[PATCH v3 0/3] iio: sps30: add support for serial interface

[PATCH v3 0/3] iio: sps30: add support for serial interface

[Tomasz Duszynski]

One can communicate with sensor either over i2c or serial interface.
This series add support for the latter. And in order to do that existing
codebase needs to be separated into core and interface specific
components.

v3:
- add i2c device matching based on id table
- constify structure
- rephrase comment regarding reading serial number
- check serial number length

v2:
- simplify Kconfig by hiding core component selection
- export symbols as GPL compatible
- drop excessive ops wrappers
- rework ops to use __be32
- rework polling for measurements, sensor produces measurements within
  1s so instead of polling just wait 1s
- simplify frame ready condition (serial)
- don't mix char with unsigned version
- calculate checksum during frame validation (serial)
- uncomment return status in frame validation (serial)
- pass part name to probe instead of KBUILD_MODNAME

Tomasz Duszynski (3):
  iio: sps30: separate core and interface specific code
  iio: sps30: add support for serial interface
  dt-bindings: iio: chemical: sps30: update binding with serial example

 .../iio/chemical/sensirion,sps30.yaml         |   7 +-
 MAINTAINERS                                   |   2 +
 drivers/iio/chemical/Kconfig                  |  27 +-
 drivers/iio/chemical/Makefile                 |   2 +
 drivers/iio/chemical/sps30.c                  | 269 ++---------
 drivers/iio/chemical/sps30.h                  |  35 ++
 drivers/iio/chemical/sps30_i2c.c              | 258 +++++++++++
 drivers/iio/chemical/sps30_serial.c           | 431 ++++++++++++++++++
 8 files changed, 804 insertions(+), 227 deletions(-)
 create mode 100644 drivers/iio/chemical/sps30.h
 create mode 100644 drivers/iio/chemical/sps30_i2c.c
 create mode 100644 drivers/iio/chemical/sps30_serial.c

--
2.31.1

[PATCH v3 1/3] iio: sps30: separate core and interface specific code

[Tomasz Duszynski]

Move code responsible for handling i2c communication to a separate file.
Rationale for this change is preparation for adding support for serial
communication.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
---
 MAINTAINERS                      |   1 +
 drivers/iio/chemical/Kconfig     |  16 +-
 drivers/iio/chemical/Makefile    |   1 +
 drivers/iio/chemical/sps30.c     | 269 ++++++-------------------------
 drivers/iio/chemical/sps30.h     |  35 ++++
 drivers/iio/chemical/sps30_i2c.c | 258 +++++++++++++++++++++++++++++
 6 files changed, 354 insertions(+), 226 deletions(-)
 create mode 100644 drivers/iio/chemical/sps30.h
 create mode 100644 drivers/iio/chemical/sps30_i2c.c

diff --git a/MAINTAINERS b/MAINTAINERS
index ccc59fd7e5c0..4b39a9c48736 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16137,6 +16137,7 @@ M:	Tomasz Duszynski <tduszyns@gmail.com>
 S:	Maintained
 F:	Documentation/devicetree/bindings/iio/chemical/sensirion,sps30.yaml
 F:	drivers/iio/chemical/sps30.c
+F:	drivers/iio/chemical/sps30_i2c.c
 
 SERIAL DEVICE BUS
 M:	Rob Herring <robh@kernel.org>
diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
index 10bb431bc3ce..2b45a76ab7bc 100644
--- a/drivers/iio/chemical/Kconfig
+++ b/drivers/iio/chemical/Kconfig
@@ -132,17 +132,21 @@ config SENSIRION_SGP30
 	  module will be called sgp30.
 
 config SPS30
-	tristate "SPS30 particulate matter sensor"
-	depends on I2C
-	select CRC8
+	tristate
 	select IIO_BUFFER
 	select IIO_TRIGGERED_BUFFER
+
+config SPS30_I2C
+	tristate "SPS30 particulate matter sensor I2C driver"
+	depends on I2C
+	select SPS30
+	select CRC8
 	help
-	  Say Y here to build support for the Sensirion SPS30 particulate
-	  matter sensor.
+	  Say Y here to build support for the Sensirion SPS30 I2C interface
+	  driver.
 
