/* pmc93x6_eeprom.c - PMC's 93LC46 EEPROM Device
 *
 *    The 93LC46 is a low-power, serial Electrically Erasable and
 *    Programmable Read Only Memory organized as 128 8-bit bytes.
 *
 *    Accesses to the 93LC46 are done in a bit serial stream, organized
 *    in a 3 wire format.  Writes are internally timed by the device
 *    (the In data bit is pulled low until the write is complete and
 *    then is pulled high) and take about 6 milliseconds.
 *
 * Copyright (C) 2003-2005  SBE, Inc.
 *
 *   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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/types.h>
#include "pmcc4_sysdep.h"
#include "sbecom_inline_linux.h"
#include "pmcc4.h"
#include "sbe_promformat.h"
#include "pmc93x6_eeprom.h"

#ifndef TRUE
#define TRUE   1
#define FALSE  0
#endif

/*------------------------------------------------------------------------
 *      EEPROM address definitions
 *------------------------------------------------------------------------
 *
 *      The offset in the definitions below allows the test to skip over
 *      areas of the EEPROM that other programs (such a VxWorks) are
 *      using.
 */

#define EE_MFG      (long)0	/* Index to manufacturing record */
#define EE_FIRST    0x28	/* Index to start testing at */
#define EE_LIMIT    128		/* Index to end testing at */

/*  Bit Ordering for Instructions
 *
 *  A0, A1, A2, A3, A4, A5, A6, OP0, OP1, SB   (lsb, or 1st bit out)
 *
 */

#define EPROM_EWEN      0x0019	/* Erase/Write enable (reversed) */
#define EPROM_EWDS      0x0001	/* Erase/Write disable (reversed) */
#define EPROM_READ      0x0003	/* Read (reversed) */
#define EPROM_WRITE     0x0005	/* Write (reversed) */
#define EPROM_ERASE     0x0007	/* Erase (reversed) */
#define EPROM_ERAL      0x0009	/* Erase All (reversed) */
#define EPROM_WRAL      0x0011	/* Write All (reversed) */

#define EPROM_ADR_SZ    7	/* Number of bits in offset address */
#define EPROM_OP_SZ     3	/* Number of bits in command */
#define SIZE_ADDR_OP    (EPROM_ADR_SZ + EPROM_OP_SZ)
#define LC46A_MAX_OPS   10	/* Number of bits in Instruction */
#define NUM_OF_BITS     8	/* Number of bits in data */

/* EEPROM signal bits */
#define EPROM_ACTIVE_OUT_BIT    0x0001	/* Out data bit */
#define EPROM_ACTIVE_IN_BIT     0x0002	/* In data bit */
#define ACTIVE_IN_BIT_SHIFT     0x0001	/* Shift In data bit to LSB */
#define EPROM_ENCS              0x0004	/* Set EEPROM CS during operation */

/*------------------------------------------------------------------------
 *      The ByteReverse table is used to reverses the 8 bits within a byte
 *------------------------------------------------------------------------
 */

static unsigned char ByteReverse[256];
static int ByteReverseBuilt = FALSE;

/*------------------------------------------------------------------------
 *      mfg_template - initial serial EEPROM data structure
 *------------------------------------------------------------------------
 */

static u8 mfg_template[sizeof(FLD_TYPE2)] = {
	PROM_FORMAT_TYPE2,	/* type; */
	0x00, 0x1A,		/* length[2]; */
	0x00, 0x00, 0x00, 0x00,	/* Crc32[4]; */
	0x11, 0x76,		/* Id[2]; */
	0x07, 0x05,		/* SubId[2] E1; */
	0x00, 0xA0, 0xD6, 0x00, 0x00, 0x00,	/* Serial[6]; */
	0x00, 0x00, 0x00, 0x00,	/* CreateTime[4]; */
	0x00, 0x00, 0x00, 0x00,	/* HeatRunTime[4]; */
	0x00, 0x00, 0x00, 0x00,	/* HeatRunIterations[4]; */
	0x00, 0x00, 0x00, 0x00,	/* HeatRunErrors[4]; */
};

/*------------------------------------------------------------------------
 *      BuildByteReverse - build the 8-bit reverse table
 *------------------------------------------------------------------------
 *
 *      The 'ByteReverse' table reverses the 8 bits within a byte
 *      (the MSB becomes the LSB etc.).
 */

static void BuildByteReverse(void)
{
	/* Used to build by powers to 2 */
	long half;
	int i;

