board/compulab/common/eeprom.c - filogic/uboot - Gitiles

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * (C) Copyright 2011 CompuLab, Ltd. <www.compulab.co.il>
  *
  * Authors: Nikita Kiryanov <nikita@compulab.co.il>
  *	    Igor Grinberg <grinberg@compulab.co.il>
  */

 #include <i2c.h>
 #include <vsprintf.h>
 #include <eeprom_layout.h>
 #include <eeprom_field.h>
 #include <asm/setup.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
 #include "eeprom.h"

 #define EEPROM_LAYOUT_VER_OFFSET	44
 #define BOARD_SERIAL_OFFSET		20
 #define BOARD_SERIAL_OFFSET_LEGACY	8
 #define BOARD_REV_OFFSET		0
 #define BOARD_REV_OFFSET_LEGACY		6
 #define BOARD_REV_SIZE			2
 #define PRODUCT_NAME_OFFSET		128
 #define PRODUCT_NAME_SIZE		16
 #define MAC_ADDR_OFFSET			4
 #define MAC_ADDR_OFFSET_LEGACY		0

 #define LAYOUT_INVALID	0
 #define LAYOUT_LEGACY	0xff

 static int cl_eeprom_bus;
 static int cl_eeprom_layout; /* Implicitly LAYOUT_INVALID */

 static int cl_eeprom_read(uint offset, uchar *buf, int len)
 {
 	struct udevice *eeprom;
 	int res;

 	res = i2c_get_chip_for_busnum(cl_eeprom_bus, CONFIG_SYS_I2C_EEPROM_ADDR,
 				      CONFIG_SYS_I2C_EEPROM_ADDR_LEN, &eeprom);
 	if (res)
 		return res;

 	return dm_i2c_read(eeprom, offset, (uint8_t *)buf, len);
 }

 static int cl_eeprom_setup(uint eeprom_bus)
 {
 	int res;

 	/*
 	 * We know the setup was already done when the layout is set to a valid
 	 * value and we're using the same bus as before.
 	 */
 	if (cl_eeprom_layout != LAYOUT_INVALID && eeprom_bus == cl_eeprom_bus)
 		return 0;

 	cl_eeprom_bus = eeprom_bus;
 	res = cl_eeprom_read(EEPROM_LAYOUT_VER_OFFSET,
 			     (uchar *)&cl_eeprom_layout, 1);
 	if (res) {
 		cl_eeprom_layout = LAYOUT_INVALID;
 		return res;
 	}

 	if (cl_eeprom_layout == 0 || cl_eeprom_layout >= 0x20)
 		cl_eeprom_layout = LAYOUT_LEGACY;

 	return 0;
 }

 void get_board_serial(struct tag_serialnr *serialnr)
 {
 	u32 serial[2];
 	uint offset;

 	memset(serialnr, 0, sizeof(*serialnr));

 	if (cl_eeprom_setup(CONFIG_SYS_I2C_EEPROM_BUS))
 		return;

 	offset = (cl_eeprom_layout != LAYOUT_LEGACY) ?
 		BOARD_SERIAL_OFFSET : BOARD_SERIAL_OFFSET_LEGACY;

 	if (cl_eeprom_read(offset, (uchar *)serial, 8))
 		return;

 	if (serial[0] != 0xffffffff && serial[1] != 0xffffffff) {
 		serialnr->low = serial[0];
 		serialnr->high = serial[1];
 	}
 }

 /*
  * Routine: cl_eeprom_read_mac_addr
  * Description: read mac address and store it in buf.
  */
 int cl_eeprom_read_mac_addr(uchar *buf, uint eeprom_bus)
 {
 	uint offset;
 	int err;

 	err = cl_eeprom_setup(eeprom_bus);
 	if (err)
 		return err;

 	offset = (cl_eeprom_layout != LAYOUT_LEGACY) ?
 			MAC_ADDR_OFFSET : MAC_ADDR_OFFSET_LEGACY;

 	return cl_eeprom_read(offset, buf, 6);
 }

 static u32 board_rev;

