summaryrefslogtreecommitdiff
path: root/sys/dev/ic/z8530reg.h
blob: 30abf6206b2c22e59effa85186b81f1144bcebf8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
/*	$NetBSD: z8530reg.h,v 1.4 1995/08/20 13:24:05 leo Exp $ */

/*
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Lawrence Berkeley Laboratory.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)zsreg.h	8.1 (Berkeley) 6/11/93
 */

/*
 * Zilog SCC registers, as implemented on the Sun-4c.
 *
 * Each Z8530 implements two channels (called `a' and `b').
 *
 * The damnable chip was designed to fit on Z80 I/O ports, and thus
 * has everything multiplexed out the wazoo.  We have to select
 * a register, then read or write the register, and so on.  Worse,
 * the parameter bits are scattered all over the register space.
 * This thing is full of `miscellaneous' control registers.
 *
 * Worse yet, the registers have incompatible functions on read
 * and write operations.  We describe the registers below according
 * to whether they are `read registers' (RR) or `write registers' (WR).
 * As if this were not enough, some of the channel B status bits show
 * up in channel A, and vice versa.  The blasted thing shares write
 * registers 2 and 9 across both channels, and reads registers 2 and 3
 * differently for the two channels.  We can, however, ignore this much
 * of the time.
 */
#ifndef LOCORE
struct zschan {
#if (BYTE_ORDER == BIG_ENDIAN) && !defined(atari)
	volatile u_char	zc_csr;		/* ctrl,status, and indirect access */
	u_char		zc_xxx0;
	volatile u_char	zc_data;	/* data */
	u_char		zc_xxx1;
#else
	u_char		zc_xxx0;
	volatile u_char	zc_csr;		/* ctrl,status, and indirect access */
    	u_char		zc_xxx1;
    	volatile u_char	zc_data;	/* data */
#endif
};

struct zsdevice {
	struct	zschan zs_chan[2];
};
#endif

/*
 * Some of the names in this files were chosen to make the hsis driver
 * work unchanged (which means that they will match some in SunOS).
 *
 * `S.C.' stands for Special Condition, which is any of these:
 *	receiver overrun	(aka silo overflow)
 *	framing error		(missing stop bit, etc)
 *	end of frame		(in synchronous modes)
 *	parity error		(when `parity error is S.C.' is set)
 */

/*
 * Registers with only a single `numeric value' get a name.
 * Other registers hold bits and are only numbered; the bit
 * definitions imply the register number (see below).
 *
 * We never use the receive and transmit data registers as
 * indirects (choosing instead the zc_data register), so they
 * are not defined here.
 */
#define	ZSRR_IVEC	2	/* interrupt vector (channel 0) */
#define	ZSRR_IPEND	3	/* interrupt pending (ch. 0 only) */
#define	ZSRR_BAUDLO	12	/* baud rate generator (low half) */
#define	ZSRR_BAUDHI	13	/* baud rate generator (high half) */

#define	ZSWR_IVEC	2	/* interrupt vector (shared) */
#define	ZSWR_TXSYNC	6	/* sync transmit char (monosync mode) */
#define	ZSWR_RXSYNC	7	/* sync receive char (monosync mode) */
#define	ZSWR_SYNCLO	6	/* sync low byte (bisync mode) */
#define	ZSWR_SYNCHI	7	/* sync high byte (bisync mode) */
#define	ZSWR_SDLC_ADDR	6	/* SDLC address (SDLC mode) */
#define	ZSWR_SDLC_FLAG	7	/* SDLC flag 0x7E (SDLC mode) */
#define	ZSWR_BAUDLO	12	/* baud rate generator (low half) */
#define	ZSWR_BAUDHI	13	/* baud rate generator (high half) */

/*
 * Registers 0 through 7 may be written with any one of the 8 command
 * modifiers, and/or any one of the 4 reset modifiers, defined below.
 * To write registers 8 through 15, however, the command modifier must
 * always be `point high'.  Rather than track this bizzareness all over
 * the driver, we try to avoid using any modifiers, ever (but they are
 * defined here if you want them).
 */
#define	ZSM_RESET_TXUEOM	0xc0	/* reset xmit underrun / eom latch */
#define	ZSM_RESET_TXCRC		0x80	/* reset xmit crc generator */
#define	ZSM_RESET_RXCRC		0x40	/* reset recv crc checker */
#define	ZSM_NULL		0x00	/* nothing special */

