1 /*        $NetBSD: z8530reg.h,v 1.13 2022/05/24 20:50:19 andvar Exp $ */
2 
3 /*
4  * Copyright (c) 1992, 1993
5  *        The Regents of the University of California.  All rights reserved.
6  *
7  * This software was developed by the Computer Systems Engineering group
8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9  * contributed to Berkeley.
10  *
11  * All advertising materials mentioning features or use of this software
12  * must display the following acknowledgement:
13  *        This product includes software developed by the University of
14  *        California, Lawrence Berkeley Laboratory.
15  *
16  * Redistribution and use in source and binary forms, with or without
17  * modification, are permitted provided that the following conditions
18  * are met:
19  * 1. Redistributions of source code must retain the above copyright
20  *    notice, this list of conditions and the following disclaimer.
21  * 2. Redistributions in binary form must reproduce the above copyright
22  *    notice, this list of conditions and the following disclaimer in the
23  *    documentation and/or other materials provided with the distribution.
24  * 3. Neither the name of the University nor the names of its contributors
25  *    may be used to endorse or promote products derived from this software
26  *    without specific prior written permission.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38  * SUCH DAMAGE.
39  *
40  *        @(#)zsreg.h         8.1 (Berkeley) 6/11/93
41  */
42 
43 /*
44  * Zilog SCC registers, as implemented on the Sun-4c.
45  *
46  * Each Z8530 implements two channels (called `a' and `b').
47  *
48  * The damnable chip was designed to fit on Z80 I/O ports, and thus
49  * has everything multiplexed out the wazoo.  We have to select
50  * a register, then read or write the register, and so on.  Worse,
51  * the parameter bits are scattered all over the register space.
52  * This thing is full of `miscellaneous' control registers.
53  *
54  * Worse yet, the registers have incompatible functions on read
55  * and write operations.  We describe the registers below according
56  * to whether they are `read registers' (RR) or `write registers' (WR).
57  * As if this were not enough, some of the channel B status bits show
58  * up in channel A, and vice versa.  The blasted thing shares write
59  * registers 2 and 9 across both channels, and reads registers 2 and 3
60  * differently for the two channels.  We can, however, ignore this much
61  * of the time.
62  *
63  * This file also includes flags for the Z85C30 and Z85230 enhanced scc.
64  * The CMOS 8530 includes extra SDLC functionality, and is used in a
65  * number of Macs (often in the Z85C80, an 85C30 combined w/ a SCSI
66  * controller). -wrs
67  *
68  * Some of the names in this files were chosen to make the hsis driver
69  * work unchanged (which means that they will match some in SunOS).
70  *
71  * `S.C.' stands for Special Condition, which is any of these:
72  *        receiver overrun    (aka silo overflow)
73  *        framing error                 (missing stop bit, etc)
74  *        end of frame                  (in synchronous modes)
75  *        parity error                  (when `parity error is S.C.' is set)
76  *
77  * Registers with only a single `numeric value' get a name.
78  * Other registers hold bits and are only numbered; the bit
79  * definitions imply the register number (see below).
80  *
81  * We never use the receive and transmit data registers as
82  * indirects (choosing instead the zc_data register), so they
83  * are not defined here.
84  */
85 #define   ZSRR_IVEC 2         /* interrupt vector (channel 0) */
86 #define   ZSRR_IPEND          3         /* interrupt pending (ch. 0 only) */
87 #define   ZSRR_TXSYNC         6         /* sync transmit char (monosync mode) */
88 #define   ZSRR_RXSYNC         7         /* sync receive char (monosync mode) */
89 #define   ZSRR_SYNCLO         6         /* sync low byte (bisync mode) */
90 #define   ZSRR_SYNCHI         7         /* sync high byte (bisync mode) */
91 #define   ZSRR_SDLC_ADDR      6         /* SDLC address (SDLC mode) */
92 #define   ZSRR_SDLC_FLAG      7         /* SDLC flag 0x7E (SDLC mode) */
93 #define   ZSRR_BAUDLO         12        /* baud rate generator (low half) */
94 #define   ZSRR_BAUDHI         13        /* baud rate generator (high half) */
95 #define   ZSRR_ENHANCED       14        /* read address of WR7' - yes, it's not 7!*/
96 
97 #define   ZSWR_IVEC 2         /* interrupt vector (shared) */
98 #define   ZSWR_TXSYNC         6         /* sync transmit char (monosync mode) */
99 #define   ZSWR_RXSYNC         7         /* sync receive char (monosync mode) */
100 #define   ZSWR_SYNCLO         6         /* sync low byte (bisync mode) */
101 #define   ZSWR_SYNCHI         7         /* sync high byte (bisync mode) */
102 #define   ZSWR_SDLC_ADDR      6         /* SDLC address (SDLC mode) */
103 #define   ZSWR_SDLC_FLAG      7         /* SDLC flag 0x7E (SDLC mode) */
104 #define   ZSWR_BAUDLO         12        /* baud rate generator (low half) */
105 #define   ZSWR_BAUDHI         13        /* baud rate generator (high half) */
106 #define   ZSWR_ENHANCED       7         /* write address of WR7' */
107 
108 /*
109  * Registers 0 through 7 may be written with any one of the 8 command
110  * modifiers, and/or any one of the 4 reset modifiers, defined below.
111  * To write registers 8 through 15, however, the command modifier must
112  * always be `point high'.  Rather than track this bizzareness all over
113  * the driver, we try to avoid using any modifiers, ever (but they are
114  * defined here if you want them).
115  */
116 #define   ZSM_RESET_TXUEOM    0xc0      /* reset xmit underrun / eom latch */
117 #define   ZSM_RESET_TXCRC               0x80      /* reset xmit crc generator */
118 #define   ZSM_RESET_RXCRC               0x40      /* reset recv crc checker */
119 #define   ZSM_NULL            0x00      /* nothing special */
120 
121 #define   ZSM_RESET_IUS                 0x38      /* reset interrupt under service */
122 #define   ZSM_RESET_ERR                 0x30      /* reset error cond */
123 #define   ZSM_RESET_TXINT               0x28      /* reset xmit interrupt pending */
124 #define   ZSM_EI_NEXTRXC                0x20      /* enable int. on next rcvd char */
125 #define   ZSM_SEND_ABORT                0x18      /* send abort (SDLC) */
126 #define   ZSM_RESET_STINT               0x10      /* reset external/status interrupt */
127 #define   ZSM_POINTHIGH                 0x08      /* `point high' (use r8-r15) */
128 #define   ZSM_NULL            0x00      /* nothing special */
129 
130 /*
131  * Commands for Write Register 0 (`Command Register').
132  * These are just the command modifiers or'ed with register number 0
133  * (which of course equals the command modifier).
134  */
135 #define   ZSWR0_RESET_EOM               ZSM_RESET_TXUEOM
136 #define   ZSWR0_RESET_TXCRC   ZSM_RESET_TXCRC
137 #define   ZSWR0_RESET_RXCRC   ZSM_RESET_RXCRC
138 #define   ZSWR0_CLR_INTR                ZSM_RESET_IUS
139 #define   ZSWR0_RESET_ERRORS  ZSM_RESET_ERR
140 #define   ZSWR0_EI_NEXTRXC    ZSM_EI_NEXTRXC
141 #define   ZSWR0_SEND_ABORT    ZSM_SEND_ABORT
142 #define   ZSWR0_RESET_STATUS  ZSM_RESET_STINT
143 #define   ZSWR0_RESET_TXINT   ZSM_RESET_TXINT
144 
145 /*
146  * Bits in Write Register 1 (`Transmit/Receive Interrupt and Data
147  * Transfer Mode Definition').  Note that bits 3 and 4 are taken together
148  * as a single unit, and bits 5 and 6 are useful only if bit 7 is set.
149  */
150 #define   ZSWR1_REQ_WAIT                0x80      /* WAIT*-REQ* pin gives WAIT* */
151 #define   ZSWR1_REQ_REQ                 0xc0      /* WAIT*-REQ* pin gives REQ* */
152 #define   ZSWR1_REQ_TX                  0x00      /* WAIT*-REQ* pin follows xmit buf */
153 #define   ZSWR1_REQ_RX                  0x20      /* WAIT*-REQ* pin follows recv buf */
154 
155 #define   ZSWR1_RIE_NONE                0x00      /* disable rxint entirely */
156 #define   ZSWR1_RIE_FIRST               0x08      /* rxint on first char & on S.C. */
157 #define   ZSWR1_RIE           0x10      /* rxint per char & on S.C. */
158 #define   ZSWR1_RIE_SPECIAL_ONLY        0x18      /* rxint on S.C. only */
159 
160 #define   ZSWR1_PE_SC                   0x04      /* parity error is special condition */
161 #define   ZSWR1_TIE           0x02      /* transmit interrupt enable */
162 #define   ZSWR1_SIE           0x01      /* external/status interrupt enable */
163 
164 #define   ZSWR1_IMASK         0x1F      /* mask of all itr. enable bits. */
165 
166 /* HSIS compat */
167 #define   ZSWR1_REQ_ENABLE    (ZSWR1_REQ_WAIT | ZSWR1_REQ_TX)
168 
169 /*
170  * Bits in Write Register 3 (`Receive Parameters and Control').
171  * Bits 7 and 6 are taken as a unit.  Note that the receive bits
172  * per character ordering is insane.
173  *
174  * Here `hardware flow control' means CTS enables the transmitter
175  * and DCD enables the receiver.  The latter is neither interesting
176  * nor useful, and gets in our way, making it almost unusable.
177  */
178 #define   ZSWR3_RX_5                    0x00      /* receive 5 bits per char */
179 #define   ZSWR3_RX_7                    0x40      /* receive 7 bits per char */
180 #define   ZSWR3_RX_6                    0x80      /* receive 6 bits per char */
181 #define   ZSWR3_RX_8                    0xc0      /* receive 8 bits per char */
182 #define   ZSWR3_RXSIZE                  0xc0      /* receive char size mask */
183 
184 #define   ZSWR3_HFC           0x20      /* hardware flow control */
185 #define   ZSWR3_HUNT                    0x10      /* enter hunt mode */
186 #define   ZSWR3_RXCRC_ENABLE  0x08      /* enable recv crc calculation */
187 #define   ZSWR3_ADDR_SEARCH_MODE        0x04      /* address search mode (SDLC only) */
188 #define   ZSWR3_SDLC_SHORT_ADDR         0x02      /* short address mode (SDLC only) */
189 #define   ZSWR3_SYNC_LOAD_INH 0x02      /* sync character load inhibit */
190 #define   ZSWR3_RX_ENABLE               0x01      /* receiver enable */
191 
192 /*
193  * Bits in Write Register 4 (`Transmit/Receive Miscellaneous Parameters
194  * and Modes').  Bits 7&6, 5&4, and 3&2 are taken as units.
195  */
196 #define   ZSWR4_CLK_X1                  0x00      /* clock divisor = 1 */
197 #define   ZSWR4_CLK_X16                 0x40      /* clock divisor = 16 */
198 #define   ZSWR4_CLK_X32                 0x80      /* clock divisor = 32 */
199 #define   ZSWR4_CLK_X64                 0xc0      /* clock divisor = 64 */
200 #define   ZSWR4_CLK_MASK                0xc0      /* clock divisor mask */
201 
202 #define   ZSWR4_MONOSYNC                0x00      /* 8 bit sync char (sync only) */
203 #define   ZSWR4_BISYNC                  0x10      /* 16 bit sync char (sync only) */
204 #define   ZSWR4_SDLC                    0x20      /* SDLC mode */
205 #define   ZSWR4_EXTSYNC                 0x30      /* external sync mode */
206 #define   ZSWR4_SYNC_MASK               0x30      /* sync mode bit mask */
207 
208 #define   ZSWR4_SYNCMODE                0x00      /* no stop bit (sync mode only) */
209 #define   ZSWR4_ONESB                   0x04      /* 1 stop bit */
210 #define   ZSWR4_1P5SB                   0x08      /* 1.5 stop bits (clk cannot be 1x) */
211 #define   ZSWR4_TWOSB                   0x0c      /* 2 stop bits */
212 #define   ZSWR4_SBMASK                  0x0c      /* mask of all stop bits */
213 
214 #define   ZSWR4_EVENP                   0x02      /* check for even parity */
215 #define   ZSWR4_PARENB                  0x01      /* enable parity checking */
216 #define   ZSWR4_PARMASK                 0x03      /* mask of all parity bits */
217 
218 /*
219  * Bits in Write Register 5 (`Transmit Parameter and Controls').
220  * Bits 6 and 5 are taken as a unit; the ordering is, as with RX
221  * bits per char, not sensible.
222  */
223 #define   ZSWR5_DTR           0x80      /* assert (set to -12V) DTR */
224 
225 #define   ZSWR5_TX_5                    0x00      /* transmit 5 or fewer bits */
226 #define   ZSWR5_TX_7                    0x20      /* transmit 7 bits */
227 #define   ZSWR5_TX_6                    0x40      /* transmit 6 bits */
228 #define   ZSWR5_TX_8                    0x60      /* transmit 8 bits */
229 #define   ZSWR5_TXSIZE                  0x60      /* transmit char size mask */
230 
231 #define   ZSWR5_BREAK                   0x10      /* send break (continuous 0s) */
232 #define   ZSWR5_TX_ENABLE               0x08      /* enable transmitter */
233 #define   ZSWR5_CRC16                   0x04      /* use CRC16 (off => use SDLC) */
234 #define   ZSWR5_RTS           0x02      /* assert RTS */
235 #define   ZSWR5_TXCRC_ENABLE  0x01      /* enable xmit crc calculation */
236 
237 #ifdef not_done_here
238 /*
239  * Bits in Write Register 7 when the chip is in SDLC mode.
240  */
241 #define   ZSWR7_SDLCFLAG                0x7e      /* this value makes SDLC mode work */
242 #endif
243 
244 /*
245  * Bits in Write Register 7' (ZSWR_ENHANCED above). This register is
246  * only available on the 85230. Despite the fact it contains flags
247  * and not a single value, the register was named as it is read
248  * via RR14. Weird.
249  */
250                               /*        0x80      unused */
251 #define   ZSWR7P_EXTEND_READ  0x40      /* modify read map; make most regs readable */
252 #define   ZSWR7P_TX_FIFO                0x20      /* change level for Tx FIFO empty int */
253 #define   ZSWR7P_DTR_TIME               0x10      /* modifies deact. speed of /DTR//REQ */
254 #define   ZSWR7P_RX_FIFO                0x08      /* Rx FIFO int on 1/2 full? */
255 #define   ZSWR7P_RTS_DEACT    0x04      /* automatically deassert RTS */
256 #define   ZSWR7P_AUTO_EOM_RESET         0x02      /* automatically reset EMO/Tx Underrun */
257 #define   ZSWR7P_AUTO_TX_FLAG 0x01      /* Auto send SDLC flag at transmit start */
258 
259 /*
260  * Bits in Write Register 9 (`Master Interrupt Control').  Bits 7 & 6
261  * are taken as a unit and indicate the type of reset; 00 means no reset
262  * (and is not defined here).
