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Date:   Sat, 5 Oct 2019 16:36:41 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Gwendal Grignou <gwendal@chromium.org>
Cc:     knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net,
        lee.jones@linaro.org, bleung@chromium.org,
        enric.balletbo@collabora.com, dianders@chromium.org,
        groeck@chromium.org, fabien.lahoudere@collabora.com,
        linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org
Subject: Re: [PATCH 02/13] platform: cros_ec: Add cros_ec_sensor_hub driver
Message-ID: <20191005163635.0797abd1@archlinux>
In-Reply-To: <20191005163505.707292c8@archlinux>
References: <20190922175021.53449-1-gwendal@chromium.org>
        <20190922175021.53449-3-gwendal@chromium.org>
        <20191005163505.707292c8@archlinux>
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On Sat, 5 Oct 2019 16:35:05 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> On Sun, 22 Sep 2019 10:50:10 -0700
> Gwendal Grignou <gwendal@chromium.org> wrote:
> 
> > Similar to HID sensor stack, the new driver sits between cros_ec_dev
> > and the iio device drivers:
> > 
> > EC based iio device topology would be:
> > iio:device1 ->
> > ...0/0000:00:1f.0/PNP0C09:00/GOOG0004:00/cros-ec-dev.6.auto/
> >                                          cros-ec-sensorhub.7.auto/
> >                                          cros-ec-accel.15.auto/
> >                                          iio:device1
> > 
> > It will be expanded to control EC sensor FIFO.
> > 
> > Signed-off-by: Gwendal Grignou <gwendal@chromium.org>  
> 
> Minor bits inline.
> 
> My assumption for this sensor hub is it just acts as a
> combiner of data and doesn't guarantee that the sample
> rates are the same or anything like that?  If it does
> it would be much nicer to support as a single sensor, but
> if not this approach is the best way.
Ah. I'd missed the point.  This is really a bit rework of
existing functionality, not a new device type.  Ignore me ;)
> 
> > ---
> >  drivers/iio/common/cros_ec_sensors/Kconfig    |   2 +-
> >  drivers/platform/chrome/Kconfig               |  18 +-
> >  drivers/platform/chrome/Makefile              |   1 +
> >  drivers/platform/chrome/cros_ec_sensorhub.c   | 211 ++++++++++++++++++
> >  .../linux/platform_data/cros_ec_sensorhub.h   |  21 ++
> >  5 files changed, 249 insertions(+), 4 deletions(-)
> >  create mode 100644 drivers/platform/chrome/cros_ec_sensorhub.c
> >  create mode 100644 include/linux/platform_data/cros_ec_sensorhub.h
> > 
> > diff --git a/drivers/iio/common/cros_ec_sensors/Kconfig b/drivers/iio/common/cros_ec_sensors/Kconfig
> > index cdbb29cfb907..fefad9572790 100644
> > --- a/drivers/iio/common/cros_ec_sensors/Kconfig
> > +++ b/drivers/iio/common/cros_ec_sensors/Kconfig
> > @@ -4,7 +4,7 @@
> >  #
> >  config IIO_CROS_EC_SENSORS_CORE
> >  	tristate "ChromeOS EC Sensors Core"
> > -	depends on SYSFS && CROS_EC
> > +	depends on SYSFS && CROS_EC_SENSORHUB
> >  	select IIO_BUFFER
> >  	select IIO_TRIGGERED_BUFFER
> >  	help
> > diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
> > index ee5f08ea57b6..add967236cfb 100644
> > --- a/drivers/platform/chrome/Kconfig
> > +++ b/drivers/platform/chrome/Kconfig
> > @@ -132,9 +132,9 @@ config CROS_EC_LPC
> >  	  module will be called cros_ec_lpcs.
> >  
> >  config CROS_EC_PROTO
> > -        bool
> > -        help
> > -          ChromeOS EC communication protocol helpers.
> > +	bool
> > +	help
> > +	  ChromeOS EC communication protocol helpers.  
> As already pointed out. Not relevant.
