tpm/tpm_i2c_atmel: Return -E2BIG when the transfer is incomplete

[ Upstream commit 442601e87a4769a8daba4976ec3afa5222ca211d ]

Return -E2BIG when the transfer is incomplete. The upper layer does
not retry, so not doing that is incorrect behaviour.

Cc: stable@vger.kernel.org
Fixes: a2871c62e186 ("tpm: Add support for Atmel I2C TPMs")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/char/tpm/tpm_i2c_atmel.c

@@ -69,6 +69,10 @@ static int i2c_atmel_send(struct tpm_chip *chip, u8 *buf, size_t len)
 	if (status < 0)
 		return status;
 
+	/* The upper layer does not support incomplete sends. */
+	if (status != len)
+		return -E2BIG;
+
 	return 0;
 }