263  */
264 #define   ZSWR9_HARD_RESET    0xc0      /* force hardware reset */
265 #define   ZSWR9_A_RESET                 0x80      /* reset channel A (0) */
266 #define   ZSWR9_B_RESET                 0x40      /* reset channel B (1) */
267 #define   ZSWR9_SOFT_INTAC    0x20      /* Not in NMOS version */
268 
269 #define   ZSWR9_STATUS_HIGH   0x10      /* status in high bits of intr vec */
270 #define   ZSWR9_MASTER_IE               0x08      /* master interrupt enable */
271 #define   ZSWR9_DLC           0x04      /* disable lower chain */
272 #define   ZSWR9_NO_VECTOR               0x02      /* no vector */
273 #define   ZSWR9_VECTOR_INCL_STAT        0x01      /* vector includes status */
274 
275 /*
276  * Bits in Write Register 10 (`Miscellaneous Transmitter/Receiver Control
277  * Bits').  Bits 6 & 5 are taken as a unit, and some of the bits are
278  * meaningful only in certain modes.  Bleah.
279  */
280 #define   ZSWR10_PRESET_ONES  0x80      /* preset CRC to all 1 (else all 0) */
281 
282 #define   ZSWR10_NRZ                    0x00      /* NRZ encoding */
283 #define   ZSWR10_NRZI                   0x20      /* NRZI encoding */
284 #define   ZSWR10_FM1                    0x40      /* FM1 encoding */
285 #define   ZSWR10_FM0                    0x60      /* FM0 encoding */
286 
287 #define   ZSWR10_GA_ON_POLL   0x10      /* go active on poll (loop mode) */
288 #define   ZSWR10_MARK_IDLE    0x08      /* all 1s (vs flag) when idle (SDLC) */
289 #define   ZSWR10_ABORT_ON_UNDERRUN 0x4  /* abort on xmit underrun (SDLC) */
290 #define   ZSWR10_LOOP_MODE    0x02      /* loop mode (SDLC) */
291 #define   ZSWR10_6_BIT_SYNC   0x01      /* 6 bits per sync char (sync modes) */
292 
293 /*
294  * Bits in Write Register 11 (`Clock Mode Control').  Bits 6&5, 4&3, and
295  * 1&0 are taken as units.  Various bits depend on other bits in complex
296  * ways; see the Zilog manual.
297  */
298 #define   ZSWR11_XTAL                   0x80      /* have xtal between RTxC* and SYNC* */
299                                                   /* (else have TTL oscil. on RTxC*) */
300 #define   ZSWR11_RXCLK_RTXC   0x00      /* recv clock taken from RTxC* pin */
301 #define   ZSWR11_RXCLK_TRXC   0x20      /* recv clock taken from TRxC* pin */
302 #define   ZSWR11_RXCLK_BAUD   0x40      /* recv clock taken from BRG */
303 #define   ZSWR11_RXCLK_DPLL   0x60      /* recv clock taken from DPLL */
304 
305 #define   ZSWR11_TXCLK_RTXC   0x00      /* xmit clock taken from RTxC* pin */
306 #define   ZSWR11_TXCLK_TRXC   0x08      /* xmit clock taken from TRxC* pin */
307 #define   ZSWR11_TXCLK_BAUD   0x10      /* xmit clock taken from BRG */
308 #define   ZSWR11_TXCLK_DPLL   0x18      /* xmit clock taken from DPLL */
309 
310 #define   ZSWR11_TRXC_OUT_ENA 0x04      /* TRxC* pin will be an output */
311                                                   /* (unless it is being used above) */
312 #define   ZSWR11_TRXC_XTAL    0x00      /* TRxC output from xtal oscillator */
313 #define   ZSWR11_TRXC_XMIT    0x01      /* TRxC output from xmit clock */
314 #define   ZSWR11_TRXC_BAUD    0x02      /* TRxC output from BRG */
315 #define   ZSWR11_TRXC_DPLL    0x03      /* TRxC output from DPLL */
316 
317 /*
318  * Formula for Write Registers 12 and 13 (`Lower Byte of Baud Rate
319  * Generator Time Constant' and `Upper Byte of ...').  Inputs:
320  *
321  *        f         BRG input clock frequency (in Hz) AFTER division
322  *                  by 1, 16, 32, or 64 (per clock divisor in WR4)
323  *        bps       desired rate in bits per second (9600, etc)
324  *
325  * We want
326  *
327  *          f
328  *        ----- + 0.5 - 2
329  *        2 bps
330  *
331  * rounded down to an integer.  This can be computed entirely
332  * in integer arithmetic as:
333  *
334  *        f + bps
335  *        ------- - 2
336  *         2 bps
337  */
338 #define   BPS_TO_TCONST(f, bps)         ((((f) + (bps)) / (2 * (bps))) - 2)
339 
340 /* inverse of above: given a BRG Time Constant, return Bits Per Second */
341 #define   TCONST_TO_BPS(f, tc)          ((f) / 2 / ((tc) + 2))
342 
343 /*
344  * Bits in Write Register 14 (`Miscellaneous Control Bits').
