kernel: add kernel module for Sensirion SPS30 PMS

Adds into 4.19 backported kernel module from 5.1 for Sensirion SPS30
particulate matter sensor, for kernel 5.4 backported dependency fix.

Signed-off-by: Petr Štetiar <ynezz@true.cz>

1 files changed, 297 insertions, 0 deletions

diff --git a/target/linux/generic/backport-4.19/502-v5.1-iio-chemical-sps30-allow-changing-self-cleaning-peri.patch b/target/linux/generic/backport-4.19/502-v5.1-iio-chemical-sps30-allow-changing-self-cleaning-peri.patch
new file mode 100644
index 0000000000..ca3e23b8fc
--- /dev/null
+++ b/target/linux/generic/backport-4.19/502-v5.1-iio-chemical-sps30-allow-changing-self-cleaning-peri.patch
@@ -0,0 +1,297 @@
+From 62129a0849d27cc94ced832bcf9dcde283dcbe08 Mon Sep 17 00:00:00 2001
+From: Tomasz Duszynski <tduszyns@gmail.com>
+Date: Tue, 15 Jan 2019 20:00:06 +0100
+Subject: [PATCH] iio: chemical: sps30: allow changing self cleaning period
+
+Sensor can periodically trigger self cleaning. Period can be changed by
+writing a new value to a dedicated attribute. Upon attribute read
+current period gets returned.
+
+Signed-off-by: Tomasz Duszynski <tduszyns@gmail.com>
+Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
+---
+ Documentation/ABI/testing/sysfs-bus-iio-sps30 |  20 +++
+ drivers/iio/chemical/sps30.c                  | 143 +++++++++++++++---
+ 2 files changed, 145 insertions(+), 18 deletions(-)
+
+diff --git a/Documentation/ABI/testing/sysfs-bus-iio-sps30 b/Documentation/ABI/testing/sysfs-bus-iio-sps30
+index e7ce2c57635e..143df8e89d08 100644
+--- a/Documentation/ABI/testing/sysfs-bus-iio-sps30
++++ b/Documentation/ABI/testing/sysfs-bus-iio-sps30
+@@ -6,3 +6,23 @@ Description:
+ 		Writing 1 starts sensor self cleaning. Internal fan accelerates
+ 		to its maximum speed and keeps spinning for about 10 seconds in
+ 		order to blow out accumulated dust.
++
++What:		/sys/bus/iio/devices/iio:deviceX/cleaning_period
++Date:		January 2019
++KernelVersion:	5.1
++Contact:	linux-iio@vger.kernel.org
++Description:
++		Sensor is capable of triggering self cleaning periodically.
++		Period can be changed by writing a new value here. Upon reading
++		the current one is returned. Units are seconds.
++
++		Writing 0 disables periodical self cleaning entirely.
++
++What:		/sys/bus/iio/devices/iio:deviceX/cleaning_period_available
++Date:		January 2019
++KernelVersion:	5.1
++Contact:	linux-iio@vger.kernel.org
++Description:
++		The range of available values in seconds represented as the
++		minimum value, the step and the maximum value, all enclosed in
++		square brackets.
+diff --git a/drivers/iio/chemical/sps30.c b/drivers/iio/chemical/sps30.c
+index f3b4390c8f5c..376fac41ecb5 100644
+--- a/drivers/iio/chemical/sps30.c
++++ b/drivers/iio/chemical/sps30.c
+@@ -5,9 +5,6 @@
+  * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
+  *
+  * I2C slave address: 0x69
+- *
+- * TODO:
+- *  - support for reading/setting auto cleaning interval
+  */
+ 
+ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+@@ -21,6 +18,7 @@
+ #include <linux/iio/sysfs.h>
+ #include <linux/iio/trigger_consumer.h>
+ #include <linux/iio/triggered_buffer.h>
++#include <linux/kernel.h>
+ #include <linux/module.h>
+ 
+ #define SPS30_CRC8_POLYNOMIAL 0x31
+@@ -28,6 +26,9 @@
+ #define SPS30_MAX_READ_SIZE 48
+ /* 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
+@@ -37,6 +38,9 @@
+ #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,
+@@ -45,6 +49,11 @@ enum {
+ 	PM10,
+ };
+ 
++enum {
++	RESET,
++	MEASURING,
++};
++
+ struct sps30_state {
