/*
 * Copyright (c) 2006, 2007 QLogic Corporation. All rights reserved.
 * Copyright (c) 2003, 2004, 2005, 2006 PathScale, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/delay.h>
#include <linux/pci.h>
#include <linux/vmalloc.h>

#include "ipath_kernel.h"

/*
 * InfiniPath I2C driver for a serial eeprom.  This is not a generic
 * I2C interface.  For a start, the device we're using (Atmel AT24C11)
 * doesn't work like a regular I2C device.  It looks like one
 * electrically, but not logically.  Normal I2C devices have a single
 * 7-bit or 10-bit I2C address that they respond to.  Valid 7-bit
 * addresses range from 0x03 to 0x77.  Addresses 0x00 to 0x02 and 0x78
 * to 0x7F are special reserved addresses (e.g. 0x00 is the "general
 * call" address.)  The Atmel device, on the other hand, responds to ALL
 * 7-bit addresses.  It's designed to be the only device on a given I2C
 * bus.  A 7-bit address corresponds to the memory address within the
 * Atmel device itself.
 *
 * Also, the timing requirements mean more than simple software
 * bitbanging, with readbacks from chip to ensure timing (simple udelay
 * is not enough).
 *
 * This all means that accessing the device is specialized enough
 * that using the standard kernel I2C bitbanging interface would be
 * impossible.  For example, the core I2C eeprom driver expects to find
 * a device at one or more of a limited set of addresses only.  It doesn't
 * allow writing to an eeprom.  It also doesn't provide any means of
 * accessing eeprom contents from within the kernel, only via sysfs.
 */

/* Added functionality for IBA7220-based cards */
#define IPATH_EEPROM_DEV_V1 0xA0
#define IPATH_EEPROM_DEV_V2 0xA2
#define IPATH_TEMP_DEV 0x98
#define IPATH_BAD_DEV (IPATH_EEPROM_DEV_V2+2)
#define IPATH_NO_DEV (0xFF)

/*
 * The number of I2C chains is proliferating. Table below brings
 * some order to the madness. The basic principle is that the
 * table is scanned from the top, and a "probe" is made to the
 * device probe_dev. If that succeeds, the chain is considered
 * to be of that type, and dd->i2c_chain_type is set to the index+1
 * of the entry.
 * The +1 is so static initialization can mean "unknown, do probe."
 */
static struct i2c_chain_desc {
	u8 probe_dev;	/* If seen at probe, chain is this type */
	u8 eeprom_dev;	/* Dev addr (if any) for EEPROM */
	u8 temp_dev;	/* Dev Addr (if any) for Temp-sense */
} i2c_chains[] = {
	{ IPATH_BAD_DEV, IPATH_NO_DEV, IPATH_NO_DEV }, /* pre-iba7220 bds */
	{ IPATH_EEPROM_DEV_V1, IPATH_EEPROM_DEV_V1, IPATH_TEMP_DEV}, /* V1 */
	{ IPATH_EEPROM_DEV_V2, IPATH_EEPROM_DEV_V2, IPATH_TEMP_DEV}, /* V2 */
	{ IPATH_NO_DEV }
};

enum i2c_type {
	i2c_line_scl = 0,
	i2c_line_sda
};

enum i2c_state {
	i2c_line_low = 0,
	i2c_line_high
};

#define READ_CMD 1
#define WRITE_CMD 0

/**
 * i2c_gpio_set - set a GPIO line
 * @dd: the infinipath device
 * @line: the line to set
 * @new_line_state: the state to set
 *
 * Returns 0 if the line was set to the new state successfully, non-zero
 * on error.
 */
static int i2c_gpio_set(struct ipath_devdata *dd,
			enum i2c_type line,
			enum i2c_state new_line_state)
{
	u64 out_mask, dir_mask, *gpioval;
	unsigned long flags = 0;

	gpioval = &dd->ipath_gpio_out;

	if (line == i2c_line_scl) {
		dir_mask = dd->ipath_gpio_scl;
		out_mask = (1UL << dd->ipath_gpio_scl_num);
	} else {
		dir_mask = dd->ipath_gpio_sda;
		out_mask = (1UL << dd->ipath_gpio_sda_num);
	}

	spin_lock_irqsave(&dd->ipath_gpio_lock, flags);
	if (new_line_state == i2c_line_high) {
		/* tri-state the output rather than force high */
		dd->ipath_extctrl &= ~dir_mask;
	} else {
		/* config line to be an output */
		dd->ipath_extctrl |= dir_mask;
	}
	ipath_write_kreg(dd, dd->ipath_kregs->kr_extctrl, dd->ipath_extctrl);

