Initial version of eeprog with 16 byte page write support

24cXX.c

@@ -2,6 +2,8 @@
     copyright            : (C) by 2003-2004 Stefano Barbato
     email                : stefano@codesink.org
 
+    (C) 2021 Raptor Engineering, LLC
+
     $Id: 24cXX.c,v 1.5 2004/02/29 11:05:28 tat Exp $
  ***************************************************************************/
 
@@ -47,14 +49,13 @@ static int i2c_write_2b(struct eeprom *e, __u8 buf[2])
 	return r;
 }
 
-static int i2c_write_3b(struct eeprom *e, __u8 buf[3])
+static int i2c_write_arbitrary(struct eeprom *e, __u8 *buf, int len)
 {
 	int r;
-	// we must simulate a plain I2C byte write with SMBus functions
-	// the __u16 data field will be byte swapped by the SMBus protocol
-	r = i2c_smbus_write_word_data(e->fd, buf[0], buf[2] << 8 | buf[1]);
+        // we must simulate a plain I2C byte write with SMBus functions
+	r = i2c_smbus_write_i2c_block_data(e->fd, buf[0], len-1, buf+1);
 	if(r < 0)
-		fprintf(stderr, "Error i2c_write_3b: %s\n", strerror(errno));
+		fprintf(stderr, "Error i2c_write_arbitrary: %s\n", strerror(errno));
 	usleep(10);
 	return r;
 }
@@ -174,18 +175,29 @@ int eeprom_read_byte(struct eeprom* e, __u16 mem_addr)
 	return r;
 }
 
-int eeprom_write_byte(struct eeprom *e, __u16 mem_addr, __u8 data)
+int eeprom_write_byte(struct eeprom *e, __u16 mem_addr, __u8* data, int data_len)
 {
+	int ret = 0;
+	int offset = 0;
+	__u8 write_buffer[MAX_PAGE_SIZE+2];
 	if(e->type == EEPROM_TYPE_8BIT_ADDR) {
-		__u8 buf[2] = { mem_addr & 0x00ff, data };
-		return i2c_write_2b(e, buf);
-	} else if(e->type == EEPROM_TYPE_16BIT_ADDR) {
-		__u8 buf[3] =
-			{ (mem_addr >> 8) & 0x00ff, mem_addr & 0x00ff, data };
-		return i2c_write_3b(e, buf);
+		write_buffer[0] = mem_addr & 0x00ff;
+		offset = 1;
 	}
-	fprintf(stderr, "ERR: unknown eeprom type\n");
-	return -1;
+	else if(e->type == EEPROM_TYPE_16BIT_ADDR) {
+		write_buffer[0] = (mem_addr >> 8) & 0xff;
+		write_buffer[1] = mem_addr & 0xff;
+		offset = 2;
+	}
+	else {
+		fprintf(stderr, "ERR: unknown eeprom type\n");
+		return -1;
+	}
+	memcpy(write_buffer+offset, data, data_len);
+
+	ret = i2c_write_arbitrary(e, write_buffer, data_len+offset);
+	usleep(5000);
+	return ret;
 }
 
 int eeprom_wait_ready(struct eeprom *e, int max_ms_to_wait)

24cXX.h

@@ -2,6 +2,8 @@
     copyright            : (C) by 2003-2004 Stefano Barbato
     email                : stefano@codesink.org
 
+    (C) 2021 Raptor Engineering, LLC
+
     $Id: 24cXX.h,v 1.6 2004/02/29 11:05:28 tat Exp $
  ***************************************************************************/
 
@@ -21,6 +23,10 @@
 #define EEPROM_TYPE_8BIT_ADDR	1
 #define EEPROM_TYPE_16BIT_ADDR 	2
 
+// SMBus is limited to 32 bytes
+// Unfortunately, the 16-bit addressing on the EEPROM chews up one of those bytes, and further downgrades the max transfer size to 16 bytes of data (since we have to stay power of 2 aligned)
+#define MAX_PAGE_SIZE 16
+
 struct eeprom
 {
 	char *dev; 	// device file i.e. /dev/i2c-N
@@ -52,7 +58,7 @@ int eeprom_read_current_byte(struct eeprom *e);
  * writes [data] at memory address [mem_addr]
  * Note: eeprom must have been selected by ioctl(fd,I2C_SLAVE,address)
  */
-int eeprom_write_byte(struct eeprom *e, __u16 mem_addr, __u8 data);
+int eeprom_write_byte(struct eeprom *e, __u16 mem_addr, __u8 *data, int data_len);
 /*
  * wait for the eeprom to accept new commands, to be called after a write
  */

Makefile

-CFLAGS=-g -I. -Wall -O2   
+CFLAGS=-g -I. -Wall -O2 -march=armv6
 
 all: eeprog 
 

eeprog.c

@@ -2,6 +2,8 @@
     copyright            : (C) by 2003-2004 Stefano Barbato
     email                : stefano@codesink.org
 
+    (C) 2021 Raptor Engineering, LLC
+
     $Id: eeprog.c,v 1.28 2004/02/29 11:06:41 tat Exp $
  ***************************************************************************/
 
@@ -143,13 +145,41 @@ int read_from_eeprom(struct eeprom *e, int addr, int size, int hex)
 
 int write_to_eeprom(struct eeprom *e, int addr, int timeout)
 {
+	int actual_page_size = MAX_PAGE_SIZE;
+	int buffer_index = 0;
+	int current_byte = 0;
+	__u8 buffer[MAX_PAGE_SIZE];
+	__u32 mask = 0;
+
+	mask = (1 << actual_page_size) - 1;
+	if (addr & mask) {
+		actual_page_size = 1;
+	}
+	print_info("  Using page size: %d\n", actual_page_size);
+
 	int c;
 	while((c = getchar()) != EOF)
 	{
-		print_info(".");
+		buffer[buffer_index] = c;
+		buffer_index++;
+		if (buffer_index >= actual_page_size)
+		{
+			print_info(".");
+			fflush(stdout);
+			die_if(eeprom_write_byte(e, addr, buffer, buffer_index), "write error");
+			die_if(eeprom_wait_ready(e, timeout), "write timeout");
+			buffer_index = 0;
+			addr = addr + actual_page_size;
+		}
+	}
+	// Flush any remaining bytes one by one
+	for (current_byte = 0; current_byte<buffer_index; current_byte++)
+	{
+		print_info("+");
 		fflush(stdout);
-		die_if(eeprom_write_byte(e, addr++, c), "write error");
+		die_if(eeprom_write_byte(e, addr++, buffer + current_byte, 1), "write error");
 		die_if(eeprom_wait_ready(e, timeout), "write timeout");
+		buffer_index = 0;
 	}
 	print_info("\n\n");
 	return 0;