Linux-2.6.33.2/drivers/char/rio/rioparam.c
/*
** -----------------------------------------------------------------------------
**
** Perle Specialix driver for Linux
** Ported from existing RIO Driver for SCO sources.
*
* (C) 1990 - 2000 Specialix International Ltd., Byfleet, Surrey, UK.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
**
** Module : rioparam.c
** SID : 1.3
** Last Modified : 11/6/98 10:33:45
** Retrieved : 11/6/98 10:33:50
**
** ident @(#)rioparam.c 1.3
**
** -----------------------------------------------------------------------------
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/tty.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/string.h>
#include <asm/uaccess.h>
#include <linux/termios.h>
#include <linux/serial.h>
#include <linux/generic_serial.h>
#include "linux_compat.h"
#include "rio_linux.h"
#include "pkt.h"
#include "daemon.h"
#include "rio.h"
#include "riospace.h"
#include "cmdpkt.h"
#include "map.h"
#include "rup.h"
#include "port.h"
#include "riodrvr.h"
#include "rioinfo.h"
#include "func.h"
#include "errors.h"
#include "pci.h"
#include "parmmap.h"
#include "unixrup.h"
#include "board.h"
#include "host.h"
#include "phb.h"
#include "link.h"
#include "cmdblk.h"
#include "route.h"
#include "cirrus.h"
#include "rioioctl.h"
#include "param.h"