	/* set output as well (no real verify) */
	if (new_line_state == i2c_line_high)
		*gpioval |= out_mask;
	else
		*gpioval &= ~out_mask;

	ipath_write_kreg(dd, dd->ipath_kregs->kr_gpio_out, *gpioval);
	spin_unlock_irqrestore(&dd->ipath_gpio_lock, flags);

	return 0;
}

/**
 * i2c_gpio_get - get a GPIO line state
 * @dd: the infinipath device
 * @line: the line to get
 * @curr_statep: where to put the line state
 *
 * Returns 0 if the line was set to the new state successfully, non-zero
 * on error.  curr_state is not set on error.
 */
static int i2c_gpio_get(struct ipath_devdata *dd,
			enum i2c_type line,
			enum i2c_state *curr_statep)
{
	u64 read_val, mask;
	int ret;
	unsigned long flags = 0;

	/* check args */
	if (curr_statep == NULL) {
		ret = 1;
		goto bail;
	}

	/* config line to be an input */
	if (line == i2c_line_scl)
		mask = dd->ipath_gpio_scl;
	else
		mask = dd->ipath_gpio_sda;

	spin_lock_irqsave(&dd->ipath_gpio_lock, flags);
	dd->ipath_extctrl &= ~mask;
	ipath_write_kreg(dd, dd->ipath_kregs->kr_extctrl, dd->ipath_extctrl);
	/*
	 * Below is very unlikely to reflect true input state if Output
	 * Enable actually changed.
	 */
	read_val = ipath_read_kreg64(dd, dd->ipath_kregs->kr_extstatus);
	spin_unlock_irqrestore(&dd->ipath_gpio_lock, flags);

	if (read_val & mask)
		*curr_statep = i2c_line_high;
	else
		*curr_statep = i2c_line_low;

	ret = 0;

bail:
	return ret;
}

/**
 * i2c_wait_for_writes - wait for a write
 * @dd: the infinipath device
 *
 * We use this instead of udelay directly, so we can make sure
 * that previous register writes have been flushed all the way
 * to the chip.  Since we are delaying anyway, the cost doesn't
 * hurt, and makes the bit twiddling more regular
 */
static void i2c_wait_for_writes(struct ipath_devdata *dd)
{
	(void)ipath_read_kreg32(dd, dd->ipath_kregs->kr_scratch);
	rmb();
}

static void scl_out(struct ipath_devdata *dd, u8 bit)
{
	udelay(1);
	i2c_gpio_set(dd, i2c_line_scl, bit ? i2c_line_high : i2c_line_low);

	i2c_wait_for_writes(dd);
}

static void sda_out(struct ipath_devdata *dd, u8 bit)
{
	i2c_gpio_set(dd, i2c_line_sda, bit ? i2c_line_high : i2c_line_low);

	i2c_wait_for_writes(dd);
}

static u8 sda_in(struct ipath_devdata *dd, int wait)
{
	enum i2c_state bit;

	if (i2c_gpio_get(dd, i2c_line_sda, &bit))
		ipath_dbg("get bit failed!\n");

	if (wait)
		i2c_wait_for_writes(dd);

	return bit == i2c_line_high ? 1U : 0;
}

/**
 * i2c_ackrcv - see if ack following write is true
 * @dd: the infinipath device
 */
static int i2c_ackrcv(struct ipath_devdata *dd)
{
	u8 ack_received;

	/* AT ENTRY SCL = LOW */
	/* change direction, ignore data */
	ack_received = sda_in(dd, 1);
	scl_out(dd, i2c_line_high);
	ack_received = sda_in(dd, 1) == 0;
	scl_out(dd, i2c_line_low);
	return ack_received;
}

/**
 * rd_byte - read a byte, leaving ACK, STOP, etc up to caller
 * @dd: the infinipath device
 *
 * Returns byte shifted out of device
 */
static int rd_byte(struct ipath_devdata *dd)
{
	int bit_cntr, data;

	data = 0;

	for (bit_cntr = 7; bit_cntr >= 0; --bit_cntr) {
		data <<= 1;
		scl_out(dd, i2c_line_high);
		data |= sda_in(dd, 0);
		scl_out(dd, i2c_line_low);
	}
	return data;
}

/**
 * wr_byte - write a byte, one bit at a time
 * @dd: the infinipath device
 * @data: the byte to write
 *
 * Returns 0 if we got the following ack, otherwise 1
 */
static int wr_byte(struct ipath_devdata *dd, u8 data)
{
	int bit_cntr;
	u8 bit;

	for (bit_cntr = 7; bit_cntr >= 0; bit_cntr--) {
		bit = (data >> bit_cntr) & 1;
		sda_out(dd, bit);
		scl_out(dd, i2c_line_high);
		scl_out(dd, i2c_line_low);
	}
	return (!i2c_ackrcv(dd)) ? 1 : 0;
}

static void send_ack(struct ipath_devdata *dd)
{
	sda_out(dd, i2c_line_low);
	scl_out(dd, i2c_line_high);
	scl_out(dd, i2c_line_low);
	sda_out(dd, i2c_line_high);
}