> >  
> >  config CROS_KBD_LED_BACKLIGHT
> >  	tristate "Backlight LED support for Chrome OS keyboards"
> > @@ -190,6 +190,18 @@ config CROS_EC_DEBUGFS
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called cros_ec_debugfs.
> >  
> > +config CROS_EC_SENSORHUB
> > +	tristate "ChromeOS EC MEMS Senosr Hub"
> > +	depends on CROS_EC && IIO
> > +	help
> > +	  Allow loading IIO sensors. This driver is loaded by MFD and will in
> > +	  turn query the EC and register the sensors.
> > +	  It also spreads the sensor data coming from the EC to the IIO sensorr
> > +	  object.
> > +
> > +	  To compile this driver as a module, choose M here: the
> > +	  module will be called cros_ec_sensorhub.
> > +
> >  config CROS_EC_SYSFS
> >  	tristate "ChromeOS EC control and information through sysfs"
> >  	depends on MFD_CROS_EC_DEV && SYSFS
> > diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
> > index 477ec3d1d1c9..a164c40dc099 100644
> > --- a/drivers/platform/chrome/Makefile
> > +++ b/drivers/platform/chrome/Makefile
> > @@ -17,6 +17,7 @@ obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o cros_ec_trace.o
> >  obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
> >  obj-$(CONFIG_CROS_EC_CHARDEV)		+= cros_ec_chardev.o
> >  obj-$(CONFIG_CROS_EC_LIGHTBAR)		+= cros_ec_lightbar.o
> > +obj-$(CONFIG_CROS_EC_SENSORHUB)		+= cros_ec_sensorhub.o
> >  obj-$(CONFIG_CROS_EC_VBC)		+= cros_ec_vbc.o
> >  obj-$(CONFIG_CROS_EC_DEBUGFS)		+= cros_ec_debugfs.o
> >  obj-$(CONFIG_CROS_EC_SYSFS)		+= cros_ec_sysfs.o
> > diff --git a/drivers/platform/chrome/cros_ec_sensorhub.c b/drivers/platform/chrome/cros_ec_sensorhub.c
> > new file mode 100644
> > index 000000000000..80688018ef66
> > --- /dev/null
> > +++ b/drivers/platform/chrome/cros_ec_sensorhub.c
> > @@ -0,0 +1,211 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * SensorHub: driver that discover sensors behind
> > + * a ChromeOS Embedded controller.
> > + *
> > + * Copyright 2019 Google LLC
> > + */
> > +
> > +#include <linux/init.h>
> > +#include <linux/device.h>
> > +#include <linux/fs.h>
> > +#include <linux/miscdevice.h>
> > +#include <linux/module.h>
> > +#include <linux/mfd/core.h>
> > +#include <linux/mfd/cros_ec.h>
> > +#include <linux/platform_data/cros_ec_commands.h>
> > +#include <linux/platform_data/cros_ec_proto.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/poll.h>
> > +#include <linux/slab.h>
> > +#include <linux/types.h>
> > +#include <linux/uaccess.h>
> > +
> > +#include <linux/platform_data/cros_ec_sensorhub.h>
> > +
> > +#define DRV_NAME		"cros-ec-sensorhub"
> > +
> > +static int cros_ec_sensors_register(struct device *dev,
> > +		struct cros_ec_dev *ec)
> > +{
> > +	int ret, i, id, sensor_num;
> > +	struct mfd_cell *sensor_cells;
> > +	struct cros_ec_sensor_platform *sensor_platforms;
> > +	int sensor_type[MOTIONSENSE_TYPE_MAX] = { 0 };
> > +	struct ec_params_motion_sense *params;
> > +	struct ec_response_motion_sense *resp;
> > +	struct cros_ec_command *msg;
> > +
> > +	sensor_num = cros_ec_get_sensor_count(ec);
> > +	if (sensor_num < 0) {
> > +		dev_err(dev,
> > +			"Unable to retrieve sensor information (err:%d)\n",
> > +			sensor_num);
> > +		return sensor_num;
> > +	}
> > +
> > +	if (sensor_num == 0) {
> > +		dev_err(dev, "Zero sensors reported.\n");
> > +		return -EINVAL;
> > +	}
> > +
> > +	/*
> > +	 * Build an array of sensors driver and register them all.  
