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
  53 #define DRIVER_DESC     "RC transmitter with 5-byte Zhen Hua protocol joystick driver"
  54
  55 MODULE_DESCRIPTION(DRIVER_DESC);
  56 MODULE_LICENSE("GPL");
  57
  58 /*
  59  * Constants.
  60  */
  61
  62 #define ZHENHUA_MAX_LENGTH 5
  63
  64 /*
  65  * Zhen Hua data.
  66  */
  67
  68 struct zhenhua {
  69         struct input_dev *dev;
  70         int idx;
  71         unsigned char data[ZHENHUA_MAX_LENGTH];
  72         char phys[32];
  73 };
  74
  75
  76 /* bits in all incoming bytes needs to be "reversed" */
  77 static int zhenhua_bitreverse(int x)
  78 {
  79         x = ((x & 0xaa) >> 1) | ((x & 0x55) << 1);
  80         x = ((x & 0xcc) >> 2) | ((x & 0x33) << 2);
  81         x = ((x & 0xf0) >> 4) | ((x & 0x0f) << 4);
  82         return x;
  83 }
  84
  85 /*
  86  * zhenhua_process_packet() decodes packets the driver receives from the
  87  * RC transmitter. It updates the data accordingly.
  88  */
  89
  90 static void zhenhua_process_packet(struct zhenhua *zhenhua)
  91 {
  92         struct input_dev *dev = zhenhua->dev;
  93         unsigned char *data = zhenhua->data;
  94
  95         input_report_abs(dev, ABS_Y, data[1]);
  96         input_report_abs(dev, ABS_X, data[2]);
  97         input_report_abs(dev, ABS_RZ, data[3]);
  98         input_report_abs(dev, ABS_Z, data[4]);
  99
 100         input_sync(dev);
 101 }
 102
 103 /*
 104  * zhenhua_interrupt() is called by the low level driver when characters
 105  * are ready for us. We then buffer them for further processing, or call the
 106  * packet processing routine.
 107  */
 108
 109 static irqreturn_t zhenhua_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
 110 {
 111         struct zhenhua *zhenhua = serio_get_drvdata(serio);
 112
 113         /* All Zhen Hua packets are 5 bytes. The fact that the first byte
 114          * is allways 0xf7 and all others are in range 0x32 - 0xc8 (50-200)
 115          * can be used to check and regain sync. */
 116
 117         if (data == 0xef)
 118                 zhenhua->idx = 0;       /* this byte starts a new packet */
 119         else if (zhenhua->idx == 0)
 120                 return IRQ_HANDLED;     /* wrong MSB -- ignore this byte */
 121
 122         if (zhenhua->idx < ZHENHUA_MAX_LENGTH)
 123                 zhenhua->data[zhenhua->idx++] = zhenhua_bitreverse(data);
 124
 125         if (zhenhua->idx == ZHENHUA_MAX_LENGTH) {
 126                 zhenhua_process_packet(zhenhua);
 127                 zhenhua->idx = 0;
 128         }
 129
 130         return IRQ_HANDLED;
 131 }
 132
 133 /*
 134  * zhenhua_disconnect() is the opposite of zhenhua_connect()
 135  */
 136
 137 static void zhenhua_disconnect(struct serio *serio)
 138 {
 139         struct zhenhua *zhenhua = serio_get_drvdata(serio);
 140
 141         serio_close(serio);
 142         serio_set_drvdata(serio, NULL);
 143         input_unregister_device(zhenhua->dev);
 144         kfree(zhenhua);
 145 }
 146
 147 /*
 148  * zhenhua_connect() is the routine that is called when someone adds a
 149  * new serio device. It looks for the Twiddler, and if found, registers
 150  * it as an input device.
 151  */
 152
 153 static int zhenhua_connect(struct serio *serio, struct serio_driver *drv)
 154 {
 155         struct zhenhua *zhenhua;
 156         struct input_dev *input_dev;
 157         int err = -ENOMEM;
 158
 159         zhenhua = kzalloc(sizeof(struct zhenhua), GFP_KERNEL);
 160         input_dev = input_allocate_device();
 161         if (!zhenhua || !input_dev)
 162                 goto fail1;
 163
 164         zhenhua->dev = input_dev;
 165         snprintf(zhenhua->phys, sizeof(zhenhua->phys), "%s/input0", serio->phys);
 166
 167         input_dev->name = "Zhen Hua 5-byte device";
 168         input_dev->phys = zhenhua->phys;
 169         input_dev->id.bustype = BUS_RS232;
 170         input_dev->id.vendor = SERIO_ZHENHUA;
 171         input_dev->id.product = 0x0001;
 172         input_dev->id.version = 0x0100;
 173         input_dev->dev.parent = &serio->dev;
 174
 175         input_dev->evbit[0] = BIT(EV_ABS);
 176         input_set_abs_params(input_dev, ABS_X, 50, 200, 0, 0);
 177         input_set_abs_params(input_dev, ABS_Y, 50, 200, 0, 0);
 178         input_set_abs_params(input_dev, ABS_Z, 50, 200, 0, 0);
 179         input_set_abs_params(input_dev, ABS_RZ, 50, 200, 0, 0);
 180
 181         serio_set_drvdata(serio, zhenhua);
 182
 183         err = serio_open(serio, drv);
 184         if (err)
 185                 goto fail2;
 186
 187         err = input_register_device(zhenhua->dev);
 188         if (err)
 189                 goto fail3;
 190
 191         return 0;
 192
 193  fail3: serio_close(serio);
 194  fail2: serio_set_drvdata(serio, NULL);
 195  fail1: input_free_device(input_dev);
 196         kfree(zhenhua);
 197         return err;
 198 }
 199
 200 /*
 201  * The serio driver structure.
 202  */
 203
 204 static struct serio_device_id zhenhua_serio_ids[] = {
 205         {
 206                 .type   = SERIO_RS232,
 207                 .proto  = SERIO_ZHENHUA,
 208                 .id     = SERIO_ANY,
 209                 .extra  = SERIO_ANY,
 210         },
 211         { 0 }
 212 };
 213
 214 MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids);
 215
 216 static struct serio_driver zhenhua_drv = {
 217         .driver         = {
 218                 .name   = "zhenhua",
 219         },
 220         .description    = DRIVER_DESC,
 221         .id_table       = zhenhua_serio_ids,
 222         .interrupt      = zhenhua_interrupt,
 223         .connect        = zhenhua_connect,
 224         .disconnect     = zhenhua_disconnect,
 225 };
 226
 227 module_serio_driver(zhenhua_drv);