/**
 * i2c_startcmd - transmit the start condition, followed by address/cmd
 * @dd: the infinipath device
 * @offset_dir: direction byte
 *
 *      (both clock/data high, clock high, data low while clock is high)
 */
static int i2c_startcmd(struct ipath_devdata *dd, u8 offset_dir)
{
	int res;

	/* issue start sequence */
	sda_out(dd, i2c_line_high);
	scl_out(dd, i2c_line_high);
	sda_out(dd, i2c_line_low);
	scl_out(dd, i2c_line_low);

	/* issue length and direction byte */
	res = wr_byte(dd, offset_dir);

	if (res)
		ipath_cdbg(VERBOSE, "No ack to complete start\n");

	return res;
}

/**
 * stop_cmd - transmit the stop condition
 * @dd: the infinipath device
 *
 * (both clock/data low, clock high, data high while clock is high)
 */
static void stop_cmd(struct ipath_devdata *dd)
{
	scl_out(dd, i2c_line_low);
	sda_out(dd, i2c_line_low);
	scl_out(dd, i2c_line_high);
	sda_out(dd, i2c_line_high);
	udelay(2);
}

/**
 * eeprom_reset - reset I2C communication
 * @dd: the infinipath device
 */

static int eeprom_reset(struct ipath_devdata *dd)
{
	int clock_cycles_left = 9;
	u64 *gpioval = &dd->ipath_gpio_out;
	int ret;
	unsigned long flags;

	spin_lock_irqsave(&dd->ipath_gpio_lock, flags);
	/* Make sure shadows are consistent */
	dd->ipath_extctrl = ipath_read_kreg64(dd, dd->ipath_kregs->kr_extctrl);
	*gpioval = ipath_read_kreg64(dd, dd->ipath_kregs->kr_gpio_out);
	spin_unlock_irqrestore(&dd->ipath_gpio_lock, flags);

	ipath_cdbg(VERBOSE, "Resetting i2c eeprom; initial gpioout reg "
		   "is %llx\n", (unsigned long long) *gpioval);

	/*
	 * This is to get the i2c into a known state, by first going low,
	 * then tristate sda (and then tristate scl as first thing
	 * in loop)
	 */
	scl_out(dd, i2c_line_low);
	sda_out(dd, i2c_line_high);

	/* Clock up to 9 cycles looking for SDA hi, then issue START and STOP */
	while (clock_cycles_left--) {
		scl_out(dd, i2c_line_high);

		/* SDA seen high, issue START by dropping it while SCL high */
		if (sda_in(dd, 0)) {
			sda_out(dd, i2c_line_low);
			scl_out(dd, i2c_line_low);
			/* ATMEL spec says must be followed by STOP. */
			scl_out(dd, i2c_line_high);
			sda_out(dd, i2c_line_high);
			ret = 0;
			goto bail;
		}

		scl_out(dd, i2c_line_low);
	}

	ret = 1;

bail:
	return ret;
}

/*
 * Probe for I2C device at specified address. Returns 0 for "success"
 * to match rest of this file.
 * Leave bus in "reasonable" state for further commands.
 */
static int i2c_probe(struct ipath_devdata *dd, int devaddr)
{
	int ret = 0;

	ret = eeprom_reset(dd);
	if (ret) {
		ipath_dev_err(dd, "Failed reset probing device 0x%02X\n",
			      devaddr);
		return ret;
	}
	/*
	 * Reset no longer leaves bus in start condition, so normal
	 * i2c_startcmd() will do.
	 */
	ret = i2c_startcmd(dd, devaddr | READ_CMD);
	if (ret)
		ipath_cdbg(VERBOSE, "Failed startcmd for device 0x%02X\n",
			   devaddr);
	else {
		/*
		 * Device did respond. Complete a single-byte read, because some
		 * devices apparently cannot handle STOP immediately after they
		 * ACK the start-cmd.
		 */
		int data;
		data = rd_byte(dd);
		stop_cmd(dd);
		ipath_cdbg(VERBOSE, "Response from device 0x%02X\n", devaddr);
	}
	return ret;
}

/*
 * Returns the "i2c type". This is a pointer to a struct that describes
 * the I2C chain on this board. To minimize impact on struct ipath_devdata,
 * the (small integer) index into the table is actually memoized, rather
 * then the pointer.
 * Memoization is because the type is determined on the first call per chip.
 * An alternative would be to move type determination to early
 * init code.
 */
static struct i2c_chain_desc *ipath_i2c_type(struct ipath_devdata *dd)
{
	int idx;

	/* Get memoized index, from previous successful probes */
	idx = dd->ipath_i2c_chain_type - 1;
	if (idx >= 0 && idx < (ARRAY_SIZE(i2c_chains) - 1))
		goto done;

	idx = 0;
	while (i2c_chains[idx].probe_dev != IPATH_NO_DEV) {
		/* if probe succeeds, this is type */
		if (!i2c_probe(dd, i2c_chains[idx].probe_dev))
			break;
		++idx;
	}

