frame */
if (!priv->num && size && buf[0] != SPS30_SERIAL_SOF_EOF)
return 1;
if (priv->num + size >= ARRAY_SIZE(priv->buf))
size = ARRAY_SIZE(priv->buf) - priv->num;
for (i = 0; i < size; i++) {
byte = buf[i];
/* remove stuffed bytes on-the-fly */
if (byte == SPS30_SERIAL_ESCAPE_CHAR) {
priv->escaped = true;
continue;
}
byte = sps30_serial_get_byte(priv->escaped, byte);
if (priv->escaped && !byte)
dev_warn(state->dev, "unrecognized escaped char (0x%02x)\n", byte);
priv->buf[priv->num++] = byte;
/* EOF received */
if (!priv->escaped && byte == SPS30_SERIAL_SOF_EOF) {
if (priv->num < SPS30_SERIAL_FRAME_MIN_SIZE)
continue;
priv->done = true;
complete(&priv->new_frame);
i++;
break;
}
priv->escaped = false;
}
return i;
}
static const struct serdev_device_ops sps30_serial_device_ops = {
.receive_buf = sps30_serial_receive_buf,
.write_wakeup = serdev_device_write_wakeup,
};
static int sps30_serial_start_meas(struct sps30_state *state)
{
/* request BE IEEE754 formatted data */
unsigned char buf[] = { 0x01, 0x03 };
return sps30_serial_command(state, SPS30_SERIAL_START_MEAS, buf, sizeof(buf), NULL, 0);
}
static int sps30_serial_stop_meas(struct sps30_state *state)
{
return sps30_serial_command(state, SPS30_SERIAL_STOP_MEAS, NULL, 0, NULL, 0);
}
static int sps30_serial_reset(struct sps30_state *state)
{
int ret;
ret = sps30_serial_command(state, SPS30_SERIAL_RESET, NULL, 0, NULL, 0);
msleep(500);
return ret;
}
static int sps30_serial_read_meas(struct sps30_state *state, __be32 *meas, size_t num)
{
int ret;
/* measurements are ready within a second */
if (msleep_interruptible(1000))
return -EINTR;
ret = sps30_serial_command(state, SPS30_SERIAL_READ_MEAS, NULL, 0, meas, num * sizeof(num));
if (ret < 0)
return ret;
/* if measurements aren't ready sensor returns empty frame */
if (ret == SPS30_SERIAL_FRAME_MIN_SIZE)
return -ETIMEDOUT;
if (ret != num * sizeof(*meas))
return -EIO;
return 0;
}
static int sps30_serial_clean_fan(struct sps30_state *state)
{
return sps30_serial_command(state, SPS30_SERIAL_CLEAN_FAN, NULL, 0, NULL, 0);
}
static int sps30_serial_read_cleaning_period(struct sps30_state *state, __be32 *period)
{
unsigned char buf[] = { 0x00 };
int ret;
ret = sps30_serial_command(state, SPS30_SERIAL_PERIOD, buf, sizeof(buf),
period, sizeof(*period));
if (ret < 0)
return ret;
if (ret != sizeof(*period))
return -EIO;
return 0;
}
static int sps30_serial_write_cleaning_period(struct sps30_state *state, __be32 period)
{
unsigned char buf[5] = { 0x00 };
memcpy(buf + 1, &period, sizeof(period));
return sps30_serial_command(state, SPS30_SERIAL_PERIOD, buf, sizeof(buf), NULL, 0);
}
static int sps30_serial_show_info(struct sps30_state *state)
{
/*
* tell device do return serial number and add extra nul byte just in case
* serial number isn't a valid string
*/
unsigned char buf[32 + 1] = { 0x03 };
struct device *dev = state->dev;
int ret;
ret = sps30_serial_command(state, SPS30_SERIAL_DEV_INFO, buf, 1, buf, sizeof(buf) - 1);
if (ret < 0)
return ret;
if (ret != sizeof(buf) - 1)
return -EIO;
dev_info(dev, "serial number: %s\n", buf);
ret = sps30_serial_command(state, SPS30_SERIAL_READ_VERSION, NULL, 0, buf, sizeof(buf) - 1);
if (ret < 0)
return ret;
if (ret < 2)
return -EIO;
dev_info(dev, "fw version: %u.%u\n", buf[0], buf[1]);
return 0;
}
static const struct sps30_ops sps30_serial_ops = {
.start_meas = sps30_serial_start_meas,
.stop_meas = sps30_serial_stop_meas,
.read_meas = sps30_serial_read_meas,
.reset = sps30_serial_reset,
.clean_fan = sps30_serial_clean_fan,
.read_cleaning_period = sps30_serial_read_cleaning_period,
.write_cleaning_period = sps30_serial_write_cleaning_period,
.show_info = sps30_serial_show_info,
};
static int sps30_serial_probe(struct serdev_device *serdev)
{
struct device *dev = &serdev->dev;
struct sps30_serial_priv *priv;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
init_completion(&priv->new_frame);
serdev_device_set_client_ops(serdev, &sps30_serial_device_ops);
ret = devm_serdev_device_open(dev, serdev);
if (ret)
return ret;
serdev_device_set_baudrate(serdev, 115200);
serdev_device_set_flow_control(serdev, false);
ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
if (ret)
return ret;
return sps30_probe(dev, SPS30_SERIAL_DEV_NAME, priv, &sps30_serial_ops);
}
static const struct of_device_id sps30_serial_of_match[] = {
{ .compatible = "sensirion,sps30" },
{ }
};
MODULE_DEVICE_TABLE(of, sps30_serial_of_match);
static struct serdev_device_driver sps30_serial_driver = {
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = sps30_serial_of_match,
},
.probe = sps30_serial_probe,
};
module_serdev_device_driver(sps30_serial_driver);
MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor serial driver");
MODULE_LICENSE("GPL v2");
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