Date:   Fri,  5 Apr 2019 09:34:30 +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 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 deltas or subscribe
to the data buffer feed automaticaly by a new value using a
trigger gpio. The buffer payload is: |16 bits delta X|16 bits delta Y|timestamp|.
The possible I2C adresses are 0x73, 0x75 and 0x79.

Unfortunately, the device configuration must be hardcoded in the initialization
function and can't be changed "on-the-fly" in user space due to the lack of
configuration interface.

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 | 407 +++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 431 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 d08aeb4..bdf1bd0 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 cb59932..fdda2e1 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 0000000..3d17fda
--- /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 0000000..cf29491
--- /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 0000000..f416bfa
--- /dev/null
+++ b/drivers/iio/ot/pat9125.c
@@ -0,0 +1,407 @@
+// SPDX-License-Identifier: (GPL-2.0)
+/*
+ * Copyright (C) 2018 BayLibre, SAS
+ * Author: Alexandre Mergnat <amergnat@...libre.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/regmap.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/events.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/kfifo_buf.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
+
+/* Masks */
+#define PAT9125_VALID_MOTION_DATA_MASK	0x80
+#define PAT9125_RESET_MASK		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
+#define PAT9125_SAMPLED_VAL_BYTE_SIZE		2	/* 12 bits by default */
+#define PAT9125_TIMESTAMP_BYTE_SIZE		8	/* 64 bits */
+#define PAT9125_PAYLOAD_BYTE_SIZE \
+	(2 * PAT9125_SAMPLED_VAL_BYTE_SIZE + PAT9125_TIMESTAMP_BYTE_SIZE)
+#define PAT9125_REALBITS_XY_VAL \
+	(2 * PAT9125_SAMPLED_VAL_BIT_SIZE)
+#define PAT9125_STORAGEBITS_XY_VAL \
+	(2 * PAT9125_SAMPLED_VAL_BYTE_SIZE)
+
+struct pat9125_data {
+	struct i2c_client *client;
+	struct regmap *regmap;
+	s16 delta_x;
+	s16 delta_y;
+};
+
+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_AND_Y,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.address = 0,
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',			\
+			.realbits = 24,			\
+			.storagebits = 32,		\
+			.shift = 8,			\
+			.endianness = IIO_BE,		\
+		},
+		.event_spec = &pat9125_event,
+		.num_event_specs = 1,
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(1),
+};
+
+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_xy = 0;
+	int r;
+
+	r = regmap_read(regmap, PAT9125_MOTION_STATUS_REG, &status);
+	if (r < 0)
+		return r;
+
+	/* Check motion bit in bit7 */
+	if (status & PAT9125_VALID_MOTION_DATA_MASK) {
+		r = regmap_read(regmap, PAT9125_DELTA_X_LO_REG, &val_x);
+		if (r < 0)
+			return r;
+
+		r = regmap_read(regmap, PAT9125_DELTA_Y_LO_REG, &val_y);
+		if (r < 0)
+			return r;
+
+		r = regmap_read(regmap, PAT9125_DELTA_XY_HI_REG, &val_xy);
+		if (r < 0)
+			return r;
+
+		data->delta_x = val_x | ((val_xy << 4) & 0xF00);
+		data->delta_y = val_y | ((val_xy << 8) & 0xF00);
+
+		if (data->delta_x & 0x800)
+			data->delta_x |= 0xF000;
+
+		if (data->delta_y & 0x800)
+			data->delta_y |= 0xF000;
+	}
+
+	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;
+
+		*val = data->delta_x;
+		*val2 = data->delta_y;
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+
+	return -EINVAL;
+}
+
+/**
+ * pat9125_read_event_value() - return last sampled value.
+ **/
+static int pat9125_read_event_value(struct iio_dev *indio_dev,
+				    const struct iio_chan_spec *chan,
+				    enum iio_event_type type,
+				    enum iio_event_direction dir,
+				    enum iio_event_info info,
+				    int *val,
+				    int *val2)
+{
+	struct pat9125_data *data = iio_priv(indio_dev);
