diff options
Diffstat (limited to 'drivers/iio/chemical/sps30_serial.c')
| -rw-r--r-- | drivers/iio/chemical/sps30_serial.c | 432 |
1 files changed, 432 insertions, 0 deletions
diff --git a/drivers/iio/chemical/sps30_serial.c b/drivers/iio/chemical/sps30_serial.c new file mode 100644 index 000000000..164f4b3e0 --- /dev/null +++ b/drivers/iio/chemical/sps30_serial.c @@ -0,0 +1,432 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * 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"); +MODULE_IMPORT_NS(IIO_SPS30); |