Re: [RFC 1/1] iio: common: cros_ec_sensors: add extra sensor API

[Jonathan Cameron <jic23@jic23.retrosnub.co.uk>]

On Fri,  3 May 2019 12:54:46 +0200
Fabien Lahoudere <fabien.lahoudere@collabora.com> wrote:

> From: Gwendal Grignou <gwendal@chromium.org>
> 
> Version 3 of the EC protocol provides min and max frequencies and fifo
> size for EC sensors.
> The driver allows EC to set parameters for version 3 and set default values
> for earlier versions.
> The sysfs entries are read only and cannot be used to impact on values.
> 
> Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
> Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.com>
Mostly changes in here will follow from comments on the cover letter
but a few other things inline.

Thanks,

Jonathan
> ---
>  .../ABI/testing/sysfs-bus-iio-cros-ec         |  24 ++++
>  .../cros_ec_sensors/cros_ec_sensors_core.c    | 126 +++++++++++++++++-
>  .../linux/iio/common/cros_ec_sensors_core.h   |   7 +
>  include/linux/mfd/cros_ec_commands.h          |  21 +++
>  4 files changed, 177 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-cros-ec b/Documentation/ABI/testing/sysfs-bus-iio-cros-ec
> index 0e95c2ca105c..85d266f4a57e 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio-cros-ec
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-cros-ec
> @@ -26,3 +26,27 @@ Description:
>  		driver and represents the sensor ID as exposed by the EC. This
>  		ID is used by the Android sensor service hardware abstraction
>  		layer (sensor HAL) through the Android container on ChromeOS.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/min_frequency
> +Date:		April 2019
> +KernelVersion:	5.0
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		This attribute is exposed by CrOS EC sensors. It defines the
> +		minimum frequency used by the sensor.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/max_frequency
> +Date:		April 2019
> +KernelVersion:	5.0
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		This attribute is exposed by CrOS EC sensors. It defines the
> +		maximum frequency used by the sensor.
> +
See reply to the cover letter on these.  Bonus points if you implement them
with the read_avail callback.

> +What:		/sys/bus/iio/devices/iio:deviceX/max_events
> +Date:		April 2019
> +KernelVersion:	5.0
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		This attribute is exposed by CrOS EC sensors. It defines the
> +		maximum number of events in the	fifo.

Why does userspace care?

> diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
> index 719a0df5aeeb..84908a4085ef 100644
> --- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
> +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
> @@ -19,12 +19,84 @@
>  #include <linux/slab.h>
>  #include <linux/platform_device.h>
>  
> +/*
> + * Hard coded to the first device to support sensor fifo.  The EC has a 2048
> + * byte fifo and will trigger an interrupt when fifo is 2/3 full.
> + */
> +#define CROS_EC_FIFO_SIZE (2048 * 2 / 3)
> +
>  static char *cros_ec_loc[] = {
>  	[MOTIONSENSE_LOC_BASE] = "base",
>  	[MOTIONSENSE_LOC_LID] = "lid",
>  	[MOTIONSENSE_LOC_MAX] = "unknown",
>  };
>  
> +static void get_default_min_max_freq_and_fifo_size(enum motionsensor_type type,
> +						   u32 *min_freq,
> +						   u32 *max_freq,
> +						   u32 *max_fifo_events)
> +{
> +	/* we don't know fifo size, set to size previously used by sensor HAL */
> +	*max_fifo_events = CROS_EC_FIFO_SIZE;
> +
> +	switch (type) {
> +	case MOTIONSENSE_TYPE_ACCEL:
> +	case MOTIONSENSE_TYPE_GYRO:
> +		*min_freq = 12500;
> +		*max_freq = 100000;
> +		break;
> +	case MOTIONSENSE_TYPE_MAG:
> +		*min_freq = 5000;
> +		*max_freq = 25000;
> +		break;
> +	case MOTIONSENSE_TYPE_PROX:
> +	case MOTIONSENSE_TYPE_LIGHT:
> +		*min_freq = 100;
> +		*max_freq = 50000;
> +		break;
> +	case MOTIONSENSE_TYPE_BARO:
> +		*min_freq = 250;
> +		*max_freq = 20000;
> +		break;
> +	case MOTIONSENSE_TYPE_ACTIVITY:
> +	default:
> +		*max_fifo_events = 0;
> +		*min_freq = 0;
> +		*max_freq = 0;
> +		break;
> +	}
> +}
> +
> +static int cros_ec_get_host_cmd_version_mask(struct cros_ec_device *ec_dev,
> +					     u16 cmd_offset, u16 cmd, u32 *mask)
> +{
> +	struct {
> +		struct cros_ec_command msg;
> +		union {
> +			struct ec_params_get_cmd_versions params;
> +			struct ec_response_get_cmd_versions resp;
> +		};
> +	} __packed buf;
> +	struct ec_params_get_cmd_versions *params = &buf.params;
> +	struct ec_response_get_cmd_versions *resp = &buf.resp;
> +	struct cros_ec_command *msg = &buf.msg;
> +	int ret;
> +
> +	memset(&buf, 0, sizeof(buf));
> +	msg->command = EC_CMD_GET_CMD_VERSIONS + cmd_offset;
> +	msg->insize = sizeof(*resp);
> +	msg->outsize = sizeof(*params);
You could, I think, use c99 structure initialization to set these neatly
and avoid the need for the memset being explicit.


