Input: add Zhen Hua driver

This is a driver for Zhen Hua PPM-4CH RC transmitter (commonly used in cheap
Ready To Fly RC helicopters by Walkera) which using "Zhen Hua 5-byte protocol"
for using them as a four axis joystick via serial port.  Transmitter connected
to serial port (19200 8N1) sending periodically 5 bytes where first byte is for
synchronization and next four bytes are values of axis.

Signed-off-by: Martin Kebert <gkmarty@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/joystick/Kconfig

@@ -193,6 +193,18 @@ config JOYSTICK_TWIDJOY
 	  To compile this driver as a module, choose M here: the
 	  module will be called twidjoy.
 
+config JOYSTICK_ZHENHUA
+	tristate "5-byte Zhenhua RC transmitter"
+	select SERIO
+	help
+	  Say Y here if you have a Zhen Hua PPM-4CH transmitter which is
+	  supplied with a ready to fly micro electric indoor helicopters
+	  such as EasyCopter, Lama, MiniCopter, DragonFly or Jabo and want
+	  to use it via serial cable as a joystick.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called zhenhua.
+
 config JOYSTICK_DB9
 	tristate "Multisystem, Sega Genesis, Saturn joysticks and gamepads"
 	depends on PARPORT

drivers/input/joystick/Makefile

@@ -27,5 +27,6 @@ obj-$(CONFIG_JOYSTICK_TURBOGRAFX)	+= turbografx.o
 obj-$(CONFIG_JOYSTICK_TWIDJOY)		+= twidjoy.o
 obj-$(CONFIG_JOYSTICK_WARRIOR)		+= warrior.o
 obj-$(CONFIG_JOYSTICK_XPAD)		+= xpad.o
+obj-$(CONFIG_JOYSTICK_ZHENHUA)		+= zhenhua.o
 