#define	ZSM_RESET_IUS		0x38	/* reset interrupt under service */
#define	ZSM_RESET_ERR		0x30	/* reset error cond */
#define	ZSM_RESET_TXINT		0x28	/* reset xmit interrupt pending */
#define	ZSM_EI_NEXTRXC		0x20	/* enable int. on next rcvd char */
#define	ZSM_SEND_ABORT		0x18	/* send abort (SDLC) */
#define	ZSM_RESET_STINT		0x10	/* reset external/status interrupt */
#define	ZSM_POINTHIGH		0x08	/* `point high' (use r8-r15) */
#define	ZSM_NULL		0x00	/* nothing special */

/*
 * Commands for Write Register 0 (`Command Register').
 * These are just the command modifiers or'ed with register number 0
 * (which of course equals the command modifier).
 */
#define	ZSWR0_RESET_EOM		ZSM_RESET_TXUEOM
#define	ZSWR0_RESET_TXCRC	ZSM_RESET_TXCRC
#define	ZSWR0_RESET_RXCRC	ZSM_RESET_RXCRC
#define	ZSWR0_CLR_INTR		ZSM_RESET_IUS
#define	ZSWR0_RESET_ERRORS	ZSM_RESET_ERR
#define	ZSWR0_EI_NEXTRXC	ZSM_EI_NEXTRXC
#define	ZSWR0_SEND_ABORT	ZSM_SEND_ABORT
#define	ZSWR0_RESET_STATUS	ZSM_RESET_STINT
#define	ZSWR0_RESET_TXINT	ZSM_RESET_TXINT

/*
 * Bits in Write Register 1 (`Transmit/Receive Interrupt and Data
 * Transfer Mode Definition').  Note that bits 3 and 4 are taken together
 * as a single unit, and bits 5 and 6 are useful only if bit 7 is set.
 */
#define	ZSWR1_REQ_WAIT		0x80	/* WAIT*-REQ* pin gives WAIT* */
#define	ZSWR1_REQ_REQ		0xc0	/* WAIT*-REQ* pin gives REQ* */
#define	ZSWR1_REQ_TX		0x00	/* WAIT*-REQ* pin follows xmit buf */
#define	ZSWR1_REQ_RX		0x20	/* WAIT*-REQ* pin follows recv buf */

#define	ZSWR1_RIE_NONE		0x00	/* disable rxint entirely */
#define	ZSWR1_RIE_FIRST		0x08	/* rxint on first char & on S.C. */
#define	ZSWR1_RIE		0x10	/* rxint per char & on S.C. */
#define	ZSWR1_RIE_SPECIAL_ONLY	0x18	/* rxint on S.C. only */

#define	ZSWR1_PE_SC		0x04	/* parity error is special condition */
#define	ZSWR1_TIE		0x02	/* transmit interrupt enable */
#define	ZSWR1_SIE		0x01	/* external/status interrupt enable */

/* HSIS compat */
#define	ZSWR1_REQ_ENABLE	(ZSWR1_REQ_WAIT | ZSWR1_REQ_TX)

/*
 * Bits in Write Register 3 (`Receive Parameters and Control').
 * Bits 7 and 6 are taken as a unit.  Note that the receive bits
 * per character ordering is insane.
 *
 * Here `hardware flow control' means CTS enables the transmitter
 * and DCD enables the receiver.  The latter is neither interesting
 * nor useful, and gets in our way, making it almost unusable.
 */
#define	ZSWR3_RX_5		0x00	/* receive 5 bits per char */
#define	ZSWR3_RX_7		0x40	/* receive 7 bits per char */
#define	ZSWR3_RX_6		0x80	/* receive 6 bits per char */
#define	ZSWR3_RX_8		0xc0	/* receive 8 bits per char */

#define	ZSWR3_HFC		0x20	/* hardware flow control */
#define	ZSWR3_HUNT		0x10	/* enter hunt mode */
#define	ZSWR3_RXCRC_ENABLE	0x08	/* enable recv crc calculation */
#define	ZSWR3_ADDR_SEARCH_MODE	0x04	/* address search mode (SDLC only) */
#define	ZSWR3_SYNC_LOAD_INH	0x02	/* sync character load inhibit */
#define	ZSWR3_RX_ENABLE		0x01	/* receiver enable */