 /*
  * Routine: cl_eeprom_get_board_rev
  * Description: read system revision from eeprom
  */
 u32 cl_eeprom_get_board_rev(uint eeprom_bus)
 {
 	char str[5]; /* Legacy representation can contain at most 4 digits */
 	uint offset = BOARD_REV_OFFSET_LEGACY;

 	if (board_rev)
 		return board_rev;

 	if (cl_eeprom_setup(eeprom_bus))
 		return 0;

 	if (cl_eeprom_layout != LAYOUT_LEGACY)
 		offset = BOARD_REV_OFFSET;

 	if (cl_eeprom_read(offset, (uchar *)&board_rev, BOARD_REV_SIZE))
 		return 0;

 	/*
 	 * Convert legacy syntactic representation to semantic
 	 * representation. i.e. for rev 1.00: 0x100 --> 0x64
 	 */
 	if (cl_eeprom_layout == LAYOUT_LEGACY) {
 		sprintf(str, "%x", board_rev);
 		board_rev = dectoul(str, NULL);
 	}

 	return board_rev;
 };

 /*
  * Routine: cl_eeprom_get_board_rev
  * Description: read system revision from eeprom
  *
  * @buf: buffer to store the product name
  * @eeprom_bus: i2c bus num of the eeprom
  *
  * @return: 0 on success, < 0 on failure
  */
 int cl_eeprom_get_product_name(uchar *buf, uint eeprom_bus)
 {
 	int err;

 	if (buf == NULL)
 		return -EINVAL;

 	err = cl_eeprom_setup(eeprom_bus);
 	if (err)
 		return err;

 	err = cl_eeprom_read(PRODUCT_NAME_OFFSET, buf, PRODUCT_NAME_SIZE);
 	if (!err) /* Protect ourselves from invalid data (unterminated str) */
 		buf[PRODUCT_NAME_SIZE - 1] = '\0';

 	return err;
 }

 #ifdef CONFIG_CMD_EEPROM_LAYOUT
 /**
  * eeprom_field_print_bin_ver() - print a "version field" which contains binary
  *				  data
  *
  * Treat the field data as simple binary data, and print it formatted as a
  * version number (2 digits after decimal point).
  * The field size must be exactly 2 bytes.
  *
  * Sample output:
  *      Field Name      123.45
  *
  * @field:	an initialized field to print
  */
 void eeprom_field_print_bin_ver(const struct eeprom_field *field)
 {
 	if ((field->buf[0] == 0xff) && (field->buf[1] == 0xff)) {
 		field->buf[0] = 0;
 		field->buf[1] = 0;
 	}

 	printf(PRINT_FIELD_SEGMENT, field->name);
 	int major = (field->buf[1] << 8 | field->buf[0]) / 100;
 	int minor = (field->buf[1] << 8 | field->buf[0]) - major * 100;
 	printf("%d.%02d\n", major, minor);
 }

 /**
  * eeprom_field_update_bin_ver() - update a "version field" which contains
  *				   binary data
  *
  * This function takes a version string in the form of x.y (x and y are both
  * decimal values, y is limited to two digits), translates it to the binary
  * form, then writes it to the field. The field size must be exactly 2 bytes.
  *
  * This function strictly enforces the data syntax, and will not update the
  * field if there's any deviation from it. It also protects from overflow.
  *
  * @field:	an initialized field
  * @value:	a version string
  *
  * Returns 0 on success, -1 on failure.
  */
 int eeprom_field_update_bin_ver(struct eeprom_field *field, char *value)
 {
 	char *endptr;
 	char *tok = strtok(value, ".");
 	if (tok == NULL)
 		return -1;

 	int num = simple_strtol(tok, &endptr, 0);
 	if (*endptr != '\0')
 		return -1;

 	tok = strtok(NULL, "");
 	if (tok == NULL)
 		return -1;

 	int remainder = simple_strtol(tok, &endptr, 0);
 	if (*endptr != '\0')
 		return -1;

 	num = num * 100 + remainder;
 	if (num >> 16)
 		return -1;

 	field->buf[0] = (unsigned char)num;
 	field->buf[1] = num >> 8;

 	return 0;
 }

 char *months[12] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
 		    "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};