> +	params->cmd = cmd;
> +	ret = cros_ec_cmd_xfer_status(ec_dev, msg);
> +	if (ret >= 0) {
> +		if (msg->result == EC_RES_SUCCESS)
> +			*mask = resp->version_mask;
> +		else
> +			*mask = 0;
> +	}
> +	return ret;
> +}
> +
>  int cros_ec_sensors_core_init(struct platform_device *pdev,
>  			      struct iio_dev *indio_dev,
>  			      bool physical_device)
> @@ -33,6 +105,8 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
>  	struct cros_ec_sensors_core_state *state = iio_priv(indio_dev);
>  	struct cros_ec_dev *ec = dev_get_drvdata(pdev->dev.parent);
>  	struct cros_ec_sensor_platform *sensor_platform = dev_get_platdata(dev);
> +	u32 ver_mask;
> +	int ret;
>  
>  	platform_set_drvdata(pdev, indio_dev);
>  
> @@ -47,8 +121,16 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
>  
>  	mutex_init(&state->cmd_lock);
>  
> +	/* determine what version of MOTIONSENSE CMD EC has */
> +	ret = cros_ec_get_host_cmd_version_mask(state->ec,
> +						ec->cmd_offset,
> +						EC_CMD_MOTION_SENSE_CMD,
> +						&ver_mask);
> +	if (ret < 0 || ver_mask == 0)
> +		return -ENODEV;
> +
>  	/* Set up the host command structure. */
> -	state->msg->version = 2;
> +	state->msg->version = fls(ver_mask) - 1;
>  	state->msg->command = EC_CMD_MOTION_SENSE_CMD + ec->cmd_offset;
>  	state->msg->outsize = sizeof(struct ec_params_motion_sense);
>  
> @@ -66,6 +148,20 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
>  		}
>  		state->type = state->resp->info.type;
>  		state->loc = state->resp->info.location;
> +		if (state->msg->version < 3) {
> +			get_default_min_max_freq_and_fifo_size(
> +					state->resp->info.type,
> +					&state->min_freq,
> +					&state->max_freq,
> +					&state->fifo_max_event_count);
> +		} else {
> +			state->min_freq =
> +				state->resp->info_3.min_frequency;
> +			state->max_freq =
> +				state->resp->info_3.max_frequency;
> +			state->fifo_max_event_count =
> +				state->resp->info_3.fifo_max_event_count;
> +		}
>  	}
>  
>  	return 0;
> @@ -134,6 +230,19 @@ static ssize_t cros_ec_sensors_loc(struct iio_dev *indio_dev,
>  	return snprintf(buf, PAGE_SIZE, "%s\n", cros_ec_loc[st->loc]);
>  }
>  
> +#define DEVICE_STATE_INT_ATTR(_name, _var) \
> +static ssize_t cros_ec_sensors_##_name(struct iio_dev *indio_dev, \
> +		uintptr_t private, const struct iio_chan_spec *chan, \
> +		char *buf) \
> +{ \
> +	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev); \
> +	return snprintf(buf, PAGE_SIZE, "%d\n", st->_var); \