	/*
	 * Old EEPROM (first entry) may require a reset after probe,
	 * rather than being able to "start" after "stop"
	 */
	if (idx == 0)
		eeprom_reset(dd);

	if (i2c_chains[idx].probe_dev == IPATH_NO_DEV)
		idx = -1;
	else
		dd->ipath_i2c_chain_type = idx + 1;
done:
	return (idx >= 0) ? i2c_chains + idx : NULL;
}

static int ipath_eeprom_internal_read(struct ipath_devdata *dd,
					u8 eeprom_offset, void *buffer, int len)
{
	int ret;
	struct i2c_chain_desc *icd;
	u8 *bp = buffer;

	ret = 1;
	icd = ipath_i2c_type(dd);
	if (!icd)
		goto bail;

	if (icd->eeprom_dev == IPATH_NO_DEV) {
		/* legacy not-really-I2C */
		ipath_cdbg(VERBOSE, "Start command only address\n");
		eeprom_offset = (eeprom_offset << 1) | READ_CMD;
		ret = i2c_startcmd(dd, eeprom_offset);
	} else {
		/* Actual I2C */
		ipath_cdbg(VERBOSE, "Start command uses devaddr\n");
		if (i2c_startcmd(dd, icd->eeprom_dev | WRITE_CMD)) {
			ipath_dbg("Failed EEPROM startcmd\n");
			stop_cmd(dd);
			ret = 1;
			goto bail;
		}
		ret = wr_byte(dd, eeprom_offset);
		stop_cmd(dd);
		if (ret) {
			ipath_dev_err(dd, "Failed to write EEPROM address\n");
			ret = 1;
			goto bail;
		}
		ret = i2c_startcmd(dd, icd->eeprom_dev | READ_CMD);
	}
	if (ret) {
		ipath_dbg("Failed startcmd for dev %02X\n", icd->eeprom_dev);
		stop_cmd(dd);
		ret = 1;
		goto bail;
	}

	/*
	 * eeprom keeps clocking data out as long as we ack, automatically
	 * incrementing the address.
	 */
	while (len-- > 0) {
		/* get and store data */
		*bp++ = rd_byte(dd);
		/* send ack if not the last byte */
		if (len)
			send_ack(dd);
	}

	stop_cmd(dd);

	ret = 0;

bail:
	return ret;
}

static int ipath_eeprom_internal_write(struct ipath_devdata *dd, u8 eeprom_offset,
				       const void *buffer, int len)
{
	int sub_len;
	const u8 *bp = buffer;
	int max_wait_time, i;
	int ret;
	struct i2c_chain_desc *icd;

	ret = 1;
	icd = ipath_i2c_type(dd);
	if (!icd)
		goto bail;

	while (len > 0) {
		if (icd->eeprom_dev == IPATH_NO_DEV) {
			if (i2c_startcmd(dd,
					 (eeprom_offset << 1) | WRITE_CMD)) {
				ipath_dbg("Failed to start cmd offset %u\n",
					eeprom_offset);
				goto failed_write;
			}
		} else {
			/* Real I2C */
			if (i2c_startcmd(dd, icd->eeprom_dev | WRITE_CMD)) {
				ipath_dbg("Failed EEPROM startcmd\n");
				goto failed_write;
			}
			ret = wr_byte(dd, eeprom_offset);
			if (ret) {
				ipath_dev_err(dd, "Failed to write EEPROM "
					      "address\n");
				goto failed_write;
			}
		}

		sub_len = min(len, 4);
		eeprom_offset += sub_len;
		len -= sub_len;

		for (i = 0; i < sub_len; i++) {
			if (wr_byte(dd, *bp++)) {
				ipath_dbg("no ack after byte %u/%u (%u "
					  "total remain)\n", i, sub_len,
					  len + sub_len - i);
				goto failed_write;
			}
		}

		stop_cmd(dd);

		/*
		 * wait for write complete by waiting for a successful
		 * read (the chip replies with a zero after the write
		 * cmd completes, and before it writes to the eeprom.
		 * The startcmd for the read will fail the ack until
		 * the writes have completed.   We do this inline to avoid
		 * the debug prints that are in the real read routine
		 * if the startcmd fails.
		 * We also use the proper device address, so it doesn't matter
		 * whether we have real eeprom_dev. legacy likes any address.
		 */
		max_wait_time = 100;
		while (i2c_startcmd(dd, icd->eeprom_dev | READ_CMD)) {
			stop_cmd(dd);
			if (!--max_wait_time) {
				ipath_dbg("Did not get successful read to "
					  "complete write\n");
				goto failed_write;
			}
		}
		/* now read (and ignore) the resulting byte */
		rd_byte(dd);
		stop_cmd(dd);
	}

