drivers/input/joystick/zhenhua.c

   1 /*
   2  *  derived from "twidjoy.c"
   3  *
   4  *  Copyright (c) 2008 Martin Kebert
   5  *  Copyright (c) 2001 Arndt Schoenewald
   6  *  Copyright (c) 2000-2001 Vojtech Pavlik
   7  *  Copyright (c) 2000 Mark Fletcher
   8  *
   9  */
  10
  11 /*
  12  * Driver to use 4CH RC transmitter using Zhen Hua 5-byte protocol (Walkera Lama,
  13  * EasyCopter etc.) as a joystick under Linux.
  14  *
  15  * RC transmitters using Zhen Hua 5-byte protocol are cheap four channels
  16  * transmitters for control a RC planes or RC helicopters with possibility to
  17  * connect on a serial port.
  18  * Data coming from transmitter is in this order:
  19  * 1. byte = synchronisation byte
  20  * 2. byte = X axis
  21  * 3. byte = Y axis
  22  * 4. byte = RZ axis
  23  * 5. byte = Z axis
  24  * (and this is repeated)
  25  *
  26  * For questions or feedback regarding this driver module please contact:
  27  * Martin Kebert <gkmarty@gmail.com> - but I am not a C-programmer nor kernel
  28  * coder :-(
  29  */
  30
  31 /*
  32  * This program is free software; you can redistribute it and/or modify
  33  * it under the terms of the GNU General Public License as published by
  34  * the Free Software Foundation; either version 2 of the License, or
  35  * (at your option) any later version.
  36  *
  37  * This program is distributed in the hope that it will be useful,
  38  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  39  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  40  * GNU General Public License for more details.
  41  *
  42  * You should have received a copy of the GNU General Public License
  43  * along with this program; if not, write to the Free Software
  44  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  45  */
  46
  47 #include <linux/kernel.h>
  48 #include <linux/module.h>
  49 #include <linux/slab.h>
  50 #include <linux/input.h>
  51 #include <linux/serio.h>
  52 #include <linux/init.h>
  53
  54 #define DRIVER_DESC     "RC transmitter with 5-byte Zhen Hua protocol joystick driver"
  55
  56 MODULE_DESCRIPTION(DRIVER_DESC);
  57 MODULE_LICENSE("GPL");
  58
  59 /*
  60  * Constants.
  61  */
  62
  63 #define ZHENHUA_MAX_LENGTH 5
  64
  65 /*
  66  * Zhen Hua data.
  67  */
  68
  69 struct zhenhua {
  70         struct input_dev *dev;
  71         int idx;
  72         unsigned char data[ZHENHUA_MAX_LENGTH];
  73         char phys[32];
  74 };
  75
  76
  77 /* bits in all incoming bytes needs to be "reversed" */
  78 static int zhenhua_bitreverse(int x)
  79 {
  80         x = ((x & 0xaa) >> 1) | ((x & 0x55) << 1);
  81         x = ((x & 0xcc) >> 2) | ((x & 0x33) << 2);
  82         x = ((x & 0xf0) >> 4) | ((x & 0x0f) << 4);
  83         return x;
  84 }
  85
  86 /*
  87  * zhenhua_process_packet() decodes packets the driver receives from the
  88  * RC transmitter. It updates the data accordingly.
  89  */
  90
  91 static void zhenhua_process_packet(struct zhenhua *zhenhua)
  92 {
  93         struct input_dev *dev = zhenhua->dev;
  94         unsigned char *data = zhenhua->data;
  95
  96         input_report_abs(dev, ABS_Y, data[1]);
  97         input_report_abs(dev, ABS_X, data[2]);
  98         input_report_abs(dev, ABS_RZ, data[3]);
  99         input_report_abs(dev, ABS_Z, data[4]);
 100
 101         input_sync(dev);
 102 }
 103
 104 /*
 105  * zhenhua_interrupt() is called by the low level driver when characters
 106  * are ready for us. We then buffer them for further processing, or call the
 107  * packet processing routine.