+ 	struct i2c_client *client;
+ 	/*
+@@ -52,6 +61,7 @@ struct sps30_state {
+ 	 * Must be held whenever sequence of commands is to be executed.
+ 	 */
+ 	struct mutex lock;
++	int state;
+ };
+ 
+ DECLARE_CRC8_TABLE(sps30_crc8_table);
+@@ -107,6 +117,9 @@ static int sps30_do_cmd(struct sps30_state *state, u16 cmd, u8 *data, int size)
+ 	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;
+ 	case SPS30_READ_DATA_READY_FLAG:
+ 	case SPS30_READ_DATA:
+ 	case SPS30_READ_SERIAL:
+@@ -114,6 +127,15 @@ static int sps30_do_cmd(struct sps30_state *state, u16 cmd, u8 *data, int size)
+ 		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)
+@@ -170,6 +192,14 @@ static int sps30_do_meas(struct sps30_state *state, s32 *data, int size)
+ 	int i, ret, tries = 5;
+ 	u8 tmp[16];
+ 
++	if (state->state == RESET) {
++		ret = sps30_do_cmd(state, SPS30_START_MEAS, NULL, 0);
++		if (ret)
++			return ret;
++
++		state->state = MEASURING;
++	}
++
+ 	while (tries--) {
+ 		ret = sps30_do_cmd(state, SPS30_READ_DATA_READY_FLAG, tmp, 2);
+ 		if (ret)
+@@ -276,6 +306,24 @@ 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)
+@@ -296,10 +344,82 @@ static ssize_t start_cleaning_store(struct device *dev,
+ 	return len;
+ }
+ 
++static ssize_t cleaning_period_show(struct device *dev,
++				      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];
++	int ret;
++
++	mutex_lock(&state->lock);
++	ret = sps30_do_cmd(state, SPS30_READ_AUTO_CLEANING_PERIOD, tmp, 4);
++	mutex_unlock(&state->lock);
++	if (ret)
++		return ret;
++
++	return sprintf(buf, "%d\n", get_unaligned_be32(tmp));
++}
++
++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;
++
++	if ((val < SPS30_AUTO_CLEANING_PERIOD_MIN) ||
++	    (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);
++	if (ret) {
++		mutex_unlock(&state->lock);
++		return ret;
++	}
++
++	msleep(20);
++
++	/*
++	 * sensor requires reset in order to return up to date self cleaning
++	 * period
++	 */
++	ret = sps30_do_cmd_reset(state);
++	if (ret)
++		dev_warn(dev,
++			 "period changed but reads will return the old value\n");
++
++	mutex_unlock(&state->lock);
++
++	return len;
++}
++
++static ssize_t cleaning_period_available_show(struct device *dev,
++					      struct device_attribute *attr,
++					      char *buf)
++{
++	return snprintf(buf, PAGE_SIZE, "[%d %d %d]\n",
++			SPS30_AUTO_CLEANING_PERIOD_MIN, 1,
++			SPS30_AUTO_CLEANING_PERIOD_MAX);
++}
++
+ static IIO_DEVICE_ATTR_WO(start_cleaning, 0);
++static IIO_DEVICE_ATTR_RW(cleaning_period, 0);
++static IIO_DEVICE_ATTR_RO(cleaning_period_available, 0);
+ 
+ static struct attribute *sps30_attrs[] = {
+ 	&iio_dev_attr_start_cleaning.dev_attr.attr,
++	&iio_dev_attr_cleaning_period.dev_attr.attr,
++	&iio_dev_attr_cleaning_period_available.dev_attr.attr,
+ 	NULL
+ };
+ 
+@@ -362,6 +482,7 @@ static int sps30_probe(struct i2c_client *client)
+ 	state = iio_priv(indio_dev);
+ 	i2c_set_clientdata(client, indio_dev);
+ 	state->client = client;
++	state->state = RESET;
+ 	indio_dev->dev.parent = &client->dev;
+ 	indio_dev->info = &sps30_info;
+ 	indio_dev->name = client->name;
+@@ -373,19 +494,11 @@ static int sps30_probe(struct i2c_client *client)
+ 	mutex_init(&state->lock);
+ 	crc8_populate_msb(sps30_crc8_table, SPS30_CRC8_POLYNOMIAL);
+ 
+-	ret = sps30_do_cmd(state, SPS30_RESET, NULL, 0);
++	ret = sps30_do_cmd_reset(state);
+ 	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) {
+@@ -395,12 +508,6 @@ static int sps30_probe(struct i2c_client *client)
+ 	/* 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;