drivers/usb/serial/ch341.c

   1 /*
   2  * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
   3  *
   4  * ch341.c implements a serial port driver for the Winchiphead CH341.
   5  *
   6  * The CH341 device can be used to implement an RS232 asynchronous
   7  * serial port, an IEEE-1284 parallel printer port or a memory-like
   8  * interface. In all cases the CH341 supports an I2C interface as well.
   9  * This driver only supports the asynchronous serial interface.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License version
  13  * 2 as published by the Free Software Foundation.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/tty.h>
  19 #include <linux/module.h>
  20 #include <linux/usb.h>
  21 #include <linux/usb/serial.h>
  22 #include <linux/serial.h>
  23
  24 #define DEFAULT_BAUD_RATE 2400
  25 #define DEFAULT_TIMEOUT   1000
  26
  27 static int debug;
  28
  29 static struct usb_device_id id_table [] = {
  30         { USB_DEVICE(0x4348, 0x5523) },
  31         { USB_DEVICE(0x1a86, 0x7523) },
  32         { },
  33 };
  34 MODULE_DEVICE_TABLE(usb, id_table);
  35
  36 struct ch341_private {
  37         unsigned baud_rate;
  38         u8 dtr;
  39         u8 rts;
  40 };
  41
  42 static int ch341_control_out(struct usb_device *dev, u8 request,
  43                              u16 value, u16 index)
  44 {
  45         int r;
  46         dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
  47                 (int)request, (int)value, (int)index);
  48
  49         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
  50                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
  51                             value, index, NULL, 0, DEFAULT_TIMEOUT);
  52
  53         return r;
  54 }
  55
  56 static int ch341_control_in(struct usb_device *dev,
  57                             u8 request, u16 value, u16 index,
  58                             char *buf, unsigned bufsize)
  59 {
  60         int r;
  61         dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
  62                 (int)request, (int)value, (int)index, buf, (int)bufsize);
  63
  64         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
  65                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
  66                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
  67         return r;
  68 }
  69
  70 static int ch341_set_baudrate(struct usb_device *dev,
  71                               struct ch341_private *priv)
  72 {
  73         short a, b;
  74         int r;
  75
  76         dbg("ch341_set_baudrate(%d)", priv->baud_rate);
  77         switch (priv->baud_rate) {
  78         case 2400:
  79                 a = 0xd901;
  80                 b = 0x0038;
  81                 break;
  82         case 4800:
  83                 a = 0x6402;
  84                 b = 0x001f;
  85                 break;
  86         case 9600:
  87                 a = 0xb202;
  88                 b = 0x0013;
  89                 break;
  90         case 19200:
  91                 a = 0xd902;
  92                 b = 0x000d;
  93                 break;
  94         case 38400:
  95                 a = 0x6403;
  96                 b = 0x000a;
  97                 break;
  98         case 115200:
  99                 a = 0xcc03;
 100                 b = 0x0008;
 101                 break;
 102         default:
 103                 return -EINVAL;
 104         }
 105
 106         r = ch341_control_out(dev, 0x9a, 0x1312, a);
 107         if (!r)
 108                 r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
 109
 110         return r;
 111 }
 112
 113 static int ch341_set_handshake(struct usb_device *dev,
 114                                struct ch341_private *priv)
 115 {
 116         dbg("ch341_set_handshake(%d,%d)", priv->dtr, priv->rts);
 117         return ch341_control_out(dev, 0xa4,
 118                 ~((priv->dtr?1<<5:0)|(priv->rts?1<<6:0)), 0);
 119 }
 120
 121 static int ch341_get_status(struct usb_device *dev)
 122 {
 123         char *buffer;
 124         int r;
 125         const unsigned size = 8;
 126
 127         dbg("ch341_get_status()");
 128
 129         buffer = kmalloc(size, GFP_KERNEL);
 130         if (!buffer)
 131                 return -ENOMEM;
 132
 133         r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
 134         if (r < 0)
 135                 goto out;
 136
 137         /* Not having the datasheet for the CH341, we ignore the bytes returned
 138          * from the device. Return error if the device did not respond in time.
