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/bitrev.h> 51 #include <linux/input.h> 52 #include <linux/serio.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 * zhenhua_process_packet() decodes packets the driver receives from the 78 * RC transmitter. It updates the data accordingly. 79 */ 80 81 static void zhenhua_process_packet(struct zhenhua *zhenhua) 82 { 83 struct input_dev *dev = zhenhua->dev; 84 unsigned char *data = zhenhua->data; 85 86 input_report_abs(dev, ABS_Y, data[1]); 87 input_report_abs(dev, ABS_X, data[2]); 88 input_report_abs(dev, ABS_RZ, data[3]); 89 input_report_abs(dev, ABS_Z, data[4]); 90 91 input_sync(dev); 92 } 93 94 /* 95 * zhenhua_interrupt() is called by the low level driver when characters 96 * are ready for us. We then buffer them for further processing, or call the 97 * packet processing routine. 98 */ 99 100 static irqreturn_t zhenhua_interrupt(struct serio *serio, unsigned char data, unsigned int flags) 101 { 102 struct zhenhua *zhenhua = serio_get_drvdata(serio); 103 104 /* All Zhen Hua packets are 5 bytes. The fact that the first byte 105 * is allways 0xf7 and all others are in range 0x32 - 0xc8 (50-200) 106 * can be used to check and regain sync. */ 107 108 if (data == 0xef) 109 zhenhua->idx = 0; /* this byte starts a new packet */ 110 else if (zhenhua->idx == 0) 111 return IRQ_HANDLED; /* wrong MSB -- ignore this byte */ 112 113 if (zhenhua->idx < ZHENHUA_MAX_LENGTH) 114 zhenhua->data[zhenhua->idx++] = bitrev8(data); 115 116 if (zhenhua->idx == ZHENHUA_MAX_LENGTH) { 117 zhenhua_process_packet(zhenhua); 118 zhenhua->idx = 0; 119 } 120 121 return IRQ_HANDLED; 122 } 123 124 /* 125 * zhenhua_disconnect() is the opposite of zhenhua_connect() 126 */ 127 128 static void zhenhua_disconnect(struct serio *serio) 129 { 130 struct zhenhua *zhenhua = serio_get_drvdata(serio); 131 132 serio_close(serio); 133 serio_set_drvdata(serio, NULL); 134 input_unregister_device(zhenhua->dev); 135 kfree(zhenhua); 136 } 137 138 /* 139 * zhenhua_connect() is the routine that is called when someone adds a 140 * new serio device. It looks for the Twiddler, and if found, registers 141 * it as an input device. 142 */ 143 144 static int zhenhua_connect(struct serio *serio, struct serio_driver *drv) 145 { 146 struct zhenhua *zhenhua; 147 struct input_dev *input_dev; 148 int err = -ENOMEM; 149 150 zhenhua = kzalloc(sizeof(struct zhenhua), GFP_KERNEL); 151 input_dev = input_allocate_device(); 152 if (!zhenhua || !input_dev) 153 goto fail1; 154 155 zhenhua->dev = input_dev; 156 snprintf(zhenhua->phys, sizeof(zhenhua->phys), "%s/input0", serio->phys); 157 158 input_dev->name = "Zhen Hua 5-byte device"; 159 input_dev->phys = zhenhua->phys; 160 input_dev->id.bustype = BUS_RS232; 161 input_dev->id.vendor = SERIO_ZHENHUA; 162 input_dev->id.product = 0x0001; 163 input_dev->id.version = 0x0100; 164 input_dev->dev.parent = &serio->dev; 165 166 input_dev->evbit[0] = BIT(EV_ABS); 167 input_set_abs_params(input_dev, ABS_X, 50, 200, 0, 0); 168 input_set_abs_params(input_dev, ABS_Y, 50, 200, 0, 0); 169 input_set_abs_params(input_dev, ABS_Z, 50, 200, 0, 0); 170 input_set_abs_params(input_dev, ABS_RZ, 50, 200, 0, 0); 171 172 serio_set_drvdata(serio, zhenhua); 173 174 err = serio_open(serio, drv); 175 if (err) 176 goto fail2; 177 178 err = input_register_device(zhenhua->dev); 179 if (err) 180 goto fail3; 181 182 return 0; 183 184 fail3: serio_close(serio); 185 fail2: serio_set_drvdata(serio, NULL); 186 fail1: input_free_device(input_dev); 187 kfree(zhenhua); 188 return err; 189 } 190 191 /* 192 * The serio driver structure. 193 */ 194 195 static const struct serio_device_id zhenhua_serio_ids[] = { 196 { 197 .type = SERIO_RS232, 198 .proto = SERIO_ZHENHUA, 199 .id = SERIO_ANY, 200 .extra = SERIO_ANY, 201 }, 202 { 0 } 203 }; 204 205 MODULE_DEVICE_TABLE(serio, zhenhua_serio_ids); 206 207 static struct serio_driver zhenhua_drv = { 208 .driver = { 209 .name = "zhenhua", 210 }, 211 .description = DRIVER_DESC, 212 .id_table = zhenhua_serio_ids, 213 .interrupt = zhenhua_interrupt, 214 .connect = zhenhua_connect, 215 .disconnect = zhenhua_disconnect, 216 }; 217 218 module_serio_driver(zhenhua_drv); 219