 /**
  * eeprom_field_print_date() - print a field which contains date data
  *
  * Treat the field data as simple binary data, and print it formatted as a date.
  * Sample output:
  *      Field Name      07/Feb/2014
  *      Field Name      56/BAD/9999
  *
  * @field:	an initialized field to print
  */
 void eeprom_field_print_date(const struct eeprom_field *field)
 {
 	printf(PRINT_FIELD_SEGMENT, field->name);
 	printf("%02d/", field->buf[0]);
 	if (field->buf[1] >= 1 && field->buf[1] <= 12)
 		printf("%s", months[field->buf[1] - 1]);
 	else
 		printf("BAD");

 	printf("/%d\n", field->buf[3] << 8 | field->buf[2]);
 }

 static int validate_date(unsigned char day, unsigned char month,
 			unsigned int year)
 {
 	int days_in_february;

 	switch (month) {
 	case 0:
 	case 2:
 	case 4:
 	case 6:
 	case 7:
 	case 9:
 	case 11:
 		if (day > 31)
 			return -1;
 		break;
 	case 3:
 	case 5:
 	case 8:
 	case 10:
 		if (day > 30)
 			return -1;
 		break;
 	case 1:
 		days_in_february = 28;
 		if (year % 4 == 0) {
 			if (year % 100 != 0)
 				days_in_february = 29;
 			else if (year % 400 == 0)
 				days_in_february = 29;
 		}

 		if (day > days_in_february)
 			return -1;

 		break;
 	default:
 		return -1;
 	}

 	return 0;
 }

 /**
  * eeprom_field_update_date() - update a date field which contains binary data
  *
  * This function takes a date string in the form of x/Mon/y (x and y are both
  * decimal values), translates it to the binary representation, then writes it
  * to the field.
  *
  * This function strictly enforces the data syntax, and will not update the
  * field if there's any deviation from it. It also protects from overflow in the
  * year value, and checks the validity of the date.
  *
  * @field:	an initialized field
  * @value:	a date string
  *
  * Returns 0 on success, -1 on failure.
  */
 int eeprom_field_update_date(struct eeprom_field *field, char *value)
 {
 	char *endptr;
 	char *tok1 = strtok(value, "/");
 	char *tok2 = strtok(NULL, "/");
 	char *tok3 = strtok(NULL, "/");

 	if (tok1 == NULL || tok2 == NULL || tok3 == NULL) {
 		printf("%s: syntax error\n", field->name);
 		return -1;
 	}

 	unsigned char day = (unsigned char)simple_strtol(tok1, &endptr, 0);
 	if (*endptr != '\0' || day == 0) {
 		printf("%s: invalid day\n", field->name);
 		return -1;
 	}

 	unsigned char month;
 	for (month = 1; month <= 12; month++)
 		if (!strcmp(tok2, months[month - 1]))
 			break;

 	unsigned int year = simple_strtol(tok3, &endptr, 0);
 	if (*endptr != '\0') {
 		printf("%s: invalid year\n", field->name);
 		return -1;
 	}

 	if (validate_date(day, month - 1, year)) {
 		printf("%s: invalid date\n", field->name);
 		return -1;
 	}

 	if (year >> 16) {
 		printf("%s: year overflow\n", field->name);
 		return -1;
 	}

 	field->buf[0] = day;
 	field->buf[1] = month;
 	field->buf[2] = (unsigned char)year;
 	field->buf[3] = (unsigned char)(year >> 8);

 	return 0;
 }

 #define	LAYOUT_VERSION_LEGACY 1
 #define	LAYOUT_VERSION_VER1 2
 #define	LAYOUT_VERSION_VER2 3
 #define	LAYOUT_VERSION_VER3 4