/*
** The Scam, based on email from jeremyr@bugs.specialix.co.uk....
**
** To send a command on a particular port, you put a packet with the
** command bit set onto the port. The command bit is in the len field,
** and gets ORed in with the actual byte count.
**
** When you send a packet with the command bit set the first
** data byte (data[0]) is interpreted as the command to execute.
** It also governs what data structure overlay should accompany the packet.
** Commands are defined in cirrus/cirrus.h
**
** If you want the command to pre-emt data already on the queue for the
** port, set the pre-emptive bit in conjunction with the command bit.
** It is not defined what will happen if you set the preemptive bit
** on a packet that is NOT a command.
**
** Pre-emptive commands should be queued at the head of the queue using
** add_start(), whereas normal commands and data are enqueued using
** add_end().
**
** Most commands do not use the remaining bytes in the data array. The
** exceptions are OPEN MOPEN and CONFIG. (NB. As with the SI CONFIG and
** OPEN are currently analogous). With these three commands the following
** 11 data bytes are all used to pass config information such as baud rate etc.
** The fields are also defined in cirrus.h. Some contain straightforward
** information such as the transmit XON character. Two contain the transmit and
** receive baud rates respectively. For most baud rates there is a direct
** mapping between the rates defined in <sys/termio.h> and the byte in the
** packet. There are additional (non UNIX-standard) rates defined in
** /u/dos/rio/cirrus/h/brates.h.
**
** The rest of the data fields contain approximations to the Cirrus registers
** that are used to program number of bits etc. Each registers bit fields is
** defined in cirrus.h.
**
** NB. Only use those bits that are defined as being driver specific
** or common to the RTA and the driver.
**
** All commands going from RTA->Host will be dealt with by the Host code - you
** will never see them. As with the SI there will be three fields to look out
** for in each phb (not yet defined - needs defining a.s.a.p).
**
** modem_status - current state of handshake pins.
**
** port_status - current port status - equivalent to hi_stat for SI, indicates
** if port is IDLE_OPEN, IDLE_CLOSED etc.
**
** break_status - bit X set if break has been received.
**
** Happy hacking.
**
*/
/*
** RIOParam is used to open or configure a port. You pass it a PortP,
** which will have a tty struct attached to it. You also pass a command,
** either OPEN or CONFIG. The port's setup is taken from the t_ fields
** of the tty struct inside the PortP, and the port is either opened
** or re-configured. You must also tell RIOParam if the device is a modem
** device or not (i.e. top bit of minor number set or clear - take special
** care when deciding on this!).
** RIOParam neither flushes nor waits for drain, and is NOT preemptive.
**
** RIOParam assumes it will be called at splrio(), and also assumes
** that CookMode is set correctly in the port structure.
**
** NB. for MPX
** tty lock must NOT have been previously acquired.
*/
int RIOParam(struct Port *PortP, int cmd, int Modem, int SleepFlag)
{
struct tty_struct *TtyP;
int retval;
struct phb_param __iomem *phb_param_ptr;
struct PKT __iomem *PacketP;
int res;
u8 Cor1 = 0, Cor2 = 0, Cor4 = 0, Cor5 = 0;
u8 TxXon = 0, TxXoff = 0, RxXon = 0, RxXoff = 0;
u8 LNext = 0, TxBaud = 0, RxBaud = 0;
int retries = 0xff;
unsigned long flags;
func_enter();
TtyP = PortP->gs.port.tty;
rio_dprintk(RIO_DEBUG_PARAM, "RIOParam: Port:%d cmd:%d Modem:%d SleepFlag:%d Mapped: %d, tty=%p\n", PortP->PortNum, cmd, Modem, SleepFlag, PortP->Mapped, TtyP);
if (!TtyP) {
rio_dprintk(RIO_DEBUG_PARAM, "Can't call rioparam with null tty.\n");
func_exit();
return RIO_FAIL;
}
rio_spin_lock_irqsave(&PortP->portSem, flags);
if (cmd == RIOC_OPEN) {
/*
** If the port is set to store or lock the parameters, and it is
** paramed with OPEN, we want to restore the saved port termio, but
** only if StoredTermio has been saved, i.e. NOT 1st open after reboot.
*/
}
/*
** wait for space
*/
while (!(res = can_add_transmit(&PacketP, PortP)) || (PortP->InUse != NOT_INUSE)) {
if (retries-- <= 0) {
break;
}
if (PortP->InUse != NOT_INUSE) {
rio_dprintk(RIO_DEBUG_PARAM, "Port IN_USE for pre-emptive command\n");
