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