patch-2.4.15 linux/drivers/scsi/sym53c8xx_2/sym_nvram.c

• Lines: 731
• Date: Fri Nov 9 15:22:54 2001
• Orig file: v2.4.14/linux/drivers/scsi/sym53c8xx_2/sym_nvram.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.14/linux/drivers/scsi/sym53c8xx_2/sym_nvram.c linux/drivers/scsi/sym53c8xx_2/sym_nvram.c
@@ -0,0 +1,730 @@
+/*
+ * Device driver for the SYMBIOS/LSILOGIC 53C8XX and 53C1010 family 
+ * of PCI-SCSI IO processors.
+ *
+ * Copyright (C) 1999-2001  Gerard Roudier <groudier@free.fr>
+ *
+ * This driver is derived from the Linux sym53c8xx driver.
+ * Copyright (C) 1998-2000  Gerard Roudier
+ *
+ * The sym53c8xx driver is derived from the ncr53c8xx driver that had been 
+ * a port of the FreeBSD ncr driver to Linux-1.2.13.
+ *
+ * The original ncr driver has been written for 386bsd and FreeBSD by
+ *         Wolfgang Stanglmeier        <wolf@cologne.de>
+ *         Stefan Esser                <se@mi.Uni-Koeln.de>
+ * Copyright (C) 1994  Wolfgang Stanglmeier
+ *
+ * Other major contributions:
+ *
+ * NVRAM detection and reading.
+ * Copyright (C) 1997 Richard Waltham <dormouse@farsrobt.demon.co.uk>
+ *
+ *-----------------------------------------------------------------------------
+ *
+ * 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. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * Where this Software is combined with software released under the terms of 
+ * the GNU Public License ("GPL") and the terms of the GPL would require the 
+ * combined work to also be released under the terms of the GPL, the terms
+ * and conditions of this License will apply in addition to those of the
+ * GPL with the exception of any terms or conditions of this License that
+ * conflict with, or are expressly prohibited by, the GPL.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHOR 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.
+ */
+
+#ifdef __FreeBSD__
+#include <dev/sym/sym_glue.h>
+#else
+#include "sym_glue.h"
+#endif
+
+/*
+ *  Some poor and bogus sync table that refers to Tekram NVRAM layout.
+ */
+#if SYM_CONF_NVRAM_SUPPORT
+static u_char Tekram_sync[16] =
+	{25,31,37,43, 50,62,75,125, 12,15,18,21, 6,7,9,10};
+#ifdef	SYM_CONF_DEBUG_NVRAM
+static u_char Tekram_boot_delay[7] = {3, 5, 10, 20, 30, 60, 120};
+#endif
+#endif
+
+/*
+ *  Get host setup from NVRAM.
+ */
+void sym_nvram_setup_host (hcb_p np, struct sym_nvram *nvram)
+{
+#if SYM_CONF_NVRAM_SUPPORT
+	/*
+	 *  Get parity checking, host ID, verbose mode 
+	 *  and miscellaneous host flags from NVRAM.
+	 */
+	switch(nvram->type) {
+	case SYM_SYMBIOS_NVRAM:
+		if (!(nvram->data.Symbios.flags & SYMBIOS_PARITY_ENABLE))
+			np->rv_scntl0  &= ~0x0a;
+		np->myaddr = nvram->data.Symbios.host_id & 0x0f;
+		if (nvram->data.Symbios.flags & SYMBIOS_VERBOSE_MSGS)
+			np->verbose += 1;
+		if (nvram->data.Symbios.flags1 & SYMBIOS_SCAN_HI_LO)
+			np->usrflags |= SYM_SCAN_TARGETS_HILO;
+		if (nvram->data.Symbios.flags2 & SYMBIOS_AVOID_BUS_RESET)
+			np->usrflags |= SYM_AVOID_BUS_RESET;
+		break;
+	case SYM_TEKRAM_NVRAM:
+		np->myaddr = nvram->data.Tekram.host_id & 0x0f;
+		break;
+	default:
+		break;
+	}
+#endif
+}
+
+/*
+ *  Get target setup from NVRAM.