}
if (!res) {
rio_dprintk(RIO_DEBUG_PARAM, "Port has no space on transmit queue\n");
}
if (SleepFlag != OK_TO_SLEEP) {
rio_spin_unlock_irqrestore(&PortP->portSem, flags);
func_exit();
return RIO_FAIL;
}
rio_dprintk(RIO_DEBUG_PARAM, "wait for can_add_transmit\n");
rio_spin_unlock_irqrestore(&PortP->portSem, flags);
retval = RIODelay(PortP, HUNDRED_MS);
rio_spin_lock_irqsave(&PortP->portSem, flags);
if (retval == RIO_FAIL) {
rio_dprintk(RIO_DEBUG_PARAM, "wait for can_add_transmit broken by signal\n");
rio_spin_unlock_irqrestore(&PortP->portSem, flags);
func_exit();
return -EINTR;
}
if (PortP->State & RIO_DELETED) {
rio_spin_unlock_irqrestore(&PortP->portSem, flags);
func_exit();
return 0;
}
}
if (!res) {
rio_spin_unlock_irqrestore(&PortP->portSem, flags);
func_exit();
return RIO_FAIL;
}
rio_dprintk(RIO_DEBUG_PARAM, "can_add_transmit() returns %x\n", res);
rio_dprintk(RIO_DEBUG_PARAM, "Packet is %p\n", PacketP);
phb_param_ptr = (struct phb_param __iomem *) PacketP->data;
switch (TtyP->termios->c_cflag & CSIZE) {
case CS5:
{
rio_dprintk(RIO_DEBUG_PARAM, "5 bit data\n");
Cor1 |= RIOC_COR1_5BITS;
break;
}
case CS6:
{
rio_dprintk(RIO_DEBUG_PARAM, "6 bit data\n");
Cor1 |= RIOC_COR1_6BITS;
break;
}
case CS7:
{
rio_dprintk(RIO_DEBUG_PARAM, "7 bit data\n");
Cor1 |= RIOC_COR1_7BITS;
break;
}
case CS8:
{
rio_dprintk(RIO_DEBUG_PARAM, "8 bit data\n");
Cor1 |= RIOC_COR1_8BITS;
break;
}
}
if (TtyP->termios->c_cflag & CSTOPB) {
rio_dprintk(RIO_DEBUG_PARAM, "2 stop bits\n");
Cor1 |= RIOC_COR1_2STOP;
} else {
rio_dprintk(RIO_DEBUG_PARAM, "1 stop bit\n");
Cor1 |= RIOC_COR1_1STOP;
}
if (TtyP->termios->c_cflag & PARENB) {
rio_dprintk(RIO_DEBUG_PARAM, "Enable parity\n");
Cor1 |= RIOC_COR1_NORMAL;
} else {
rio_dprintk(RIO_DEBUG_PARAM, "Disable parity\n");
Cor1 |= RIOC_COR1_NOP;
}
if (TtyP->termios->c_cflag & PARODD) {
rio_dprintk(RIO_DEBUG_PARAM, "Odd parity\n");
Cor1 |= RIOC_COR1_ODD;
} else {
rio_dprintk(RIO_DEBUG_PARAM, "Even parity\n");
Cor1 |= RIOC_COR1_EVEN;
}
/*
** COR 2
*/
if (TtyP->termios->c_iflag & IXON) {
rio_dprintk(RIO_DEBUG_PARAM, "Enable start/stop output control\n");
Cor2 |= RIOC_COR2_IXON;
} else {
if (PortP->Config & RIO_IXON) {
rio_dprintk(RIO_DEBUG_PARAM, "Force enable start/stop output control\n");
Cor2 |= RIOC_COR2_IXON;
} else
rio_dprintk(RIO_DEBUG_PARAM, "IXON has been disabled.\n");
}
if (TtyP->termios->c_iflag & IXANY) {
if (PortP->Config & RIO_IXANY) {
rio_dprintk(RIO_DEBUG_PARAM, "Enable any key to restart output\n");
Cor2 |= RIOC_COR2_IXANY;
} else
rio_dprintk(RIO_DEBUG_PARAM, "IXANY has been disabled due to sanity reasons.\n");
}
if (TtyP->termios->c_iflag & IXOFF) {
rio_dprintk(RIO_DEBUG_PARAM, "Enable start/stop input control 2\n");
Cor2 |= RIOC_COR2_IXOFF;
}
if (TtyP->termios->c_cflag & HUPCL) {
rio_dprintk(RIO_DEBUG_PARAM, "Hangup on last close\n");
Cor2 |= RIOC_COR2_HUPCL;
}
if (C_CRTSCTS(TtyP)) {
rio_dprintk(RIO_DEBUG_PARAM, "Rx hardware flow control enabled\n");
Cor2 |= RIOC_COR2_CTSFLOW;
Cor2 |= RIOC_COR2_RTSFLOW;
} else {
rio_dprintk(RIO_DEBUG_PARAM, "Rx hardware flow control disabled\n");
Cor2 &= ~RIOC_COR2_CTSFLOW;
Cor2 &= ~RIOC_COR2_RTSFLOW;
}
if (TtyP->termios->c_cflag & CLOCAL) {
rio_dprintk(RIO_DEBUG_PARAM, "Local line\n");
} else {
rio_dprintk(RIO_DEBUG_PARAM, "Possible Modem line\n");
}
/*
** COR 4 (there is no COR 3)
*/
if (TtyP->termios->c_iflag & IGNBRK) {
rio_dprintk(RIO_DEBUG_PARAM, "Ignore break condition\n");
Cor4 |= RIOC_COR4_IGNBRK;
}
if (!(TtyP->termios->c_iflag & BRKINT)) {
rio_dprintk(RIO_DEBUG_PARAM, "Break generates NULL condition\n");
Cor4 |= RIOC_COR4_NBRKINT;
} else {
rio_dprintk(RIO_DEBUG_PARAM, "Interrupt on break condition\n");
}
if (TtyP->termios->c_iflag & INLCR) {
rio_dprintk(RIO_DEBUG_PARAM, "Map newline to carriage return on input\n");
Cor4 |= RIOC_COR4_INLCR;
}
if (TtyP->termios->c_iflag & IGNCR) {
rio_dprintk(RIO_DEBUG_PARAM, "Ignore carriage return on input\n");
Cor4 |= RIOC_COR4_IGNCR;
}
if (TtyP->termios->c_iflag & ICRNL) {
rio_dprintk(RIO_DEBUG_PARAM, "Map carriage return to newline on input\n");
Cor4 |= RIOC_COR4_ICRNL;
}
if (TtyP->termios->c_iflag & IGNPAR) {
rio_dprintk(RIO_DEBUG_PARAM, "Ignore characters with parity errors\n");
Cor4 |= RIOC_COR4_IGNPAR;
}
if (TtyP->termios->c_iflag & PARMRK) {
rio_dprintk(RIO_DEBUG_PARAM, "Mark parity errors\n");
Cor4 |= RIOC_COR4_PARMRK;
