[PATCH 1/2] tpm: Make response length of tpm2_get_capability() configurable

[Ilias Apalodimas]

A following patch introduces EFI_TCG2_PROTOCOL.
One of the functions of that protocol is GetCapability().
In order to parse device capabilities we need to access a u32
before the properties which the current implementation ignores
while reading device properties.

So let's make the response length configurable and prepare the
functions for EFI_TCG2_PROTOCOL.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
 cmd/tpm-v2.c     |  2 +-
 include/tpm-v2.h | 12 +++++++-----
 lib/tpm-v2.c     | 10 +++++++---
 3 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c
index e6742656f578..c2df1c34043a 100644
--- a/cmd/tpm-v2.c
+++ b/cmd/tpm-v2.c
@@ -183,7 +183,7 @@ static int do_tpm_get_capability(struct cmd_tbl *cmdtp, int flag, int argc,
 	data = map_sysmem(simple_strtoul(argv[3], NULL, 0), 0);
 	count = simple_strtoul(argv[4], NULL, 0);
 
-	rc = tpm2_get_capability(dev, capability, property, data, count);
+	rc = tpm2_get_capability(dev, capability, property, data, count, false);
 	if (rc)
 		goto unmap_data;
 
diff --git a/include/tpm-v2.h b/include/tpm-v2.h
index f6c045d35480..ee74028ca83b 100644
--- a/include/tpm-v2.h
+++ b/include/tpm-v2.h
@@ -257,15 +257,17 @@ u32 tpm2_pcr_read(struct udevice *dev, u32 idx, unsigned int idx_min_sz,
  * to query property index that is 4-byte wide.
  *
  * @dev		TPM device
- * @capability	Partition of capabilities
- * @property	Further definition of capability, limited to be 4 bytes wide
- * @buf		Output buffer for capability information
- * @prop_count	Size of output buffer
+ * @capability		Partition of capabilities
+ * @property		Further definition of capability, limited to be 4 bytes
+ *			wide
+ * @buf			Output buffer for capability information
+ * @prop_count		Size of output buffer
+ * @get_count		Include tpmu property count
  *
  * @return code of the operation
  */
 u32 tpm2_get_capability(struct udevice *dev, u32 capability, u32 property,
-			void *buf, size_t prop_count);
+			void *buf, size_t prop_count, bool get_count);
 
 /**
  * Issue a TPM2_DictionaryAttackLockReset command.
diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
index a4c352e3ef75..b58c1057995b 100644
--- a/lib/tpm-v2.c
+++ b/lib/tpm-v2.c
@@ -161,7 +161,7 @@ u32 tpm2_pcr_read(struct udevice *dev, u32 idx, unsigned int idx_min_sz,
 }
 
 u32 tpm2_get_capability(struct udevice *dev, u32 capability, u32 property,
-			void *buf, size_t prop_count)
+			void *buf, size_t prop_count, bool get_count)
 {
 	u8 command_v2[COMMAND_BUFFER_SIZE] = {
 		tpm_u16(TPM2_ST_NO_SESSIONS),		/* TAG */
@@ -181,13 +181,17 @@ u32 tpm2_get_capability(struct udevice *dev, u32 capability, u32 property,
 	if (ret)
 		return ret;
 
+	/* When reading PCR properties we need the count */
+	properties_off = sizeof(u16) + sizeof(u32) + sizeof(u32) +
+			 sizeof(u8) + sizeof(u32);
 	/*
 	 * In the response buffer, the properties are located after the:
 	 * tag (u16), response size (u32), response code (u32),
 	 * YES/NO flag (u8), TPM_CAP (u32) and TPMU_CAPABILITIES (u32).
 	 */
-	properties_off = sizeof(u16) + sizeof(u32) + sizeof(u32) +
-			 sizeof(u8) + sizeof(u32) + sizeof(u32);
+	if (!get_count)
+		properties_off += sizeof(u32);
+
 	memcpy(buf, &response[properties_off], response_len - properties_off);
 
 	return 0;
-- 
2.29.2