 #define DEFINE_PRINT_UPDATE(x) eeprom_field_print_##x, eeprom_field_update_##x

 struct eeprom_field layout_v2[15] = {
 	{ "Major Revision",            2, NULL, DEFINE_PRINT_UPDATE(bin_ver) },
 	{ "Minor Revision",            2, NULL, DEFINE_PRINT_UPDATE(bin_ver) },
 	{ "1st MAC Address",           6, NULL, DEFINE_PRINT_UPDATE(mac) },
 	{ "2nd MAC Address",           6, NULL, DEFINE_PRINT_UPDATE(mac) },
 	{ "Production Date",           4, NULL, DEFINE_PRINT_UPDATE(date) },
 	{ "Serial Number",            12, NULL, DEFINE_PRINT_UPDATE(bin_rev) },
 	{ "3rd MAC Address (WIFI)",    6, NULL, DEFINE_PRINT_UPDATE(mac) },
 	{ "4th MAC Address (Bluetooth)", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
 	{ "Layout Version",            1, NULL, DEFINE_PRINT_UPDATE(bin) },
 	{ RESERVED_FIELDS,            83, NULL, DEFINE_PRINT_UPDATE(reserved) },
 	{ "Product Name",             16, NULL, DEFINE_PRINT_UPDATE(ascii) },
 	{ "Product Options #1",       16, NULL, DEFINE_PRINT_UPDATE(ascii) },
 	{ "Product Options #2",       16, NULL, DEFINE_PRINT_UPDATE(ascii) },
 	{ "Product Options #3",       16, NULL, DEFINE_PRINT_UPDATE(ascii) },
 	{ RESERVED_FIELDS,            64, NULL, eeprom_field_print_reserved,
 						eeprom_field_update_ascii },
 };

 struct eeprom_field layout_v3[16] = {
 	{ "Major Revision",            2, NULL, DEFINE_PRINT_UPDATE(bin_ver) },
 	{ "Minor Revision",            2, NULL, DEFINE_PRINT_UPDATE(bin_ver) },
 	{ "1st MAC Address",           6, NULL, DEFINE_PRINT_UPDATE(mac) },
 	{ "2nd MAC Address",           6, NULL, DEFINE_PRINT_UPDATE(mac) },
 	{ "Production Date",           4, NULL, DEFINE_PRINT_UPDATE(date) },
 	{ "Serial Number",            12, NULL, DEFINE_PRINT_UPDATE(bin_rev) },
 	{ "3rd MAC Address (WIFI)",    6, NULL, DEFINE_PRINT_UPDATE(mac) },
 	{ "4th MAC Address (Bluetooth)", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
 	{ "Layout Version",            1, NULL, DEFINE_PRINT_UPDATE(bin) },
 	{ "CompuLab EEPROM ID",        3, NULL, DEFINE_PRINT_UPDATE(bin) },
 	{ RESERVED_FIELDS,            80, NULL, DEFINE_PRINT_UPDATE(reserved) },
 	{ "Product Name",             16, NULL, DEFINE_PRINT_UPDATE(ascii) },
 	{ "Product Options #1",       16, NULL, DEFINE_PRINT_UPDATE(ascii) },
 	{ "Product Options #2",       16, NULL, DEFINE_PRINT_UPDATE(ascii) },
 	{ "Product Options #3",       16, NULL, DEFINE_PRINT_UPDATE(ascii) },
 	{ RESERVED_FIELDS,            64, NULL, eeprom_field_print_reserved,
 						eeprom_field_update_ascii },
 };

 void eeprom_layout_assign(struct eeprom_layout *layout, int layout_version)
 {
 	switch (layout->layout_version) {
 	case LAYOUT_VERSION_VER2:
 		layout->fields = layout_v2;
 		layout->num_of_fields = ARRAY_SIZE(layout_v2);
 		break;
 	case LAYOUT_VERSION_VER3:
 		layout->fields = layout_v3;
 		layout->num_of_fields = ARRAY_SIZE(layout_v3);
 		break;
 	default:
 		__eeprom_layout_assign(layout, layout_version);
 	}
 }

 int eeprom_parse_layout_version(char *str)
 {
 	if (!strcmp(str, "legacy"))
 		return LAYOUT_VERSION_LEGACY;
 	else if (!strcmp(str, "v1"))
 		return LAYOUT_VERSION_VER1;
 	else if (!strcmp(str, "v2"))
 		return LAYOUT_VERSION_VER2;
 	else if (!strcmp(str, "v3"))
 		return LAYOUT_VERSION_VER3;
 	else
 		return LAYOUT_VERSION_UNRECOGNIZED;
 }