 139          */
 140         r = 0;
 141
 142 out:    kfree(buffer);
 143         return r;
 144 }
 145
 146 /* -------------------------------------------------------------------------- */
 147
 148 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 149 {
 150         char *buffer;
 151         int r;
 152         const unsigned size = 8;
 153
 154         dbg("ch341_configure()");
 155
 156         buffer = kmalloc(size, GFP_KERNEL);
 157         if (!buffer)
 158                 return -ENOMEM;
 159
 160         /* expect two bytes 0x27 0x00 */
 161         r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
 162         if (r < 0)
 163                 goto out;
 164
 165         r = ch341_control_out(dev, 0xa1, 0, 0);
 166         if (r < 0)
 167                 goto out;
 168
 169         r = ch341_set_baudrate(dev, priv);
 170         if (r < 0)
 171                 goto out;
 172
 173         /* expect two bytes 0x56 0x00 */
 174         r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
 175         if (r < 0)
 176                 goto out;
 177
 178         r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
 179         if (r < 0)
 180                 goto out;
 181
 182         /* expect 0xff 0xee */
 183         r = ch341_get_status(dev);
 184         if (r < 0)
 185                 goto out;
 186
 187         r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
 188         if (r < 0)
 189                 goto out;
 190
 191         r = ch341_set_baudrate(dev, priv);
 192         if (r < 0)
 193                 goto out;
 194
 195         r = ch341_set_handshake(dev, priv);
 196         if (r < 0)
 197                 goto out;
 198
 199         /* expect 0x9f 0xee */
 200         r = ch341_get_status(dev);
 201
 202 out:    kfree(buffer);
 203         return r;
 204 }
 205
 206 /* allocate private data */
 207 static int ch341_attach(struct usb_serial *serial)
 208 {
 209         struct ch341_private *priv;
 210         int r;
 211
 212         dbg("ch341_attach()");
 213
 214         /* private data */
 215         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 216         if (!priv)
 217                 return -ENOMEM;
 218
 219         priv->baud_rate = DEFAULT_BAUD_RATE;
 220         priv->dtr = 1;
 221         priv->rts = 1;
 222
 223         r = ch341_configure(serial->dev, priv);
 224         if (r < 0)
 225                 goto error;
 226
 227         usb_set_serial_port_data(serial->port[0], priv);
 228         return 0;
 229
 230 error:  kfree(priv);
 231         return r;
 232 }
 233
 234 /* open this device, set default parameters */
 235 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port,
 236                                 struct file *filp)
 237 {
 238         struct usb_serial *serial = port->serial;
 239         struct ch341_private *priv = usb_get_serial_port_data(serial->port[0]);
 240         int r;
 241
 242         dbg("ch341_open()");
 243
 244         priv->baud_rate = DEFAULT_BAUD_RATE;
 245         priv->dtr = 1;
 246         priv->rts = 1;
 247
 248         r = ch341_configure(serial->dev, priv);
 249         if (r)
 250                 goto out;
 251
 252         r = ch341_set_handshake(serial->dev, priv);
 253         if (r)
 254                 goto out;
 255
 256         r = ch341_set_baudrate(serial->dev, priv);
 257         if (r)
 258                 goto out;
 259
 260         r = usb_serial_generic_open(tty, port, filp);
 261
 262 out:    return r;
 263 }
 264
 265 /* Old_termios contains the original termios settings and
 266  * tty->termios contains the new setting to be used.
 267  */
 268 static void ch341_set_termios(struct tty_struct *tty,
 269                 struct usb_serial_port *port, struct ktermios *old_termios)
 270 {
 271         struct ch341_private *priv = usb_get_serial_port_data(port);
 272         unsigned baud_rate;
 273
 274         dbg("ch341_set_termios()");
 275
 276         baud_rate = tty_get_baud_rate(tty);
 277
 278         switch (baud_rate) {
 279         case 2400:
 280         case 4800:
 281         case 9600:
 282         case 19200:
 283         case 38400:
 284         case 115200:
 285                 priv->baud_rate = baud_rate;
 286                 break;
 287         default:
 288                 dbg("Rate %d not supported, using %d",
 289                         baud_rate, DEFAULT_BAUD_RATE);
 290                 priv->baud_rate = DEFAULT_BAUD_RATE;
 291         }
 292
 293         ch341_set_baudrate(port->serial->dev, priv);
 294
 295         /* Unimplemented:
 296          * (cflag & CSIZE) : data bits [5, 8]
 297          * (cflag & PARENB) : parity {NONE, EVEN, ODD}
 298          * (cflag & CSTOPB) : stop bits [1, 2]
 299          */
 300
 301          /* Copy back the old hardware settings */
 302          tty_termios_copy_hw(tty->termios, old_termios);
 303          /* And re-encode with the new baud */
 304          tty_encode_baud_rate(tty, baud_rate, baud_rate);
 305 }
 306
 307 static struct usb_driver ch341_driver = {
 308         .name           = "ch341",
 309         .probe          = usb_serial_probe,
 310         .disconnect     = usb_serial_disconnect,
 311         .id_table       = id_table,
 312         .no_dynamic_id  = 1,
 313 };
 314
 315 static struct usb_serial_driver ch341_device = {
 316         .driver = {
 317                 .owner  = THIS_MODULE,
 318                 .name   = "ch341-uart",
 319         },
 320         .id_table         = id_table,
 321         .usb_driver       = &ch341_driver,
 322         .num_ports        = 1,
 323         .open             = ch341_open,
 324         .set_termios      = ch341_set_termios,
 325         .attach           = ch341_attach,
 326 };
 327
 328 static int __init ch341_init(void)
 329 {
 330         int retval;
 331
 332         retval = usb_serial_register(&ch341_device);
 333         if (retval)
 334                 return retval;
 335         retval = usb_register(&ch341_driver);
 336         if (retval)
 337                 usb_serial_deregister(&ch341_device);
 338         return retval;
 339 }
 340
 341 static void __exit ch341_exit(void)
 342 {
 343         usb_deregister(&ch341_driver);
 344         usb_serial_deregister(&ch341_device);
 345 }
 346
 347 module_init(ch341_init);
 348 module_exit(ch341_exit);
 349 MODULE_LICENSE("GPL");
 350
 351 module_param(debug, bool, S_IRUGO | S_IWUSR);
 352 MODULE_PARM_DESC(debug, "Debug enabled or not");
 353
 354 /* EOF ch341.c */