iio: cros_ec: Add cros_ec barometer driver

Handle the barometer sensor presented by the ChromeOS EC Sensor hub.
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Enric Balletbo Serra <enric.balletbo@collabora.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/pressure/Kconfig

@@ -42,6 +42,16 @@ config BMP280_SPI
 	depends on SPI_MASTER
 	select REGMAP
 
+config IIO_CROS_EC_BARO
+	tristate "ChromeOS EC Barometer Sensor"
+	depends on IIO_CROS_EC_SENSORS_CORE
+	help
+	  Say yes here to build support for the Barometer sensor when
+	  presented by the ChromeOS EC Sensor hub.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called cros_ec_baro.
+
 config HID_SENSOR_PRESS
 	depends on HID_SENSOR_HUB
 	select IIO_BUFFER

drivers/iio/pressure/Makefile

@@ -8,6 +8,7 @@ obj-$(CONFIG_BMP280) += bmp280.o
 bmp280-objs := bmp280-core.o bmp280-regmap.o
 obj-$(CONFIG_BMP280_I2C) += bmp280-i2c.o
 obj-$(CONFIG_BMP280_SPI) += bmp280-spi.o
+obj-$(CONFIG_IIO_CROS_EC_BARO) += cros_ec_baro.o
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_HP03) += hp03.o
 obj-$(CONFIG_MPL115) += mpl115.o

