[PATCH v2 4/4] tpm: tpm_crb: Use cached tpm2_acpi_start_method

[Siddharth Chintamaneni <sidchintamaneni@gmail.com>]

Check the cached tpm2_acpi_start_method value at the start of
crb_acpi_probe() before mapping the ACPI TPM2 table for CRB-specific
parameters. This avoids mapping the table when it is absent or when the
device uses ACPI_TPM2_MEMORY_MAPPED and belongs to tpm_tis.

Signed-off-by: Siddharth Chintamaneni <sidchintamaneni@gmail.com>
---
 drivers/char/tpm/tpm_crb.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 4749a9183726..c1c2b72459a2 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -945,18 +945,23 @@ static int crb_acpi_probe(struct platform_device *pdev)
 	if (!device)
 		return -ENODEV;
 
-	status = acpi_get_table(ACPI_SIG_TPM2, 1,
-				(struct acpi_table_header **) &buf);
-	if (ACPI_FAILURE(status) || buf->header.length < sizeof(*buf)) {
+	sm = tpm2_acpi_start_method;
+	if (sm == ACPI_TPM2_NOT_ALLOWED) {
 		dev_err(dev, FW_BUG "failed to get TPM2 ACPI table\n");
 		return -EINVAL;
 	}
 
 	/* Should the FIFO driver handle this? */
-	sm = buf->start_method;
-	if (sm == ACPI_TPM2_MEMORY_MAPPED) {
-		rc = -ENODEV;
-		goto out;
+	if (sm == ACPI_TPM2_MEMORY_MAPPED)
+		return -ENODEV;
+
+	status = acpi_get_table(ACPI_SIG_TPM2, 1,
+				(struct acpi_table_header **)&buf);
+	if (ACPI_FAILURE(status) || buf->header.length < sizeof(*buf)) {
+		dev_err(dev, FW_BUG "failed to get TPM2 ACPI table\n");
+		if (ACPI_SUCCESS(status))
+			acpi_put_table((struct acpi_table_header *)buf);
+		return -EINVAL;
 	}
 
 	priv = devm_kzalloc_obj(dev, struct crb_priv);
-- 
2.45.4