}
/*
** Set the RAISEMOD flag to ensure that the modem lines are raised
** on reception of a config packet.
** The download code handles the zero baud condition.
*/
Cor4 |= RIOC_COR4_RAISEMOD;
/*
** COR 5
*/
Cor5 = RIOC_COR5_CMOE;
/*
** Set to monitor tbusy/tstop (or not).
*/
if (PortP->MonitorTstate)
Cor5 |= RIOC_COR5_TSTATE_ON;
else
Cor5 |= RIOC_COR5_TSTATE_OFF;
/*
** Could set LNE here if you wanted LNext processing. SVR4 will use it.
*/
if (TtyP->termios->c_iflag & ISTRIP) {
rio_dprintk(RIO_DEBUG_PARAM, "Strip input characters\n");
if (!(PortP->State & RIO_TRIAD_MODE)) {
Cor5 |= RIOC_COR5_ISTRIP;
}
}
if (TtyP->termios->c_oflag & ONLCR) {
rio_dprintk(RIO_DEBUG_PARAM, "Map newline to carriage-return, newline on output\n");
if (PortP->CookMode == COOK_MEDIUM)
Cor5 |= RIOC_COR5_ONLCR;
}
if (TtyP->termios->c_oflag & OCRNL) {
rio_dprintk(RIO_DEBUG_PARAM, "Map carriage return to newline on output\n");
if (PortP->CookMode == COOK_MEDIUM)
Cor5 |= RIOC_COR5_OCRNL;
}
if ((TtyP->termios->c_oflag & TABDLY) == TAB3) {
rio_dprintk(RIO_DEBUG_PARAM, "Tab delay 3 set\n");
if (PortP->CookMode == COOK_MEDIUM)
Cor5 |= RIOC_COR5_TAB3;
}
/*
** Flow control bytes.
*/
TxXon = TtyP->termios->c_cc[VSTART];
TxXoff = TtyP->termios->c_cc[VSTOP];
RxXon = TtyP->termios->c_cc[VSTART];
RxXoff = TtyP->termios->c_cc[VSTOP];
/*
** LNEXT byte
*/
LNext = 0;
/*
** Baud rate bytes
*/
rio_dprintk(RIO_DEBUG_PARAM, "Mapping of rx/tx baud %x (%x)\n", TtyP->termios->c_cflag, CBAUD);
switch (TtyP->termios->c_cflag & CBAUD) {
#define e(b) case B ## b : RxBaud = TxBaud = RIO_B ## b ;break
e(50);
e(75);
e(110);
e(134);
e(150);
e(200);
e(300);
e(600);
e(1200);
e(1800);
e(2400);
e(4800);
e(9600);
e(19200);
e(38400);
e(57600);
e(115200); /* e(230400);e(460800); e(921600); */
}
rio_dprintk(RIO_DEBUG_PARAM, "tx baud 0x%x, rx baud 0x%x\n", TxBaud, RxBaud);
/*
** Leftovers
*/
if (TtyP->termios->c_cflag & CREAD)
rio_dprintk(RIO_DEBUG_PARAM, "Enable receiver\n");
#ifdef RCV1EN
if (TtyP->termios->c_cflag & RCV1EN)
rio_dprintk(RIO_DEBUG_PARAM, "RCV1EN (?)\n");
#endif
#ifdef XMT1EN
if (TtyP->termios->c_cflag & XMT1EN)
rio_dprintk(RIO_DEBUG_PARAM, "XMT1EN (?)\n");
#endif
if (TtyP->termios->c_lflag & ISIG)
rio_dprintk(RIO_DEBUG_PARAM, "Input character signal generating enabled\n");
if (TtyP->termios->c_lflag & ICANON)
rio_dprintk(RIO_DEBUG_PARAM, "Canonical input: erase and kill enabled\n");
if (TtyP->termios->c_lflag & XCASE)
rio_dprintk(RIO_DEBUG_PARAM, "Canonical upper/lower presentation\n");
if (TtyP->termios->c_lflag & ECHO)
rio_dprintk(RIO_DEBUG_PARAM, "Enable input echo\n");
if (TtyP->termios->c_lflag & ECHOE)
rio_dprintk(RIO_DEBUG_PARAM, "Enable echo erase\n");