	ByteReverse[0] = 0;

	for (half = 1; half < sizeof(ByteReverse); half <<= 1)
		for (i = 0; i < half; i++)
			ByteReverse[half + i] =
			    (char)(ByteReverse[i] | (0x80 / half));

	ByteReverseBuilt = TRUE;
}

/*------------------------------------------------------------------------
 *      eeprom_delay - small delay for EEPROM timing
 *------------------------------------------------------------------------
 */

static void eeprom_delay(void)
{
	int timeout;

	for (timeout = 20; timeout; --timeout)
		OS_uwait_dummy();
}

/*------------------------------------------------------------------------
 *      eeprom_put_byte - Send a byte to the EEPROM serially
 *------------------------------------------------------------------------
 *
 *      Given the PCI address and the data, this routine serially sends
 *      the data to the EEPROM.
 */

static void eeprom_put_byte(long addr, long data, int count)
{
	u_int32_t output;

	while (--count >= 0) {
		/* Get next data bit */
		output = (data & EPROM_ACTIVE_OUT_BIT) ? 1 : 0;
		/* Add Chip Select */
		output |= EPROM_ENCS;
		data >>= 1;

		eeprom_delay();
		/* Output it */
		pci_write_32((u_int32_t *) addr, output);
	}
}

/*------------------------------------------------------------------------
 *      eeprom_get_byte - Receive a byte from the EEPROM serially
 *------------------------------------------------------------------------
 *
 *      Given the PCI address, this routine serially fetches the data
 *      from the  EEPROM.
 */

static u_int32_t eeprom_get_byte(long addr)
{
	u_int32_t input;
	u_int32_t data;
	int count;

/*  Start the Reading of DATA
 *
 *  The first read is a dummy as the data is latched in the
 *  EPLD and read on the next read access to the EEPROM.
 */

	input = pci_read_32((u_int32_t *) addr);

	data = 0;
	count = NUM_OF_BITS;
	while (--count >= 0) {
		eeprom_delay();
		input = pci_read_32((u_int32_t *) addr);

		/* Shift data over */
		data <<= 1;
		data |= (input & EPROM_ACTIVE_IN_BIT) ? 1 : 0;

	}

	return data;
}

/*------------------------------------------------------------------------
 *      disable_pmc_eeprom - Disable writes to the EEPROM
 *------------------------------------------------------------------------
 *
 *      Issue the EEPROM command to disable writes.
 */

static void disable_pmc_eeprom(long addr)
{
	eeprom_put_byte(addr, EPROM_EWDS, SIZE_ADDR_OP);

	/* this removes Chip Select from EEPROM */
	pci_write_32((u_int32_t *) addr, 0);
}

/*------------------------------------------------------------------------
 *      enable_pmc_eeprom - Enable writes to the EEPROM
 *------------------------------------------------------------------------
 *
 *      Issue the EEPROM command to enable writes.
 */

static void enable_pmc_eeprom(long addr)
{
	eeprom_put_byte(addr, EPROM_EWEN, SIZE_ADDR_OP);

	/* this removes Chip Select from EEPROM */
	pci_write_32((u_int32_t *) addr, 0);
}

/*------------------------------------------------------------------------
 *      pmc_eeprom_read - EEPROM location read
 *------------------------------------------------------------------------
 *
 *      Given a EEPROM PCI address and location offset, this routine returns
 *      the contents of the specified location to the calling routine.
 */

static u_int32_t pmc_eeprom_read(long addr, long mem_offset)
{
	/* Data from chip */
	u_int32_t data;

	if (!ByteReverseBuilt)
		BuildByteReverse();

	/* Reverse address */
	mem_offset = ByteReverse[0x7F & mem_offset];

	/*
	 * NOTE: The max offset address is 128 or half the reversal table. So
	 * the LSB is always zero and counts as a built in shift of one bit.
	 * So even though we need to shift 3 bits to make room for the command,
	 * we only need to shift twice more because of the built in shift.
	 */

	/* Shift for command */
	mem_offset <<= 2;
	/* Add command */
	mem_offset |= EPROM_READ;

	/* Output chip address */
	eeprom_put_byte(addr, mem_offset, SIZE_ADDR_OP);

	/* Read chip data */
	data = eeprom_get_byte(addr);

