Date:   Tue, 23 Apr 2019 10:40:46 +0000
From:   Alexandre Mergnat <amergnat@...libre.com>
To:     robh+dt@...nel.org, mark.rutland@....com, jic23@...nel.org,
        knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net
Cc:     linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        baylibre-upstreaming@...ups.io,
        Alexandre Mergnat <amergnat@...libre.com>
Subject: [PATCH v2 3/3] iio: Add PAT9125 optical tracker sensor

This adds support for PixArt Imaging’s miniature low power
optical navigation chip using LASER light source
enabling digital surface tracking.

This IIO driver allow to read delta position on 2 axis (X and Y).
The values can be taken through ponctual "read_raw" which will issue
a read in the device registers to return the delta between last read/buffering
or subscribe to the data buffer feed automaticaly by a new value using an
IIO trigger. The buffer payload is: |32 bits delta X|32 bits delta Y|timestamp|.
It also provide an IIO trigger which fire when a motion is detected.
This trigger should be reset after each fire by a simple "read_raw" if you aren't
in buffer mode.

The possible I2C adresses are 0x73, 0x75 and 0x79.

X and Y axis resolution can be setup independently through module parameter.

The "ot" directory is added to coutain Optical Tracker drivers.

Signed-off-by: Alexandre Mergnat <amergnat@...libre.com>
---
 drivers/iio/Kconfig      |   1 +
 drivers/iio/Makefile     |   1 +
 drivers/iio/ot/Kconfig   |  16 ++
 drivers/iio/ot/Makefile  |   6 +
 drivers/iio/ot/pat9125.c | 487 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 511 insertions(+)
 create mode 100644 drivers/iio/ot/Kconfig
 create mode 100644 drivers/iio/ot/Makefile
 create mode 100644 drivers/iio/ot/pat9125.c

diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index d08aeb41cd07..bdf1bd061168 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -86,6 +86,7 @@ source "drivers/iio/light/Kconfig"
 source "drivers/iio/magnetometer/Kconfig"
 source "drivers/iio/multiplexer/Kconfig"
 source "drivers/iio/orientation/Kconfig"
+source "drivers/iio/ot/Kconfig"
 if IIO_TRIGGER
    source "drivers/iio/trigger/Kconfig"
 endif #IIO_TRIGGER
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index cb5993251381..fdda2e185005 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -32,6 +32,7 @@ obj-y += light/
 obj-y += magnetometer/
 obj-y += multiplexer/
 obj-y += orientation/
+obj-y += ot/
 obj-y += potentiometer/
 obj-y += potentiostat/
 obj-y += pressure/
diff --git a/drivers/iio/ot/Kconfig b/drivers/iio/ot/Kconfig
new file mode 100644
index 000000000000..3d17fdaa06ed
--- /dev/null
+++ b/drivers/iio/ot/Kconfig
@@ -0,0 +1,16 @@
+#
+# Optical tracker sensors
+#
+# When adding new entries keep the list in alphabetical order
+
+menu "Optical tracker sensors"
+
+config PAT9125
+	tristate "Optical tracker PAT9125 I2C driver"
+	depends on I2C
+	select IIO_BUFFER
+	help
+	  Say yes here to build support for PAT9125 optical tracker
+	  sensors.
+
+endmenu
diff --git a/drivers/iio/ot/Makefile b/drivers/iio/ot/Makefile
new file mode 100644
index 000000000000..cf294917ae2c
--- /dev/null
+++ b/drivers/iio/ot/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for industrial I/O Optical tracker sensor drivers
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_PAT9125) += pat9125.o
diff --git a/drivers/iio/ot/pat9125.c b/drivers/iio/ot/pat9125.c
new file mode 100644
index 000000000000..48c1651b4e6a
--- /dev/null
+++ b/drivers/iio/ot/pat9125.c
@@ -0,0 +1,487 @@
+// SPDX-License-Identifier: (GPL-2.0)
+/*
+ * Copyright (C) 2019 BayLibre, SAS
+ * Author: Alexandre Mergnat <amergnat@...libre.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/events.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/kfifo_buf.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+/* I2C Address function to ID pin*/
+#define PAT9125_I2C_ADDR_HI		0x73
+#define PAT9125_I2C_ADDR_LO		0x75
+#define PAT9125_I2C_ADDR_NC		0x79
+
+/* Registers */
+#define PAT9125_PRD_ID1_REG		0x00
+#define PAT9125_PRD_ID2_REG		0x01
+#define PAT9125_MOTION_STATUS_REG	0x02
+#define PAT9125_DELTA_X_LO_REG		0x03
+#define PAT9125_DELTA_Y_LO_REG		0x04
+#define PAT9125_OP_MODE_REG		0x05
+#define PAT9125_CONFIG_REG		0x06
+#define PAT9125_WRITE_PROTEC_REG	0x09
+#define PAT9125_SLEEP1_REG		0x0A
+#define PAT9125_SLEEP2_REG		0x0B
+#define PAT9125_RES_X_REG		0x0D
+#define PAT9125_RES_Y_REG		0x0E
+#define PAT9125_DELTA_XY_HI_REG		0x12
+#define PAT9125_SHUTER_REG		0x14
+#define PAT9125_FRAME_AVG_REG		0x17
+#define PAT9125_ORIENTATION_REG		0x19
+
+/* Bits */
+#define PAT9125_VALID_MOTION_DATA_BIT	0x80
+#define PAT9125_RESET_BIT		0x80
+
+/* Registers' values */
+#define PAT9125_SENSOR_ID_VAL			0x31
+#define PAT9125_DISABLE_WRITE_PROTECT_VAL	0x5A
+#define PAT9125_ENABLE_WRITE_PROTECT_VAL	0x00
+#define PAT9125_CPI_RESOLUTION_X_VAL		0x65
+#define PAT9125_CPI_RESOLUTION_Y_VAL		0xFF
+
+/* Default Value of sampled value size */
+#define PAT9125_SAMPLED_VAL_BIT_SIZE		12
+
+struct pat9125_data {
+	struct regmap *regmap;
+	struct iio_trigger *indio_trig;	/* Motion detection */
+	s64 ts;				/* Timestamp */
+	s32 delta_x;
+	s32 delta_y;
+	s32 motion_detected;
+	bool buffer_mode;
+};
+
+static u8 x_resolution = 0x14;
+module_param(x_resolution, byte, 0644);
+MODULE_PARM_DESC(x_resolution, "CPI resolution setting for X axis.");
+
+static u8 y_resolution = 0x14;
+module_param(y_resolution, byte, 0644);
+MODULE_PARM_DESC(y_resolution, "CPI resolution setting for Y axis.");
+
+static const struct iio_event_spec pat9125_event = {
+	.type = IIO_EV_TYPE_THRESH,
+	.dir = IIO_EV_DIR_RISING,
+	.mask_separate = BIT(IIO_EV_INFO_VALUE),
+};
+
+static const struct iio_chan_spec pat9125_channels[] = {
+	{
+		.type = IIO_DISTANCE,
+		.modified = 1,
+		.channel2 = IIO_MOD_X,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',			\
+			.realbits = 32,			\
+			.storagebits = 32,		\
+			.shift = 0,			\
+			.endianness = IIO_LE,		\
+		},
+		.event_spec = &pat9125_event,
+		.num_event_specs = 1,
+	},
+	{
+		.type = IIO_DISTANCE,
+		.modified = 1,
+		.channel2 = IIO_MOD_Y,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 's',			\
+			.realbits = 32,			\
+			.storagebits = 32,		\
+			.shift = 0,			\
+			.endianness = IIO_LE,		\
+		},
+		.event_spec = &pat9125_event,
