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    SubjectRe: [PATCH v4 2/3] iio: chemical: add support for Sensirion SPS30 sensor
    On Fri, 14 Dec 2018 19:28:02 +0100
    Tomasz Duszynski <tduszyns@gmail.com> wrote:

    > Add support for Sensirion SPS30 particulate matter sensor.
    >
    > Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
    One minor thing inline I'll fix whilst applying.
    Please check I didn't mess it up though!

    Thanks,

    Jonathan

    > ---
    > drivers/iio/chemical/Kconfig | 11 +
    > drivers/iio/chemical/Makefile | 1 +
    > drivers/iio/chemical/sps30.c | 406 ++++++++++++++++++++++++++++++++++
    > 3 files changed, 418 insertions(+)
    > create mode 100644 drivers/iio/chemical/sps30.c
    >
    > diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
    > index b8e005be4f87..57832b4360e9 100644
    > --- a/drivers/iio/chemical/Kconfig
    > +++ b/drivers/iio/chemical/Kconfig
    > @@ -61,6 +61,17 @@ config IAQCORE
    > iAQ-Core Continuous/Pulsed VOC (Volatile Organic Compounds)
    > sensors
    >
    > +config SPS30
    > + tristate "SPS30 particulate matter sensor"
    > + depends on I2C
    > + select CRC8
    > + help
    > + Say Y here to build support for the Sensirion SPS30 particulate
    > + matter sensor.
    > +
    > + To compile this driver as a module, choose M here: the module will
    > + be called sps30.
    > +
    > config VZ89X
    > tristate "SGX Sensortech MiCS VZ89X VOC sensor"
    > depends on I2C
    > diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
    > index 2f4c4ba4d781..9f42f4252151 100644
    > --- a/drivers/iio/chemical/Makefile
    > +++ b/drivers/iio/chemical/Makefile
    > @@ -9,4 +9,5 @@ obj-$(CONFIG_BME680_I2C) += bme680_i2c.o
    > obj-$(CONFIG_BME680_SPI) += bme680_spi.o
    > obj-$(CONFIG_CCS811) += ccs811.o
    > obj-$(CONFIG_IAQCORE) += ams-iaq-core.o
    > +obj-$(CONFIG_SPS30) += sps30.o
    > obj-$(CONFIG_VZ89X) += vz89x.o
    > diff --git a/drivers/iio/chemical/sps30.c b/drivers/iio/chemical/sps30.c
    > new file mode 100644
    > index 000000000000..f1cea8699c78
    > --- /dev/null
    > +++ b/drivers/iio/chemical/sps30.c
    > @@ -0,0 +1,406 @@
    > +// SPDX-License-Identifier: GPL-2.0
    > +/*
    > + * Sensirion SPS30 particulate matter sensor driver
    > + *
    > + * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
    > + *
    > + * I2C slave address: 0x69
    > + *
    > + * TODO:
    > + * - support for turning on fan cleaning
    > + * - support for reading/setting auto cleaning interval
    > + */
    > +
    > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
    > +
    > +#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/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
    > +
    > +/* 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
    > +
    > +enum {
    > + PM1,
    > + PM2P5,
    > + PM4,
    > + PM10,
    > +};
    > +
    > +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;
    > +};
    > +
    > +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:
    > + ret = sps30_write_then_read(state, buf, 2, NULL, 0);
    > + break;
    > + 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;
    > + }
    > +
    > + 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 int 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, int *data, int size)
    > +{
    > + int i, ret, tries = 5;
    > + u8 tmp[16];
    > +
    > + 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)
    > + 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, data[4 + 2]; /* PM1, PM2P5, PM4, PM10, timestamp */

    Totally trivial and I'll fix it, but data should be a fixed
    width data type, not an int. s32 will do nicely.


