iio: cros_ec: Add lid angle driver

Add a IIO driver that reports the angle between the lid and the base for
ChromeOS convertible device.

Tested on eve with ToT EC firmware.
Check driver is loaded and lid angle is correct.
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>

drivers/iio/common/cros_ec_sensors/Kconfig

@@ -20,3 +20,12 @@ config IIO_CROS_EC_SENSORS
 	  Accelerometers, Gyroscope and Magnetometer that are
 	  presented by the ChromeOS EC Sensor hub.
 	  Creates an IIO device for each functions.
+
+config IIO_CROS_EC_SENSORS_LID_ANGLE
+	tristate "ChromeOS EC Sensor for lid angle"
+	depends on IIO_CROS_EC_SENSORS_CORE
+	help
+	  Module to report the angle between lid and base for some
+	  convertible devices.
+	  This module is loaded when the EC can calculate the angle between the base
+	  and the lid.

drivers/iio/common/cros_ec_sensors/Makefile

@@ -4,3 +4,4 @@
 
 obj-$(CONFIG_IIO_CROS_EC_SENSORS_CORE) += cros_ec_sensors_core.o
 obj-$(CONFIG_IIO_CROS_EC_SENSORS) += cros_ec_sensors.o
+obj-$(CONFIG_IIO_CROS_EC_SENSORS_LID_ANGLE) += cros_ec_lid_angle.o

drivers/iio/common/cros_ec_sensors/cros_ec_lid_angle.c

+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * cros_ec_lid_angle - Driver for CrOS EC lid angle sensor.
+ *
+ * Copyright 2018 Google, Inc
+ *
+ * This driver uses the cros-ec interface to communicate with the Chrome OS
+ * EC about counter sensors. Counters are presented through
+ * iio sysfs.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/common/cros_ec_sensors_core.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/kfifo_buf.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/kernel.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define DRV_NAME "cros-ec-lid-angle"
+
+/*
+ * One channel for the lid angle, the other for timestamp.
+ */
+static const struct iio_chan_spec cros_ec_lid_angle_channels[] = {
+	{
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_type.realbits = CROS_EC_SENSOR_BITS,
+		.scan_type.storagebits = CROS_EC_SENSOR_BITS,
+		.scan_type.sign = 'u',
+		.type = IIO_ANGL
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(1)
+};
+
+/* State data for ec_sensors iio driver. */
+struct cros_ec_lid_angle_state {
+	/* Shared by all sensors */
+	struct cros_ec_sensors_core_state core;
+};
+
+static int cros_ec_sensors_read_lid_angle(struct iio_dev *indio_dev,
+					  unsigned long scan_mask, s16 *data)
+{
+	struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
+	int ret;
+
+	st->param.cmd = MOTIONSENSE_CMD_LID_ANGLE;
+	ret = cros_ec_motion_send_host_cmd(st, sizeof(st->resp->lid_angle));
+	if (ret) {
+		dev_warn(&indio_dev->dev, "Unable to read lid angle\n");
+		return ret;
+	}
+
+	*data = st->resp->lid_angle.value;
+	return 0;
+}
+
+static int cros_ec_lid_angle_read(struct iio_dev *indio_dev,
+				    struct iio_chan_spec const *chan,
+				    int *val, int *val2, long mask)
+{
+	struct cros_ec_lid_angle_state *st = iio_priv(indio_dev);
+	s16 data;
+	int ret;
+
+	mutex_lock(&st->core.cmd_lock);
+	ret = cros_ec_sensors_read_lid_angle(indio_dev, 1, &data);
+	if (ret == 0) {
+		*val = data;
+		ret = IIO_VAL_INT;
+	}
+	mutex_unlock(&st->core.cmd_lock);
+	return ret;
+}
+
+static const struct iio_info cros_ec_lid_angle_info = {
+	.read_raw = &cros_ec_lid_angle_read,
+};
+
+static int cros_ec_lid_angle_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct iio_dev *indio_dev;
+	struct cros_ec_lid_angle_state *state;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*state));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	ret = cros_ec_sensors_core_init(pdev, indio_dev, false);
+	if (ret)
+		return ret;
+
+	indio_dev->info = &cros_ec_lid_angle_info;
+	state = iio_priv(indio_dev);
+	indio_dev->channels = cros_ec_lid_angle_channels;
+	indio_dev->num_channels = ARRAY_SIZE(cros_ec_lid_angle_channels);
+
+	state->core.read_ec_sensors_data = cros_ec_sensors_read_lid_angle;
+
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
+			cros_ec_sensors_capture, NULL);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct platform_device_id cros_ec_lid_angle_ids[] = {
+	{
+		.name = DRV_NAME,
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, cros_ec_lid_angle_ids);
+
+static struct platform_driver cros_ec_lid_angle_platform_driver = {
+	.driver = {
+		.name	= DRV_NAME,
+		.pm	= &cros_ec_sensors_pm_ops,
+	},
+	.probe		= cros_ec_lid_angle_probe,
+	.id_table	= cros_ec_lid_angle_ids,
+};
+module_platform_driver(cros_ec_lid_angle_platform_driver);
+
+MODULE_DESCRIPTION("ChromeOS EC driver for reporting convertible lid angle.");
+MODULE_LICENSE("GPL v2");