 int eeprom_layout_detect(unsigned char *data)
 {
 	switch (data[EEPROM_LAYOUT_VER_OFFSET]) {
 	case 0xff:
 	case 0:
 		return LAYOUT_VERSION_VER1;
 	case 2:
 		return LAYOUT_VERSION_VER2;
 	case 3:
 		return LAYOUT_VERSION_VER3;
 	}

 	if (data[EEPROM_LAYOUT_VER_OFFSET] >= 0x20)
 		return LAYOUT_VERSION_LEGACY;

 	return LAYOUT_VERSION_UNRECOGNIZED;
 }
 #endif
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* (C) Copyright 2011 CompuLab, Ltd. <www.compulab.co.il>
	*
	* Authors: Nikita Kiryanov <nikita@compulab.co.il>
	* Igor Grinberg <grinberg@compulab.co.il>
	*/

	#include <i2c.h>
	#include <vsprintf.h>
	#include <eeprom_layout.h>
	#include <eeprom_field.h>
	#include <asm/setup.h>
	#include <linux/kernel.h>
	#include <linux/string.h>
	#include "eeprom.h"

	#define EEPROM_LAYOUT_VER_OFFSET 44
	#define BOARD_SERIAL_OFFSET 20
	#define BOARD_SERIAL_OFFSET_LEGACY 8
	#define BOARD_REV_OFFSET 0
	#define BOARD_REV_OFFSET_LEGACY 6
	#define BOARD_REV_SIZE 2
	#define PRODUCT_NAME_OFFSET 128
	#define PRODUCT_NAME_SIZE 16
	#define MAC_ADDR_OFFSET 4
	#define MAC_ADDR_OFFSET_LEGACY 0

	#define LAYOUT_INVALID 0
	#define LAYOUT_LEGACY 0xff

	static int cl_eeprom_bus;
	static int cl_eeprom_layout; /* Implicitly LAYOUT_INVALID */

	static int cl_eeprom_read(uint offset, uchar *buf, int len)
	{
	struct udevice *eeprom;
	int res;

	res = i2c_get_chip_for_busnum(cl_eeprom_bus, CONFIG_SYS_I2C_EEPROM_ADDR,
	CONFIG_SYS_I2C_EEPROM_ADDR_LEN, &eeprom);
	if (res)
	return res;

	return dm_i2c_read(eeprom, offset, (uint8_t *)buf, len);
	}

	static int cl_eeprom_setup(uint eeprom_bus)
	{
	int res;

	/*
	* We know the setup was already done when the layout is set to a valid
	* value and we're using the same bus as before.
	*/
	if (cl_eeprom_layout != LAYOUT_INVALID && eeprom_bus == cl_eeprom_bus)
	return 0;

	cl_eeprom_bus = eeprom_bus;
	res = cl_eeprom_read(EEPROM_LAYOUT_VER_OFFSET,
	(uchar *)&cl_eeprom_layout, 1);
	if (res) {
	cl_eeprom_layout = LAYOUT_INVALID;
	return res;
	}

	if (cl_eeprom_layout == 0 \|\| cl_eeprom_layout >= 0x20)
	cl_eeprom_layout = LAYOUT_LEGACY;

	return 0;
	}

	void get_board_serial(struct tag_serialnr *serialnr)
	{
	u32 serial[2];
	uint offset;

	memset(serialnr, 0, sizeof(*serialnr));

	if (cl_eeprom_setup(CONFIG_SYS_I2C_EEPROM_BUS))
	return;

	offset = (cl_eeprom_layout != LAYOUT_LEGACY) ?
	BOARD_SERIAL_OFFSET : BOARD_SERIAL_OFFSET_LEGACY;

	if (cl_eeprom_read(offset, (uchar *)serial, 8))
	return;

	if (serial[0] != 0xffffffff && serial[1] != 0xffffffff) {
	serialnr->low = serial[0];
	serialnr->high = serial[1];
	}
	}

	/*
	* Routine: cl_eeprom_read_mac_addr
	* Description: read mac address and store it in buf.
	*/
	int cl_eeprom_read_mac_addr(uchar *buf, uint eeprom_bus)
	{
	uint offset;
	int err;

	err = cl_eeprom_setup(eeprom_bus);
	if (err)
	return err;

	offset = (cl_eeprom_layout != LAYOUT_LEGACY) ?
	MAC_ADDR_OFFSET : MAC_ADDR_OFFSET_LEGACY;

	return cl_eeprom_read(offset, buf, 6);
	}

	static u32 board_rev;