/*
 * Bits in Write Register 4 (`Transmit/Receive Miscellaneous Parameters
 * and Modes').  Bits 7&6, 5&4, and 3&2 are taken as units.
 */
#define	ZSWR4_CLK_X1		0x00	/* clock divisor = 1 */
#define	ZSWR4_CLK_X16		0x40	/* clock divisor = 16 */
#define	ZSWR4_CLK_X32		0x80	/* clock divisor = 32 */
#define	ZSWR4_CLK_X64		0xc0	/* clock divisor = 64 */

#define	ZSWR4_MONOSYNC		0x00	/* 8 bit sync char (sync only) */
#define	ZSWR4_BISYNC		0x10	/* 16 bit sync char (sync only) */
#define	ZSWR4_SDLC		0x20	/* SDLC mode */
#define	ZSWR4_EXTSYNC		0x30	/* external sync mode */

#define	ZSWR4_SYNCMODE		0x00	/* one of the above sync modes */
#define	ZSWR4_ONESB		0x04	/* 1 stop bit */
#define	ZSWR4_1P5SB		0x08	/* 1.5 stop bits (clk cannot be 1x) */
#define	ZSWR4_TWOSB		0x0c	/* 2 stop bits */

#define	ZSWR4_EVENP		0x02	/* check for even parity */
#define	ZSWR4_PARENB		0x01	/* enable parity checking */

/*
 * Bits in Write Register 5 (`Transmit Parameter and Controls').
 * Bits 6 and 5 are taken as a unit; the ordering is, as with RX
 * bits per char, not sensible.
 */
#define	ZSWR5_DTR		0x80	/* assert (set to -12V) DTR */

#define	ZSWR5_TX_5		0x00	/* transmit 5 or fewer bits */
#define	ZSWR5_TX_7		0x20	/* transmit 7 bits */
#define	ZSWR5_TX_6		0x40	/* transmit 6 bits */
#define	ZSWR5_TX_8		0x60	/* transmit 8 bits */

#define	ZSWR5_BREAK		0x10	/* send break (continuous 0s) */
#define	ZSWR5_TX_ENABLE		0x08	/* enable transmitter */
#define	ZSWR5_CRC16		0x04	/* use CRC16 (off => use SDLC) */
#define	ZSWR5_RTS		0x02	/* assert RTS */
#define	ZSWR5_TXCRC_ENABLE	0x01	/* enable xmit crc calculation */

#ifdef not_done_here
/*
 * Bits in Write Register 7 when the chip is in SDLC mode.
 */
#define	ZSWR7_SDLCFLAG		0x7e	/* this value makes SDLC mode work */
#endif

/*
 * Bits in Write Register 9 (`Master Interrupt Control').  Bits 7 & 6
 * are taken as a unit and indicate the type of reset; 00 means no reset
 * (and is not defined here).
 */
#define	ZSWR9_HARD_RESET	0xc0	/* force hardware reset */
#define	ZSWR9_A_RESET		0x80	/* reset channel A (0) */
#define	ZSWR9_B_RESET		0x40	/* reset channel B (1) */
			/*	0x20	   unused */

#define	ZSWR9_STATUS_HIGH	0x10	/* status in high bits of intr vec */
#define	ZSWR9_MASTER_IE		0x08	/* master interrupt enable */
#define	ZSWR9_DLC		0x04	/* disable lower chain */
#define	ZSWR9_NO_VECTOR		0x02	/* no vector */
#define	ZSWR9_VECTOR_INCL_STAT	0x01	/* vector includes status */

/*
 * Bits in Write Register 10 (`Miscellaneous Transmitter/Receiver Control
 * Bits').  Bits 6 & 5 are taken as a unit, and some of the bits are
 * meaningful only in certain modes.  Bleah.
 */
#define	ZSWR10_PRESET_ONES	0x80	/* preset CRC to all 1 (else all 0) */

#define	ZSWR10_NRZ		0x00	/* NRZ encoding */
#define	ZSWR10_NRZI		0x20	/* NRZI encoding */
#define	ZSWR10_FM1		0x40	/* FM1 encoding */
#define	ZSWR10_FM0		0x60	/* FM0 encoding */

#define	ZSWR10_GA_ON_POLL	0x10	/* go active on poll (loop mode) */
#define	ZSWR10_MARK_IDLE	0x08	/* all 1s (vs flag) when idle (SDLC) */
#define	ZSWR10_ABORT_ON_UNDERRUN 0x4	/* abort on xmit underrun (SDLC) */
#define	ZSWR10_LOOP_MODE	0x02	/* loop mode (SDLC) */
#define	ZSWR10_6_BIT_SYNC	0x01	/* 6 bits per sync char (sync modes) */