+ */
+#if SYM_CONF_NVRAM_SUPPORT
+static void sym_Symbios_setup_target(hcb_p np,int target, Symbios_nvram *nvram);
+static void sym_Tekram_setup_target(hcb_p np,int target, Tekram_nvram *nvram);
+#endif
+
+void sym_nvram_setup_target (hcb_p np, int target, struct sym_nvram *nvp)
+{
+#if SYM_CONF_NVRAM_SUPPORT
+	switch(nvp->type) {
+	case SYM_SYMBIOS_NVRAM:
+		sym_Symbios_setup_target (np, target, &nvp->data.Symbios);
+		break;
+	case SYM_TEKRAM_NVRAM:
+		sym_Tekram_setup_target (np, target, &nvp->data.Tekram);
+		break;
+	default:
+		break;
+	}
+#endif
+}
+
+#if SYM_CONF_NVRAM_SUPPORT
+/*
+ *  Get target set-up from Symbios format NVRAM.
+ */
+static void
+sym_Symbios_setup_target(hcb_p np, int target, Symbios_nvram *nvram)
+{
+	tcb_p tp = &np->target[target];
+	Symbios_target *tn = &nvram->target[target];
+
+	tp->tinfo.user.period = tn->sync_period ? (tn->sync_period + 3) / 4 : 0;
+	tp->tinfo.user.width  = tn->bus_width == 0x10 ? BUS_16_BIT : BUS_8_BIT;
+	tp->usrtags =
+		(tn->flags & SYMBIOS_QUEUE_TAGS_ENABLED)? SYM_SETUP_MAX_TAG : 0;
+
+	if (!(tn->flags & SYMBIOS_DISCONNECT_ENABLE))
+		tp->usrflags &= ~SYM_DISC_ENABLED;
+	if (!(tn->flags & SYMBIOS_SCAN_AT_BOOT_TIME))
+		tp->usrflags |= SYM_SCAN_BOOT_DISABLED;
+	if (!(tn->flags & SYMBIOS_SCAN_LUNS))
+		tp->usrflags |= SYM_SCAN_LUNS_DISABLED;
+}
+
+/*
+ *  Get target set-up from Tekram format NVRAM.
+ */
+static void
+sym_Tekram_setup_target(hcb_p np, int target, Tekram_nvram *nvram)
+{
+	tcb_p tp = &np->target[target];
+	struct Tekram_target *tn = &nvram->target[target];
+	int i;
+
+	if (tn->flags & TEKRAM_SYNC_NEGO) {
+		i = tn->sync_index & 0xf;
+		tp->tinfo.user.period = Tekram_sync[i];
+	}
+
+	tp->tinfo.user.width =
+		(tn->flags & TEKRAM_WIDE_NEGO) ? BUS_16_BIT : BUS_8_BIT;
+
+	if (tn->flags & TEKRAM_TAGGED_COMMANDS) {
+		tp->usrtags = 2 << nvram->max_tags_index;
+	}
+
+	if (tn->flags & TEKRAM_DISCONNECT_ENABLE)
+		tp->usrflags |= SYM_DISC_ENABLED;
+ 
+	/* If any device does not support parity, we will not use this option */
+	if (!(tn->flags & TEKRAM_PARITY_CHECK))
+		np->rv_scntl0  &= ~0x0a; /* SCSI parity checking disabled */
+}
+
+#ifdef	SYM_CONF_DEBUG_NVRAM
+/*
+ *  Dump Symbios format NVRAM for debugging purpose.
