i2c: pasemi: Improve error recovery

Add handling for all the missing error condition, and better recovery in
pasemi_smb_clear().

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Hector Martin <marcan@marcan.st>
Co-developed-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Link: https://lore.kernel.org/r/20250427-pasemi-fixes-v3-3-af28568296c0@svenpeter.dev
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

Author: marcan

drivers/i2c/busses/i2c-pasemi-core.c

@@ -87,12 +87,31 @@ static void pasemi_reset(struct pasemi_smbus *smbus)
 	reinit_completion(&smbus->irq_completion);
 }
 
-static void pasemi_smb_clear(struct pasemi_smbus *smbus)
+static int pasemi_smb_clear(struct pasemi_smbus *smbus)
 {
 	unsigned int status;
+	int ret;
+
+	/* First wait for the bus to go idle */
+	ret = readx_poll_timeout(ioread32, smbus->ioaddr + REG_SMSTA,
+				 status, !(status & (SMSTA_XIP | SMSTA_JAM)),
+				 USEC_PER_MSEC,
+				 USEC_PER_MSEC * PASEMI_TRANSFER_TIMEOUT_MS);
+
+	if (ret < 0) {
+		dev_err(smbus->dev, "Bus is still stuck (status 0x%08x)\n", status);
+		return -EIO;
+	}
+
+	/* If any badness happened or there is data in the FIFOs, reset the FIFOs */
+	if ((status & (SMSTA_MRNE | SMSTA_JMD | SMSTA_MTO | SMSTA_TOM | SMSTA_MTN | SMSTA_MTA)) ||
+	    !(status & SMSTA_MTE))
+		pasemi_reset(smbus);
 
-	status = reg_read(smbus, REG_SMSTA);
+	/* Clear the flags */
 	reg_write(smbus, REG_SMSTA, status);
+
+	return 0;
 }
 
 static int pasemi_smb_waitready(struct pasemi_smbus *smbus)
@@ -130,9 +149,35 @@ static int pasemi_smb_waitready(struct pasemi_smbus *smbus)
 		}
 	}
 
+	/* Controller timeout? */
+	if (status & SMSTA_TOM) {
+		dev_err(smbus->dev, "Controller timeout, status 0x%08x\n", status);
+		return -EIO;
+	}
+
+	/* Peripheral timeout? */
+	if (status & SMSTA_MTO) {
+		dev_err(smbus->dev, "Peripheral timeout, status 0x%08x\n", status);
+		return -ETIME;
+	}
+
+	/* Still stuck in a transaction? */
+	if (status & SMSTA_XIP) {
+		dev_err(smbus->dev, "Bus stuck, status 0x%08x\n", status);
+		return -EIO;
+	}
+
+	/* Arbitration loss? */
+	if (status & SMSTA_MTA) {
+		dev_err(smbus->dev, "Arbitration loss, status 0x%08x\n", status);
+		return -EBUSY;
+	}
+
 	/* Got NACK? */
-	if (status & SMSTA_MTN)
+	if (status & SMSTA_MTN) {
+		dev_err(smbus->dev, "NACK, status 0x%08x\n", status);
 		return -ENXIO;
+	}
 
 	/* Clear XEN */
 	reg_write(smbus, REG_SMSTA, SMSTA_XEN);
@@ -194,9 +239,9 @@ static int pasemi_i2c_xfer(struct i2c_adapter *adapter,
 	struct pasemi_smbus *smbus = adapter->algo_data;
 	int ret, i;
 
-	pasemi_smb_clear(smbus);
-
-	ret = 0;
+	ret = pasemi_smb_clear(smbus);
+	if (ret)
+		return ret;
 
 	for (i = 0; i < num && !ret; i++)
 		ret = pasemi_i2c_xfer_msg(adapter, &msgs[i], (i == (num - 1)));
@@ -217,7 +262,9 @@ static int pasemi_smb_xfer(struct i2c_adapter *adapter,
 	addr <<= 1;
 	read_flag = read_write == I2C_SMBUS_READ;
 
-	pasemi_smb_clear(smbus);
+	err = pasemi_smb_clear(smbus);
+	if (err)
+		return err;
 
 	switch (size) {
 	case I2C_SMBUS_QUICK: