freebsd-skq/sys/dev/zs/z8530reg.h
Warner Losh f36cfd49ad Remove advertising clause from University of California Regent's
license, per letter dated July 22, 1999 and email from Peter Wemm,
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452 lines
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C

/* $NetBSD: z8530reg.h,v 1.8 1996/12/13 21:02:39 gwr 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.
* 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
*
* $FreeBSD$
*/
/*
* 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.
*
* This file also includes flags for the Z85C30 and Z85230 enhanced scc.
* The CMOS 8530 includes extra SDLC functionality, and is used in a
* number of Macs (often in the Z85C80, an 85C30 combined w/ a SCSI
* controller). -wrs
*
* 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 ZS_NCHAN 2
#define ZSRR_IVEC 2 /* interrupt vector (channel 0) */
#define ZSRR_IPEND 3 /* interrupt pending (ch. 0 only) */
#define ZSRR_TXSYNC 6 /* sync transmit char (monosync mode) */
#define ZSRR_RXSYNC 7 /* sync receive char (monosync mode) */
#define ZSRR_SYNCLO 6 /* sync low byte (bisync mode) */
#define ZSRR_SYNCHI 7 /* sync high byte (bisync mode) */
#define ZSRR_SDLC_ADDR 6 /* SDLC address (SDLC mode) */
#define ZSRR_SDLC_FLAG 7 /* SDLC flag 0x7E (SDLC mode) */
#define ZSRR_BAUDLO 12 /* baud rate generator (low half) */
#define ZSRR_BAUDHI 13 /* baud rate generator (high half) */
#define ZSRR_ENHANCED 14 /* read address of WR7' - yes, it's not 7!*/
#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) */
#define ZSWR_ENHANCED 7 /* write address of WR7' */
/*
* 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 */
#define ZSWR1_IMASK 0x1F /* mask of all itr. enable bits. */
/* 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_RXSIZE 0xc0 /* receive char size mask */
#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_SDLC_SHORT_ADDR 0x02 /* short address 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_CLK_MASK 0xc0 /* clock divisor mask */
#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_SYNC_MASK 0x30 /* sync mode bit mask */
#define ZSWR4_SYNCMODE 0x00 /* no stop bit (sync mode only) */
#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_SBMASK 0x0c /* mask of all stop bits */
#define ZSWR4_EVENP 0x02 /* check for even parity */
#define ZSWR4_PARENB 0x01 /* enable parity checking */
#define ZSWR4_PARMASK 0x03 /* mask of all parity bits */
/*
* 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_TXSIZE 0x60 /* transmit char size mask */
#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 7' (ZSWR_ENHANCED above). This register is
* only available on the 85230. Dispite the fact it contains flags
* and not a single value, the register was named as it is read
* via RR14. Weird.
*/
/* 0x80 unused */
#define ZSWR7P_EXTEND_READ 0x40 /* modify read map; make most regs readable */
#define ZSWR7P_TX_FIFO 0x20 /* change level for Tx FIFO empty int */
#define ZSWR7P_DTR_TIME 0x10 /* modifies deact. speed of /DTR//REQ */
#define ZSWR7P_RX_FIFO 0x08 /* Rx FIFO int on 1/2 full? */
#define ZSWR7P_RTS_DEACT 0x04 /* automatically deassert RTS */
#define ZSWR7P_AUTO_EOM_RESET 0x02 /* automatically reset EMO/Tx Underrun */
#define ZSWR7P_AUTO_TX_FLAG 0x01 /* Auto send SDLC flag at transmit start */
/*
* 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) */
#define ZSWR9_SOFT_INTAC 0x20 /* Not in NMOS version */
#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 RTxC* 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 RTxC* pin */
#define ZSWR11_TXCLK_TRXC 0x08 /* xmit clock taken from TRxC* 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).
*
* NOTE: ZSWR15_SDLC_FIFO & ZSWR15_ENABLE_ENHANCED should not be
* set on an NMOS 8530. Also, ZSWR15_ENABLE_ENHANCED is only
* available on the 85230.
*/
#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 */
#define ZSWR15_SDLC_FIFO 0x04 /* enable SDLC FIFO enhancements */
#define ZSWR15_ZERO_COUNT_IE 0x02 /* enable BRG-counter = 0 status int */
#define ZSWR15_ENABLE_ENHANCED 0x01 /* enable writing WR7' at reg 7 */
/*
* 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 */