+ */
+static void sym_display_Symbios_nvram(sdev_p np, Symbios_nvram *nvram)
+{
+	int i;
+
+	/* display Symbios nvram host data */
+	printf("%s: HOST ID=%d%s%s%s%s%s%s\n",
+		sym_name(np), nvram->host_id & 0x0f,
+		(nvram->flags  & SYMBIOS_SCAM_ENABLE)	? " SCAM"	:"",
+		(nvram->flags  & SYMBIOS_PARITY_ENABLE)	? " PARITY"	:"",
+		(nvram->flags  & SYMBIOS_VERBOSE_MSGS)	? " VERBOSE"	:"", 
+		(nvram->flags  & SYMBIOS_CHS_MAPPING)	? " CHS_ALT"	:"", 
+		(nvram->flags2 & SYMBIOS_AVOID_BUS_RESET)?" NO_RESET"	:"",
+		(nvram->flags1 & SYMBIOS_SCAN_HI_LO)	? " HI_LO"	:"");
+
+	/* display Symbios nvram drive data */
+	for (i = 0 ; i < 15 ; i++) {
+		struct Symbios_target *tn = &nvram->target[i];
+		printf("%s-%d:%s%s%s%s WIDTH=%d SYNC=%d TMO=%d\n",
+		sym_name(np), i,
+		(tn->flags & SYMBIOS_DISCONNECT_ENABLE)	? " DISC"	: "",
+		(tn->flags & SYMBIOS_SCAN_AT_BOOT_TIME)	? " SCAN_BOOT"	: "",
+		(tn->flags & SYMBIOS_SCAN_LUNS)		? " SCAN_LUNS"	: "",
+		(tn->flags & SYMBIOS_QUEUE_TAGS_ENABLED)? " TCQ"	: "",
+		tn->bus_width,
+		tn->sync_period / 4,
+		tn->timeout);
+	}
+}
+
+/*
+ *  Dump TEKRAM format NVRAM for debugging purpose.
+ */
+static void sym_display_Tekram_nvram(sdev_p np, Tekram_nvram *nvram)
+{
+	int i, tags, boot_delay;
+	char *rem;
+
+	/* display Tekram nvram host data */
+	tags = 2 << nvram->max_tags_index;
+	boot_delay = 0;
+	if (nvram->boot_delay_index < 6)
+		boot_delay = Tekram_boot_delay[nvram->boot_delay_index];
+	switch((nvram->flags & TEKRAM_REMOVABLE_FLAGS) >> 6) {
+	default:
+	case 0:	rem = "";			break;
+	case 1: rem = " REMOVABLE=boot device";	break;
+	case 2: rem = " REMOVABLE=all";		break;
+	}
+
+	printf("%s: HOST ID=%d%s%s%s%s%s%s%s%s%s BOOT DELAY=%d tags=%d\n",
+		sym_name(np), nvram->host_id & 0x0f,
+		(nvram->flags1 & SYMBIOS_SCAM_ENABLE)	? " SCAM"	:"",
+		(nvram->flags & TEKRAM_MORE_THAN_2_DRIVES) ? " >2DRIVES":"",
+		(nvram->flags & TEKRAM_DRIVES_SUP_1GB)	? " >1GB"	:"",
+		(nvram->flags & TEKRAM_RESET_ON_POWER_ON) ? " RESET"	:"",
+		(nvram->flags & TEKRAM_ACTIVE_NEGATION)	? " ACT_NEG"	:"",
+		(nvram->flags & TEKRAM_IMMEDIATE_SEEK)	? " IMM_SEEK"	:"",
+		(nvram->flags & TEKRAM_SCAN_LUNS)	? " SCAN_LUNS"	:"",
+		(nvram->flags1 & TEKRAM_F2_F6_ENABLED)	? " F2_F6"	:"",
+		rem, boot_delay, tags);
+
+	/* display Tekram nvram drive data */
+	for (i = 0; i <= 15; i++) {
+		int sync, j;
+		struct Tekram_target *tn = &nvram->target[i];
+		j = tn->sync_index & 0xf;
+		sync = Tekram_sync[j];
+		printf("%s-%d:%s%s%s%s%s%s PERIOD=%d\n",
+		sym_name(np), i,
+		(tn->flags & TEKRAM_PARITY_CHECK)	? " PARITY"	: "",
+		(tn->flags & TEKRAM_SYNC_NEGO)		? " SYNC"	: "",
+		(tn->flags & TEKRAM_DISCONNECT_ENABLE)	? " DISC"	: "",
+		(tn->flags & TEKRAM_START_CMD)		? " START"	: "",
+		(tn->flags & TEKRAM_TAGGED_COMMANDS)	? " TCQ"	: "",
+		(tn->flags & TEKRAM_WIDE_NEGO)		? " WIDE"	: "",
+		sync);
+	}
+}
+#endif	/* SYM_CONF_DEBUG_NVRAM */
+#endif	/* SYM_CONF_NVRAM_SUPPORT */
+
+
+/*
+ *  Try reading Symbios or Tekram NVRAM
+ */
+#if SYM_CONF_NVRAM_SUPPORT
+static int sym_read_Symbios_nvram (sdev_p np, Symbios_nvram *nvram);
+static int sym_read_Tekram_nvram  (sdev_p np, Tekram_nvram *nvram);
+#endif
+
+int sym_read_nvram (sdev_p np, struct sym_nvram *nvp)
+{
+#if SYM_CONF_NVRAM_SUPPORT
+	/*
+	 *  Try to read SYMBIOS nvram.
