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); 228