 	  To compile this driver as a module, choose M here: the module will
-	  be called sps30.
+	  be called sps30_i2c.
 
 config VZ89X
 	tristate "SGX Sensortech MiCS VZ89X VOC sensor"
diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
index fef63dd5bf92..41c264a229c0 100644
--- a/drivers/iio/chemical/Makefile
+++ b/drivers/iio/chemical/Makefile
@@ -17,4 +17,5 @@ obj-$(CONFIG_SCD30_I2C) += scd30_i2c.o
 obj-$(CONFIG_SCD30_SERIAL) += scd30_serial.o
 obj-$(CONFIG_SENSIRION_SGP30)	+= sgp30.o
 obj-$(CONFIG_SPS30) += sps30.o
+obj-$(CONFIG_SPS30_I2C) += sps30_i2c.o
 obj-$(CONFIG_VZ89X)		+= vz89x.o
diff --git a/drivers/iio/chemical/sps30.c b/drivers/iio/chemical/sps30.c
index 7486591588c3..d51314505115 100644
--- a/drivers/iio/chemical/sps30.c
+++ b/drivers/iio/chemical/sps30.c
@@ -3,11 +3,8 @@
  * 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>
@@ -19,27 +16,14 @@
 #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
+#include "sps30.h"
+
 /* 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,
@@ -52,114 +36,9 @@ enum {
 	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 & 0xff);
-		fallthrough;
-	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)
+static s32 sps30_float_to_int_clamped(__be32 *fp)
 {
-	int val = get_unaligned_be32(fp);
+	int val = be32_to_cpup(fp);
 	int mantissa = val & GENMASK(22, 0);
 	/* this is fine since passed float is always non-negative */
 	int exp = val >> 23;
@@ -188,38 +67,35 @@ static s32 sps30_float_to_int_clamped(const u8 *fp)
 
 static int sps30_do_meas(struct sps30_state *state, s32 *data, int size)
 {
-	int i, ret, tries = 5;
-	u8 tmp[16];
+	int i, ret;
 
 	if (state->state == RESET) {
-		ret = sps30_do_cmd(state, SPS30_START_MEAS, NULL, 0);
+		ret = state->ops->start_meas(state);
 		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;
+	ret = state->ops->read_meas(state, (__be32 *)data, size);
+	if (ret)
+		return ret;
 
-		/* new measurements ready to be read */
-		if (tmp[1] == 1)
-			break;
+	for (i = 0; i < size; i++)
+		data[i] = sps30_float_to_int_clamped((__be32 *)&data[i]);
 
-		msleep_interruptible(300);
-	}
+	return 0;
+}
 
-	if (tries == -1)
-		return -ETIMEDOUT;
+static int sps30_do_reset(struct sps30_state *state)
+{
+	int ret;
 
-	ret = sps30_do_cmd(state, SPS30_READ_DATA, tmp, sizeof(int) * size);
+	ret = state->ops->reset(state);
 	if (ret)
 		return ret;
 
-	for (i = 0; i < size; i++)
-		data[i] = sps30_float_to_int_clamped(&tmp[4 * i]);
+	state->state = RESET;
 
 	return 0;
 }
@@ -310,24 +186,6 @@ static int sps30_read_raw(struct iio_dev *indio_dev,
 	return -EINVAL;
 }
 
-static int sps30_do_cmd_reset(struct sps30_state *state)
-{
-	int ret;
-
-	ret = sps30_do_cmd(state, SPS30_RESET, NULL, 0);
-	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);
-	state->state = RESET;
-
-	return ret;
-}
-
 static ssize_t start_cleaning_store(struct device *dev,
 				    struct device_attribute *attr,
 				    const char *buf, size_t len)
@@ -340,7 +198,7 @@ static ssize_t start_cleaning_store(struct device *dev,
 		return -EINVAL;
 
 	mutex_lock(&state->lock);
-	ret = sps30_do_cmd(state, SPS30_START_FAN_CLEANING, NULL, 0);
+	ret = state->ops->clean_fan(state);
 	mutex_unlock(&state->lock);
 	if (ret)
 		return ret;
@@ -349,31 +207,29 @@ static ssize_t start_cleaning_store(struct device *dev,
 }
 
