iio: cros_ec_sensors_core: Add common functions for the ChromeOS EC Sensor Hub.

Add the core functions to be able to support the sensors attached behind
the ChromeOS Embedded Controller and used by other IIO cros-ec sensor
drivers.

The cros_ec_sensor_core driver matches with current driver in ChromeOS
4.4 tree, so it includes all the fixes at the moment. The support for
this driver was made by Gwendal Grignou. The original patch and all the
fixes has been squashed and rebased on top of mainline.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Guenter Roeck <groeck@chromium.org>
[eballetbo: split, squash and rebase on top of mainline the patches
found in ChromeOS tree]
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 175 insertions, 0 deletions

diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.h b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.h
new file mode 100644
index 000000000000..8bc2ca3c2e2e
--- /dev/null
+++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.h
@@ -0,0 +1,175 @@
+/*
+ * ChromeOS EC sensor hub
+ *
+ * Copyright (C) 2016 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.
+ */
+
+#ifndef __CROS_EC_SENSORS_CORE_H
+#define __CROS_EC_SENSORS_CORE_H
+
+#include <linux/irqreturn.h>
+
+enum {
+	CROS_EC_SENSOR_X,
+	CROS_EC_SENSOR_Y,
+	CROS_EC_SENSOR_Z,
+	CROS_EC_SENSOR_MAX_AXIS,
+};
+
+/* EC returns sensor values using signed 16 bit registers */
+#define CROS_EC_SENSOR_BITS 16
+
+/*
+ * 4 16 bit channels are allowed.
+ * Good enough for current sensors, they use up to 3 16 bit vectors.
+ */
+#define CROS_EC_SAMPLE_SIZE  (sizeof(s64) * 2)
+
+/* Minimum sampling period to use when device is suspending */
+#define CROS_EC_MIN_SUSPEND_SAMPLING_FREQUENCY 1000  /* 1 second */
+
+/**
+ * struct cros_ec_sensors_core_state - state data for EC sensors IIO driver
+ * @ec:				cros EC device structure
+ * @cmd_lock:			lock used to prevent simultaneous access to the
+ *				commands.
+ * @msg:			cros EC command structure
+ * @param:			motion sensor parameters structure
+ * @resp:			motion sensor response structure
+ * @type:			type of motion sensor
+ * @loc:			location where the motion sensor is placed
+ * @calib:			calibration parameters. Note that trigger
+ *				captured data will always provide the calibrated
+ *				data
+ * @samples:			static array to hold data from a single capture.
+ *				For each channel we need 2 bytes, except for
+ *				the timestamp. The timestamp is always last and
+ *				is always 8-byte aligned.
+ * @read_ec_sensors_data:	function used for accessing sensors values
+ * @cuur_sampl_freq:		current sampling period
+ */
+struct cros_ec_sensors_core_state {
+	struct cros_ec_device *ec;
+	struct mutex cmd_lock;
+
+	struct cros_ec_command *msg;
+	struct ec_params_motion_sense param;
+	struct ec_response_motion_sense *resp;
+
+	enum motionsensor_type type;
+	enum motionsensor_location loc;
+
+	s16 calib[CROS_EC_SENSOR_MAX_AXIS];
+
+	u8 samples[CROS_EC_SAMPLE_SIZE];
+
+	int (*read_ec_sensors_data)(struct iio_dev *indio_dev,
+				    unsigned long scan_mask, s16 *data);
+
+	int curr_sampl_freq;
+};
+
+/**
+ * cros_ec_sensors_read_lpc() - retrieve data from EC shared memory
+ * @indio_dev:	pointer to IIO device
+ * @scan_mask:	bitmap of the sensor indices to scan
+ * @data:	location to store data
+ *
+ * This is the safe function for reading the EC data. It guarantees that the
+ * data sampled was not modified by the EC while being read.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+int cros_ec_sensors_read_lpc(struct iio_dev *indio_dev, unsigned long scan_mask,
+			     s16 *data);
+
+/**
+ * cros_ec_sensors_read_cmd() - retrieve data using the EC command protocol
+ * @indio_dev:	pointer to IIO device
+ * @scan_mask:	bitmap of the sensor indices to scan
+ * @data:	location to store data
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+int cros_ec_sensors_read_cmd(struct iio_dev *indio_dev, unsigned long scan_mask,
+			     s16 *data);
+
+/**
+ * cros_ec_sensors_core_init() - basic initialization of the core structure
+ * @pdev:		platform device created for the sensors
+ * @indio_dev:		iio device structure of the device
+ * @physical_device:	true if the device refers to a physical device
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+int cros_ec_sensors_core_init(struct platform_device *pdev,
+			      struct iio_dev *indio_dev, bool physical_device);
+
+/**
+ * cros_ec_sensors_capture() - the trigger handler function
+ * @irq:	the interrupt number.
+ * @p:		a pointer to the poll function.
+ *
+ * On a trigger event occurring, if the pollfunc is attached then this
+ * handler is called as a threaded interrupt (and hence may sleep). It
+ * is responsible for grabbing data from the device and pushing it into
+ * the associated buffer.
+ *
+ * Return: IRQ_HANDLED
+ */
+irqreturn_t cros_ec_sensors_capture(int irq, void *p);
+
+/**
+ * cros_ec_motion_send_host_cmd() - send motion sense host command
+ * @st:		pointer to state information for device
+ * @opt_length:	optional length to reduce the response size, useful on the data
+ *		path. Otherwise, the maximal allowed response size is used
+ *
+ * When called, the sub-command is assumed to be set in param->cmd.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+int cros_ec_motion_send_host_cmd(struct cros_ec_sensors_core_state *st,
+				 u16 opt_length);
+
+/**
+ * cros_ec_sensors_core_read() - function to request a value from the sensor
+ * @st:		pointer to state information for device
+ * @chan:	channel specification structure table
+ * @val:	will contain one element making up the returned value
+ * @val2:	will contain another element making up the returned value
+ * @mask:	specifies which values to be requested
+ *
+ * Return:	the type of value returned by the device
+ */
+int cros_ec_sensors_core_read(struct cros_ec_sensors_core_state *st,
+			      struct iio_chan_spec const *chan,
+			      int *val, int *val2, long mask);
+
+/**
+ * cros_ec_sensors_core_write() - function to write a value to the sensor
+ * @st:		pointer to state information for device
+ * @chan:	channel specification structure table
+ * @val:	first part of value to write
+ * @val2:	second part of value to write
+ * @mask:	specifies which values to write
+ *
+ * Return:	the type of value returned by the device
+ */
+int cros_ec_sensors_core_write(struct cros_ec_sensors_core_state *st,
+			       struct iio_chan_spec const *chan,
+			       int val, int val2, long mask);
+
+/* List of extended channel specification for all sensors */
+extern const struct iio_chan_spec_ext_info cros_ec_sensors_ext_info[];
+
+#endif  /* __CROS_EC_SENSORS_CORE_H */