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Subject[PATCH v2 2/3] iio: chemical: add support for Sensirion SPS30 sensor
Date
Add support for Sensirion SPS30 particulate matter sensor.

Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
---
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..4857b6164dd2
--- /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) "sps30: " fmt
+
+#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 = ((int)fp[0] << 24) | ((int)fp[1] << 16) | ((int)fp[2] << 8) |
+ (int)fp[3];
+ 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 */
+
+ 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");
--
2.19.2
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