 static ssize_t cleaning_period_show(struct device *dev,
-				      struct device_attribute *attr,
-				      char *buf)
+				    struct device_attribute *attr,
+				    char *buf)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct sps30_state *state = iio_priv(indio_dev);
-	u8 tmp[4];
+	__be32 val;
 	int ret;
 
 	mutex_lock(&state->lock);
-	ret = sps30_do_cmd(state, SPS30_READ_AUTO_CLEANING_PERIOD, tmp, 4);
+	ret = state->ops->read_cleaning_period(state, &val);
 	mutex_unlock(&state->lock);
 	if (ret)
 		return ret;
 
-	return sprintf(buf, "%d\n", get_unaligned_be32(tmp));
+	return sprintf(buf, "%d\n", be32_to_cpu(val));
 }
 
-static ssize_t cleaning_period_store(struct device *dev,
-				       struct device_attribute *attr,
-				       const char *buf, size_t len)
+static ssize_t cleaning_period_store(struct device *dev, struct device_attribute *attr,
+				     const char *buf, size_t len)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct sps30_state *state = iio_priv(indio_dev);
 	int val, ret;
-	u8 tmp[4];
 
 	if (kstrtoint(buf, 0, &val))
 		return -EINVAL;
@@ -382,10 +238,8 @@ static ssize_t cleaning_period_store(struct device *dev,
 	    (val > SPS30_AUTO_CLEANING_PERIOD_MAX))
 		return -EINVAL;
 
-	put_unaligned_be32(val, tmp);
-
 	mutex_lock(&state->lock);
-	ret = sps30_do_cmd(state, SPS30_AUTO_CLEANING_PERIOD, tmp, 0);
+	ret = state->ops->write_cleaning_period(state, cpu_to_be32(val));
 	if (ret) {
 		mutex_unlock(&state->lock);
 		return ret;
@@ -397,7 +251,7 @@ static ssize_t cleaning_period_store(struct device *dev,
 	 * sensor requires reset in order to return up to date self cleaning
 	 * period
 	 */
-	ret = sps30_do_cmd_reset(state);
+	ret = sps30_do_reset(state);
 	if (ret)
 		dev_warn(dev,
 			 "period changed but reads will return the old value\n");
@@ -460,90 +314,65 @@ static const struct iio_chan_spec sps30_channels[] = {
 	IIO_CHAN_SOFT_TIMESTAMP(4),
 };
 
-static void sps30_stop_meas(void *data)
+static void sps30_devm_stop_meas(void *data)
 {
 	struct sps30_state *state = data;
 
-	sps30_do_cmd(state, SPS30_STOP_MEAS, NULL, 0);
+	if (state->state == MEASURING)
+		state->ops->stop_meas(state);
 }
 
 static const unsigned long sps30_scan_masks[] = { 0x0f, 0x00 };
 
-static int sps30_probe(struct i2c_client *client)
+int sps30_probe(struct device *dev, const char *name, void *priv, const struct sps30_ops *ops)
 {
 	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));
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*state));
 	if (!indio_dev)
 		return -ENOMEM;
 
+	dev_set_drvdata(dev, indio_dev);
+
 	state = iio_priv(indio_dev);
-	i2c_set_clientdata(client, indio_dev);
-	state->client = client;
-	state->state = RESET;
+	state->dev = dev;
+	state->priv = priv;
+	state->ops = ops;
+	mutex_init(&state->lock);
+
 	indio_dev->info = &sps30_info;
-	indio_dev->name = client->name;
+	indio_dev->name = 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_reset(state);
+	ret = sps30_do_reset(state);
 	if (ret) {
-		dev_err(&client->dev, "failed to reset device\n");
+		dev_err(dev, "failed to reset device\n");
 		return ret;
 	}
 
-	ret = sps30_do_cmd(state, SPS30_READ_SERIAL, buf, sizeof(buf));
+	ret = state->ops->show_info(state);
 	if (ret) {
-		dev_err(&client->dev, "failed to read serial number\n");
+		dev_err(dev, "failed to read device info\n");
 		return ret;
 	}
-	/* returned serial number is already NUL terminated */
-	dev_info(&client->dev, "serial number: %s\n", buf);
 