+
+	switch (info) {
+	case IIO_EV_INFO_VALUE:
+		val[0] = data->delta_x;
+		val[1] = data->delta_y;
+		*val2 = 2;
+		return IIO_VAL_INT_MULTIPLE;
+	default:
+		return -EINVAL;
+	}
+}
+
+/**
+ * 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);
+	int ret = 0;
+	u8 *payload;
+	s64 last_timestamp = iio_get_time_ns(indio_dev);
+
+	payload = kmalloc(sizeof(s64) + 2 *
+		  PAT9125_SAMPLED_VAL_BYTE_SIZE, GFP_KERNEL);
+
+	ret = pat9125_read_delta(data);
+	if (ret)
+		return ret;
+	memcpy(&payload[0], &data->delta_x, 2);
+	memcpy(&payload[2], &data->delta_y, 2);
+
+	iio_push_to_buffers_with_timestamp(indio_dev, payload, last_timestamp);
+	iio_push_event(indio_dev,
+		       IIO_MOD_EVENT_CODE(IIO_DISTANCE,
+					  0,
+					  IIO_MOD_X_AND_Y,
+					  IIO_EV_TYPE_THRESH,
+					  IIO_EV_DIR_RISING),
+		       last_timestamp);
+
+	return IRQ_HANDLED;
+}
+
+static int pat9125_configure_ring(struct iio_dev *indio_dev)
+{
+	struct iio_buffer *buffer;
+	struct pat9125_data *data = iio_priv(indio_dev);
+
+	buffer = devm_iio_kfifo_allocate(&data->client->dev);
+	if (!buffer)
+		return -ENOMEM;
+
+	iio_device_attach_buffer(indio_dev, buffer);
+	indio_dev->modes |= INDIO_BUFFER_SOFTWARE;
+
+	return 0;
+}
+
+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,
+	.read_event_value = &pat9125_read_event_value,
+};
+
+static int pat9125_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct pat9125_data *data;
+	struct iio_dev *indio_dev;
+	int r, 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);
+	data->client = client;
+
+	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;
+
+	r = pat9125_configure_ring(indio_dev);
+	if (r < 0) {
+		dev_err(&client->dev, "FIFO buffer allocation failed");
+		return r;
+	}
+
+	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 */
+	r = regmap_read(data->regmap, PAT9125_PRD_ID1_REG, &sensor_pid);
+	if (r < 0)
+		goto reg_access_fail;
+	if (sensor_pid != PAT9125_SENSOR_ID_VAL)
+		return -ENODEV;
+
+	/* Software reset (i.e. set bit7 to 1).
+	 * It will reset to 0 automatically
+	 */
+	r = regmap_write_bits(data->regmap,
+			      PAT9125_CONFIG_REG,
+			      PAT9125_RESET_MASK,
+			      1);
+	if (r < 0)
+		goto reg_access_fail;
+
+	/* Delay 20ms */
+	msleep(20);
+
+	/* Disable write protect */
+	r = regmap_write(data->regmap,
+			 PAT9125_WRITE_PROTEC_REG,
+			 PAT9125_DISABLE_WRITE_PROTECT_VAL);
+	if (r < 0)
+		goto reg_access_fail;
+
+	/* Set X-axis resolution (depends on application) */
+	r = regmap_write(data->regmap,
+			 PAT9125_RES_X_REG,
+			 0x0A);
+	if (r < 0)
+		goto reg_access_fail;
+
+	/* Set Y-axis resolution (depends on application) */
+	r = regmap_write(data->regmap,
+			 PAT9125_RES_Y_REG,
+			 0x0A);
+	if (r < 0)
+		goto reg_access_fail;
+
+	/* Enable write protection */
+	r = regmap_write(data->regmap,
+			 PAT9125_WRITE_PROTEC_REG,
+			 PAT9125_ENABLE_WRITE_PROTECT_VAL);
+	if (r < 0)
+		goto reg_access_fail;
+
+	r = devm_iio_device_register(&client->dev, indio_dev);
+	if (r) {
+		dev_err(&client->dev, "IIO device register failed");
+		return r;
+	}
+
+	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 */
+	r = pat9125_read_delta(data);
+	if (r)
+		goto reg_access_fail;
+
+	/* Init GPIO IRQ */
+	if (client->irq) {
+		r = devm_request_threaded_irq(&client->dev,
+					      client->irq,
+					      NULL,
+					      pat9125_event_handler,
+					      IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+					      "pat9125",
+					      indio_dev);
+		if (r)
+			return r;
+	}
+	return 0;
+
+reg_access_fail:
+	dev_err(&client->dev, "register access failed %d", r);
+	return r;
+}
+
+static int pat9125_remove(struct i2c_client *client)
+{
+	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");
+
-- 
2.7.4

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