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SubjectRe: [PATCH v2] iio: chemical: sps30: allow changing self cleaning period
On Fri, 11 Jan 2019 21:35:33 +0100
Tomasz Duszynski <tduszyns@gmail.com> wrote:

> 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>
Looks good to me, but... The docs need to say what the unit is.
I'd like seconds ideally but right now it doesn't say.

Thanks,

Jonathan

> ---
> v2:
> * return available values formated as a range
> * tweak naming a little (interval -> period)
>
> Documentation/ABI/testing/sysfs-bus-iio-sps30 | 19 +++
> drivers/iio/chemical/sps30.c | 143 +++++++++++++++---
> 2 files changed, 144 insertions(+), 18 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-sps30 b/Documentation/ABI/testing/sysfs-bus-iio-sps30
> index e7ce2c57635e..68fbaf2ad30d 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio-sps30
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-sps30
> @@ -6,3 +6,22 @@ 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?

> +
> + 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 represented as the minimum value,
> + the step and the maximum value, all enclosed in square brackets.
Also units?

> diff --git a/drivers/iio/chemical/sps30.c b/drivers/iio/chemical/sps30.c
> index f3b4390c8f5c..fe5f6309191b 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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