From: Stefan Roese <sr@denx.de>
Date: Thu, 18 Nov 2021 08:18:41 +0000 (+0100)
Subject: i2c: mvtwsi: Swab the register address if its size is > 1
X-Git-Url: http://git.dujemihanovic.xyz/?a=commitdiff_plain;h=ccea46c05b08b34ef829d460e50e2ce9bc17cdc7;p=u-boot.git

i2c: mvtwsi: Swab the register address if its size is > 1

Testing on Armada XP with an EEPROM using register address with size
of 2 has shown, that the register address bytes are sent to the I2C
EEPROM in the incorrect order. This patch swabs the address bytes so
that the correct address is transferred to the I2C device.

BTW: This worked without any issues before migrating Armada XP to
DM I2C.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Heiko Schocher <hs@denx.de>
Cc: Samuel Holland <samuel@sholland.org>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: Pali Rohár <pali@kernel.org>
Cc: Marek Behún <marek.behun@nic.cz>
Tested-by: Marek Behún <marek.behun@nic.cz>
---

diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c
index 236bfb8d8e..ff21e3c52b 100644
--- a/drivers/i2c/mvtwsi.c
+++ b/drivers/i2c/mvtwsi.c
@@ -860,6 +860,9 @@ static int mvtwsi_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
 {
 	struct mvtwsi_i2c_dev *dev = dev_get_priv(bus);
 	struct i2c_msg *dmsg, *omsg, dummy;
+	u8 *addr_buf_ptr;
+	u8 addr_buf[4];
+	int i;
 
 	memset(&dummy, 0, sizeof(struct i2c_msg));
 
@@ -873,12 +876,17 @@ static int mvtwsi_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
 	omsg = nmsgs == 1 ? &dummy : msg;
 	dmsg = nmsgs == 1 ? msg : msg + 1;
 
+	/* We need to swap the register address if its size is > 1 */
+	addr_buf_ptr = &addr_buf[0];
+	for (i = omsg->len; i > 0; i--)
+		*addr_buf_ptr++ = omsg->buf[i - 1];
+
 	if (dmsg->flags & I2C_M_RD)
-		return __twsi_i2c_read(dev->base, dmsg->addr, omsg->buf,
+		return __twsi_i2c_read(dev->base, dmsg->addr, addr_buf,
 				       omsg->len, dmsg->buf, dmsg->len,
 				       dev->tick);
 	else
-		return __twsi_i2c_write(dev->base, dmsg->addr, omsg->buf,
+		return __twsi_i2c_write(dev->base, dmsg->addr, addr_buf,
 					omsg->len, dmsg->buf, dmsg->len,
 					dev->tick);
 }