	/* Remove Chip Select from EEPROM */
	pci_write_32((u_int32_t *) addr, 0);

	return (data & 0x000000FF);
}

/*------------------------------------------------------------------------
 *      pmc_eeprom_write - EEPROM location write
 *------------------------------------------------------------------------
 *
 *      Given a EEPROM PCI address, location offset and value, this
 *      routine writes the value to the specified location.
 *
 *      Note: it is up to the caller to determine if the write
 *      operation succeeded.
 */

static int pmc_eeprom_write(long addr, long mem_offset, u_int32_t data)
{
	u_int32_t temp;
	int count;

	if (!ByteReverseBuilt)
		BuildByteReverse();

	/* Reverse address */
	mem_offset = ByteReverse[0x7F & mem_offset];

	/*
	 * NOTE: The max offset address is 128 or half the reversal table. So
	 * the LSB is always zero and counts as a built in shift of one bit.
	 * So even though we need to shift 3 bits to make room for the command,
	 * we only need to shift twice more because of the built in shift.
	 */

	/* Shift for command */
	mem_offset <<= 2;
	/* Add command */
	mem_offset |= EPROM_WRITE;

	/* Output chip address */
	eeprom_put_byte(addr, mem_offset, SIZE_ADDR_OP);

	/* Reverse data */
	data = ByteReverse[0xFF & data];
	/* Output chip data */
	eeprom_put_byte(addr, data, NUM_OF_BITS);

	/* Remove Chip Select from EEPROM */
	pci_write_32((u_int32_t *) addr, 0);

/*
 *  Must see Data In at a low state before completing this transaction.
 *
 *  Afterwards, the data bit will return to a high state, ~6 ms, terminating
 *  the operation.
 */
	/* Re-enable Chip Select */
	pci_write_32((u_int32_t *) addr, EPROM_ENCS);
	/* discard first read */
	temp = pci_read_32((u_int32_t *) addr);
	temp = pci_read_32((u_int32_t *) addr);
	if (temp & EPROM_ACTIVE_IN_BIT) {
		temp = pci_read_32((u_int32_t *) addr);
		if (temp & EPROM_ACTIVE_IN_BIT) {
			/* Remove Chip Select from EEPROM */
			pci_write_32((u_int32_t *) addr, 0);
			return 1;
		}
	}
	count = 1000;
	while (count--) {
		for (temp = 0; temp < 0x10; temp++)
			OS_uwait_dummy();

		if (pci_read_32((u_int32_t *) addr) & EPROM_ACTIVE_IN_BIT)
			break;
	}

	if (count == -1)
		return 2;

	return 0;
}

/*------------------------------------------------------------------------
 *      pmcGetBuffValue - read the specified value from buffer
 *------------------------------------------------------------------------
 */

static long pmcGetBuffValue(char *ptr, int size)
{
	long value = 0;
	int index;

	for (index = 0; index < size; ++index) {
		value <<= 8;
		value |= ptr[index] & 0xFF;
	}

	return value;
}

/*------------------------------------------------------------------------
 *      pmcSetBuffValue - save the specified value to buffer
 *------------------------------------------------------------------------
 */

static void pmcSetBuffValue(char *ptr, long value, int size)
{
	int index = size;

	while (--index >= 0) {
		ptr[index] = (char)(value & 0xFF);
		value >>= 8;
	}
}

/*------------------------------------------------------------------------
 *      pmc_eeprom_read_buffer - read EEPROM data into specified buffer
 *------------------------------------------------------------------------
 */

void
pmc_eeprom_read_buffer(long addr, long mem_offset, char *dest_ptr, int size)
{
	while (--size >= 0)
		*dest_ptr++ = (char)pmc_eeprom_read(addr, mem_offset++);
}

/*------------------------------------------------------------------------
 *      pmc_eeprom_write_buffer - write EEPROM data from specified buffer
 *------------------------------------------------------------------------
 */

void
pmc_eeprom_write_buffer(long addr, long mem_offset, char *dest_ptr, int size)
{
	enable_pmc_eeprom(addr);

	while (--size >= 0)
		pmc_eeprom_write(addr, mem_offset++, *dest_ptr++);

	disable_pmc_eeprom(addr);
}

/*------------------------------------------------------------------------
 *      pmcCalcCrc - calculate the CRC for the serial EEPROM structure
 *------------------------------------------------------------------------
 */

static u_int32_t pmcCalcCrc_T01(void *bufp)
{
	FLD_TYPE2 *buf = bufp;
	/* CRC of the structure */
	u_int32_t crc;