> +}
> +
> +DEVICE_STATE_INT_ATTR(min_freq, min_freq);
> +DEVICE_STATE_INT_ATTR(max_freq, max_freq);
> +DEVICE_STATE_INT_ATTR(max_events, fifo_max_event_count);
> +
>  const struct iio_chan_spec_ext_info cros_ec_sensors_ext_info[] = {
>  	{
>  		.name = "calibrate",
> @@ -145,6 +254,21 @@ const struct iio_chan_spec_ext_info cros_ec_sensors_ext_info[] = {
>  		.shared = IIO_SHARED_BY_ALL,
>  		.read = cros_ec_sensors_loc
>  	},
> +	{
> +		.name = "min_frequency",
> +		.shared = IIO_SHARED_BY_ALL,
> +		.read = cros_ec_sensors_min_freq
> +	},
> +	{
> +		.name = "max_frequency",
> +		.shared = IIO_SHARED_BY_ALL,
> +		.read = cros_ec_sensors_max_freq
> +	},
> +	{
> +		.name = "max_events",
> +		.shared = IIO_SHARED_BY_ALL,
> +		.read = cros_ec_sensors_max_events
> +	},
>  	{ },
>  };
>  EXPORT_SYMBOL_GPL(cros_ec_sensors_ext_info);
> diff --git a/include/linux/iio/common/cros_ec_sensors_core.h b/include/linux/iio/common/cros_ec_sensors_core.h
> index ce16445411ac..4742a9637a85 100644
> --- a/include/linux/iio/common/cros_ec_sensors_core.h
> +++ b/include/linux/iio/common/cros_ec_sensors_core.h
> @@ -78,6 +78,13 @@ struct cros_ec_sensors_core_state {
>  				    unsigned long scan_mask, s16 *data);
>  
>  	int curr_sampl_freq;
> +
> +	/* Min and Max Sampling Frequency in mHz */
> +	u32 min_freq;
> +	u32 max_freq;
> +
> +	/* event fifo size represented in number of events */
> +	u32 fifo_max_event_count;
>  };
>  
>  /**
> diff --git a/include/linux/mfd/cros_ec_commands.h b/include/linux/mfd/cros_ec_commands.h
> index 43bee4f7d137..7fbf29416a0b 100644
> --- a/include/linux/mfd/cros_ec_commands.h
> +++ b/include/linux/mfd/cros_ec_commands.h
> @@ -1714,6 +1714,27 @@ struct ec_response_motion_sense {
>  			uint8_t chip;
>  		} info;
>  
> +		/* Used for MOTIONSENSE_CMD_INFO version 3 */
> +		struct __ec_todo_unpacked {
> +			/* Should be element of enum motionsensor_type. */
> +			u8 type;
> +
> +			/* Should be element of enum motionsensor_location. */
> +			u8 location;
> +
> +			/* Should be element of enum motionsensor_chip. */
> +			u8 chip;
> +
> +			/* Minimum sensor sampling frequency */
> +			u32 min_frequency;
> +
> +			/* Maximum sensor sampling frequency */
> +			u32 max_frequency;
> +
> +			/* Max number of sensor events that could be in fifo */
> +			u32 fifo_max_event_count;
> +		} info_3;
> +
>  		/* Used for MOTIONSENSE_CMD_DATA */
>  		struct ec_response_motion_sensor_data data;
>