> 
> Single line comment syntax.
> 
> > +	 */
> > +	msg = kzalloc(sizeof(struct cros_ec_command) +
> > +		      max(sizeof(*params), sizeof(*resp)), GFP_KERNEL);
> > +	if (msg == NULL) {
> > +		ret = -ENOMEM;
> > +		goto error;
> > +	}
> > +
> > +	msg->version = 1;
> > +	msg->command = EC_CMD_MOTION_SENSE_CMD + ec->cmd_offset;
> > +	msg->outsize = sizeof(*params);
> > +	msg->insize = sizeof(*resp);
> > +	params = (struct ec_params_motion_sense *)msg->data;
> > +	resp = (struct ec_response_motion_sense *)msg->data;
> > +
> > +	/*
> > +	 * Allocate 1 extra sensor if lid angle sensor is needed.  
> 
> Single line comment is enough.
> 
> > +	 */
> > +	sensor_cells = kcalloc(sensor_num + 1, sizeof(struct mfd_cell),
> > +			       GFP_KERNEL);
> > +	if (sensor_cells == NULL) {
> > +		ret = -ENOMEM;
> > +		goto error;
> > +	}
> > +
> > +	sensor_platforms = kcalloc(sensor_num,
> > +				   sizeof(struct cros_ec_sensor_platform),
> > +				   GFP_KERNEL);
> > +	if (sensor_platforms == NULL) {
> > +		ret = -ENOMEM;
> > +		goto error_platforms;
> > +	}
> > +
> > +	id = 0;
> > +	for (i = 0; i < sensor_num; i++) {
> > +		params->cmd = MOTIONSENSE_CMD_INFO;
> > +		params->info.sensor_num = i;
> > +		ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
> > +		if (ret < 0) {
> > +			dev_warn(dev, "no info for EC sensor %d : %d/%d\n",
> > +				 i, ret, msg->result);
> > +			continue;
> > +		}
> > +		switch (resp->info.type) {
> > +		case MOTIONSENSE_TYPE_ACCEL:
> > +			sensor_cells[id].name = "cros-ec-accel";
> > +			break;
> > +		case MOTIONSENSE_TYPE_BARO:
> > +			sensor_cells[id].name = "cros-ec-baro";
> > +			break;
> > +		case MOTIONSENSE_TYPE_GYRO:
> > +			sensor_cells[id].name = "cros-ec-gyro";
> > +			break;
> > +		case MOTIONSENSE_TYPE_MAG:
> > +			sensor_cells[id].name = "cros-ec-mag";
> > +			break;
> > +		case MOTIONSENSE_TYPE_PROX:
> > +			sensor_cells[id].name = "cros-ec-prox";
> > +			break;
> > +		case MOTIONSENSE_TYPE_LIGHT:
> > +			sensor_cells[id].name = "cros-ec-light";
> > +			break;
> > +		case MOTIONSENSE_TYPE_ACTIVITY:
> > +			sensor_cells[id].name = "cros-ec-activity";
> > +			break;
> > +		default:
> > +			dev_warn(dev, "unknown type %d\n", resp->info.type);
> > +			continue;
> > +		}
> > +		sensor_platforms[id].sensor_num = i;
> > +		sensor_cells[id].platform_data = &sensor_platforms[id];
> > +		sensor_cells[id].pdata_size =
> > +			sizeof(struct cros_ec_sensor_platform);
> > +
> > +		sensor_type[resp->info.type]++;
> > +		id++;
> > +	}
> > +
> > +	if (sensor_type[MOTIONSENSE_TYPE_ACCEL] >= 2)
> > +		ec->has_kb_wake_angle = true;
> > +
> > +	if (cros_ec_check_features(ec,
> > +				EC_FEATURE_REFINED_TABLET_MODE_HYSTERESIS)) {
> > +		sensor_cells[id].name = "cros-ec-lid-angle";
> > +		id++;
> > +	}
> > +
> > +	ret = mfd_add_hotplug_devices(dev, sensor_cells, id);
> > +	kfree(sensor_platforms);
> > +error_platforms:
> > +	kfree(sensor_cells);
> > +error:
> > +	kfree(msg);
> > +	return ret;