	ret = 0;
	goto bail;

failed_write:
	stop_cmd(dd);
	ret = 1;

bail:
	return ret;
}

/**
 * ipath_eeprom_read - receives bytes from the eeprom via I2C
 * @dd: the infinipath device
 * @eeprom_offset: address to read from
 * @buffer: where to store result
 * @len: number of bytes to receive
 */
int ipath_eeprom_read(struct ipath_devdata *dd, u8 eeprom_offset,
			void *buff, int len)
{
	int ret;

	ret = mutex_lock_interruptible(&dd->ipath_eep_lock);
	if (!ret) {
		ret = ipath_eeprom_internal_read(dd, eeprom_offset, buff, len);
		mutex_unlock(&dd->ipath_eep_lock);
	}

	return ret;
}

/**
 * ipath_eeprom_write - writes data to the eeprom via I2C
 * @dd: the infinipath device
 * @eeprom_offset: where to place data
 * @buffer: data to write
 * @len: number of bytes to write
 */
int ipath_eeprom_write(struct ipath_devdata *dd, u8 eeprom_offset,
			const void *buff, int len)
{
	int ret;

	ret = mutex_lock_interruptible(&dd->ipath_eep_lock);
	if (!ret) {
		ret = ipath_eeprom_internal_write(dd, eeprom_offset, buff, len);
		mutex_unlock(&dd->ipath_eep_lock);
	}

	return ret;
}

static u8 flash_csum(struct ipath_flash *ifp, int adjust)
{
	u8 *ip = (u8 *) ifp;
	u8 csum = 0, len;

	/*
	 * Limit length checksummed to max length of actual data.
	 * Checksum of erased eeprom will still be bad, but we avoid
	 * reading past the end of the buffer we were passed.
	 */
	len = ifp->if_length;
	if (len > sizeof(struct ipath_flash))
		len = sizeof(struct ipath_flash);
	while (len--)
		csum += *ip++;
	csum -= ifp->if_csum;
	csum = ~csum;
	if (adjust)
		ifp->if_csum = csum;

	return csum;
}

/**
 * ipath_get_guid - get the GUID from the i2c device
 * @dd: the infinipath device
 *
 * We have the capability to use the ipath_nguid field, and get
 * the guid from the first chip's flash, to use for all of them.
 */
void ipath_get_eeprom_info(struct ipath_devdata *dd)
{
	void *buf;
	struct ipath_flash *ifp;
	__be64 guid;
	int len, eep_stat;
	u8 csum, *bguid;
	int t = dd->ipath_unit;
	struct ipath_devdata *dd0 = ipath_lookup(0);

	if (t && dd0->ipath_nguid > 1 && t <= dd0->ipath_nguid) {
		u8 oguid;
		dd->ipath_guid = dd0->ipath_guid;
		bguid = (u8 *) & dd->ipath_guid;

		oguid = bguid[7];
		bguid[7] += t;
		if (oguid > bguid[7]) {
			if (bguid[6] == 0xff) {
				if (bguid[5] == 0xff) {
					ipath_dev_err(
						dd,
						"Can't set %s GUID from "
						"base, wraps to OUI!\n",
						ipath_get_unit_name(t));
					dd->ipath_guid = 0;
					goto bail;
				}
				bguid[5]++;
			}
			bguid[6]++;
		}
		dd->ipath_nguid = 1;

		ipath_dbg("nguid %u, so adding %u to device 0 guid, "
			  "for %llx\n",
			  dd0->ipath_nguid, t,
			  (unsigned long long) be64_to_cpu(dd->ipath_guid));
		goto bail;
	}

	/*
	 * read full flash, not just currently used part, since it may have
	 * been written with a newer definition
	 * */
	len = sizeof(struct ipath_flash);
	buf = vmalloc(len);
	if (!buf) {
		ipath_dev_err(dd, "Couldn't allocate memory to read %u "
			      "bytes from eeprom for GUID\n", len);
		goto bail;
	}

	mutex_lock(&dd->ipath_eep_lock);
	eep_stat = ipath_eeprom_internal_read(dd, 0, buf, len);
	mutex_unlock(&dd->ipath_eep_lock);

	if (eep_stat) {
		ipath_dev_err(dd, "Failed reading GUID from eeprom\n");
		goto done;
	}
	ifp = (struct ipath_flash *)buf;

	csum = flash_csum(ifp, 0);
	if (csum != ifp->if_csum) {
		dev_info(&dd->pcidev->dev, "Bad I2C flash checksum: "
			 "0x%x, not 0x%x\n", csum, ifp->if_csum);
		goto done;
	}
	if (*(__be64 *) ifp->if_guid == 0ULL ||
	    *(__be64 *) ifp->if_guid == __constant_cpu_to_be64(-1LL)) {
		ipath_dev_err(dd, "Invalid GUID %llx from flash; "
			      "ignoring\n",
			      *(unsigned long long *) ifp->if_guid);
		/* don't allow GUID if all 0 or all 1's */
		goto done;
	}

