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Subject[PATCH v3] iio: chemical: sps30: allow changing self cleaning period
Date
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>
---
v3:
* fix allowed period range check

v2:
* return available values formated as a range
* tweak naming a little (interval -> period)

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;
--
2.20.1
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