+		.num_event_specs = 1,
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(2),
+};
+
+static int pat9125_read_delta(struct pat9125_data *data)
+{
+	struct regmap *regmap = data->regmap;
+	int status = 0;
+	int val_x = 0;
+	int val_y = 0;
+	int val_high_nibbles = 0;
+	int old_motion_status;
+	int ret;
+
+	old_motion_status = data->motion_detected;
+	data->motion_detected = 0;
+	ret = regmap_read(regmap, PAT9125_MOTION_STATUS_REG, &status);
+	if (ret < 0) {
+		data->motion_detected = old_motion_status;
+		return ret;
+	}
+
+	/* Check if motion is detected */
+	if (status & PAT9125_VALID_MOTION_DATA_BIT) {
+		ret = regmap_read(regmap, PAT9125_DELTA_X_LO_REG, &val_x);
+		if (ret < 0)
+			return ret;
+
+		ret = regmap_read(regmap, PAT9125_DELTA_Y_LO_REG, &val_y);
+		if (ret < 0)
+			return ret;
+
+		ret = regmap_read(regmap, PAT9125_DELTA_XY_HI_REG, &val_high_nibbles);
+		if (ret < 0)
+			return ret;
+
+		val_x |= (val_high_nibbles << 4) & 0xF00;
+		val_y |= (val_high_nibbles << 8) & 0xF00;
+
+		val_x = sign_extend32(val_x,
+			PAT9125_SAMPLED_VAL_BIT_SIZE - 1);
+
+		val_y = sign_extend32(val_y,
+			PAT9125_SAMPLED_VAL_BIT_SIZE - 1);
+
+
+		data->delta_x += val_x;
+		data->delta_y += val_y;
+	}
+
+	return 0;
+}
+
+/**
+ * pat9125_read_raw() - Sample and return the value(s)
+ * function to the associated channel info enum.
+ **/
+static int pat9125_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct pat9125_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = pat9125_read_delta(data);
+		if (ret)
+			return ret;
+		switch (chan->channel2) {
+		case IIO_MOD_X:
+			*val = data->delta_x;
+			data->delta_x = 0;
+			break;
+		case IIO_MOD_Y:
+			*val = data->delta_y;
+			data->delta_y = 0;
+			break;
+		default:
+			return -EINVAL;
+		}
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+	return -EINVAL;
+}
+
+static irqreturn_t pat9125_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct pat9125_data *data = iio_priv(indio_dev);
+	u8 buf[16]; /* Payload: Delta_X (4) | Delta_Y (4) | Timestamp (8) */
+	int ret;
+
+	ret = pat9125_read_delta(data);
+	if (ret) {
+		iio_trigger_notify_done(indio_dev->trig);
+		return IRQ_NONE;
+	}
+	data->ts = iio_get_time_ns(indio_dev);
+	memcpy(&buf[0], &data->delta_x, 4);
+	memcpy(&buf[4], &data->delta_y, 4);
+	data->delta_x = 0;
+	data->delta_y = 0;
+	iio_push_to_buffers_with_timestamp(indio_dev, buf, data->ts);
+	iio_trigger_notify_done(indio_dev->trig);
+	return IRQ_HANDLED;
+}
+
+/**
+ * pat9125_event_handler() - handling ring and non ring events
+ * @irq: The irq being handled.
+ * @private: struct iio_device pointer for the device.
+ */
+static irqreturn_t pat9125_event_handler(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct pat9125_data *data = iio_priv(indio_dev);
+
+	iio_trigger_poll(data->indio_trig);
+	data->motion_detected = 1;
+	return IRQ_HANDLED;
+}
+
+static int pat9125_buffer_postenable(struct iio_dev *indio_dev)
+{
+	struct pat9125_data *data = iio_priv(indio_dev);
+	int ret = 0;
+
+	ret = iio_triggered_buffer_postenable(indio_dev);
+	if (ret)
+		return ret;
+	data->buffer_mode = true;
+	/* Release IRQ on the chip */
+	return pat9125_read_delta(data);
+}
+
+static int pat9125_buffer_predisable(struct iio_dev *indio_dev)
+{
+	struct pat9125_data *data = iio_priv(indio_dev);
+
+	data->buffer_mode = false;
+	return iio_triggered_buffer_predisable(indio_dev);
+}
+
+static const struct iio_buffer_setup_ops pat9125_buffer_ops = {
+	.preenable = NULL,
+	.postenable = pat9125_buffer_postenable,
+	.predisable = pat9125_buffer_predisable,
+	.postdisable = NULL,
+};
+
+
+static const struct regmap_config pat9125_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const struct iio_info pat9125_info = {
+	.read_raw = pat9125_read_raw,
+};
+
+/*
+ * To avoid infinite loop in "iio_trigger_notify_done",
+ * try_reenable must return 0 when it isn't in buffer mode.
+ * This implementation avoid corner case.
+ */
+static int pat9125_trig_try_reen(struct iio_trigger *trig)
+{
+	struct pat9125_data *data = iio_trigger_get_drvdata(trig);
+
+	if (data->buffer_mode)
+		return data->motion_detected;
+	else
+		return 0;
+}
+
+static const struct iio_trigger_ops pat9125_trigger_ops = {
+	.try_reenable = pat9125_trig_try_reen,
+};
+
+static int pat9125_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct pat9125_data *data;
+	struct iio_dev *indio_dev;
+	int ret, sensor_pid;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev) {
+		dev_err(&client->dev, "IIO device allocation failed");
+		return -ENOMEM;
+	}
+