	/* complain, but allow it */
	if (*(u64 *) ifp->if_guid == 0x100007511000000ULL)
		dev_info(&dd->pcidev->dev, "Warning, GUID %llx is "
			 "default, probably not correct!\n",
			 *(unsigned long long *) ifp->if_guid);

	bguid = ifp->if_guid;
	if (!bguid[0] && !bguid[1] && !bguid[2]) {
		/* original incorrect GUID format in flash; fix in
		 * core copy, by shifting up 2 octets; don't need to
		 * change top octet, since both it and shifted are
		 * 0.. */
		bguid[1] = bguid[3];
		bguid[2] = bguid[4];
		bguid[3] = bguid[4] = 0;
		guid = *(__be64 *) ifp->if_guid;
		ipath_cdbg(VERBOSE, "Old GUID format in flash, top 3 zero, "
			   "shifting 2 octets\n");
	} else
		guid = *(__be64 *) ifp->if_guid;
	dd->ipath_guid = guid;
	dd->ipath_nguid = ifp->if_numguid;
	/*
	 * Things are slightly complicated by the desire to transparently
	 * support both the Pathscale 10-digit serial number and the QLogic
	 * 13-character version.
	 */
	if ((ifp->if_fversion > 1) && ifp->if_sprefix[0]
		&& ((u8 *)ifp->if_sprefix)[0] != 0xFF) {
		/* This board has a Serial-prefix, which is stored
		 * elsewhere for backward-compatibility.
		 */
		char *snp = dd->ipath_serial;
		memcpy(snp, ifp->if_sprefix, sizeof ifp->if_sprefix);
		snp[sizeof ifp->if_sprefix] = '\0';
		len = strlen(snp);
		snp += len;
		len = (sizeof dd->ipath_serial) - len;
		if (len > sizeof ifp->if_serial) {
			len = sizeof ifp->if_serial;
		}
		memcpy(snp, ifp->if_serial, len);
	} else
		memcpy(dd->ipath_serial, ifp->if_serial,
		       sizeof ifp->if_serial);
	if (!strstr(ifp->if_comment, "Tested successfully"))
		ipath_dev_err(dd, "Board SN %s did not pass functional "
			"test: %s\n", dd->ipath_serial,
			ifp->if_comment);

	ipath_cdbg(VERBOSE, "Initted GUID to %llx from eeprom\n",
		   (unsigned long long) be64_to_cpu(dd->ipath_guid));

	memcpy(&dd->ipath_eep_st_errs, &ifp->if_errcntp, IPATH_EEP_LOG_CNT);
	/*
	 * Power-on (actually "active") hours are kept as little-endian value
	 * in EEPROM, but as seconds in a (possibly as small as 24-bit)
	 * atomic_t while running.
	 */
	atomic_set(&dd->ipath_active_time, 0);
	dd->ipath_eep_hrs = ifp->if_powerhour[0] | (ifp->if_powerhour[1] << 8);

done:
	vfree(buf);

bail:;
}

/**
 * ipath_update_eeprom_log - copy active-time and error counters to eeprom
 * @dd: the infinipath device
 *
 * Although the time is kept as seconds in the ipath_devdata struct, it is
 * rounded to hours for re-write, as we have only 16 bits in EEPROM.
 * First-cut code reads whole (expected) struct ipath_flash, modifies,
 * re-writes. Future direction: read/write only what we need, assuming
 * that the EEPROM had to have been "good enough" for driver init, and
 * if not, we aren't making it worse.
 *
 */

int ipath_update_eeprom_log(struct ipath_devdata *dd)
{
	void *buf;
	struct ipath_flash *ifp;
	int len, hi_water;
	uint32_t new_time, new_hrs;
	u8 csum;
	int ret, idx;
	unsigned long flags;

	/* first, check if we actually need to do anything. */
	ret = 0;
	for (idx = 0; idx < IPATH_EEP_LOG_CNT; ++idx) {
		if (dd->ipath_eep_st_new_errs[idx]) {
			ret = 1;
			break;
		}
	}
	new_time = atomic_read(&dd->ipath_active_time);

	if (ret == 0 && new_time < 3600)
		return 0;

	/*
	 * The quick-check above determined that there is something worthy
	 * of logging, so get current contents and do a more detailed idea.
	 * read full flash, not just currently used part, since it may have
	 * been written with a newer definition
	 */
	len = sizeof(struct ipath_flash);
	buf = vmalloc(len);
	ret = 1;
	if (!buf) {
		ipath_dev_err(dd, "Couldn't allocate memory to read %u "
				"bytes from eeprom for logging\n", len);
		goto bail;
	}