+	 *  Try to read TEKRAM nvram if Symbios nvram not found.
+	 */
+	if	(SYM_SETUP_SYMBIOS_NVRAM &&
+		 !sym_read_Symbios_nvram (np, &nvp->data.Symbios)) {
+		nvp->type = SYM_SYMBIOS_NVRAM;
+#ifdef SYM_CONF_DEBUG_NVRAM
+		sym_display_Symbios_nvram(np, &nvp->data.Symbios);
+#endif
+	}
+	else if	(SYM_SETUP_TEKRAM_NVRAM &&
+		 !sym_read_Tekram_nvram (np, &nvp->data.Tekram)) {
+		nvp->type = SYM_TEKRAM_NVRAM;
+#ifdef SYM_CONF_DEBUG_NVRAM
+		sym_display_Tekram_nvram(np, &nvp->data.Tekram);
+#endif
+	}
+	else
+		nvp->type = 0;
+#else
+	nvp->type = 0;
+#endif
+	return nvp->type;
+}
+
+
+#if SYM_CONF_NVRAM_SUPPORT
+/*
+ *  24C16 EEPROM reading.
+ *
+ *  GPOI0 - data in/data out
+ *  GPIO1 - clock
+ *  Symbios NVRAM wiring now also used by Tekram.
+ */
+
+#define SET_BIT 0
+#define CLR_BIT 1
+#define SET_CLK 2
+#define CLR_CLK 3
+
+/*
+ *  Set/clear data/clock bit in GPIO0
+ */
+static void S24C16_set_bit(sdev_p np, u_char write_bit, u_char *gpreg, 
+			  int bit_mode)
+{
+	UDELAY (5);
+	switch (bit_mode){
+	case SET_BIT:
+		*gpreg |= write_bit;
+		break;
+	case CLR_BIT:
+		*gpreg &= 0xfe;
+		break;
+	case SET_CLK:
+		*gpreg |= 0x02;
+		break;
+	case CLR_CLK:
+		*gpreg &= 0xfd;
+		break;
+
+	}
+	OUTB (nc_gpreg, *gpreg);
+	UDELAY (5);
+}
+
+/*
+ *  Send START condition to NVRAM to wake it up.
+ */
+static void S24C16_start(sdev_p np, u_char *gpreg)
+{
+	S24C16_set_bit(np, 1, gpreg, SET_BIT);
+	S24C16_set_bit(np, 0, gpreg, SET_CLK);
+	S24C16_set_bit(np, 0, gpreg, CLR_BIT);
+	S24C16_set_bit(np, 0, gpreg, CLR_CLK);
+}
+
+/*
+ *  Send STOP condition to NVRAM - puts NVRAM to sleep... ZZzzzz!!