+	data = iio_priv(indio_dev);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->name = id->name;
+	indio_dev->channels = pat9125_channels;
+	indio_dev->num_channels = ARRAY_SIZE(pat9125_channels);
+	indio_dev->info = &pat9125_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	data->motion_detected = 0;
+	data->buffer_mode = false;
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL, pat9125_trigger_handler,
+					 &pat9125_buffer_ops);
+	if (ret) {
+		dev_err(&client->dev, "unable to setup triggered buffer\n");
+		return ret;
+	}
+
+	data->indio_trig = devm_iio_trigger_alloc(&client->dev, "%s-dev%d",
+		indio_dev->name, indio_dev->id);
+	if (!data->indio_trig) {
+		return -ENOMEM;
+	}
+	data->indio_trig->dev.parent = &client->dev;
+	data->indio_trig->ops = &pat9125_trigger_ops;
+	iio_trigger_set_drvdata(data->indio_trig, data);
+	ret = iio_trigger_register(data->indio_trig);
+	if (ret) {
+		iio_trigger_unregister(data->indio_trig);
+		return ret;
+	}
+
+	data->regmap = devm_regmap_init_i2c(client, &pat9125_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(&client->dev, "regmap init failed %ld",
+			PTR_ERR(data->regmap));
+		return PTR_ERR(data->regmap);
+	}
+
+	/* Check device ID */
+	ret = regmap_read(data->regmap, PAT9125_PRD_ID1_REG, &sensor_pid);
+	if (ret < 0) {
+		dev_err(&client->dev, "register 0x%x access failed %d",
+			PAT9125_PRD_ID1_REG, ret);
+		return ret;
+	}
+	if (sensor_pid != PAT9125_SENSOR_ID_VAL)
+		return -ENODEV;
+
+	/* 
+	 * Software reset
+	 */
+	ret = regmap_write_bits(data->regmap,
+			      PAT9125_CONFIG_REG,
+			      PAT9125_RESET_BIT,
+			      1);
+	if (ret < 0) {
+		dev_err(&client->dev, "register 0x%x access failed %d",
+			PAT9125_CONFIG_REG, ret);
+		return ret;
+	}
+
+	msleep(20);
+
+	ret = regmap_write(data->regmap,
+			 PAT9125_WRITE_PROTEC_REG,
+			 PAT9125_DISABLE_WRITE_PROTECT_VAL);
+	if (ret < 0) {
+		dev_err(&client->dev, "register 0x%x access failed %d",
+			PAT9125_WRITE_PROTEC_REG, ret);
+		return ret;
+	}
+	ret = regmap_write(data->regmap,
+			 PAT9125_RES_X_REG,
+			 x_resolution);
+	if (ret < 0) {
+		dev_err(&client->dev, "register 0x%x access failed %d",
+			PAT9125_RES_X_REG, ret);
+		return ret;
+	}
+	ret = regmap_write(data->regmap,
+			 PAT9125_RES_Y_REG,
+			 y_resolution);
+	if (ret < 0) {
+		dev_err(&client->dev, "register 0x%x access failed %d",
+			PAT9125_RES_Y_REG, ret);
+		return ret;
+	}
+	/* Enable write protection */
+	ret = regmap_write(data->regmap,
+			 PAT9125_WRITE_PROTEC_REG,
+			 PAT9125_ENABLE_WRITE_PROTECT_VAL);
+	if (ret < 0) {
+		dev_err(&client->dev, "register 0x%x access failed %d",
+			PAT9125_WRITE_PROTEC_REG, ret);
+		return ret;
+	}
+
+	ret = devm_iio_device_register(&client->dev, indio_dev);
+	if (ret) {
+		dev_err(&client->dev, "IIO device register failed");
+		iio_triggered_buffer_cleanup(indio_dev);
+		return ret;
+	}
+
+	i2c_set_clientdata(client, indio_dev);
+
+	dev_info(&client->dev, "%s: sensor '%s'\n",
+		 dev_name(&indio_dev->dev),
+		 client->name);
+
+	/* Make read to reset motion bit status */
+	ret = pat9125_read_delta(data);
+	if (ret) {
+		dev_err(&client->dev, "Read register failed");
+		return ret;
+	}
+
+	/* Init GPIO IRQ */
+	if (client->irq) {
+		ret = devm_request_threaded_irq(&client->dev,
+					      client->irq,
+					      pat9125_event_handler,
+					      NULL,
+					      IRQF_TRIGGER_FALLING,
+					      "pat9125",
+					      indio_dev);
+		if (ret) {
+			dev_err(&client->dev, "GPIO IRQ init failed");
+			return ret;
+		}
+	}
+	return 0;
+}
+
+static int pat9125_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = devm_iio_device_alloc(&client->dev, sizeof(struct pat9125_data));
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+
+	dev_info(&client->dev, "PAT9125 removed\n");
+
+	return 0;
+}
+
+static const struct i2c_device_id pat9125_id[] = {
+	{ "pat9125", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, pat9125_id);
+
+static const unsigned short normal_i2c[] = {
+	PAT9125_I2C_ADDR_HI,
+	PAT9125_I2C_ADDR_LO,
+	PAT9125_I2C_ADDR_NC,
+	I2C_CLIENT_END
+};
+
+static struct i2c_driver pat9125_driver = {
+	.driver = {
+		.name = "pat9125",
+	},
+	.probe = pat9125_probe,
+	.remove = pat9125_remove,
+	.address_list = normal_i2c,
+	.id_table = pat9125_id,
+};
+
+module_i2c_driver(pat9125_driver);
+
+MODULE_AUTHOR("Alexandre Mergnat <amergnat@...libre.com>");
+MODULE_DESCRIPTION("Optical Tracking sensor");
+MODULE_LICENSE("GPL");
\ No newline at end of file
-- 
2.17.1

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