	/* Grab semaphore and read current EEPROM. If we get an
	 * error, let go, but if not, keep it until we finish write.
	 */
	ret = mutex_lock_interruptible(&dd->ipath_eep_lock);
	if (ret) {
		ipath_dev_err(dd, "Unable to acquire EEPROM for logging\n");
		goto free_bail;
	}
	ret = ipath_eeprom_internal_read(dd, 0, buf, len);
	if (ret) {
		mutex_unlock(&dd->ipath_eep_lock);
		ipath_dev_err(dd, "Unable read EEPROM for logging\n");
		goto free_bail;
	}
	ifp = (struct ipath_flash *)buf;

	csum = flash_csum(ifp, 0);
	if (csum != ifp->if_csum) {
		mutex_unlock(&dd->ipath_eep_lock);
		ipath_dev_err(dd, "EEPROM cks err (0x%02X, S/B 0x%02X)\n",
				csum, ifp->if_csum);
		ret = 1;
		goto free_bail;
	}
	hi_water = 0;
	spin_lock_irqsave(&dd->ipath_eep_st_lock, flags);
	for (idx = 0; idx < IPATH_EEP_LOG_CNT; ++idx) {
		int new_val = dd->ipath_eep_st_new_errs[idx];
		if (new_val) {
			/*
			 * If we have seen any errors, add to EEPROM values
			 * We need to saturate at 0xFF (255) and we also
			 * would need to adjust the checksum if we were
			 * trying to minimize EEPROM traffic
			 * Note that we add to actual current count in EEPROM,
			 * in case it was altered while we were running.
			 */
			new_val += ifp->if_errcntp[idx];
			if (new_val > 0xFF)
				new_val = 0xFF;
			if (ifp->if_errcntp[idx] != new_val) {
				ifp->if_errcntp[idx] = new_val;
				hi_water = offsetof(struct ipath_flash,
						if_errcntp) + idx;
			}
			/*
			 * update our shadow (used to minimize EEPROM
			 * traffic), to match what we are about to write.
			 */
			dd->ipath_eep_st_errs[idx] = new_val;
			dd->ipath_eep_st_new_errs[idx] = 0;
		}
	}
	/*
	 * now update active-time. We would like to round to the nearest hour
	 * but unless atomic_t are sure to be proper signed ints we cannot,
	 * because we need to account for what we "transfer" to EEPROM and
	 * if we log an hour at 31 minutes, then we would need to set
	 * active_time to -29 to accurately count the _next_ hour.
	 */
	if (new_time >= 3600) {
		new_hrs = new_time / 3600;
		atomic_sub((new_hrs * 3600), &dd->ipath_active_time);
		new_hrs += dd->ipath_eep_hrs;
		if (new_hrs > 0xFFFF)
			new_hrs = 0xFFFF;
		dd->ipath_eep_hrs = new_hrs;
		if ((new_hrs & 0xFF) != ifp->if_powerhour[0]) {
			ifp->if_powerhour[0] = new_hrs & 0xFF;
			hi_water = offsetof(struct ipath_flash, if_powerhour);
		}
		if ((new_hrs >> 8) != ifp->if_powerhour[1]) {
			ifp->if_powerhour[1] = new_hrs >> 8;
			hi_water = offsetof(struct ipath_flash, if_powerhour)
					+ 1;
		}
	}
	/*
	 * There is a tiny possibility that we could somehow fail to write
	 * the EEPROM after updating our shadows, but problems from holding
	 * the spinlock too long are a much bigger issue.
	 */
	spin_unlock_irqrestore(&dd->ipath_eep_st_lock, flags);
	if (hi_water) {
		/* we made some change to the data, uopdate cksum and write */
		csum = flash_csum(ifp, 1);
		ret = ipath_eeprom_internal_write(dd, 0, buf, hi_water + 1);
	}
	mutex_unlock(&dd->ipath_eep_lock);
	if (ret)
		ipath_dev_err(dd, "Failed updating EEPROM\n");

free_bail:
	vfree(buf);
bail:
	return ret;

}

/**
 * ipath_inc_eeprom_err - increment one of the four error counters
 * that are logged to EEPROM.
 * @dd: the infinipath device
 * @eidx: 0..3, the counter to increment
 * @incr: how much to add
 *
 * Each counter is 8-bits, and saturates at 255 (0xFF). They
 * are copied to the EEPROM (aka flash) whenever ipath_update_eeprom_log()
 * is called, but it can only be called in a context that allows sleep.
 * This function can be called even at interrupt level.
 */

void ipath_inc_eeprom_err(struct ipath_devdata *dd, u32 eidx, u32 incr)
{
	uint new_val;
	unsigned long flags;

	spin_lock_irqsave(&dd->ipath_eep_st_lock, flags);
	new_val = dd->ipath_eep_st_new_errs[eidx] + incr;
	if (new_val > 255)
		new_val = 255;
	dd->ipath_eep_st_new_errs[eidx] = new_val;
	spin_unlock_irqrestore(&dd->ipath_eep_st_lock, flags);
	return;
}

