[PATCH RFC] tpm, tpm_tis: detect TPM2 devices

[Jarkko Sakkinen]

It turned out that the root cause in b371616b8 was not entirely correct
for https://bugzilla.kernel.org/show_bug.cgi?id=98181.

All TPM 2.0 FIFO and CRB devices have the same HID. For FIFO devices
the start method is 6 as it is defined in

http://www.trustedcomputinggroup.org/resources/tcg_acpi_specification

This patch changes FIFO and CRB drivers so that they check start method
value and initialize only if the start method has a proper value for
that particular interface.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
 drivers/char/tpm/tpm.h     |  7 +++++++
 drivers/char/tpm/tpm_crb.c | 20 +++++---------------
 drivers/char/tpm/tpm_tis.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 55 insertions(+), 17 deletions(-)

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index f8319a0..39be5ac 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -115,6 +115,13 @@ enum tpm2_startup_types {
 	TPM2_SU_STATE	= 0x0001,
 };
 
+enum tpm2_start_method {
+	TPM2_START_ACPI = 2,
+	TPM2_START_FIFO = 6,
+	TPM2_START_CRB = 7,
+	TPM2_START_CRB_WITH_ACPI = 8,
+};
+
 struct tpm_chip;
 
 struct tpm_vendor_specific {
diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
index 1267322..b4564b6 100644
--- a/drivers/char/tpm/tpm_crb.c
+++ b/drivers/char/tpm/tpm_crb.c
@@ -34,12 +34,6 @@ enum crb_defaults {
 	CRB_ACPI_START_INDEX = 1,
 };
 
-enum crb_start_method {
-	CRB_SM_ACPI_START = 2,
-	CRB_SM_CRB = 7,
-	CRB_SM_CRB_WITH_ACPI_START = 8,
-};
-
 struct acpi_tpm2 {
 	struct acpi_table_header hdr;
 	u16 platform_class;
@@ -233,13 +227,9 @@ static int crb_acpi_add(struct acpi_device *device)
 		return -ENODEV;
 	}
 
-	/* At least some versions of AMI BIOS have a bug that TPM2 table has
-	 * zero address for the control area and therefore we must fail.
-	*/
-	if (!buf->control_area_pa) {
-		dev_err(dev, "TPM2 ACPI table has a zero address for the control area\n");
-		return -EINVAL;
-	}
+	/* Should the FIFO driver handle this? */
+	if (buf->start_method == TPM2_START_FIFO)
+		return -ENODEV;
 
 	if (buf->hdr.length < sizeof(struct acpi_tpm2)) {
 		dev_err(dev, "TPM2 ACPI table has wrong size");
@@ -259,11 +249,11 @@ static int crb_acpi_add(struct acpi_device *device)
 	 * report only ACPI start but in practice seems to require both
 	 * ACPI start and CRB start.
 	 */
-	if (sm == CRB_SM_CRB || sm == CRB_SM_CRB_WITH_ACPI_START ||
+	if (sm == TPM2_START_CRB || sm == TPM2_START_FIFO ||
 	    !strcmp(acpi_device_hid(device), "MSFT0101"))
 		priv->flags |= CRB_FL_CRB_START;
 
-	if (sm == CRB_SM_ACPI_START || sm == CRB_SM_CRB_WITH_ACPI_START)
+	if (sm == TPM2_START_ACPI || sm == TPM2_START_CRB_WITH_ACPI)
 		priv->flags |= CRB_FL_ACPI_START;
 
 	priv->cca = (struct crb_control_area __iomem *)
diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
index f2dffa7..4760804 100644
--- a/drivers/char/tpm/tpm_tis.c
+++ b/drivers/char/tpm/tpm_tis.c
@@ -28,6 +28,7 @@
 #include <linux/wait.h>
 #include <linux/acpi.h>
 #include <linux/freezer.h>
+#include <acpi/actbl2.h>
 #include "tpm.h"
 
 enum tis_access {
@@ -91,7 +92,7 @@ struct priv_data {
 };
 
 #if defined(CONFIG_PNP) && defined(CONFIG_ACPI)
-static int is_itpm(struct pnp_dev *dev)
+static int has_hid(struct pnp_dev *dev, const char *hid)
 {
 	struct acpi_device *acpi = pnp_acpi_device(dev);
 	struct acpi_hardware_id *id;
@@ -100,17 +101,49 @@ static int is_itpm(struct pnp_dev *dev)
 		return 0;
 
 	list_for_each_entry(id, &acpi->pnp.ids, list) {
-		if (!strcmp("INTC0102", id->id))
+		if (!strcmp(hid, id->id))
 			return 1;
 	}
 
 	return 0;
 }
+
+static inline int is_itpm(struct pnp_dev *dev)
+{
+	return has_hid(dev, "INTC0102");
+}
+
+static inline int validate_pnp_dev(struct pnp_dev *dev)
+{
+	struct acpi_table_tpm2 *tbl;
+	acpi_status st;
+
+	if (!has_hid(dev, "MSFT0101"))
+		return 0;
+
+	st = acpi_get_table(ACPI_SIG_TPM2, 1,
+			    (struct acpi_table_header **) &tbl);
+	if (ACPI_FAILURE(st)) {
+		dev_err(&dev->dev, "failed to get TPM2 ACPI table\n");
+		return -ENODEV;
+	}
+
+	/*  Should the CRB driver handle this? */
+	if (le32_to_cpu(tbl->start_method) != TPM2_START_FIFO)
+		return -ENODEV:
+
+	retuurn 0;
+}
 #else
 static inline int is_itpm(struct pnp_dev *dev)
 {
 	return 0;
 }
+
+static inline int validate_pnp_dev(struct pnp_dev *dev)
+{
+	return 0;
+}
 #endif
 
 /* Before we attempt to access the TPM we must see that the valid bit is set.
@@ -893,6 +926,11 @@ static int tpm_tis_pnp_init(struct pnp_dev *pnp_dev,
 	resource_size_t start, len;
 	unsigned int irq = 0;
 	acpi_handle acpi_dev_handle = NULL;
+	int ret;
+
+	ret = validate_pnp_dev(pnp_dev);
+	if (ret)
+		return ret;
 
 	start = pnp_mem_start(pnp_dev, 0);
 	len = pnp_mem_len(pnp_dev, 0);
@@ -921,6 +959,9 @@ static struct pnp_device_id tpm_pnp_tbl[] = {
 	{"BCM0102", 0},		/* Broadcom */
 	{"NSC1200", 0},		/* National */
 	{"ICO0102", 0},		/* Intel */
+#ifdef CONFIG_ACPI
+	{"MSFT0101", 0},	/* TPM 2.0 */
+#endif
 	/* Add new here */
 	{"", 0},		/* User Specified */
 	{"", 0}			/* Terminator */
-- 
2.5.0

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