Re: [PATCH v3 2/3] iio: mxc4005: add triggered buffer mode for mxc4005

[Jonathan Cameron <jic23@kernel.org>]

On 20/08/15 15:37, Teodora Baluta wrote:
> This patch adds support for buffered readings for the 3-axis
> accelerometer mxc4005.
> 
> Signed-off-by: Teodora Baluta <teodora.baluta@intel.com>
Hi Teodora,

You rather missed the point on using the iio_pollfunc_store_time function.
See below.  Anyhow, as that was on the only issue, I've fixed it up.
Please check the results.

Applied to the togreg branch of iio.git - initially pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan
> ---
>  drivers/iio/accel/Kconfig   |  2 ++
>  drivers/iio/accel/mxc4005.c | 79 +++++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 78 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
> index 69302be..cd5cd24 100644
> --- a/drivers/iio/accel/Kconfig
> +++ b/drivers/iio/accel/Kconfig
> @@ -140,6 +140,8 @@ config MMA9553
>  config MXC4005
>  	tristate "Memsic MXC4005XC 3-Axis Accelerometer Driver"
>  	depends on I2C
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
>  	select REGMAP_I2C
>  	help
>  	  Say yes here to build support for the Memsic MXC4005XC 3-axis
> diff --git a/drivers/iio/accel/mxc4005.c b/drivers/iio/accel/mxc4005.c
> index e15c1bd..95b91b5 100644
> --- a/drivers/iio/accel/mxc4005.c
> +++ b/drivers/iio/accel/mxc4005.c
> @@ -19,6 +19,9 @@
>  #include <linux/acpi.h>
>  #include <linux/regmap.h>
>  #include <linux/iio/sysfs.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/trigger_consumer.h>
>  
>  #define MXC4005_DRV_NAME		"mxc4005"
>  #define MXC4005_REGMAP_NAME		"mxc4005_regmap"
> @@ -52,6 +55,7 @@ struct mxc4005_data {
>  	struct device *dev;
>  	struct mutex mutex;
>  	struct regmap *regmap;
> +	__be16 buffer[8];
>  };
>  
>  /*
> @@ -122,6 +126,20 @@ static const struct regmap_config mxc4005_regmap_config = {
>  	.writeable_reg = mxc4005_is_writeable_reg,
>  };
>  
> +static int mxc4005_read_xyz(struct mxc4005_data *data)
> +{
> +	int ret;
> +
> +	ret = regmap_bulk_read(data->regmap, MXC4005_REG_XOUT_UPPER,
> +			       (u8 *) data->buffer, sizeof(data->buffer));
> +	if (ret < 0) {
> +		dev_err(data->dev, "failed to read axes\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static int mxc4005_read_axis(struct mxc4005_data *data,
>  			     unsigned int addr)
>  {
> @@ -197,7 +215,8 @@ static int mxc4005_read_raw(struct iio_dev *indio_dev,
>  			ret = mxc4005_read_axis(data, chan->address);
>  			if (ret < 0)
>  				return ret;
> -			*val = sign_extend32(ret >> 4, 11);
> +			*val = sign_extend32(ret >> chan->scan_type.shift,
> +					     chan->scan_type.realbits - 1);
>  			return IIO_VAL_INT;
>  		default:
>  			return -EINVAL;
> @@ -239,6 +258,11 @@ static const struct iio_info mxc4005_info = {
>  	.attrs		= &mxc4005_attrs_group,
>  };
>  
> +static const unsigned long mxc4005_scan_masks[] = {
> +	BIT(AXIS_X) | BIT(AXIS_Y) | BIT(AXIS_Z),
> +	0
> +};
> +
>  #define MXC4005_CHANNEL(_axis, _addr) {				\
>  	.type = IIO_ACCEL,					\
>  	.modified = 1,						\
> @@ -246,14 +270,43 @@ static const struct iio_info mxc4005_info = {
>  	.address = _addr,					\
>  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
>  	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +	.scan_index = AXIS_##_axis,				\
> +	.scan_type = {						\
> +		.sign = 's',					\
> +		.realbits = 12,					\
> +		.storagebits = 16,				\
> +		.shift = 4,					\
> +		.endianness = IIO_BE,				\
> +	},							\
>  }
>  
>  static const struct iio_chan_spec mxc4005_channels[] = {
>  	MXC4005_CHANNEL(X, MXC4005_REG_XOUT_UPPER),
>  	MXC4005_CHANNEL(Y, MXC4005_REG_YOUT_UPPER),
>  	MXC4005_CHANNEL(Z, MXC4005_REG_ZOUT_UPPER),
> +	IIO_CHAN_SOFT_TIMESTAMP(3),
>  };
>  
> +static irqreturn_t mxc4005_trigger_handler(int irq, void *private)
> +{
> +	struct iio_poll_func *pf = private;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct mxc4005_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = mxc4005_read_xyz(data);
> +	if (ret < 0)
> +		goto err;
> +
> +	iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
> +					   iio_get_time_ns());
The whole purpose of the storetime pollfunc is to ensure we get a
timestamp as close as possible to the time of the interrupt.  Reading
the time again instead of using the stashed version is not a good plan!

> +
> +err:
> +	iio_trigger_notify_done(indio_dev->trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static int mxc4005_chip_init(struct mxc4005_data *data)
>  {
>  	int ret;
> @@ -304,23 +357,43 @@ static int mxc4005_probe(struct i2c_client *client,
>  	indio_dev->dev.parent = &client->dev;
>  	indio_dev->channels = mxc4005_channels;
>  	indio_dev->num_channels = ARRAY_SIZE(mxc4005_channels);
> +	indio_dev->available_scan_masks = mxc4005_scan_masks;
>  	indio_dev->name = MXC4005_DRV_NAME;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->info = &mxc4005_info;
>  
> +	ret = iio_triggered_buffer_setup(indio_dev,
> +					 &iio_pollfunc_store_time,
> +					 mxc4005_trigger_handler,
> +					 NULL);
> +	if (ret < 0) {
> +		dev_err(&client->dev,
> +			"failed to setup iio triggered buffer\n");
> +		return ret;
> +	}
> +
>  	ret = iio_device_register(indio_dev);
>  	if (ret < 0) {
>  		dev_err(&client->dev,
>  			"unable to register iio device %d\n", ret);
> -		return ret;
> +		goto err_buffer_cleanup;
>  	}
>  
>  	return 0;
> +
> +err_buffer_cleanup:
> +	iio_triggered_buffer_cleanup(indio_dev);
> +
> +	return ret;
>  }
>  
>  static int mxc4005_remove(struct i2c_client *client)
>  {
> -	iio_device_unregister(i2c_get_clientdata(client));
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	iio_triggered_buffer_cleanup(indio_dev);
>  
>  	return 0;
>  }
>