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 56MODULE_DESCRIPTION(DRIVER_DESC); 57MODULE_LICENSE("GPL"); 58 59/* 60 * Constants. 61 */ 62 63#define ZHENHUA_MAX_LENGTH 5 64 65/* 66 * Zhen Hua data. 67 */ 68 69struct 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" */ 78static 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 91static 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 110static 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 138static 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 154static 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 205static 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 215MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids); 216 217static 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/* 229 * The functions for inserting/removing us as a module. 230 */ 231 232static int __init zhenhua_init(void) 233{ 234 return serio_register_driver(&zhenhua_drv); 235} 236 237static void __exit zhenhua_exit(void) 238{ 239 serio_unregister_driver(&zhenhua_drv); 240} 241 242module_init(zhenhua_init); 243module_exit(zhenhua_exit); 244