static int ipath_tempsense_internal_read(struct ipath_devdata *dd, u8 regnum)
{
	int ret;
	struct i2c_chain_desc *icd;

	ret = -ENOENT;

	icd = ipath_i2c_type(dd);
	if (!icd)
		goto bail;

	if (icd->temp_dev == IPATH_NO_DEV) {
		/* tempsense only exists on new, real-I2C boards */
		ret = -ENXIO;
		goto bail;
	}

	if (i2c_startcmd(dd, icd->temp_dev | WRITE_CMD)) {
		ipath_dbg("Failed tempsense startcmd\n");
		stop_cmd(dd);
		ret = -ENXIO;
		goto bail;
	}
	ret = wr_byte(dd, regnum);
	stop_cmd(dd);
	if (ret) {
		ipath_dev_err(dd, "Failed tempsense WR command %02X\n",
			      regnum);
		ret = -ENXIO;
		goto bail;
	}
	if (i2c_startcmd(dd, icd->temp_dev | READ_CMD)) {
		ipath_dbg("Failed tempsense RD startcmd\n");
		stop_cmd(dd);
		ret = -ENXIO;
		goto bail;
	}
	/*
	 * We can only clock out one byte per command, sensibly
	 */
	ret = rd_byte(dd);
	stop_cmd(dd);

bail:
	return ret;
}

#define VALID_TS_RD_REG_MASK 0xBF

/**
 * ipath_tempsense_read - read register of temp sensor via I2C
 * @dd: the infinipath device
 * @regnum: register to read from
 *
 * returns reg contents (0..255) or < 0 for error
 */
int ipath_tempsense_read(struct ipath_devdata *dd, u8 regnum)
{
	int ret;

	if (regnum > 7)
		return -EINVAL;

	/* return a bogus value for (the one) register we do not have */
	if (!((1 << regnum) & VALID_TS_RD_REG_MASK))
		return 0;

	ret = mutex_lock_interruptible(&dd->ipath_eep_lock);
	if (!ret) {
		ret = ipath_tempsense_internal_read(dd, regnum);
		mutex_unlock(&dd->ipath_eep_lock);
	}

	/*
	 * There are three possibilities here:
	 * ret is actual value (0..255)
	 * ret is -ENXIO or -EINVAL from code in this file
	 * ret is -EINTR from mutex_lock_interruptible.
	 */
	return ret;
}

static int ipath_tempsense_internal_write(struct ipath_devdata *dd,
					  u8 regnum, u8 data)
{
	int ret = -ENOENT;
	struct i2c_chain_desc *icd;

	icd = ipath_i2c_type(dd);
	if (!icd)
		goto bail;

	if (icd->temp_dev == IPATH_NO_DEV) {
		/* tempsense only exists on new, real-I2C boards */
		ret = -ENXIO;
		goto bail;
	}
	if (i2c_startcmd(dd, icd->temp_dev | WRITE_CMD)) {
		ipath_dbg("Failed tempsense startcmd\n");
		stop_cmd(dd);
		ret = -ENXIO;
		goto bail;
	}
	ret = wr_byte(dd, regnum);
	if (ret) {
		stop_cmd(dd);
		ipath_dev_err(dd, "Failed to write tempsense command %02X\n",
			      regnum);
		ret = -ENXIO;
		goto bail;
	}
	ret = wr_byte(dd, data);
	stop_cmd(dd);
	ret = i2c_startcmd(dd, icd->temp_dev | READ_CMD);
	if (ret) {
		ipath_dev_err(dd, "Failed tempsense data wrt to %02X\n",
			      regnum);
		ret = -ENXIO;
	}

bail:
	return ret;
}

#define VALID_TS_WR_REG_MASK ((1 << 9) | (1 << 0xB) | (1 << 0xD))

/**
 * ipath_tempsense_write - write register of temp sensor via I2C
 * @dd: the infinipath device
 * @regnum: register to write
 * @data: data to write
 *
 * returns 0 for success or < 0 for error
 */
int ipath_tempsense_write(struct ipath_devdata *dd, u8 regnum, u8 data)
{
	int ret;

	if (regnum > 15 || !((1 << regnum) & VALID_TS_WR_REG_MASK))
		return -EINVAL;

	ret = mutex_lock_interruptible(&dd->ipath_eep_lock);
	if (!ret) {
		ret = ipath_tempsense_internal_write(dd, regnum, data);
		mutex_unlock(&dd->ipath_eep_lock);
	}

	/*
	 * There are three possibilities here:
	 * ret is 0 for success
	 * ret is -ENXIO or -EINVAL from code in this file
	 * ret is -EINTR from mutex_lock_interruptible.
	 */
	return ret;
}