if (TtyP->termios->c_lflag & ECHOK)
rio_dprintk(RIO_DEBUG_PARAM, "Enable echo kill\n");
if (TtyP->termios->c_lflag & ECHONL)
rio_dprintk(RIO_DEBUG_PARAM, "Enable echo newline\n");
if (TtyP->termios->c_lflag & NOFLSH)
rio_dprintk(RIO_DEBUG_PARAM, "Disable flush after interrupt or quit\n");
#ifdef TOSTOP
if (TtyP->termios->c_lflag & TOSTOP)
rio_dprintk(RIO_DEBUG_PARAM, "Send SIGTTOU for background output\n");
#endif
#ifdef XCLUDE
if (TtyP->termios->c_lflag & XCLUDE)
rio_dprintk(RIO_DEBUG_PARAM, "Exclusive use of this line\n");
#endif
if (TtyP->termios->c_iflag & IUCLC)
rio_dprintk(RIO_DEBUG_PARAM, "Map uppercase to lowercase on input\n");
if (TtyP->termios->c_oflag & OPOST)
rio_dprintk(RIO_DEBUG_PARAM, "Enable output post-processing\n");
if (TtyP->termios->c_oflag & OLCUC)
rio_dprintk(RIO_DEBUG_PARAM, "Map lowercase to uppercase on output\n");
if (TtyP->termios->c_oflag & ONOCR)
rio_dprintk(RIO_DEBUG_PARAM, "No carriage return output at column 0\n");
if (TtyP->termios->c_oflag & ONLRET)
rio_dprintk(RIO_DEBUG_PARAM, "Newline performs carriage return function\n");
if (TtyP->termios->c_oflag & OFILL)
rio_dprintk(RIO_DEBUG_PARAM, "Use fill characters for delay\n");
if (TtyP->termios->c_oflag & OFDEL)
rio_dprintk(RIO_DEBUG_PARAM, "Fill character is DEL\n");
if (TtyP->termios->c_oflag & NLDLY)
rio_dprintk(RIO_DEBUG_PARAM, "Newline delay set\n");
if (TtyP->termios->c_oflag & CRDLY)
rio_dprintk(RIO_DEBUG_PARAM, "Carriage return delay set\n");
if (TtyP->termios->c_oflag & TABDLY)
rio_dprintk(RIO_DEBUG_PARAM, "Tab delay set\n");
/*
** These things are kind of useful in a later life!
*/
PortP->Cor2Copy = Cor2;
if (PortP->State & RIO_DELETED) {
rio_spin_unlock_irqrestore(&PortP->portSem, flags);
func_exit();
return RIO_FAIL;
}
/*
** Actually write the info into the packet to be sent
*/
writeb(cmd, &phb_param_ptr->Cmd);
writeb(Cor1, &phb_param_ptr->Cor1);
writeb(Cor2, &phb_param_ptr->Cor2);
writeb(Cor4, &phb_param_ptr->Cor4);
writeb(Cor5, &phb_param_ptr->Cor5);
writeb(TxXon, &phb_param_ptr->TxXon);
writeb(RxXon, &phb_param_ptr->RxXon);
writeb(TxXoff, &phb_param_ptr->TxXoff);
writeb(RxXoff, &phb_param_ptr->RxXoff);
writeb(LNext, &phb_param_ptr->LNext);
writeb(TxBaud, &phb_param_ptr->TxBaud);
writeb(RxBaud, &phb_param_ptr->RxBaud);
/*
** Set the length/command field
*/
writeb(12 | PKT_CMD_BIT, &PacketP->len);
/*
** The packet is formed - now, whack it off
** to its final destination:
*/
add_transmit(PortP);
/*
** Count characters transmitted for port statistics reporting
*/
if (PortP->statsGather)
PortP->txchars += 12;
rio_spin_unlock_irqrestore(&PortP->portSem, flags);
rio_dprintk(RIO_DEBUG_PARAM, "add_transmit returned.\n");