> > +}
> > +
> > +static struct cros_ec_sensor_platform sensor_platforms[] = {
> > +	{ .sensor_num = 0 },
> > +	{ .sensor_num = 1 }
> > +};
> > +
> > +static const struct mfd_cell cros_ec_accel_legacy_cells[] = {
> > +	{
> > +		.name = "cros-ec-accel-legacy",
> > +		.platform_data = &sensor_platforms[0],
> > +		.pdata_size = sizeof(struct cros_ec_sensor_platform),
> > +	},
> > +	{
> > +		.name = "cros-ec-accel-legacy",
> > +		.platform_data = &sensor_platforms[1],
> > +		.pdata_size = sizeof(struct cros_ec_sensor_platform),
> > +	}
> > +};
> > +  
> one line is normally enough ;)
> > +
> > +
> > +static int cros_ec_sensorhub_probe(struct platform_device *pdev)
> > +{
> > +	struct device *dev = &pdev->dev;
> > +	struct cros_ec_dev *ec = dev_get_drvdata(dev->parent);
> > +	int ret;
> > +	struct cros_ec_sensorhub *data =
> > +		kzalloc(sizeof(struct cros_ec_sensorhub), GFP_KERNEL);
> > +
> > +	if (!data)
> > +		return -ENOMEM;
> > +
> > +	data->ec = ec;
> > +	dev_set_drvdata(dev, data);
> > +
> > +	/* check whether this EC is a sensor hub. */
> > +	if (cros_ec_check_features(ec, EC_FEATURE_MOTION_SENSE)) {
> > +		ret = cros_ec_sensors_register(dev, ec);
> > +	} else {
> > +		/* Workaroud for older EC firmware */
> > +		ret = mfd_add_hotplug_devices(dev,
> > +				cros_ec_accel_legacy_cells,
> > +				ARRAY_SIZE(cros_ec_accel_legacy_cells));
> > +	}
> > +	if (ret)
> > +		dev_err(dev, "failed to add EC sensors: error %d\n", ret);
> > +	return ret;
> > +}
> > +
> > +static struct platform_driver cros_ec_sensorhub_driver = {
> > +	.driver = {
> > +		.name = DRV_NAME,
> > +	},
> > +	.probe = cros_ec_sensorhub_probe,
> > +};
> > +
> > +module_platform_driver(cros_ec_sensorhub_driver);
> > +
> > +MODULE_ALIAS("platform:" DRV_NAME);
> > +MODULE_AUTHOR("Gwendal Grignou <gwendal@chromium.org>");
> > +MODULE_DESCRIPTION("ChromeOS EC MEMS Sensor Hub Driver");
> > +MODULE_LICENSE("GPL");
> > +
> > diff --git a/include/linux/platform_data/cros_ec_sensorhub.h b/include/linux/platform_data/cros_ec_sensorhub.h
> > new file mode 100644
> > index 000000000000..a8b64ecf5b9b
> > --- /dev/null
> > +++ b/include/linux/platform_data/cros_ec_sensorhub.h
> > @@ -0,0 +1,21 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * cros_ec_sensorhub- Chrome OS EC MEMS Sensor Hub driver.
> > + *
> > + * Copyright (C) 2019 Google, Inc  
> 
> My favourite moan of the day. what's the point of this blank line?
> 
> > + *
> > + */
> > +
> > +#ifndef __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H
> > +#define __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H
> > +
> > +#include <linux/platform_data/cros_ec_commands.h>
> > +
> > +/**
> > + * struct cros_ec_sensorhub - Sensor Hub device data.  
> 
> If it's kernel-doc should be complete (include the elements).
> 
> > + */
> > +struct cros_ec_sensorhub {
> > +	struct cros_ec_dev *ec;
> > +};
> > +
> > +#endif   /* __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H */  
>