	/*
	* Routine: cl_eeprom_get_board_rev
	* Description: read system revision from eeprom
	*/
	u32 cl_eeprom_get_board_rev(uint eeprom_bus)
	{
	char str[5]; /* Legacy representation can contain at most 4 digits */
	uint offset = BOARD_REV_OFFSET_LEGACY;

	if (board_rev)
	return board_rev;

	if (cl_eeprom_setup(eeprom_bus))
	return 0;

	if (cl_eeprom_layout != LAYOUT_LEGACY)
	offset = BOARD_REV_OFFSET;

	if (cl_eeprom_read(offset, (uchar *)&board_rev, BOARD_REV_SIZE))
	return 0;

	/*
	* Convert legacy syntactic representation to semantic
	* representation. i.e. for rev 1.00: 0x100 --> 0x64
	*/
	if (cl_eeprom_layout == LAYOUT_LEGACY) {
	sprintf(str, "%x", board_rev);
	board_rev = dectoul(str, NULL);
	}

	return board_rev;
	};

	/*
	* Routine: cl_eeprom_get_board_rev
	* Description: read system revision from eeprom
	*
	* @buf: buffer to store the product name
	* @eeprom_bus: i2c bus num of the eeprom
	*
	* @return: 0 on success, < 0 on failure
	*/
	int cl_eeprom_get_product_name(uchar *buf, uint eeprom_bus)
	{
	int err;

	if (buf == NULL)
	return -EINVAL;

	err = cl_eeprom_setup(eeprom_bus);
	if (err)
	return err;

	err = cl_eeprom_read(PRODUCT_NAME_OFFSET, buf, PRODUCT_NAME_SIZE);
	if (!err) /* Protect ourselves from invalid data (unterminated str) */
	buf[PRODUCT_NAME_SIZE - 1] = '\0';

	return err;
	}

	#ifdef CONFIG_CMD_EEPROM_LAYOUT
	/**
	* eeprom_field_print_bin_ver() - print a "version field" which contains binary
	* data
	*
	* Treat the field data as simple binary data, and print it formatted as a
	* version number (2 digits after decimal point).
	* The field size must be exactly 2 bytes.
	*
	* Sample output:
	* Field Name 123.45
	*
	* @field: an initialized field to print
	*/
	void eeprom_field_print_bin_ver(const struct eeprom_field *field)
	{
	if ((field->buf[0] == 0xff) && (field->buf[1] == 0xff)) {
	field->buf[0] = 0;
	field->buf[1] = 0;
	}

	printf(PRINT_FIELD_SEGMENT, field->name);
	int major = (field->buf[1] << 8 \| field->buf[0]) / 100;
	int minor = (field->buf[1] << 8 \| field->buf[0]) - major * 100;
	printf("%d.%02d\n", major, minor);
	}

	/**
	* eeprom_field_update_bin_ver() - update a "version field" which contains
	* binary data
	*
	* This function takes a version string in the form of x.y (x and y are both
	* decimal values, y is limited to two digits), translates it to the binary
	* form, then writes it to the field. The field size must be exactly 2 bytes.
	*
	* This function strictly enforces the data syntax, and will not update the
	* field if there's any deviation from it. It also protects from overflow.
	*
	* @field: an initialized field
	* @value: a version string
	*
	* Returns 0 on success, -1 on failure.
	*/
	int eeprom_field_update_bin_ver(struct eeprom_field field, char value)
	{
	char *endptr;
	char *tok = strtok(value, ".");
	if (tok == NULL)
	return -1;

	int num = simple_strtol(tok, &endptr, 0);
	if (*endptr != '\0')
	return -1;

	tok = strtok(NULL, "");
	if (tok == NULL)
	return -1;

	int remainder = simple_strtol(tok, &endptr, 0);
	if (*endptr != '\0')
	return -1;

	num = num * 100 + remainder;
	if (num >> 16)
	return -1;

	field->buf[0] = (unsigned char)num;
	field->buf[1] = num >> 8;

	return 0;
	}

	char *months[12] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};

