[RFC PATCH] board: ti: common: board_detect: Fix EEPROM read quirk for 2-byte

[Neha Malcom Francis]

EEPROM detection logic in ti_i2c_eeprom_get() involves figuring out
whether addressing is 1-byte or 2-byte. There are currently different
behaviours seen across boards as documented in commit bf6376642fe8
("board: ti: common: board_detect: Fix EEPROM read quirk"). Adding to
the list, we see that there are 2-byte EEPROMs that read properly
with 1-byte addressing with no offset.

For ti_i2c_eeprom_am6_get where eeprom parse operation is dynamic, the
earlier commit d2ab2a2bafd5 ("board: ti: common: board_detect: Fix
EEPROM read quirk for AM6 style data") tried to resolve this by running
ti_i2c_eeprom_get() twice. However this commit along with its former
commit fails on J7 platforms where EEPROM successfully return back the
header on 1-byte addressing and continues to do so until an offset is
introduced. So the second read incorrectly determines the EEPROM as
1-byte addressing.

A more generic solution is introduced here to solve
this issue: 1-byte read without offset and 1-byte read with offset. If
both passes, it follows 1-byte addressing else we proceed with 2-byte
addressing check.

Tested on J721E, J7200, DRA7xx, AM64x

Signed-off-by: Neha Malcom Francis <n-francis at ti.com>
Fixes: d2ab2a2bafd5 (board: ti: common: board_detect: Fix EEPROM read
quirk for AM6 style data) and bf6376642fe8 (board: ti: common: board_detect:
Fix EEPROM read quirk)
---
 board/ti/common/board_detect.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/board/ti/common/board_detect.c b/board/ti/common/board_detect.c
index c37629fe8a..b9f2ebf2a0 100644
--- a/board/ti/common/board_detect.c
+++ b/board/ti/common/board_detect.c
@@ -91,6 +91,8 @@ static int __maybe_unused ti_i2c_eeprom_get(int bus_addr, int dev_addr,
 #if CONFIG_IS_ENABLED(DM_I2C)
 	struct udevice *dev;
 	struct udevice *bus;
+	uint8_t offset_test;
+	bool one_byte_addressing = true;
 
 	rc = uclass_get_device_by_seq(UCLASS_I2C, bus_addr, &bus);
 	if (rc)
@@ -114,8 +116,23 @@ static int __maybe_unused ti_i2c_eeprom_get(int bus_addr, int dev_addr,
 	 */
 	(void)dm_i2c_read(dev, 0, ep, size);
 
+	if (*((u32 *)ep) != header)
+		one_byte_addressing = false;
+
+	/*
+	 * Handle case of bad 2 byte eeproms that responds to 1 byte addressing
+	 * but gets stuck in const addressing when read requests are performed
+	 * on offsets. We perform an offset test to make sure it is not a 2 byte
+	 * eeprom that works with 1 byte addressing but just without an offset
+	 */
+
+	rc = dm_i2c_read(dev, 0x1, &offset_test, sizeof(offset_test));
+
+	if (*((u32 *)ep) != (header & 0xFF))
+		one_byte_addressing = false;
+
 	/* Corrupted data??? */
-	if (*((u32 *)ep) != header) {
+	if (!one_byte_addressing) {
 		/*
 		 * read the eeprom header using i2c again, but use only a
 		 * 2 byte address (some newer boards need this..)
@@ -444,16 +461,6 @@ int __maybe_unused ti_i2c_eeprom_am6_get(int bus_addr, int dev_addr,
 	if (rc)
 		return rc;
 
-	/*
-	 * Handle case of bad 2 byte eeproms that responds to 1 byte addressing
-	 * but gets stuck in const addressing when read requests are performed
-	 * on offsets. We re-read the board ID to ensure we have sane data back
-	 */
-	rc = ti_i2c_eeprom_get(bus_addr, dev_addr, TI_EEPROM_HEADER_MAGIC,
-			       sizeof(board_id), (uint8_t *)&board_id);
-	if (rc)
-		return rc;
-
 	if (board_id.header.id != TI_AM6_EEPROM_RECORD_BOARD_ID) {
 		pr_err("%s: Invalid board ID record!\n", __func__);
 		return -EINVAL;
-- 
2.34.1