-	ret = devm_add_action_or_reset(&client->dev, sps30_stop_meas, state);
+	ret = devm_add_action_or_reset(dev, sps30_devm_stop_meas, state);
 	if (ret)
 		return ret;
 
-	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev, NULL,
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
 					      sps30_trigger_handler, NULL);
 	if (ret)
 		return ret;
 
-	return devm_iio_device_register(&client->dev, indio_dev);
+	return devm_iio_device_register(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);
+EXPORT_SYMBOL_GPL(sps30_probe);
 
 MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
 MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor driver");
diff --git a/drivers/iio/chemical/sps30.h b/drivers/iio/chemical/sps30.h
new file mode 100644
index 000000000000..a58ee43cf45d
--- /dev/null
+++ b/drivers/iio/chemical/sps30.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _SPS30_H
+#define _SPS30_H
+
+#include <linux/types.h>
+
+struct sps30_state;
+struct sps30_ops {
+	int (*start_meas)(struct sps30_state *state);
+	int (*stop_meas)(struct sps30_state *state);
+	int (*read_meas)(struct sps30_state *state, __be32 *meas, size_t num);
+	int (*reset)(struct sps30_state *state);
+	int (*clean_fan)(struct sps30_state *state);
+	int (*read_cleaning_period)(struct sps30_state *state, __be32 *period);
+	int (*write_cleaning_period)(struct sps30_state *state, __be32 period);
+	int (*show_info)(struct sps30_state *state);
+};
+
+struct sps30_state {
+	/* serialize access to the device */
+	struct mutex lock;
+	struct device *dev;
+	int state;
+	/*
+	 * priv pointer is solely for serdev driver private data. We keep it
+	 * here because driver_data inside dev has been already used for iio and
+	 * struct serdev_device doesn't have one.
+	 */
+	void *priv;
+	const struct sps30_ops *ops;
+};
+
+int sps30_probe(struct device *dev, const char *name, void *priv, const struct sps30_ops *ops);
+
+#endif
diff --git a/drivers/iio/chemical/sps30_i2c.c b/drivers/iio/chemical/sps30_i2c.c
new file mode 100644
index 000000000000..d33560ed7184
--- /dev/null
+++ b/drivers/iio/chemical/sps30_i2c.c
@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Sensirion SPS30 particulate matter sensor i2c driver
+ *
+ * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
+ *
+ * I2C slave address: 0x69
+ */
+#include <asm/unaligned.h>
+#include <linux/crc8.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include "sps30.h"
+
+#define SPS30_I2C_CRC8_POLYNOMIAL 0x31
+/* max number of bytes needed to store PM measurements or serial string */
+#define SPS30_I2C_MAX_BUF_SIZE 48
+
+DECLARE_CRC8_TABLE(sps30_i2c_crc8_table);
+
+#define SPS30_I2C_START_MEAS 0x0010
+#define SPS30_I2C_STOP_MEAS 0x0104
+#define SPS30_I2C_READ_MEAS 0x0300
+#define SPS30_I2C_MEAS_READY 0x0202
+#define SPS30_I2C_RESET 0xd304
+#define SPS30_I2C_CLEAN_FAN 0x5607
+#define SPS30_I2C_PERIOD 0x8004
+#define SPS30_I2C_READ_SERIAL 0xd033
+#define SPS30_I2C_READ_VERSION 0xd100
+
+static int sps30_i2c_xfer(struct sps30_state *state, unsigned char *txbuf, size_t txsize,
+			  unsigned char *rxbuf, size_t rxsize)
+{
+	struct i2c_client *client = to_i2c_client(state->dev);
+	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(client, txbuf, txsize);
+	if (ret < 0)
+		return ret;
+	if (ret != txsize)
+		return -EIO;
+
+	if (!rxsize)
+		return 0;
+
+	ret = i2c_master_recv(client, rxbuf, rxsize);
+	if (ret < 0)
+		return ret;
+	if (ret != rxsize)
+		return -EIO;
+
+	return 0;
+}
+
+static int sps30_i2c_command(struct sps30_state *state, u16 cmd, void *arg, size_t arg_size,
+			     void *rsp, size_t rsp_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.
+	 */
+	unsigned char buf[SPS30_I2C_MAX_BUF_SIZE];
+	unsigned char *tmp;
+	unsigned char crc;
+	size_t i;
+	int ret;
+
+	put_unaligned_be16(cmd, buf);
+	i = 2;
+
+	if (rsp) {
+		/* each two bytes are followed by a crc8 */
+		rsp_size += rsp_size / 2;
+	} else {
+		tmp = arg;
+
+		while (arg_size) {
+			buf[i] = *tmp++;
+			buf[i + 1] = *tmp++;
+			buf[i + 2] = crc8(sps30_i2c_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