/*
 * Bits in Write Register 11 (`Clock Mode Control').  Bits 6&5, 4&3, and
 * 1&0 are taken as units.  Various bits depend on other bits in complex
 * ways; see the Zilog manual.
 */
#define	ZSWR11_XTAL		0x80	/* have xtal between RTxC* and SYNC* */
					/* (else have TTL oscil. on RTxC*) */
#define	ZSWR11_RXCLK_RTXC	0x00	/* recv clock taken from TRxC* pin */
#define	ZSWR11_RXCLK_TRXC	0x20	/* recv clock taken from TRxC* pin */
#define	ZSWR11_RXCLK_BAUD	0x40	/* recv clock taken from BRG */
#define	ZSWR11_RXCLK_DPLL	0x60	/* recv clock taken from DPLL */

#define	ZSWR11_TXCLK_RTXC	0x00	/* xmit clock taken from TRxC* pin */
#define	ZSWR11_TXCLK_TRXC	0x08	/* xmit clock taken from RTxC* pin */
#define	ZSWR11_TXCLK_BAUD	0x10	/* xmit clock taken from BRG */
#define	ZSWR11_TXCLK_DPLL	0x18	/* xmit clock taken from DPLL */

#define	ZSWR11_TRXC_OUT_ENA	0x04	/* TRxC* pin will be an output */
					/* (unless it is being used above) */
#define	ZSWR11_TRXC_XTAL	0x00	/* TRxC output from xtal oscillator */
#define	ZSWR11_TRXC_XMIT	0x01	/* TRxC output from xmit clock */
#define	ZSWR11_TRXC_BAUD	0x02	/* TRxC output from BRG */
#define	ZSWR11_TRXC_DPLL	0x03	/* TRxC output from DPLL */

/*
 * Formula for Write Registers 12 and 13 (`Lower Byte of Baud Rate
 * Generator Time Constant' and `Upper Byte of ...').  Inputs:
 *
 *	f	BRG input clock frequency (in Hz) AFTER division
 *		by 1, 16, 32, or 64 (per clock divisor in WR4)
 *	bps	desired rate in bits per second (9600, etc)
 *
 * We want
 *
 *	  f
 *	----- + 0.5 - 2
 *	2 bps
 *
 * rounded down to an integer.  This can be computed entirely
 * in integer arithemtic as:
 *
 *	f + bps
 *	------- - 2
 *	 2 bps
 */
#define	BPS_TO_TCONST(f, bps)	((((f) + (bps)) / (2 * (bps))) - 2)

/* inverse of above: given a BRG Time Constant, return Bits Per Second */
#define	TCONST_TO_BPS(f, tc)	((f) / 2 / ((tc) + 2))

/*
 * Bits in Write Register 14 (`Miscellaneous Control Bits').
 * Bits 7 through 5 are taken as a unit and make up a `DPLL command'.
 */
#define	ZSWR14_DPLL_NOOP	0x00	/* leave DPLL alone */
#define	ZSWR14_DPLL_SEARCH	0x20	/* enter search mode */
#define	ZSWR14_DPLL_RESET_CM	0x40	/* reset `clock missing' in RR10 */
#define	ZSWR14_DPLL_DISABLE	0x60	/* disable DPLL (continuous search) */
#define	ZSWR14_DPLL_SRC_BAUD	0x80	/* set DPLL src = BRG */
#define	ZSWR14_DPLL_SRC_RTXC	0xa0	/* set DPLL src = RTxC* or xtal osc */
#define	ZSWR14_DPLL_FM		0xc0	/* operate in FM mode */
#define	ZSWR14_DPLL_NRZI	0xe0	/* operate in NRZI mode */

#define	ZSWR14_LOCAL_LOOPBACK	0x10	/* set local loopback mode */
#define	ZSWR14_AUTO_ECHO	0x08	/* set auto echo mode */
#define	ZSWR14_DTR_REQ		0x04	/* DTR* / REQ* pin gives REQ* */
#define	ZSWR14_BAUD_FROM_PCLK	0x02	/* BRG clock taken from PCLK */
					/* (else from RTxC* pin or xtal osc) */
#define	ZSWR14_BAUD_ENA		0x01	/* enable BRG countdown */