345  * Bits 7 through 5 are taken as a unit and make up a `DPLL command'.
346  */
347 #define   ZSWR14_DPLL_NOOP    0x00      /* leave DPLL alone */
348 #define   ZSWR14_DPLL_SEARCH  0x20      /* enter search mode */
349 #define   ZSWR14_DPLL_RESET_CM          0x40      /* reset `clock missing' in RR10 */
350 #define   ZSWR14_DPLL_DISABLE 0x60      /* disable DPLL (continuous search) */
351 #define   ZSWR14_DPLL_SRC_BAUD          0x80      /* set DPLL src = BRG */
352 #define   ZSWR14_DPLL_SRC_RTXC          0xa0      /* set DPLL src = RTxC* or xtal osc */
353 #define   ZSWR14_DPLL_FM                0xc0      /* operate in FM mode */
354 #define   ZSWR14_DPLL_NRZI    0xe0      /* operate in NRZI mode */
355 
356 #define   ZSWR14_LOCAL_LOOPBACK         0x10      /* set local loopback mode */
357 #define   ZSWR14_AUTO_ECHO    0x08      /* set auto echo mode */
358 #define   ZSWR14_DTR_REQ                0x04      /* DTR* / REQ* pin gives REQ* */
359 #define   ZSWR14_BAUD_FROM_PCLK         0x02      /* BRG clock taken from PCLK */
360                                                   /* (else from RTxC* pin or xtal osc) */
361 #define   ZSWR14_BAUD_ENA               0x01      /* enable BRG countdown */
362 
363 /*
364  * Bits in Write Register 15 (`External/Status Interrupt Control').
365  * Most of these cause status interrupts whenever the corresponding
366  * bit or pin changes state (i.e., any rising or falling edge).
367  *
368  * NOTE: ZSWR15_SDLC_FIFO & ZSWR15_ENABLE_ENHANCED should not be
369  * set on an NMOS 8530. Also, ZSWR15_ENABLE_ENHANCED is only
370  * available on the 85230.
371  */
372 #define   ZSWR15_BREAK_IE               0x80      /* enable break/abort status int */
373 #define   ZSWR15_TXUEOM_IE    0x40      /* enable TX underrun/EOM status int */
374 #define   ZSWR15_CTS_IE                 0x20      /* enable CTS* pin status int */
375 #define   ZSWR15_SYNCHUNT_IE  0x10      /* enable SYNC* pin/hunt status int */
376 #define   ZSWR15_DCD_IE                 0x08      /* enable DCD* pin status int */
377 #define   ZSWR15_SDLC_FIFO    0x04      /* enable SDLC FIFO enhancements */
378 #define   ZSWR15_ZERO_COUNT_IE          0x02      /* enable BRG-counter = 0 status int */
379 #define   ZSWR15_ENABLE_ENHANCED        0x01      /* enable writing WR7' at reg 7 */
380 
381 /*
382  * Bits in Read Register 0 (`Transmit/Receive Buffer Status and External
383  * Status').