+ */
+static void S24C16_stop(sdev_p np, u_char *gpreg)
+{
+	S24C16_set_bit(np, 0, gpreg, SET_CLK);
+	S24C16_set_bit(np, 1, gpreg, SET_BIT);
+}
+
+/*
+ *  Read or write a bit to the NVRAM,
+ *  read if GPIO0 input else write if GPIO0 output
+ */
+static void S24C16_do_bit(sdev_p np, u_char *read_bit, u_char write_bit, 
+			 u_char *gpreg)
+{
+	S24C16_set_bit(np, write_bit, gpreg, SET_BIT);
+	S24C16_set_bit(np, 0, gpreg, SET_CLK);
+	if (read_bit)
+		*read_bit = INB (nc_gpreg);
+	S24C16_set_bit(np, 0, gpreg, CLR_CLK);
+	S24C16_set_bit(np, 0, gpreg, CLR_BIT);
+}
+
+/*
+ *  Output an ACK to the NVRAM after reading,
+ *  change GPIO0 to output and when done back to an input
+ */
+static void S24C16_write_ack(sdev_p np, u_char write_bit, u_char *gpreg, 
+			    u_char *gpcntl)
+{
+	OUTB (nc_gpcntl, *gpcntl & 0xfe);
+	S24C16_do_bit(np, 0, write_bit, gpreg);
+	OUTB (nc_gpcntl, *gpcntl);
+}
+
+/*
+ *  Input an ACK from NVRAM after writing,
+ *  change GPIO0 to input and when done back to an output
+ */
+static void S24C16_read_ack(sdev_p np, u_char *read_bit, u_char *gpreg, 
+			   u_char *gpcntl)
+{
+	OUTB (nc_gpcntl, *gpcntl | 0x01);
+	S24C16_do_bit(np, read_bit, 1, gpreg);
+	OUTB (nc_gpcntl, *gpcntl);
+}
+
+/*
+ *  WRITE a byte to the NVRAM and then get an ACK to see it was accepted OK,
+ *  GPIO0 must already be set as an output
+ */
+static void S24C16_write_byte(sdev_p np, u_char *ack_data, u_char write_data, 
+			     u_char *gpreg, u_char *gpcntl)
+{
+	int x;
+	
+	for (x = 0; x < 8; x++)
+		S24C16_do_bit(np, 0, (write_data >> (7 - x)) & 0x01, gpreg);
+		
+	S24C16_read_ack(np, ack_data, gpreg, gpcntl);
+}
+
+/*
+ *  READ a byte from the NVRAM and then send an ACK to say we have got it,
+ *  GPIO0 must already be set as an input
+ */
+static void S24C16_read_byte(sdev_p np, u_char *read_data, u_char ack_data, 
+			    u_char *gpreg, u_char *gpcntl)
+{
+	int x;
+	u_char read_bit;
+
+	*read_data = 0;
+	for (x = 0; x < 8; x++) {
+		S24C16_do_bit(np, &read_bit, 1, gpreg);
+		*read_data |= ((read_bit & 0x01) << (7 - x));
+	}
+
+	S24C16_write_ack(np, ack_data, gpreg, gpcntl);
+}
+
+/*
+ *  Read 'len' bytes starting at 'offset'.
+ */
+static int sym_read_S24C16_nvram (sdev_p np, int offset, u_char *data, int len)
+{
+	u_char	gpcntl, gpreg;
+	u_char	old_gpcntl, old_gpreg;
+	u_char	ack_data;
+	int	retv = 1;
+	int	x;
+
+	/* save current state of GPCNTL and GPREG */
+	old_gpreg	= INB (nc_gpreg);
+	old_gpcntl	= INB (nc_gpcntl);
+	gpcntl		= old_gpcntl & 0x1c;
+
+	/* set up GPREG & GPCNTL to set GPIO0 and GPIO1 in to known state */
+	OUTB (nc_gpreg,  old_gpreg);
+	OUTB (nc_gpcntl, gpcntl);
+
+	/* this is to set NVRAM into a known state with GPIO0/1 both low */
+	gpreg = old_gpreg;
+	S24C16_set_bit(np, 0, &gpreg, CLR_CLK);
+	S24C16_set_bit(np, 0, &gpreg, CLR_BIT);
+		
+	/* now set NVRAM inactive with GPIO0/1 both high */
+	S24C16_stop(np, &gpreg);
+	
+	/* activate NVRAM */
+	S24C16_start(np, &gpreg);
+
+	/* write device code and random address MSB */
+	S24C16_write_byte(np, &ack_data,
+		0xa0 | ((offset >> 7) & 0x0e), &gpreg, &gpcntl);
+	if (ack_data & 0x01)
+		goto out;
+
+	/* write random address LSB */
+	S24C16_write_byte(np, &ack_data,
+		offset & 0xff, &gpreg, &gpcntl);
+	if (ack_data & 0x01)
+		goto out;
+
+	/* regenerate START state to set up for reading */
+	S24C16_start(np, &gpreg);
+	
+	/* rewrite device code and address MSB with read bit set (lsb = 0x01) */
+	S24C16_write_byte(np, &ack_data,
+		0xa1 | ((offset >> 7) & 0x0e), &gpreg, &gpcntl);
+	if (ack_data & 0x01)
+		goto out;
+
+	/* now set up GPIO0 for inputting data */
+	gpcntl |= 0x01;
+	OUTB (nc_gpcntl, gpcntl);
+		
+	/* input all requested data - only part of total NVRAM */
+	for (x = 0; x < len; x++) 
+		S24C16_read_byte(np, &data[x], (x == (len-1)), &gpreg, &gpcntl);
+
+	/* finally put NVRAM back in inactive mode */
+	gpcntl &= 0xfe;
+	OUTB (nc_gpcntl, gpcntl);
+	S24C16_stop(np, &gpreg);
+	retv = 0;
+out:
+	/* return GPIO0/1 to original states after having accessed NVRAM */
+	OUTB (nc_gpcntl, old_gpcntl);
+	OUTB (nc_gpreg,  old_gpreg);
+
+	return retv;
+}
+
+#undef SET_BIT 0
+#undef CLR_BIT 1
+#undef SET_CLK 2
+#undef CLR_CLK 3
+
+/*
+ *  Try reading Symbios NVRAM.
