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Date:   Mon, 21 Oct 2019 16:59:11 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Gwendal Grignou <gwendal@chromium.org>
Cc:     briannorris@chromium.org, 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 v2 03/18] platform: cros_ec: Add cros_ec_sensor_hub
 driver
Message-ID: <20191021165911.22011c08@archlinux>
In-Reply-To: <20191021055403.67849-4-gwendal@chromium.org>
References: <20191021055403.67849-1-gwendal@chromium.org>
        <20191021055403.67849-4-gwendal@chromium.org>
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On Sun, 20 Oct 2019 22:53:48 -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>

A few bits and pieces inline.

Thanks,

Jonathan


> ---
> Changes in v2:
> - Remove unerelated changes.
> - Fix spelling.
> - Use !x instead of x == NULL
> - Use platform_ API directly to register IIO sensors from
>   cros_ec_sensorhub.
> 
>  drivers/iio/common/cros_ec_sensors/Kconfig    |   2 +-
>  drivers/platform/chrome/Kconfig               |  12 ++
>  drivers/platform/chrome/Makefile              |   1 +
>  drivers/platform/chrome/cros_ec_sensorhub.c   | 202 ++++++++++++++++++
>  .../linux/platform_data/cros_ec_sensorhub.h   |  21 ++
>  5 files changed, 237 insertions(+), 1 deletion(-)
>  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 cdbb29cfb9076..fefad95727907 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 ee5f08ea57b6c..56a25317a6bee 100644
> --- a/drivers/platform/chrome/Kconfig
> +++ b/drivers/platform/chrome/Kconfig
> @@ -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 Sensor 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 sensor
> +	  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 477ec3d1d1c98..a164c40dc0996 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 0000000000000..5fea4c28c5c95
> --- /dev/null
> +++ b/drivers/platform/chrome/cros_ec_sensorhub.c
> @@ -0,0 +1,202 @@
> +// 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/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 struct device_type cros_ec_sensorhub_dev_type = {
> +	.name	= "cros_ec_iio_sensor",
> +};
> +
> +static int cros_ec_sensorhub_allocate_single_sensor(
> +		struct device *parent,
> +		char *sensor_name,
> +		int sensor_num)
> +{
> +	struct platform_device *pdev;
> +	struct cros_ec_sensor_platform sensor_platforms = {
> +		.sensor_num = sensor_num,
> +	};
> +	int ret;
> +
> +	pdev = platform_device_alloc(sensor_name, PLATFORM_DEVID_AUTO);
> +	if (!pdev)
> +		return -ENOMEM;
> +
> +	pdev->dev.parent = parent;
> +	pdev->dev.type = &cros_ec_sensorhub_dev_type;
> +
> +	ret = platform_device_add_data(pdev, &sensor_platforms,
> +			sizeof(sensor_platforms));
> +	if (ret)
> +		goto fail_device;
> +
> +	ret = platform_device_add(pdev);
> +	if (ret)
> +		goto fail_device;
> +
> +	return 0;
> +
> +fail_device:
> +	platform_device_put(pdev);
> +	return ret;
> +}
> +
> +static int cros_ec_sensorhub_register(struct device *dev,
> +		struct cros_ec_dev *ec)
> +{
> +	int ret, i, id, sensor_num;
> +	int sensor_type[MOTIONSENSE_TYPE_MAX] = { 0 };
> +	struct ec_params_motion_sense *params;
> +	struct ec_response_motion_sense *resp;
> +	struct cros_ec_command *msg;
> +	char *name;
> +
> +	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;
> +	}
> +
> +	/* Prepare a message to send INFO command to each sensor. */
> +	msg = kzalloc(sizeof(struct cros_ec_command) +
> +		      max(sizeof(*params), sizeof(*resp)), GFP_KERNEL);
> +	if (!msg) {
> +		ret = -ENOMEM;
> +		goto error;

If you get here, the kzalloc failed, so there is nothing to free.
Hence should just be a return -ENOMEM I think.

> +	}
> +
> +	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;
> +
> +	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:
> +			name = "cros-ec-accel";
> +			break;
> +		case MOTIONSENSE_TYPE_BARO:
> +			name = "cros-ec-baro";
> +			break;
> +		case MOTIONSENSE_TYPE_GYRO:
> +			name = "cros-ec-gyro";
> +			break;
> +		case MOTIONSENSE_TYPE_MAG:
> +			name = "cros-ec-mag";
> +			break;
> +		case MOTIONSENSE_TYPE_PROX:
> +			name = "cros-ec-prox";
> +			break;
> +		case MOTIONSENSE_TYPE_LIGHT:
> +			name = "cros-ec-light";
> +			break;
> +		case MOTIONSENSE_TYPE_ACTIVITY:
> +			name = "cros-ec-activity";
> +			break;
> +		default:
> +			dev_warn(dev, "unknown type %d\n", resp->info.type);
> +			continue;
> +		}
> +		ret = cros_ec_sensorhub_allocate_single_sensor(dev, name, i);
> +		if (ret)
> +			goto error;
> +
> +		sensor_type[resp->info.type]++;
> +	}
> +
> +	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)) {
> +		ret = cros_ec_sensorhub_allocate_single_sensor(
> +				dev, "cros-ec-lid-angle", 0);
> +	}
> +
> +error:
> +	kfree(msg);
> +	return ret;
> +}
> +
> +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);

Superficially this doesn't seem to be used.

> +
> +	/* Check whether this EC is a sensor hub. */
> +	if (cros_ec_check_features(ec, EC_FEATURE_MOTION_SENSE)) {
> +		ret = cros_ec_sensorhub_register(dev, ec);
> +	} else {
> +		ret = cros_ec_sensorhub_allocate_single_sensor(
> +				dev, "cros-ec-accel-legacy", 0);
> +		ret |= cros_ec_sensorhub_allocate_single_sensor(
> +				dev, "cros-ec-accel-legacy", 1);

Doing an |= with a return value is a good way to get some really
odd bugs in the future.  Please report only the first error and
cleanly.  If the first one failed we are going to fail to probe
anyway so don't call the second.


> +	}
> +	if (ret)
> +		dev_err(dev, "failed to add EC sensors: error %d\n", ret);

Is this particular error useful?  I'd be more tempted to report
and error for each of the two types of registration above with
more information on what actually failed.

> +	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 0000000000000..7737685591ad3
> --- /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
> + */
> +
> +#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.
> + */
> +struct cros_ec_sensorhub {
> +	/* Embedded Controller where the hub is located. */
> +	struct cros_ec_dev *ec;
> +};
> +
> +#endif   /* __LINUX_PLATFORM_DATA_CROS_EC_SENSORHUB_H */