	/* Calc CRC for type and length fields */
	sbeCrc((u_int8_t *) &buf->type,
	       (u_int32_t) STRUCT_OFFSET(FLD_TYPE1, Crc32),
	       (u_int32_t) 0, (u_int32_t *) &crc);

#ifdef EEPROM_TYPE_DEBUG
	/* RLD DEBUG */
	pr_info("sbeCrc: crc 1 calculated as %08x\n", crc);
#endif
	return ~crc;
}

static u_int32_t pmcCalcCrc_T02(void *bufp)
{
	FLD_TYPE2 *buf = bufp;
	/* CRC of the structure */
	u_int32_t crc;

	/* Calc CRC for type and length fields */
	sbeCrc((u_int8_t *) &buf->type,
	       (u_int32_t) STRUCT_OFFSET(FLD_TYPE2, Crc32),
	       (u_int32_t) 0, (u_int32_t *) &crc);

	/* Calc CRC for remaining fields */
	sbeCrc((u_int8_t *) &buf->Id[0],
	       (u_int32_t) (sizeof(FLD_TYPE2) - STRUCT_OFFSET(FLD_TYPE2, Id)),
	       (u_int32_t) crc, (u_int32_t *) &crc);

#ifdef EEPROM_TYPE_DEBUG
	/* RLD DEBUG */
	pr_info("sbeCrc: crc 2 calculated as %08x\n", crc);
#endif
	return crc;
}

/*------------------------------------------------------------------------
 *      pmc_init_seeprom - initialize the serial EEPROM structure
 *------------------------------------------------------------------------
 *
 *      At the front of the serial EEPROM there is a record that contains
 *      manufacturing information.  If the info does not already exist, it
 *      is created.  The only field modifiable by the operator is the
 *      serial number field.
 */

void pmc_init_seeprom(u_int32_t addr, u_int32_t serialNum)
{
	/* Memory image of structure */
	PROMFORMAT buffer;
	/* CRC of structure */
	u_int32_t crc;
	time_t createTime;

	createTime = get_seconds();

	/* use template data */
	memcpy(&buffer.fldType2, mfg_template, sizeof(buffer.fldType2));

	/* Update serial number field in buffer */
	pmcSetBuffValue(&buffer.fldType2.Serial[3], serialNum, 3);

	/* Update create time field in buffer */
	pmcSetBuffValue(&buffer.fldType2.CreateTime[0], createTime, 4);

	/* Update CRC field in buffer */
	crc = pmcCalcCrc_T02(&buffer);
	pmcSetBuffValue(&buffer.fldType2.Crc32[0], crc, 4);

#ifdef DEBUG
	for (i = 0; i < sizeof(FLD_TYPE2); ++i)
		pr_info("[%02X] = %02X\n", i, buffer.bytes[i] & 0xFF);
#endif

	/* Write structure to serial EEPROM */
	pmc_eeprom_write_buffer(addr, EE_MFG, (char *)&buffer,
				sizeof(FLD_TYPE2));
}

char pmc_verify_cksum(void *bufp)
{
	FLD_TYPE1 *buf1 = bufp;
	FLD_TYPE2 *buf2 = bufp;
	/* CRC read from EEPROM */
	u_int32_t crc1, crc2;

	/* Retrieve contents of CRC field */
	crc1 = pmcGetBuffValue(&buf1->Crc32[0], sizeof(buf1->Crc32));
#ifdef EEPROM_TYPE_DEBUG
	/* RLD DEBUG */
	pr_info("EEPROM: chksum 1 reads   as %08x\n", crc1);
#endif
	if ((buf1->type == PROM_FORMAT_TYPE1) &&
	    (pmcCalcCrc_T01((void *)buf1) == crc1))
		return PROM_FORMAT_TYPE1;	/* checksum type 1 verified */

	crc2 = pmcGetBuffValue(&buf2->Crc32[0], sizeof(buf2->Crc32));
#ifdef EEPROM_TYPE_DEBUG
	/* RLD DEBUG */
	pr_info("EEPROM: chksum 2 reads   as %08x\n", crc2);
#endif
	if ((buf2->type == PROM_FORMAT_TYPE2) &&
	    (pmcCalcCrc_T02((void *)buf2) == crc2))
		return PROM_FORMAT_TYPE2;	/* checksum type 2 verified */

	/* failed to validate */
	return PROM_FORMAT_Unk;
}