+ *  Return 0 if OK.
+ */
+static int sym_read_Symbios_nvram (sdev_p np, Symbios_nvram *nvram)
+{
+	static u_char Symbios_trailer[6] = {0xfe, 0xfe, 0, 0, 0, 0};
+	u_char *data = (u_char *) nvram;
+	int len  = sizeof(*nvram);
+	u_short	csum;
+	int x;
+
+	/* probe the 24c16 and read the SYMBIOS 24c16 area */
+	if (sym_read_S24C16_nvram (np, SYMBIOS_NVRAM_ADDRESS, data, len))
+		return 1;
+
+	/* check valid NVRAM signature, verify byte count and checksum */
+	if (nvram->type != 0 ||
+	    bcmp(nvram->trailer, Symbios_trailer, 6) ||
+	    nvram->byte_count != len - 12)
+		return 1;
+
+	/* verify checksum */
+	for (x = 6, csum = 0; x < len - 6; x++)
+		csum += data[x];
+	if (csum != nvram->checksum)
+		return 1;
+
+	return 0;
+}
+
+/*
+ *  93C46 EEPROM reading.
+ *
+ *  GPOI0 - data in
+ *  GPIO1 - data out
+ *  GPIO2 - clock
+ *  GPIO4 - chip select
+ *
+ *  Used by Tekram.
+ */
+
+/*
+ *  Pulse clock bit in GPIO0
+ */
+static void T93C46_Clk(sdev_p np, u_char *gpreg)
+{
+	OUTB (nc_gpreg, *gpreg | 0x04);
+	UDELAY (2);
+	OUTB (nc_gpreg, *gpreg);
+}
+
+/* 
+ *  Read bit from NVRAM
+ */
+static void T93C46_Read_Bit(sdev_p np, u_char *read_bit, u_char *gpreg)
+{
+	UDELAY (2);
+	T93C46_Clk(np, gpreg);
+	*read_bit = INB (nc_gpreg);
+}
+
+/*
+ *  Write bit to GPIO0
+ */
+static void T93C46_Write_Bit(sdev_p np, u_char write_bit, u_char *gpreg)
+{
+	if (write_bit & 0x01)
+		*gpreg |= 0x02;
+	else
+		*gpreg &= 0xfd;
+		
+	*gpreg |= 0x10;
+		
+	OUTB (nc_gpreg, *gpreg);
+	UDELAY (2);
+
+	T93C46_Clk(np, gpreg);
+}
+
+/*
+ *  Send STOP condition to NVRAM - puts NVRAM to sleep... ZZZzzz!!
