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Linux/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/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 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 

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