root/drivers/input/joystick/twidjoy.c

DEFINITIONS

1. twidjoy_process_packet
2. twidjoy_interrupt
3. twidjoy_disconnect
4. twidjoy_connect

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Copyright (c) 2001 Arndt Schoenewald
   4  *  Copyright (c) 2000-2001 Vojtech Pavlik
   5  *  Copyright (c) 2000 Mark Fletcher
   6  *
   7  *  Sponsored by Quelltext AG (http://www.quelltext-ag.de), Dortmund, Germany
   8  */
   9 
  10 /*
  11  * Driver to use Handykey's Twiddler (the first edition, i.e. the one with
  12  * the RS232 interface) as a joystick under Linux
  13  *
  14  * The Twiddler is a one-handed chording keyboard featuring twelve buttons on
  15  * the front, six buttons on the top, and a built-in tilt sensor. The buttons
  16  * on the front, which are grouped as four rows of three buttons, are pressed
  17  * by the four fingers (this implies only one button per row can be held down
  18  * at the same time) and the buttons on the top are for the thumb. The tilt
  19  * sensor delivers X and Y axis data depending on how the Twiddler is held.
  20  * Additional information can be found at http://www.handykey.com.
  21  *
  22  * This driver does not use the Twiddler for its intended purpose, i.e. as
  23  * a chording keyboard, but as a joystick: pressing and releasing a button
  24  * immediately sends a corresponding button event, and tilting it generates
  25  * corresponding ABS_X and ABS_Y events. This turns the Twiddler into a game
  26  * controller with amazing 18 buttons :-)
  27  *
  28  * Note: The Twiddler2 (the successor of the Twiddler that connects directly
  29  * to the PS/2 keyboard and mouse ports) is NOT supported by this driver!
  30  *
  31  * For questions or feedback regarding this driver module please contact:
  32  * Arndt Schoenewald <arndt@quelltext.com>
  33  */
  34 
  35 /*
  36  */
  37 
  38 #include <linux/kernel.h>
  39 #include <linux/module.h>
  40 #include <linux/slab.h>
  41 #include <linux/input.h>
  42 #include <linux/serio.h>
  43 
  44 #define DRIVER_DESC     "Handykey Twiddler keyboard as a joystick driver"
  45 
  46 MODULE_DESCRIPTION(DRIVER_DESC);
  47 MODULE_LICENSE("GPL");
  48 
  49 /*
  50  * Constants.
  51  */
  52 
  53 #define TWIDJOY_MAX_LENGTH 5
  54 
  55 static struct twidjoy_button_spec {
  56         int bitshift;
  57         int bitmask;
  58         int buttons[3];
  59 }
  60 twidjoy_buttons[] = {
  61         {  0, 3, { BTN_A,      BTN_B,     BTN_C    } },
  62         {  2, 3, { BTN_X,      BTN_Y,     BTN_Z    } },
  63         {  4, 3, { BTN_TL,     BTN_TR,    BTN_TR2  } },
  64         {  6, 3, { BTN_SELECT, BTN_START, BTN_MODE } },
  65         {  8, 1, { BTN_BASE5                       } },
  66         {  9, 1, { BTN_BASE                        } },
  67         { 10, 1, { BTN_BASE3                       } },
  68         { 11, 1, { BTN_BASE4                       } },
  69         { 12, 1, { BTN_BASE2                       } },
  70         { 13, 1, { BTN_BASE6                       } },
  71         { 0,  0, { 0                               } }
  72 };
  73 
  74 /*
  75  * Per-Twiddler data.
  76  */
  77 
  78 struct twidjoy {
  79         struct input_dev *dev;
  80         int idx;
  81         unsigned char data[TWIDJOY_MAX_LENGTH];
  82         char phys[32];
  83 };
  84 
  85 /*
  86  * twidjoy_process_packet() decodes packets the driver receives from the
  87  * Twiddler. It updates the data accordingly.
  88  */
  89 
  90 static void twidjoy_process_packet(struct twidjoy *twidjoy)
  91 {
  92         struct input_dev *dev = twidjoy->dev;
  93         unsigned char *data = twidjoy->data;
  94         struct twidjoy_button_spec *bp;
  95         int button_bits, abs_x, abs_y;
  96 
  97         button_bits = ((data[1] & 0x7f) << 7) | (data[0] & 0x7f);
  98 
  99         for (bp = twidjoy_buttons; bp->bitmask; bp++) {
 100                 int value = (button_bits & (bp->bitmask << bp->bitshift)) >> bp->bitshift;
 101                 int i;
 102 
 103                 for (i = 0; i < bp->bitmask; i++)
 104                         input_report_key(dev, bp->buttons[i], i+1 == value);
 105         }
 106 
 107         abs_x = ((data[4] & 0x07) << 5) | ((data[3] & 0x7C) >> 2);
 108         if (data[4] & 0x08) abs_x -= 256;
 109 
 110         abs_y = ((data[3] & 0x01) << 7) | ((data[2] & 0x7F) >> 0);
 111         if (data[3] & 0x02) abs_y -= 256;
 112 
 113         input_report_abs(dev, ABS_X, -abs_x);
 114         input_report_abs(dev, ABS_Y, +abs_y);
