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1.1 root 1: Here are some notes on writing device drivers; before reading
2:
3: them, you should familiarize yourself with the information in
4:
5: "filesys.doc", especially the material on device drivers.
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7:
8:
9: Serial Port Device Drivers
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11:
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13: Serial port device drivers should recognize the
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15: following ioctl calls:
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17: (here "f" is always a FILEPTR referring to an open
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19: file on the device)
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24:
25: ioctl(f, TIOCIBAUD, long *r):
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27:
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29: Set input speed. "r" is a pointer to a 32 bit value, and is both an
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31: input and output parameter. If *r is > 0, it represents the value
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33: to which the serial port's input speed should be set. This value
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35: is a long word representation of the speed in bits per second,
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37: e.g. to set 9600 bits per second *r should be 9600L.
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39: If *r is 0, it indicates that DTR should be dropped.
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41: If *r is < 0, the call is an inquiry call only.
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43:
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45: On return, *r is set to the value of the input speed before the
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47: ioctl call was made. If, for some reason, this value is unknown,
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49: *r is set to -1L.
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51:
52:
53: Returns:
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55: 0 on success
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57: ERANGE if the requested input speed is not available. In this case,
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59: the next lowest legal input speed available is returned in *r.
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67: ioctl(f, TIOCOBAUD, long *r):
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71: Set output speed. "r" is a pointer to a 32 bit value, and is both an
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73: input and output parameter. If *r is > 0, it represents the value
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75: to which the serial port's output speed should be set. This value
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77: is a long word representation of the speed in bits per second,
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79: e.g. to set 9600 bits per second *r should be 9600L.
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81: If *r is 0, it indicates that the device should be hung up, i.e.
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83: that DTR should no longer be asserted.
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85: If *r is < 0, no change is to be made to the output speed.
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87:
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89: On return, *r is set to the value of the output speed before the
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91: ioctl call was made. If, for some reason, this value is unknown,
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93: *r is set to -1L.
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95:
96:
97: Returns:
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99: 0 on success
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101: ERANGE if the requested output speed is not available. In this case,
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103: the next lowest legal output speed available is returned in *r.
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106:
107: Note: For many devices both the input and output speeds must always be
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109: the same. For such devices, TIOCIBAUD and TIOCOBAUD may affect both
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111: input and output speed.
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119: ioctl(f, TIOCSBRK, dummy):
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123: Causes a BREAK condition to be set on the output line.
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125: Returns:
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127: 0 on success
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129: EINVFN if the serial port cannot send BREAK
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131:
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137: ioctl(f, TIOCCBRK, dummy)
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139:
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141: Causes any existing BREAK condition to be cleared.
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143: Returns:
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145: 0 on success
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147: EINVFN if the serial port cannot send BREAK
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155: ioctl(f, TIOCGFLAGS, short *flags)
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157:
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159: Get the terminal control flags bits. 16 bit flag word
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161: pointed to by "flags" is set to reflect the current
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163: terminal state, as follows:
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165:
166:
167: TF_STOPBITS 0x0003
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169: The two low order bits describe the stop bits:
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171: 0x0000 illegal -- attempts to set this value are
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173: ignored
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175: 0x0001 1 stop bit
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177: 0x0002 1.5 stop bits
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179: 0x0003 2 stop bits
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181:
182:
183: TF_CHARBITS 0x000C
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185: The next two bits describe the number of bits
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187: transmitted per character:
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189: 0x0000 8 bits per character
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191: 0x0004 7 bits per character
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193: 0x0008 6 bits per character
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195: 0x000C 5 bits per character
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197:
198:
199: The final nybble contains miscellaneous flags:
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201: T_TANDEM 0x1000 ^S/^Q flow control active
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203: T_RTSCTS 0x2000 RTS/CTS flow control active
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205: T_EVENP 0x4000 even parity enabled
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207: T_ODDP 0x8000 odd parity enabled
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209: (note: T_EVENPAR and T_ODDPAR are mutually exclusive)
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213: All other bits are reserved, and should be set to 0.
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215:
216:
217: Returns:
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219: 0 on success
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226:
227: ioctl(f, TIOCSFLAGS, short *flags)
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229:
230:
231: Set the terminal control flags (see the description
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233: of TIOCGFLAGS for details) based on the values in the
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235: word pointed to by "flags".
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237:
238:
239: Returns:
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241: 0 on success
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243: ERANGE if an illegal or unsupported combination of flags
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245: is detected.
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249:
250:
251: INTERFACE WITH EXISTING TIOCSETP/TIOCGETP CALLS:
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253:
254:
255: The MiNT kernel will automatically make appropriate
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257: TIOCIBAUD, TIOCOBAUD, TIOCGFLAGS, and TIOCSFLAGS calls
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259: whenever a TIOCSETP or TIOCGETP Fcntl is made on a
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261: terminal. The kernel will convert a Unix style baud
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263: specification into a MiNT style one, as follows:
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265:
266:
267: value of sg_ispeed or value sent to
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269: sg_ospeed driver
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271: #define B0 0 0L
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273: #define B50 1 50L
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275: #define B75 2 75L
276:
277: #define B110 3 110L
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279: #define B134 4 134L
280:
281: #define B150 5 150L
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283: #define B200 6 200L
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285: #define B300 7 300L
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287: #define B600 8 600L
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289: #define B1200 9 1200L
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291: #define B1800 10 1800L
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293: #define B2400 11 2400L
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295: #define B4800 12 4800L
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297: #define B9600 13 9600L
298:
299: #define B19200 14 19200L
300:
301: #define B38400 15 38400L (*)
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303:
304:
305: anything else -1L
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307:
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309:
310:
311: (*) 38400 baud is not supported by the built
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313: in device drivers, but may be by external drivers
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315:
316:
317: If a speed other than those listed above is desired, the
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319: TIOCIBAUD and/or TIOCOBAUD Fcntls should be used directly.
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