+			arg_size -= 2;
+			i += 3;
+		}
+	}
+
+	ret = sps30_i2c_xfer(state, buf, i, buf, rsp_size);
+	if (ret)
+		return ret;
+
+	/* validate received data and strip off crc bytes */
+	tmp = rsp;
+	for (i = 0; i < rsp_size; i += 3) {
+		crc = crc8(sps30_i2c_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
+		if (crc != buf[i + 2]) {
+			dev_err(state->dev, "data integrity check failed\n");
+			return -EIO;
+		}
+
+		*tmp++ = buf[i];
+		*tmp++ = buf[i + 1];
+	}
+
+	return 0;
+}
+
+static int sps30_i2c_start_meas(struct sps30_state *state)
+{
+	/* request BE IEEE754 formatted data */
+	unsigned char buf[] = { 0x03, 0x00 };
+
+	return sps30_i2c_command(state, SPS30_I2C_START_MEAS, buf, sizeof(buf), NULL, 0);
+}
+
+static int sps30_i2c_stop_meas(struct sps30_state *state)
+{
+	return sps30_i2c_command(state, SPS30_I2C_STOP_MEAS, NULL, 0, NULL, 0);
+}
+
+static int sps30_i2c_reset(struct sps30_state *state)
+{
+	int ret;
+
+	ret = sps30_i2c_command(state, SPS30_I2C_RESET, NULL, 0, NULL, 0);
+	msleep(500);
+	/*
+	 * 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_i2c_stop_meas(state);
+
+	return ret;
+}
+
+static bool sps30_i2c_meas_ready(struct sps30_state *state)
+{
+	unsigned char buf[2];
+	int ret;
+
+	ret = sps30_i2c_command(state, SPS30_I2C_MEAS_READY, NULL, 0, buf, sizeof(buf));
+	if (ret)
+		return false;
+
+	return buf[1];
+}
+
+static int sps30_i2c_read_meas(struct sps30_state *state, __be32 *meas, size_t num)
+{
+	/* measurements are ready within a second */
+	if (msleep_interruptible(1000))
+		return -EINTR;
+
+	if (!sps30_i2c_meas_ready(state))
+		return -ETIMEDOUT;
+
+	return sps30_i2c_command(state, SPS30_I2C_READ_MEAS, NULL, 0, meas, sizeof(num) * num);
+}
+
+static int sps30_i2c_clean_fan(struct sps30_state *state)
+{
+	return sps30_i2c_command(state, SPS30_I2C_CLEAN_FAN, NULL, 0, NULL, 0);
+}
+
+static int sps30_i2c_read_cleaning_period(struct sps30_state *state, __be32 *period)
+{
+	return sps30_i2c_command(state, SPS30_I2C_PERIOD, NULL, 0, period, sizeof(*period));
+}
+
+static int sps30_i2c_write_cleaning_period(struct sps30_state *state, __be32 period)
+{
+	return sps30_i2c_command(state, SPS30_I2C_PERIOD, &period, sizeof(period), NULL, 0);
+}
+
+static int sps30_i2c_show_info(struct sps30_state *state)
+{
+	/* extra nul just in case */
+	unsigned char buf[32 + 1] = { 0x00 };
+	int ret;
+
+	ret = sps30_i2c_command(state, SPS30_I2C_READ_SERIAL, NULL, 0, buf, sizeof(buf) - 1);
+	if (ret)
+		return ret;
+
+	dev_info(state->dev, "serial number: %s\n", buf);
+
+	ret = sps30_i2c_command(state, SPS30_I2C_READ_VERSION, NULL, 0, buf, 2);
+	if (ret)
+		return ret;
+
+	dev_info(state->dev, "fw version: %u.%u\n", buf[0], buf[1]);
+
+	return 0;
+}
+
+static const struct sps30_ops sps30_i2c_ops = {
+	.start_meas = sps30_i2c_start_meas,
+	.stop_meas = sps30_i2c_stop_meas,
+	.read_meas = sps30_i2c_read_meas,
+	.reset = sps30_i2c_reset,
+	.clean_fan = sps30_i2c_clean_fan,
+	.read_cleaning_period = sps30_i2c_read_cleaning_period,
+	.write_cleaning_period = sps30_i2c_write_cleaning_period,
+	.show_info = sps30_i2c_show_info,
+};
+
+static int sps30_i2c_probe(struct i2c_client *client)
+{
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -EOPNOTSUPP;
+
+	crc8_populate_msb(sps30_i2c_crc8_table, SPS30_I2C_CRC8_POLYNOMIAL);
+
+	return sps30_probe(&client->dev, client->name, NULL, &sps30_i2c_ops);
+}
+
+static const struct i2c_device_id sps30_i2c_id[] = {
+	{ "sps30" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, sps30_i2c_id);
+
+static const struct of_device_id sps30_i2c_of_match[] = {
+	{ .compatible = "sensirion,sps30" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sps30_i2c_of_match);
+
+static struct i2c_driver sps30_i2c_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = sps30_i2c_of_match,
+	},
+	.id_table = sps30_i2c_id,
+	.probe_new = sps30_i2c_probe,
+};
+module_i2c_driver(sps30_i2c_driver);
+
+MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
+MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor i2c driver");
+MODULE_LICENSE("GPL v2");
-- 
2.31.1

