tpm: redefine read_log() to handle ACPI/OF at runtime

Currently, read_log() has two implementations: one for ACPI platforms
and the other for device tree(OF) based platforms. The proper one is
selected at compile time using Kconfig and #ifdef in the Makefile,
which is not the recommended approach.

This patch removes the #ifdef in the Makefile by defining a single
read_log() method, which checks for ACPI/OF event log properties at
runtime.

[jarkko.sakkinen@linux.intel.com: added tpm_ prefix to read_log*]

Suggested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Nayna Jain <nayna@linux.vnet.ibm.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
diff --git a/drivers/char/tpm/tpm_eventlog.h b/drivers/char/tpm/tpm_eventlog.h
index 6df2f8e..1660d74 100644
--- a/drivers/char/tpm/tpm_eventlog.h
+++ b/drivers/char/tpm/tpm_eventlog.h
@@ -73,20 +73,24 @@ enum tcpa_pc_event_ids {
 	HOST_TABLE_OF_DEVICES,
 };
 
-int read_log(struct tpm_chip *chip);
-
-#if defined(CONFIG_TCG_IBMVTPM) || defined(CONFIG_TCG_IBMVTPM_MODULE) || \
-	defined(CONFIG_ACPI)
-extern int tpm_bios_log_setup(struct tpm_chip *chip);
-extern void tpm_bios_log_teardown(struct tpm_chip *chip);
+#if defined(CONFIG_ACPI)
+int tpm_read_log_acpi(struct tpm_chip *chip);
 #else
-static inline int tpm_bios_log_setup(struct tpm_chip *chip)
+static inline int tpm_read_log_acpi(struct tpm_chip *chip)
 {
-	return 0;
-}
-static inline void tpm_bios_log_teardown(struct tpm_chip *chip)
-{
+	return -ENODEV;
 }
 #endif
+#if defined(CONFIG_OF)
+int tpm_read_log_of(struct tpm_chip *chip);
+#else
+static inline int tpm_read_log_of(struct tpm_chip *chip)
+{
+	return -ENODEV;
+}
+#endif
+
+int tpm_bios_log_setup(struct tpm_chip *chip);
+void tpm_bios_log_teardown(struct tpm_chip *chip);
 
 #endif