    > +
    > + mutex_lock(&state->lock);
    > + ret = sps30_do_meas(state, data, 4);
    > + mutex_unlock(&state->lock);
    > + if (ret)
    > + goto err;
    > +
    > + iio_push_to_buffers_with_timestamp(indio_dev, data,
    > + iio_get_time_ns(indio_dev));
    > +err:
    > + iio_trigger_notify_done(indio_dev->trig);
    > +
    > + return IRQ_HANDLED;
    > +}
    > +
    > +static int sps30_read_raw(struct iio_dev *indio_dev,
    > + struct iio_chan_spec const *chan,
    > + int *val, int *val2, long mask)
    > +{
    > + struct sps30_state *state = iio_priv(indio_dev);
    > + int data[4], ret = -EINVAL;
    > +
    > + switch (mask) {
    > + case IIO_CHAN_INFO_PROCESSED:
    > + switch (chan->type) {
    > + case IIO_MASSCONCENTRATION:
    > + mutex_lock(&state->lock);
    > + /* read up to the number of bytes actually needed */
    > + switch (chan->channel2) {
    > + case IIO_MOD_PM1:
    > + ret = sps30_do_meas(state, data, 1);
    > + break;
    > + case IIO_MOD_PM2P5:
    > + ret = sps30_do_meas(state, data, 2);
    > + break;
    > + case IIO_MOD_PM4:
    > + ret = sps30_do_meas(state, data, 3);
    > + break;
    > + case IIO_MOD_PM10:
    > + ret = sps30_do_meas(state, data, 4);
    > + break;
    > + }
    > + mutex_unlock(&state->lock);
    > + if (ret)
    > + return ret;
    > +
    > + *val = data[chan->address] / 100;
    > + *val2 = (data[chan->address] % 100) * 10000;
    > +
    > + return IIO_VAL_INT_PLUS_MICRO;
    > + default:
    > + return -EINVAL;
    > + }
    > + case IIO_CHAN_INFO_SCALE:
    > + switch (chan->type) {
    > + case IIO_MASSCONCENTRATION:
    > + switch (chan->channel2) {
    > + case IIO_MOD_PM1:
    > + case IIO_MOD_PM2P5:
    > + case IIO_MOD_PM4:
    > + case IIO_MOD_PM10:
    > + *val = 0;
    > + *val2 = 10000;
    > +
    > + return IIO_VAL_INT_PLUS_MICRO;
    > + }
    > + default:
    > + return -EINVAL;
    > + }
    > + }
    > +
    > + return -EINVAL;
    > +}
    > +
    > +static const struct iio_info sps30_info = {
    > + .read_raw = sps30_read_raw,
    > +};
    > +
    > +#define SPS30_CHAN(_index, _mod) { \
    > + .type = IIO_MASSCONCENTRATION, \
    > + .modified = 1, \
    > + .channel2 = IIO_MOD_ ## _mod, \
    > + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
    > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
    > + .address = _mod, \
    > + .scan_index = _index, \
    > + .scan_type = { \
    > + .sign = 'u', \
    > + .realbits = 19, \
    > + .storagebits = 32, \
    > + .endianness = IIO_CPU, \
    > + }, \
    > +}
    > +
    > +static const struct iio_chan_spec sps30_channels[] = {
    > + SPS30_CHAN(0, PM1),
    > + SPS30_CHAN(1, PM2P5),
    > + SPS30_CHAN(2, PM4),
    > + SPS30_CHAN(3, PM10),
    > + IIO_CHAN_SOFT_TIMESTAMP(4),
    > +};
    > +
    > +static void sps30_stop_meas(void *data)
    > +{
    > + struct sps30_state *state = data;
    > +
    > + sps30_do_cmd(state, SPS30_STOP_MEAS, NULL, 0);
    > +}
    > +
    > +static const unsigned long sps30_scan_masks[] = { 0x0f, 0x00 };
    > +
    > +static int sps30_probe(struct i2c_client *client)
    > +{
    > + struct iio_dev *indio_dev;
    > + struct sps30_state *state;
    > + u8 buf[32];
    > + int ret;
    > +
    > + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
    > + return -EOPNOTSUPP;
    > +
    > + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*state));
    > + if (!indio_dev)
    > + return -ENOMEM;
    > +
    > + state = iio_priv(indio_dev);
    > + i2c_set_clientdata(client, indio_dev);
    > + state->client = client;
    > + indio_dev->dev.parent = &client->dev;
    > + indio_dev->info = &sps30_info;
    > + indio_dev->name = client->name;
    > + indio_dev->channels = sps30_channels;
    > + indio_dev->num_channels = ARRAY_SIZE(sps30_channels);
    > + indio_dev->modes = INDIO_DIRECT_MODE;
    > + indio_dev->available_scan_masks = sps30_scan_masks;
    > +
    > + mutex_init(&state->lock);
    > + crc8_populate_msb(sps30_crc8_table, SPS30_CRC8_POLYNOMIAL);
    > +
    > + ret = sps30_do_cmd(state, SPS30_RESET, NULL, 0);
    > + if (ret) {
    > + dev_err(&client->dev, "failed to reset device\n");
    > + return ret;
    > + }
    > + msleep(300);
    > + /*
    > + * Power-on-reset causes sensor to produce some glitch on i2c bus and
    > + * some controllers end up in error state. Recover simply by placing
    > + * some data on the bus, for example STOP_MEAS command, which
    > + * is NOP in this case.
    > + */
    > + sps30_do_cmd(state, SPS30_STOP_MEAS, NULL, 0);
    > +
    > + ret = sps30_do_cmd(state, SPS30_READ_SERIAL, buf, sizeof(buf));
    > + if (ret) {
    > + dev_err(&client->dev, "failed to read serial number\n");
    > + return ret;
    > + }
    > + /* returned serial number is already NUL terminated */
    > + dev_info(&client->dev, "serial number: %s\n", buf);
    > +
    > + ret = sps30_do_cmd(state, SPS30_START_MEAS, NULL, 0);
    > + if (ret) {
    > + dev_err(&client->dev, "failed to start measurement\n");
    > + return ret;
    > + }
    > +
    > + ret = devm_add_action_or_reset(&client->dev, sps30_stop_meas, state);
    > + if (ret)
    > + return ret;
    > +
    > + ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev, NULL,
    > + sps30_trigger_handler, NULL);
    > + if (ret)
    > + return ret;
    > +
    > + return devm_iio_device_register(&client->dev, indio_dev);
    > +}
    > +
    > +static const struct i2c_device_id sps30_id[] = {
    > + { "sps30" },
    > + { }
    > +};
    > +MODULE_DEVICE_TABLE(i2c, sps30_id);
    > +
    > +static const struct of_device_id sps30_of_match[] = {
    > + { .compatible = "sensirion,sps30" },
    > + { }
    > +};
    > +MODULE_DEVICE_TABLE(of, sps30_of_match);
    > +
    > +static struct i2c_driver sps30_driver = {
    > + .driver = {
    > + .name = "sps30",
    > + .of_match_table = sps30_of_match,
    > + },
    > + .id_table = sps30_id,
    > + .probe_new = sps30_probe,
    > +};
    > +module_i2c_driver(sps30_driver);
    > +
    > +MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
    > +MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor driver");
    > +MODULE_LICENSE("GPL v2");

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