drivers/iio/pressure/cros_ec_baro.c

+/*
+ * cros_ec_baro - Driver for barometer sensor behind CrosEC.
+ *
+ * Copyright (C) 2017 Google, Inc
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/iio/buffer.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/slab.h>
+#include <linux/platform_device.h>
+
+#include "../common/cros_ec_sensors/cros_ec_sensors_core.h"
+
+/*
+ * One channel for pressure, the other for timestamp.
+ */
+#define CROS_EC_BARO_MAX_CHANNELS (1 + 1)
+
+/* State data for ec_sensors iio driver. */
+struct cros_ec_baro_state {
+	/* Shared by all sensors */
+	struct cros_ec_sensors_core_state core;
+
+	struct iio_chan_spec channels[CROS_EC_BARO_MAX_CHANNELS];
+};
+
+static int cros_ec_baro_read(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct cros_ec_baro_state *st = iio_priv(indio_dev);
+	u16 data = 0;
+	int ret = IIO_VAL_INT;
+	int idx = chan->scan_index;
+
+	mutex_lock(&st->core.cmd_lock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (cros_ec_sensors_read_cmd(indio_dev, 1 << idx,
+					     (s16 *)&data) < 0)
+			ret = -EIO;
+		*val = data;
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		st->core.param.cmd = MOTIONSENSE_CMD_SENSOR_RANGE;
+		st->core.param.sensor_range.data = EC_MOTION_SENSE_NO_VALUE;
+
+		if (cros_ec_motion_send_host_cmd(&st->core, 0)) {
+			ret = -EIO;
+			break;
+		}
+		*val = st->core.resp->sensor_range.ret;
+
+		/* scale * in_pressure_raw --> kPa */
+		*val2 = 10 << CROS_EC_SENSOR_BITS;
+		ret = IIO_VAL_FRACTIONAL;
+		break;
+	default:
+		ret = cros_ec_sensors_core_read(&st->core, chan, val, val2,
+						mask);
+		break;
+	}
+
+	mutex_unlock(&st->core.cmd_lock);
+
+	return ret;
+}
+
+static int cros_ec_baro_write(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int val, int val2, long mask)
+{
+	struct cros_ec_baro_state *st = iio_priv(indio_dev);
+	int ret = 0;
+
+	mutex_lock(&st->core.cmd_lock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		st->core.param.cmd = MOTIONSENSE_CMD_SENSOR_RANGE;
+		st->core.param.sensor_range.data = val;
+
+		/* Always roundup, so caller gets at least what it asks for. */
+		st->core.param.sensor_range.roundup = 1;
+
+		if (cros_ec_motion_send_host_cmd(&st->core, 0))
+			ret = -EIO;
+		break;
+	default:
+		ret = cros_ec_sensors_core_write(&st->core, chan, val, val2,
+						 mask);
+		break;
+	}
+
+	mutex_unlock(&st->core.cmd_lock);
+
+	return ret;
+}
+
+static const struct iio_info cros_ec_baro_info = {
+	.read_raw = &cros_ec_baro_read,
+	.write_raw = &cros_ec_baro_write,
+	.driver_module = THIS_MODULE,
+};
+
+static int cros_ec_baro_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cros_ec_dev *ec_dev = dev_get_drvdata(dev->parent);
+	struct cros_ec_device *ec_device;
+	struct iio_dev *indio_dev;
+	struct cros_ec_baro_state *state;
+	struct iio_chan_spec *channel;
+	int ret;
+
+	if (!ec_dev || !ec_dev->ec_dev) {
+		dev_warn(dev, "No CROS EC device found.\n");
+		return -EINVAL;
+	}
+	ec_device = ec_dev->ec_dev;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*state));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
+	if (ret)
+		return ret;
+
+	indio_dev->info = &cros_ec_baro_info;
+	state = iio_priv(indio_dev);
+	state->core.type = state->core.resp->info.type;
+	state->core.loc = state->core.resp->info.location;
+	channel = state->channels;
+	/* Common part */
+	channel->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
+	channel->info_mask_shared_by_all =
+		BIT(IIO_CHAN_INFO_SCALE) |
+		BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+		BIT(IIO_CHAN_INFO_FREQUENCY);
+	channel->scan_type.realbits = CROS_EC_SENSOR_BITS;
+	channel->scan_type.storagebits = CROS_EC_SENSOR_BITS;
+	channel->scan_type.shift = 0;
+	channel->scan_index = 0;
+	channel->ext_info = cros_ec_sensors_ext_info;
+	channel->scan_type.sign = 'u';
+
+	state->core.calib[0] = 0;
+
+	/* Sensor specific */
+	switch (state->core.type) {
+	case MOTIONSENSE_TYPE_BARO:
+		channel->type = IIO_PRESSURE;
+		break;
+	default:
+		dev_warn(dev, "Unknown motion sensor\n");
+		return -EINVAL;
+	}
+
+	/* Timestamp */
+	channel++;
+	channel->type = IIO_TIMESTAMP;
+	channel->channel = -1;
+	channel->scan_index = 1;
+	channel->scan_type.sign = 's';
+	channel->scan_type.realbits = 64;
+	channel->scan_type.storagebits = 64;
+
+	indio_dev->channels = state->channels;
+	indio_dev->num_channels = CROS_EC_BARO_MAX_CHANNELS;
+
+	state->core.read_ec_sensors_data = cros_ec_sensors_read_cmd;
+
+	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_baro_ids[] = {
+	{
+		.name = "cros-ec-baro",
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, cros_ec_baro_ids);
+
+static struct platform_driver cros_ec_baro_platform_driver = {
+	.driver = {
+		.name	= "cros-ec-baro",
+	},
+	.probe		= cros_ec_baro_probe,
+	.id_table	= cros_ec_baro_ids,
+};
+module_platform_driver(cros_ec_baro_platform_driver);
+
+MODULE_DESCRIPTION("ChromeOS EC barometer sensor driver");
+MODULE_LICENSE("GPL v2");

drivers/platform/chrome/cros_ec_dev.c

@@ -328,6 +328,9 @@ static void cros_ec_sensors_register(struct cros_ec_dev *ec)
 		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;

include/linux/mfd/cros_ec_commands.h

@@ -1441,7 +1441,8 @@ enum motionsensor_type {
 	MOTIONSENSE_TYPE_PROX = 3,
 	MOTIONSENSE_TYPE_LIGHT = 4,
 	MOTIONSENSE_TYPE_ACTIVITY = 5,
-	MOTIONSENSE_TYPE_MAX
+	MOTIONSENSE_TYPE_BARO = 6,
+	MOTIONSENSE_TYPE_MAX,
 };
 
 /* List of motion sensor locations. */