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>

3 files changed, 256 insertions, 0 deletions

diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
index 7c662ee594a3..be5c14a5a0a4 100644
--- a/drivers/input/joystick/Kconfig
+++ b/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
diff --git a/drivers/input/joystick/Makefile b/drivers/input/joystick/Makefile
index e855abb0cc51..868b746e757a 100644
--- a/drivers/input/joystick/Makefile
+++ b/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/
diff --git a/drivers/input/joystick/zhenhua.c b/drivers/input/joystick/zhenhua.c
new file mode 100644
index 000000000000..b5853125c898
--- /dev/null
+++ b/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);