384  */
385 #define   ZSRR0_BREAK                   0x80      /* break/abort detected */
386 #define   ZSRR0_TXUNDER                 0x40      /* transmit underrun/EOM (sync) */
387 #define   ZSRR0_CTS           0x20      /* clear to send */
388 #define   ZSRR0_SYNC_HUNT               0x10      /* sync/hunt (sync mode) */
389 #define   ZSRR0_DCD           0x08      /* data carrier detect */
390 #define   ZSRR0_TX_READY                0x04      /* transmit buffer empty */
391 #define   ZSRR0_ZERO_COUNT    0x02      /* zero count in baud clock */
392 #define   ZSRR0_RX_READY                0x01      /* received character ready */
393 
394 /*
395  * Bits in Read Register 1 (the Zilog book does not name this one).
396  */
397 #define   ZSRR1_EOF           0x80      /* end of frame (SDLC mode) */
398 #define   ZSRR1_FE            0x40      /* CRC/framing error */
399 #define   ZSRR1_DO            0x20      /* data (receiver) overrun */
400 #define   ZSRR1_PE            0x10      /* parity error */
401 #define   ZSRR1_RC0           0x08      /* residue code 0 (SDLC mode) */
402 #define   ZSRR1_RC1           0x04      /* residue code 1 (SDLC mode) */
403 #define   ZSRR1_RC2           0x02      /* residue code 2 (SDLC mode) */
404 #define   ZSRR1_ALL_SENT                0x01      /* all chars out of xmitter (async) */
405 
406 /*
407  * Read Register 2 in B channel contains status bits if VECTOR_INCL_STAT
408  * is set.
409  */
410 
411 /*
412  * Bits in Read Register 3 (`Interrupt Pending').  Only channel A
413  * has an RR3.
414  */
415                               /*        0x80         unused, returned as 0 */
416                               /*        0x40         unused, returned as 0 */
417 #define   ZSRR3_IP_A_RX                 0x20      /* channel A recv int pending */
418 #define   ZSRR3_IP_A_TX                 0x10      /* channel A xmit int pending */
419 #define   ZSRR3_IP_A_STAT               0x08      /* channel A status int pending */
420 #define   ZSRR3_IP_B_RX                 0x04      /* channel B recv int pending */
421 #define   ZSRR3_IP_B_TX                 0x02      /* channel B xmit int pending */
422 #define   ZSRR3_IP_B_STAT               0x01      /* channel B status int pending */
423 
424 /*
425  * Bits in Read Register 10 (`contains some miscellaneous status bits').
426  */
427 #define   ZSRR10_1_CLOCK_MISSING        0x80      /* 1 clock edge missing (FM mode) */
428 #define   ZSRR10_2_CLOCKS_MISSING       0x40      /* 2 clock edges missing (FM mode) */
429                               /*        0x20         unused */
430 #define   ZSRR10_LOOP_SENDING 0x10      /* xmitter controls loop (SDLC loop) */
431                               /*        0x08         unused */
432                               /*        0x04         unused */
433 #define   ZSRR10_ON_LOOP                0x02      /* SCC is on loop (SDLC/X.21 modes) */
434 
435 /*
436  * Bits in Read Register 15.  This register is one of the few that
437  * simply reads back the corresponding Write Register.
438  */
439 #define   ZSRR15_BREAK_IE               0x80      /* break/abort status int enable */
440 #define   ZSRR15_TXUEOM_IE    0x40      /* TX underrun/EOM status int enable */
441 #define   ZSRR15_CTS_IE                 0x20      /* CTS* pin status int enable */
442 #define   ZSRR15_SYNCHUNT_IE  0x10      /* SYNC* pin/hunt status int enable */
443 #define   ZSRR15_DCD_IE                 0x08      /* DCD* pin status int enable */
444                               /*        0x04         unused, returned as zero */
445 #define   ZSRR15_ZERO_COUNT_IE          0x02      /* BRG-counter = 0 status int enable */
446                               /*        0x01         unused, returned as zero */
447