/*
 * Bits in Write Register 15 (`External/Status Interrupt Control').
 * Most of these cause status interrupts whenever the corresponding
 * bit or pin changes state (i.e., any rising or falling edge).
 */
#define	ZSWR15_BREAK_IE		0x80	/* enable break/abort status int */
#define	ZSWR15_TXUEOM_IE	0x40	/* enable TX underrun/EOM status int */
#define	ZSWR15_CTS_IE		0x20	/* enable CTS* pin status int */
#define	ZSWR15_SYNCHUNT_IE	0x10	/* enable SYNC* pin/hunt status int */
#define	ZSWR15_DCD_IE		0x08	/* enable DCD* pin status int */
			/*	0x04	   unused, must be zero */
#define	ZSWR15_ZERO_COUNT_IE	0x02	/* enable BRG-counter = 0 status int */
			/*	0x01	   unused, must be zero */

/*
 * Bits in Read Register 0 (`Transmit/Receive Buffer Status and External
 * Status').
 */
#define	ZSRR0_BREAK		0x80	/* break/abort detected */
#define	ZSRR0_TXUNDER		0x40	/* transmit underrun/EOM (sync) */
#define	ZSRR0_CTS		0x20	/* clear to send */
#define	ZSRR0_SYNC_HUNT		0x10	/* sync/hunt (sync mode) */
#define	ZSRR0_DCD		0x08	/* data carrier detect */
#define	ZSRR0_TX_READY		0x04	/* transmit buffer empty */
#define	ZSRR0_ZERO_COUNT	0x02	/* zero count in baud clock */
#define	ZSRR0_RX_READY		0x01	/* received character ready */

/*
 * Bits in Read Register 1 (the Zilog book does not name this one).
 */
#define	ZSRR1_EOF		0x80	/* end of frame (SDLC mode) */
#define	ZSRR1_FE		0x40	/* CRC/framing error */
#define	ZSRR1_DO		0x20	/* data (receiver) overrun */
#define	ZSRR1_PE		0x10	/* parity error */
#define	ZSRR1_RC0		0x08	/* residue code 0 (SDLC mode) */
#define	ZSRR1_RC1		0x04	/* residue code 1 (SDLC mode) */
#define	ZSRR1_RC2		0x02	/* residue code 2 (SDLC mode) */
#define	ZSRR1_ALL_SENT		0x01	/* all chars out of xmitter (async) */

/*
 * Read Register 2 in B channel contains status bits if VECTOR_INCL_STAT
 * is set.
 */

/*
 * Bits in Read Register 3 (`Interrupt Pending').  Only channel A
 * has an RR3.
 */
			/*	0x80	   unused, returned as 0 */
			/*	0x40	   unused, returned as 0 */
#define	ZSRR3_IP_A_RX		0x20	/* channel A recv int pending */
#define	ZSRR3_IP_A_TX		0x10	/* channel A xmit int pending */
#define	ZSRR3_IP_A_STAT		0x08	/* channel A status int pending */
#define	ZSRR3_IP_B_RX		0x04	/* channel B recv int pending */
#define	ZSRR3_IP_B_TX		0x02	/* channel B xmit int pending */
#define	ZSRR3_IP_B_STAT		0x01	/* channel B status int pending */

/*
 * Bits in Read Register 10 (`contains some miscellaneous status bits').
 */
#define	ZSRR10_1_CLOCK_MISSING	0x80	/* 1 clock edge missing (FM mode) */
#define	ZSRR10_2_CLOCKS_MISSING	0x40	/* 2 clock edges missing (FM mode) */
			/*	0x20	   unused */
#define	ZSRR10_LOOP_SENDING	0x10	/* xmitter controls loop (SDLC loop) */
			/*	0x08	   unused */
			/*	0x04	   unused */
#define	ZSRR10_ON_LOOP		0x02	/* SCC is on loop (SDLC/X.21 modes) */

/*
 * Bits in Read Register 15.  This register is one of the few that
 * simply reads back the corresponding Write Register.
 */
#define	ZSRR15_BREAK_IE		0x80	/* break/abort status int enable */
#define	ZSRR15_TXUEOM_IE	0x40	/* TX underrun/EOM status int enable */
#define	ZSRR15_CTS_IE		0x20	/* CTS* pin status int enable */
#define	ZSRR15_SYNCHUNT_IE	0x10	/* SYNC* pin/hunt status int enable */
#define	ZSRR15_DCD_IE		0x08	/* DCD* pin status int enable */
			/*	0x04	   unused, returned as zero */
#define	ZSRR15_ZERO_COUNT_IE	0x02	/* BRG-counter = 0 status int enable */
			/*	0x01	   unused, returned as zero */