[PATCH v3 2/3] iio: sps30: add support for serial interface

[Tomasz Duszynski]

Sensor has support for both i2c and serial communication interfaces.
Both offer very similar set of features. Minor differences don't impact
overall functionality like doing measurements, etc.

Support for i2c have already been added, this patch adds support
for the latter ie. serial interface.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
---
 MAINTAINERS                         |   1 +
 drivers/iio/chemical/Kconfig        |  11 +
 drivers/iio/chemical/Makefile       |   1 +
 drivers/iio/chemical/sps30_serial.c | 431 ++++++++++++++++++++++++++++
 4 files changed, 444 insertions(+)
 create mode 100644 drivers/iio/chemical/sps30_serial.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 4b39a9c48736..cab9a63ad2cf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16138,6 +16138,7 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/iio/chemical/sensirion,sps30.yaml
 F:	drivers/iio/chemical/sps30.c
 F:	drivers/iio/chemical/sps30_i2c.c
+F:	drivers/iio/chemical/sps30_serial.c
 
 SERIAL DEVICE BUS
 M:	Rob Herring <robh@kernel.org>
diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
index 2b45a76ab7bc..a4920646e9be 100644
--- a/drivers/iio/chemical/Kconfig
+++ b/drivers/iio/chemical/Kconfig
@@ -148,6 +148,17 @@ config SPS30_I2C
 	  To compile this driver as a module, choose M here: the module will
 	  be called sps30_i2c.
 
+config SPS30_SERIAL
+	tristate "SPS30 particulate matter sensor serial driver"
+	depends on SERIAL_DEV_BUS
+	select SPS30
+	help
+	  Say Y here to build support for the Sensirion SPS30 serial interface
+	  driver.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called sps30_serial.
+
 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 41c264a229c0..4898690cc155 100644
--- a/drivers/iio/chemical/Makefile
+++ b/drivers/iio/chemical/Makefile
@@ -18,4 +18,5 @@ obj-$(CONFIG_SCD30_SERIAL) += scd30_serial.o
 obj-$(CONFIG_SENSIRION_SGP30)	+= sgp30.o
 obj-$(CONFIG_SPS30) += sps30.o
 obj-$(CONFIG_SPS30_I2C) += sps30_i2c.o
+obj-$(CONFIG_SPS30_SERIAL) += sps30_serial.o
 obj-$(CONFIG_VZ89X)		+= vz89x.o
diff --git a/drivers/iio/chemical/sps30_serial.c b/drivers/iio/chemical/sps30_serial.c
new file mode 100644
index 000000000000..3f311d50087c
--- /dev/null
+++ b/drivers/iio/chemical/sps30_serial.c
@@ -0,0 +1,431 @@
+// 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");
-- 
2.31.1