/*
** job done.
*/
func_exit();
return 0;
}
/*
** We can add another packet to a transmit queue if the packet pointer pointed
** to by the TxAdd pointer has PKT_IN_USE clear in its address.
*/
int can_add_transmit(struct PKT __iomem **PktP, struct Port *PortP)
{
struct PKT __iomem *tp;
*PktP = tp = (struct PKT __iomem *) RIO_PTR(PortP->Caddr, readw(PortP->TxAdd));
return !((unsigned long) tp & PKT_IN_USE);
}
/*
** To add a packet to the queue, you set the PKT_IN_USE bit in the address,
** and then move the TxAdd pointer along one position to point to the next
** packet pointer. You must wrap the pointer from the end back to the start.
*/
void add_transmit(struct Port *PortP)
{
if (readw(PortP->TxAdd) & PKT_IN_USE) {
rio_dprintk(RIO_DEBUG_PARAM, "add_transmit: Packet has been stolen!");
}
writew(readw(PortP->TxAdd) | PKT_IN_USE, PortP->TxAdd);
PortP->TxAdd = (PortP->TxAdd == PortP->TxEnd) ? PortP->TxStart : PortP->TxAdd + 1;
writew(RIO_OFF(PortP->Caddr, PortP->TxAdd), &PortP->PhbP->tx_add);
}
/****************************************
* Put a packet onto the end of the
* free list
****************************************/
void put_free_end(struct Host *HostP, struct PKT __iomem *PktP)
{
struct rio_free_list __iomem *tmp_pointer;
unsigned short old_end, new_end;
unsigned long flags;
rio_spin_lock_irqsave(&HostP->HostLock, flags);
/*************************************************
* Put a packet back onto the back of the free list
*
************************************************/
rio_dprintk(RIO_DEBUG_PFE, "put_free_end(PktP=%p)\n", PktP);
if ((old_end = readw(&HostP->ParmMapP->free_list_end)) != TPNULL) {
new_end = RIO_OFF(HostP->Caddr, PktP);
tmp_pointer = (struct rio_free_list __iomem *) RIO_PTR(HostP->Caddr, old_end);
writew(new_end, &tmp_pointer->next);
writew(old_end, &((struct rio_free_list __iomem *) PktP)->prev);
writew(TPNULL, &((struct rio_free_list __iomem *) PktP)->next);
writew(new_end, &HostP->ParmMapP->free_list_end);
} else { /* First packet on the free list this should never happen! */
rio_dprintk(RIO_DEBUG_PFE, "put_free_end(): This should never happen\n");
writew(RIO_OFF(HostP->Caddr, PktP), &HostP->ParmMapP->free_list_end);
tmp_pointer = (struct rio_free_list __iomem *) PktP;
writew(TPNULL, &tmp_pointer->prev);
writew(TPNULL, &tmp_pointer->next);
}
rio_dprintk(RIO_DEBUG_CMD, "Before unlock: %p\n", &HostP->HostLock);
rio_spin_unlock_irqrestore(&HostP->HostLock, flags);
}
/*
** can_remove_receive(PktP,P) returns non-zero if PKT_IN_USE is set
** for the next packet on the queue. It will also set PktP to point to the
** relevant packet, [having cleared the PKT_IN_USE bit]. If PKT_IN_USE is clear,
** then can_remove_receive() returns 0.
*/
int can_remove_receive(struct PKT __iomem **PktP, struct Port *PortP)
{
if (readw(PortP->RxRemove) & PKT_IN_USE) {
*PktP = (struct PKT __iomem *) RIO_PTR(PortP->Caddr, readw(PortP->RxRemove) & ~PKT_IN_USE);
return 1;
}
return 0;
}
/*
** To remove a packet from the receive queue you clear its PKT_IN_USE bit,
** and then bump the pointers. Once the pointers get to the end, they must
** be wrapped back to the start.
*/
void remove_receive(struct Port *PortP)
{
writew(readw(PortP->RxRemove) & ~PKT_IN_USE, PortP->RxRemove);
PortP->RxRemove = (PortP->RxRemove == PortP->RxEnd) ? PortP->RxStart : PortP->RxRemove + 1;
writew(RIO_OFF(PortP->Caddr, PortP->RxRemove), &PortP->PhbP->rx_remove);
}