+ */
+static void T93C46_Stop(sdev_p np, u_char *gpreg)
+{
+	*gpreg &= 0xef;
+	OUTB (nc_gpreg, *gpreg);
+	UDELAY (2);
+
+	T93C46_Clk(np, gpreg);
+}
+
+/*
+ *  Send read command and address to NVRAM
+ */
+static void T93C46_Send_Command(sdev_p np, u_short write_data, 
+				u_char *read_bit, u_char *gpreg)
+{
+	int x;
+
+	/* send 9 bits, start bit (1), command (2), address (6)  */
+	for (x = 0; x < 9; x++)
+		T93C46_Write_Bit(np, (u_char) (write_data >> (8 - x)), gpreg);
+
+	*read_bit = INB (nc_gpreg);
+}
+
+/*
+ *  READ 2 bytes from the NVRAM
+ */
+static void T93C46_Read_Word(sdev_p np, u_short *nvram_data, u_char *gpreg)
+{
+	int x;
+	u_char read_bit;
+
+	*nvram_data = 0;
+	for (x = 0; x < 16; x++) {
+		T93C46_Read_Bit(np, &read_bit, gpreg);
+
+		if (read_bit & 0x01)
+			*nvram_data |=  (0x01 << (15 - x));
+		else
+			*nvram_data &= ~(0x01 << (15 - x));
+	}
+}
+
+/*
+ *  Read Tekram NvRAM data.
+ */
+static int T93C46_Read_Data(sdev_p np, u_short *data,int len,u_char *gpreg)
+{
+	u_char	read_bit;
+	int	x;
+
+	for (x = 0; x < len; x++)  {
+
+		/* output read command and address */
+		T93C46_Send_Command(np, 0x180 | x, &read_bit, gpreg);
+		if (read_bit & 0x01)
+			return 1; /* Bad */
+		T93C46_Read_Word(np, &data[x], gpreg);
+		T93C46_Stop(np, gpreg);
+	}
+
+	return 0;
+}
+
+/*
+ *  Try reading 93C46 Tekram NVRAM.
+ */
+static int sym_read_T93C46_nvram (sdev_p np, Tekram_nvram *nvram)
+{
+	u_char gpcntl, gpreg;
+	u_char old_gpcntl, old_gpreg;
+	int retv = 1;
+
+	/* save current state of GPCNTL and GPREG */
+	old_gpreg	= INB (nc_gpreg);
+	old_gpcntl	= INB (nc_gpcntl);
+
+	/* set up GPREG & GPCNTL to set GPIO0/1/2/4 in to known state, 0 in,
+	   1/2/4 out */
+	gpreg = old_gpreg & 0xe9;
+	OUTB (nc_gpreg, gpreg);
+	gpcntl = (old_gpcntl & 0xe9) | 0x09;
+	OUTB (nc_gpcntl, gpcntl);
+
+	/* input all of NVRAM, 64 words */
+	retv = T93C46_Read_Data(np, (u_short *) nvram,
+				sizeof(*nvram) / sizeof(short), &gpreg);
+	
+	/* return GPIO0/1/2/4 to original states after having accessed NVRAM */
+	OUTB (nc_gpcntl, old_gpcntl);
+	OUTB (nc_gpreg,  old_gpreg);
+
+	return retv;
+}
+
+/*
+ *  Try reading Tekram NVRAM.
+ *  Return 0 if OK.
+ */
+static int sym_read_Tekram_nvram (sdev_p np, Tekram_nvram *nvram)
+{
+	u_char *data = (u_char *) nvram;
+	int len = sizeof(*nvram);
+	u_short	csum;
+	int x;
+
+	switch (np->device_id) {
+	case PCI_ID_SYM53C885:
+	case PCI_ID_SYM53C895:
+	case PCI_ID_SYM53C896:
+		x = sym_read_S24C16_nvram(np, TEKRAM_24C16_NVRAM_ADDRESS,
+					  data, len);
+		break;
+	case PCI_ID_SYM53C875:
+		x = sym_read_S24C16_nvram(np, TEKRAM_24C16_NVRAM_ADDRESS,
+					  data, len);
+		if (!x)
+			break;
+	default:
+		x = sym_read_T93C46_nvram(np, nvram);
+		break;
+	}
+	if (x)
+		return 1;
+
+	/* verify checksum */
+	for (x = 0, csum = 0; x < len - 1; x += 2)
+		csum += data[x] + (data[x+1] << 8);
+	if (csum != 0x1234)
+		return 1;
+
+	return 0;
+}
+
+#endif	/* SYM_CONF_NVRAM_SUPPORT */