[PATCH v3 3/3] dt-bindings: iio: chemical: sps30: update binding with serial example

[Tomasz Duszynski]

sps30 has gained support for serial communication so add example to the
binding file. While at it remove reg property from list of required
properties because it's no-op in case of serial communication.

Signed-off-by: Tomasz Duszynski <tomasz.duszynski@octakon.com>
---
 .../devicetree/bindings/iio/chemical/sensirion,sps30.yaml  | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/iio/chemical/sensirion,sps30.yaml b/Documentation/devicetree/bindings/iio/chemical/sensirion,sps30.yaml
index a93d1972a5c2..967500b7e773 100644
--- a/Documentation/devicetree/bindings/iio/chemical/sensirion,sps30.yaml
+++ b/Documentation/devicetree/bindings/iio/chemical/sensirion,sps30.yaml
@@ -22,7 +22,6 @@ properties:
 
 required:
   - compatible
-  - reg
 
 additionalProperties: false
 
@@ -37,5 +36,11 @@ examples:
         reg = <0x69>;
       };
     };
+  - |
+    serial {
+      air-pollution-sensor {
+        compatible = "sensirion,sps30";
+      };
+    };
 
 ...
-- 
2.31.1

Re: [PATCH v3 0/3] iio: sps30: add support for serial interface

[Jonathan Cameron]

On Mon, 3 May 2021 08:00:11 +0200
Tomasz Duszynski <tomasz.duszynski@octakon.com> wrote:

> One can communicate with sensor either over i2c or serial interface.
> This series add support for the latter. And in order to do that existing
> codebase needs to be separated into core and interface specific
> components.

I've taken the view the dt binding change is trivial enough I don't 'need'
to wait for Rob to take a look (though of course any comments are welcome!)

As such, I've applied the series to the togreg branch of iio.git and pushed
it out as testing for the autobuilders to see if we missed anything.

Thanks,

Jonathan

> 
> v3:
> - add i2c device matching based on id table
> - constify structure
> - rephrase comment regarding reading serial number
> - check serial number length
> 
> v2:
> - simplify Kconfig by hiding core component selection
> - export symbols as GPL compatible
> - drop excessive ops wrappers
> - rework ops to use __be32
> - rework polling for measurements, sensor produces measurements within
>   1s so instead of polling just wait 1s
> - simplify frame ready condition (serial)
> - don't mix char with unsigned version
> - calculate checksum during frame validation (serial)
> - uncomment return status in frame validation (serial)
> - pass part name to probe instead of KBUILD_MODNAME
> 
> Tomasz Duszynski (3):
>   iio: sps30: separate core and interface specific code
>   iio: sps30: add support for serial interface
>   dt-bindings: iio: chemical: sps30: update binding with serial example
> 
>  .../iio/chemical/sensirion,sps30.yaml         |   7 +-
>  MAINTAINERS                                   |   2 +
>  drivers/iio/chemical/Kconfig                  |  27 +-
>  drivers/iio/chemical/Makefile                 |   2 +
>  drivers/iio/chemical/sps30.c                  | 269 ++---------
>  drivers/iio/chemical/sps30.h                  |  35 ++
>  drivers/iio/chemical/sps30_i2c.c              | 258 +++++++++++
>  drivers/iio/chemical/sps30_serial.c           | 431 ++++++++++++++++++
>  8 files changed, 804 insertions(+), 227 deletions(-)
>  create mode 100644 drivers/iio/chemical/sps30.h
>  create mode 100644 drivers/iio/chemical/sps30_i2c.c
>  create mode 100644 drivers/iio/chemical/sps30_serial.c
> 
> --
> 2.31.1
>