 115 
 116         input_sync(dev);
 117 }
 118 
 119 /*
 120  * twidjoy_interrupt() is called by the low level driver when characters
 121  * are ready for us. We then buffer them for further processing, or call the
 122  * packet processing routine.
 123  */
 124 
 125 static irqreturn_t twidjoy_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
 126 {
 127         struct twidjoy *twidjoy = serio_get_drvdata(serio);
 128 
 129         /* All Twiddler packets are 5 bytes. The fact that the first byte
 130          * has a MSB of 0 and all other bytes have a MSB of 1 can be used
 131          * to check and regain sync. */
 132 
 133         if ((data & 0x80) == 0)
 134                 twidjoy->idx = 0;       /* this byte starts a new packet */
 135         else if (twidjoy->idx == 0)
 136                 return IRQ_HANDLED;     /* wrong MSB -- ignore this byte */
 137 
 138         if (twidjoy->idx < TWIDJOY_MAX_LENGTH)
 139                 twidjoy->data[twidjoy->idx++] = data;
 140 
 141         if (twidjoy->idx == TWIDJOY_MAX_LENGTH) {
 142                 twidjoy_process_packet(twidjoy);
 143                 twidjoy->idx = 0;
 144         }
 145 
 146         return IRQ_HANDLED;
 147 }
 148 
 149 /*
 150  * twidjoy_disconnect() is the opposite of twidjoy_connect()
 151  */
 152 
 153 static void twidjoy_disconnect(struct serio *serio)
 154 {
 155         struct twidjoy *twidjoy = serio_get_drvdata(serio);
 156 
 157         serio_close(serio);
 158         serio_set_drvdata(serio, NULL);
 159         input_unregister_device(twidjoy->dev);
 160         kfree(twidjoy);
 161 }
 162 
 163 /*
 164  * twidjoy_connect() is the routine that is called when someone adds a
 165  * new serio device. It looks for the Twiddler, and if found, registers
 166  * it as an input device.
 167  */
 168 
 169 static int twidjoy_connect(struct serio *serio, struct serio_driver *drv)
 170 {
 171         struct twidjoy_button_spec *bp;
 172         struct twidjoy *twidjoy;
 173         struct input_dev *input_dev;
 174         int err = -ENOMEM;
 175         int i;
 176 
 177         twidjoy = kzalloc(sizeof(struct twidjoy), GFP_KERNEL);
 178         input_dev = input_allocate_device();
 179         if (!twidjoy || !input_dev)
 180                 goto fail1;
 181 
 182         twidjoy->dev = input_dev;
 183         snprintf(twidjoy->phys, sizeof(twidjoy->phys), "%s/input0", serio->phys);
 184 
 185         input_dev->name = "Handykey Twiddler";
 186         input_dev->phys = twidjoy->phys;
 187         input_dev->id.bustype = BUS_RS232;
 188         input_dev->id.vendor = SERIO_TWIDJOY;
 189         input_dev->id.product = 0x0001;
 190         input_dev->id.version = 0x0100;
 191         input_dev->dev.parent = &serio->dev;
 192 
 193         input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 194         input_set_abs_params(input_dev, ABS_X, -50, 50, 4, 4);
 195         input_set_abs_params(input_dev, ABS_Y, -50, 50, 4, 4);
 196 
 197         for (bp = twidjoy_buttons; bp->bitmask; bp++)
 198                 for (i = 0; i < bp->bitmask; i++)
 199                         set_bit(bp->buttons[i], input_dev->keybit);
 200 
 201         serio_set_drvdata(serio, twidjoy);
 202 
 203         err = serio_open(serio, drv);
 204         if (err)
 205                 goto fail2;
 206 
 207         err = input_register_device(twidjoy->dev);
 208         if (err)
 209                 goto fail3;
 210 
 211         return 0;
 212 
 213  fail3: serio_close(serio);
 214  fail2: serio_set_drvdata(serio, NULL);
 215  fail1: input_free_device(input_dev);
 216         kfree(twidjoy);
 217         return err;
 218 }
 219 
 220 /*
 221  * The serio driver structure.
 222  */
 223 
 224 static const struct serio_device_id twidjoy_serio_ids[] = {
 225         {
 226                 .type   = SERIO_RS232,
 227                 .proto  = SERIO_TWIDJOY,
 228                 .id     = SERIO_ANY,
 229                 .extra  = SERIO_ANY,
 230         },
 231         { 0 }
 232 };
 233 
 234 MODULE_DEVICE_TABLE(serio, twidjoy_serio_ids);
 235 
 236 static struct serio_driver twidjoy_drv = {
 237         .driver         = {
 238                 .name   = "twidjoy",
 239         },
 240         .description    = DRIVER_DESC,
 241         .id_table       = twidjoy_serio_ids,
 242         .interrupt      = twidjoy_interrupt,
 243         .connect        = twidjoy_connect,
 244         .disconnect     = twidjoy_disconnect,
 245 };
 246 
 247 module_serio_driver(twidjoy_drv);