 108  */
 109
 110 static irqreturn_t zhenhua_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
 111 {
 112         struct zhenhua *zhenhua = serio_get_drvdata(serio);
 113
 114         /* All Zhen Hua packets are 5 bytes. The fact that the first byte
 115          * is allways 0xf7 and all others are in range 0x32 - 0xc8 (50-200)
 116          * can be used to check and regain sync. */
 117
 118         if (data == 0xef)
 119                 zhenhua->idx = 0;       /* this byte starts a new packet */
 120         else if (zhenhua->idx == 0)
 121                 return IRQ_HANDLED;     /* wrong MSB -- ignore this byte */
 122
 123         if (zhenhua->idx < ZHENHUA_MAX_LENGTH)
 124                 zhenhua->data[zhenhua->idx++] = zhenhua_bitreverse(data);
 125
 126         if (zhenhua->idx == ZHENHUA_MAX_LENGTH) {
 127                 zhenhua_process_packet(zhenhua);
 128                 zhenhua->idx = 0;
 129         }
 130
 131         return IRQ_HANDLED;
 132 }
 133
 134 /*
 135  * zhenhua_disconnect() is the opposite of zhenhua_connect()
 136  */
 137
 138 static void zhenhua_disconnect(struct serio *serio)
 139 {
 140         struct zhenhua *zhenhua = serio_get_drvdata(serio);
 141
 142         serio_close(serio);
 143         serio_set_drvdata(serio, NULL);
 144         input_unregister_device(zhenhua->dev);
 145         kfree(zhenhua);
 146 }
 147
 148 /*
 149  * zhenhua_connect() is the routine that is called when someone adds a
 150  * new serio device. It looks for the Twiddler, and if found, registers
 151  * it as an input device.
 152  */
 153
 154 static int zhenhua_connect(struct serio *serio, struct serio_driver *drv)
 155 {
 156         struct zhenhua *zhenhua;
 157         struct input_dev *input_dev;
 158         int err = -ENOMEM;
 159
 160         zhenhua = kzalloc(sizeof(struct zhenhua), GFP_KERNEL);
 161         input_dev = input_allocate_device();
 162         if (!zhenhua || !input_dev)
 163                 goto fail1;
 164
 165         zhenhua->dev = input_dev;
 166         snprintf(zhenhua->phys, sizeof(zhenhua->phys), "%s/input0", serio->phys);
 167
 168         input_dev->name = "Zhen Hua 5-byte device";
 169         input_dev->phys = zhenhua->phys;
 170         input_dev->id.bustype = BUS_RS232;
 171         input_dev->id.vendor = SERIO_ZHENHUA;
 172         input_dev->id.product = 0x0001;
 173         input_dev->id.version = 0x0100;
 174         input_dev->dev.parent = &serio->dev;
 175
 176         input_dev->evbit[0] = BIT(EV_ABS);
 177         input_set_abs_params(input_dev, ABS_X, 50, 200, 0, 0);
 178         input_set_abs_params(input_dev, ABS_Y, 50, 200, 0, 0);
 179         input_set_abs_params(input_dev, ABS_Z, 50, 200, 0, 0);
 180         input_set_abs_params(input_dev, ABS_RZ, 50, 200, 0, 0);
 181
 182         serio_set_drvdata(serio, zhenhua);
 183
 184         err = serio_open(serio, drv);
 185         if (err)
 186                 goto fail2;
 187
 188         err = input_register_device(zhenhua->dev);
 189         if (err)
 190                 goto fail3;
 191
 192         return 0;
 193
 194  fail3: serio_close(serio);
 195  fail2: serio_set_drvdata(serio, NULL);
 196  fail1: input_free_device(input_dev);
 197         kfree(zhenhua);
 198         return err;
 199 }
 200
 201 /*
 202  * The serio driver structure.
 203  */
 204
 205 static struct serio_device_id zhenhua_serio_ids[] = {
 206         {
 207                 .type   = SERIO_RS232,
 208                 .proto  = SERIO_ZHENHUA,
 209                 .id     = SERIO_ANY,
 210                 .extra  = SERIO_ANY,
 211         },
 212         { 0 }
 213 };
 214
 215 MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids);
 216
 217 static struct serio_driver zhenhua_drv = {
 218         .driver         = {
 219                 .name   = "zhenhua",
 220         },
 221         .description    = DRIVER_DESC,
 222         .id_table       = zhenhua_serio_ids,
 223         .interrupt      = zhenhua_interrupt,
 224         .connect        = zhenhua_connect,
 225         .disconnect     = zhenhua_disconnect,
 226 };
 227
 228 module_serio_driver(zhenhua_drv);