 obj-$(CONFIG_JOYSTICK_IFORCE)		+= iforce/

drivers/input/joystick/zhenhua.c

@@ -0,0 +1,243 @@
+/*
+ *  derived from "twidjoy.c"
+ *
+ *  Copyright (c) 2008 Martin Kebert
+ *  Copyright (c) 2001 Arndt Schoenewald
+ *  Copyright (c) 2000-2001 Vojtech Pavlik
+ *  Copyright (c) 2000 Mark Fletcher
+ *
+ */
+
+/*
+ * Driver to use 4CH RC transmitter using Zhen Hua 5-byte protocol (Walkera Lama,
+ * EasyCopter etc.) as a joystick under Linux.
+ *
+ * RC transmitters using Zhen Hua 5-byte protocol are cheap four channels
+ * transmitters for control a RC planes or RC helicopters with possibility to
+ * connect on a serial port.
+ * Data coming from transmitter is in this order:
+ * 1. byte = synchronisation byte
+ * 2. byte = X axis
+ * 3. byte = Y axis
+ * 4. byte = RZ axis
+ * 5. byte = Z axis
+ * (and this is repeated)
+ *
+ * For questions or feedback regarding this driver module please contact:
+ * Martin Kebert <gkmarty@gmail.com> - but I am not a C-programmer nor kernel
+ * coder :-(
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+#include <linux/init.h>
+
+#define DRIVER_DESC	"RC transmitter with 5-byte Zhen Hua protocol joystick driver"
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+/*
+ * Constants.
+ */
+
+#define ZHENHUA_MAX_LENGTH 5
+
+/*
+ * Zhen Hua data.
+ */
+
+struct zhenhua {
+	struct input_dev *dev;
+	int idx;
+	unsigned char data[ZHENHUA_MAX_LENGTH];
+	char phys[32];
+};
+
+
+/* bits in all incoming bytes needs to be "reversed" */
+static int zhenhua_bitreverse(int x)
+{
+	x = ((x & 0xaa) >> 1) | ((x & 0x55) << 1);
+	x = ((x & 0xcc) >> 2) | ((x & 0x33) << 2);
+	x = ((x & 0xf0) >> 4) | ((x & 0x0f) << 4);
+	return x;
+}
+
+/*
+ * zhenhua_process_packet() decodes packets the driver receives from the
+ * RC transmitter. It updates the data accordingly.
+ */
+
+static void zhenhua_process_packet(struct zhenhua *zhenhua)
+{
+	struct input_dev *dev = zhenhua->dev;
+	unsigned char *data = zhenhua->data;
+
+	input_report_abs(dev, ABS_Y, data[1]);
+	input_report_abs(dev, ABS_X, data[2]);
+	input_report_abs(dev, ABS_RZ, data[3]);
+	input_report_abs(dev, ABS_Z, data[4]);
+
+	input_sync(dev);
+}
+
+/*
+ * zhenhua_interrupt() is called by the low level driver when characters
+ * are ready for us. We then buffer them for further processing, or call the
+ * packet processing routine.
+ */
+
+static irqreturn_t zhenhua_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
+{
+	struct zhenhua *zhenhua = serio_get_drvdata(serio);
+
+	/* All Zhen Hua packets are 5 bytes. The fact that the first byte
+	 * is allways 0xf7 and all others are in range 0x32 - 0xc8 (50-200)
+	 * can be used to check and regain sync. */
+
+	if (data == 0xef)
+		zhenhua->idx = 0;	/* this byte starts a new packet */
+	else if (zhenhua->idx == 0)
+		return IRQ_HANDLED;	/* wrong MSB -- ignore this byte */
+
+	if (zhenhua->idx < ZHENHUA_MAX_LENGTH)
+		zhenhua->data[zhenhua->idx++] = zhenhua_bitreverse(data);
+
+	if (zhenhua->idx == ZHENHUA_MAX_LENGTH) {
+		zhenhua_process_packet(zhenhua);
+		zhenhua->idx = 0;
+	}
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * zhenhua_disconnect() is the opposite of zhenhua_connect()
+ */
+
+static void zhenhua_disconnect(struct serio *serio)
+{
+	struct zhenhua *zhenhua = serio_get_drvdata(serio);
+
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_unregister_device(zhenhua->dev);
+	kfree(zhenhua);
+}
+
+/*
+ * zhenhua_connect() is the routine that is called when someone adds a
+ * new serio device. It looks for the Twiddler, and if found, registers
+ * it as an input device.
+ */
+
+static int zhenhua_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct zhenhua *zhenhua;
+	struct input_dev *input_dev;
+	int err = -ENOMEM;
+
+	zhenhua = kzalloc(sizeof(struct zhenhua), GFP_KERNEL);
+	input_dev = input_allocate_device();
+	if (!zhenhua || !input_dev)
+		goto fail1;
+
+	zhenhua->dev = input_dev;
+	snprintf(zhenhua->phys, sizeof(zhenhua->phys), "%s/input0", serio->phys);
+
+	input_dev->name = "Zhen Hua 5-byte device";
+	input_dev->phys = zhenhua->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_ZHENHUA;
+	input_dev->id.product = 0x0001;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &serio->dev;
+
+	input_dev->evbit[0] = BIT(EV_ABS);
+	input_set_abs_params(input_dev, ABS_X, 50, 200, 0, 0);
+	input_set_abs_params(input_dev, ABS_Y, 50, 200, 0, 0);
+	input_set_abs_params(input_dev, ABS_Z, 50, 200, 0, 0);
+	input_set_abs_params(input_dev, ABS_RZ, 50, 200, 0, 0);
+
+	serio_set_drvdata(serio, zhenhua);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	err = input_register_device(zhenhua->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3:	serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(zhenhua);
+	return err;
+}
+
+/*
+ * The serio driver structure.
+ */
+
+static struct serio_device_id zhenhua_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_ZHENHUA,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids);
+
+static struct serio_driver zhenhua_drv = {
+	.driver		= {
+		.name	= "zhenhua",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= zhenhua_serio_ids,
+	.interrupt	= zhenhua_interrupt,
+	.connect	= zhenhua_connect,
+	.disconnect	= zhenhua_disconnect,
+};
+
+/*
+ * The functions for inserting/removing us as a module.
+ */
+
+static int __init zhenhua_init(void)
+{
+	return serio_register_driver(&zhenhua_drv);
+}
+
+static void __exit zhenhua_exit(void)
+{
+	serio_unregister_driver(&zhenhua_drv);
+}
+
+module_init(zhenhua_init);
+module_exit(zhenhua_exit);

include/linux/serio.h

@@ -211,5 +211,6 @@ static inline void serio_unpin_driver(struct serio *serio)
 #define SERIO_TOUCHWIN	0x33
 #define SERIO_TAOSEVM	0x34
 #define SERIO_FUJITSU	0x35
+#define SERIO_ZHENHUA	0x36
 
 #endif