	/**
	* eeprom_field_print_date() - print a field which contains date data
	*
	* Treat the field data as simple binary data, and print it formatted as a date.
	* Sample output:
	* Field Name 07/Feb/2014
	* Field Name 56/BAD/9999
	*
	* @field: an initialized field to print
	*/
	void eeprom_field_print_date(const struct eeprom_field *field)
	{
	printf(PRINT_FIELD_SEGMENT, field->name);
	printf("%02d/", field->buf[0]);
	if (field->buf[1] >= 1 && field->buf[1] <= 12)
	printf("%s", months[field->buf[1] - 1]);
	else
	printf("BAD");

	printf("/%d\n", field->buf[3] << 8 \| field->buf[2]);
	}

	static int validate_date(unsigned char day, unsigned char month,
	unsigned int year)
	{
	int days_in_february;

	switch (month) {
	case 0:
	case 2:
	case 4:
	case 6:
	case 7:
	case 9:
	case 11:
	if (day > 31)
	return -1;
	break;
	case 3:
	case 5:
	case 8:
	case 10:
	if (day > 30)
	return -1;
	break;
	case 1:
	days_in_february = 28;
	if (year % 4 == 0) {
	if (year % 100 != 0)
	days_in_february = 29;
	else if (year % 400 == 0)
	days_in_february = 29;
	}

	if (day > days_in_february)
	return -1;

	break;
	default:
	return -1;
	}

	return 0;
	}

	/**
	* eeprom_field_update_date() - update a date field which contains binary data
	*
	* This function takes a date string in the form of x/Mon/y (x and y are both
	* decimal values), translates it to the binary representation, then writes it
	* to the field.
	*
	* This function strictly enforces the data syntax, and will not update the
	* field if there's any deviation from it. It also protects from overflow in the
	* year value, and checks the validity of the date.
	*
	* @field: an initialized field
	* @value: a date string
	*
	* Returns 0 on success, -1 on failure.
	*/
	int eeprom_field_update_date(struct eeprom_field field, char value)
	{
	char *endptr;
	char *tok1 = strtok(value, "/");
	char *tok2 = strtok(NULL, "/");
	char *tok3 = strtok(NULL, "/");

	if (tok1 == NULL \|\| tok2 == NULL \|\| tok3 == NULL) {
	printf("%s: syntax error\n", field->name);
	return -1;
	}

	unsigned char day = (unsigned char)simple_strtol(tok1, &endptr, 0);
	if (*endptr != '\0' \|\| day == 0) {
	printf("%s: invalid day\n", field->name);
	return -1;
	}

	unsigned char month;
	for (month = 1; month <= 12; month++)
	if (!strcmp(tok2, months[month - 1]))
	break;

	unsigned int year = simple_strtol(tok3, &endptr, 0);
	if (*endptr != '\0') {
	printf("%s: invalid year\n", field->name);
	return -1;
	}

	if (validate_date(day, month - 1, year)) {
	printf("%s: invalid date\n", field->name);
	return -1;
	}

	if (year >> 16) {
	printf("%s: year overflow\n", field->name);
	return -1;
	}

	field->buf[0] = day;
	field->buf[1] = month;
	field->buf[2] = (unsigned char)year;
	field->buf[3] = (unsigned char)(year >> 8);

	return 0;
	}

	#define LAYOUT_VERSION_LEGACY 1
	#define LAYOUT_VERSION_VER1 2
	#define LAYOUT_VERSION_VER2 3
	#define LAYOUT_VERSION_VER3 4

	#define DEFINE_PRINT_UPDATE(x) eeprom_field_print_##x, eeprom_field_update_##x

	struct eeprom_field layout_v2[15] = {
	{ "Major Revision", 2, NULL, DEFINE_PRINT_UPDATE(bin_ver) },
	{ "Minor Revision", 2, NULL, DEFINE_PRINT_UPDATE(bin_ver) },
	{ "1st MAC Address", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
	{ "2nd MAC Address", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
	{ "Production Date", 4, NULL, DEFINE_PRINT_UPDATE(date) },
	{ "Serial Number", 12, NULL, DEFINE_PRINT_UPDATE(bin_rev) },
	{ "3rd MAC Address (WIFI)", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
	{ "4th MAC Address (Bluetooth)", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
	{ "Layout Version", 1, NULL, DEFINE_PRINT_UPDATE(bin) },
	{ RESERVED_FIELDS, 83, NULL, DEFINE_PRINT_UPDATE(reserved) },
	{ "Product Name", 16, NULL, DEFINE_PRINT_UPDATE(ascii) },
	{ "Product Options #1", 16, NULL, DEFINE_PRINT_UPDATE(ascii) },
	{ "Product Options #2", 16, NULL, DEFINE_PRINT_UPDATE(ascii) },
	{ "Product Options #3", 16, NULL, DEFINE_PRINT_UPDATE(ascii) },
	{ RESERVED_FIELDS, 64, NULL, eeprom_field_print_reserved,
	eeprom_field_update_ascii },
	};

	struct eeprom_field layout_v3[16] = {
	{ "Major Revision", 2, NULL, DEFINE_PRINT_UPDATE(bin_ver) },
	{ "Minor Revision", 2, NULL, DEFINE_PRINT_UPDATE(bin_ver) },
	{ "1st MAC Address", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
	{ "2nd MAC Address", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
	{ "Production Date", 4, NULL, DEFINE_PRINT_UPDATE(date) },
	{ "Serial Number", 12, NULL, DEFINE_PRINT_UPDATE(bin_rev) },
	{ "3rd MAC Address (WIFI)", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
	{ "4th MAC Address (Bluetooth)", 6, NULL, DEFINE_PRINT_UPDATE(mac) },
	{ "Layout Version", 1, NULL, DEFINE_PRINT_UPDATE(bin) },
	{ "CompuLab EEPROM ID", 3, NULL, DEFINE_PRINT_UPDATE(bin) },
	{ RESERVED_FIELDS, 80, NULL, DEFINE_PRINT_UPDATE(reserved) },
	{ "Product Name", 16, NULL, DEFINE_PRINT_UPDATE(ascii) },
	{ "Product Options #1", 16, NULL, DEFINE_PRINT_UPDATE(ascii) },
	{ "Product Options #2", 16, NULL, DEFINE_PRINT_UPDATE(ascii) },
	{ "Product Options #3", 16, NULL, DEFINE_PRINT_UPDATE(ascii) },
	{ RESERVED_FIELDS, 64, NULL, eeprom_field_print_reserved,
	eeprom_field_update_ascii },
	};

	void eeprom_layout_assign(struct eeprom_layout *layout, int layout_version)
	{
	switch (layout->layout_version) {
	case LAYOUT_VERSION_VER2:
	layout->fields = layout_v2;
	layout->num_of_fields = ARRAY_SIZE(layout_v2);
	break;
	case LAYOUT_VERSION_VER3:
	layout->fields = layout_v3;
	layout->num_of_fields = ARRAY_SIZE(layout_v3);
	break;
	default:
	__eeprom_layout_assign(layout, layout_version);
	}
	}

	int eeprom_parse_layout_version(char *str)
	{
	if (!strcmp(str, "legacy"))
	return LAYOUT_VERSION_LEGACY;
	else if (!strcmp(str, "v1"))
	return LAYOUT_VERSION_VER1;
	else if (!strcmp(str, "v2"))
	return LAYOUT_VERSION_VER2;
	else if (!strcmp(str, "v3"))
	return LAYOUT_VERSION_VER3;
	else
	return LAYOUT_VERSION_UNRECOGNIZED;
	}

	int eeprom_layout_detect(unsigned char *data)
	{
	switch (data[EEPROM_LAYOUT_VER_OFFSET]) {
	case 0xff:
	case 0:
	return LAYOUT_VERSION_VER1;
	case 2:
	return LAYOUT_VERSION_VER2;
	case 3:
	return LAYOUT_VERSION_VER3;
	}

	if (data[EEPROM_LAYOUT_VER_OFFSET] >= 0x20)
	return LAYOUT_VERSION_LEGACY;

	return LAYOUT_VERSION_UNRECOGNIZED;
	}
	#endif