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.

[[e-mail]: added tpm_ prefix to read_log*]

Suggested-by: Jason Gunthorpe <[e-mail]>
Signed-off-by: Nayna Jain <[e-mail]>
Reviewed-by: Jason Gunthorpe <[e-mail]>
Reviewed-by: Jarkko Sakkinen <[e-mail]>
Tested-by: Jarkko Sakkinen <[e-mail]>
Signed-off-by: Jarkko Sakkinen <[e-mail]>

drivers/char/tpm/Makefile

···
 # Makefile for the kernel tpm device drivers.
 #
 obj-$(CONFIG_TCG_TPM) += tpm.o
-tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o
-tpm-$(CONFIG_ACPI) += tpm_ppi.o
-
-ifdef CONFIG_ACPI
-	tpm-y += tpm_eventlog.o tpm_acpi.o
-else
-ifdef CONFIG_TCG_IBMVTPM
-	tpm-y += tpm_eventlog.o tpm_of.o
-endif
-endif
+tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o \
+		tpm_eventlog.o
+tpm-$(CONFIG_ACPI) += tpm_ppi.o tpm_acpi.o
+tpm-$(CONFIG_OF) += tpm_of.o
 obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
 obj-$(CONFIG_TCG_TIS) += tpm_tis.o
 obj-$(CONFIG_TCG_TIS_SPI) += tpm_tis_spi.o

drivers/char/tpm/tpm_acpi.c

···
  *	Stefan Berger <[e-mail]>
  *	Reiner Sailer <[e-mail]>
  *	Kylene Hall <[e-mail]>
+ *	Nayna Jain <[e-mail]>
  *
  * Maintained by: <[e-mail]>
  *
···
 };
 
 /* read binary bios log */
-int read_log(struct tpm_chip *chip)
+int tpm_read_log_acpi(struct tpm_chip *chip)
 {
 	struct acpi_tcpa *buff;
 	acpi_status status;
···
 	struct tpm_bios_log *log;
 
 	log = &chip->log;
-	if (log->bios_event_log != NULL) {
-		printk(KERN_ERR
-		       "%s: ERROR - Eventlog already initialized\n",
-		       __func__);
-		return -EFAULT;
-	}
 
 	/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
 	status = acpi_get_table(ACPI_SIG_TCPA, 1,

drivers/char/tpm/tpm_eventlog.c

···
 	.release = tpm_bios_measurements_release,
 };
 
+static int tpm_read_log(struct tpm_chip *chip)
+{
+	int rc;
+
+	if (chip->log.bios_event_log != NULL) {
+		dev_dbg(&chip->dev,
+			"%s: ERROR - event log already initialized\n",
+			__func__);
+		return -EFAULT;
+	}
+
+	rc = tpm_read_log_acpi(chip);
+	if ((rc == 0) || (rc == -ENOMEM))
+		return rc;
+
+	rc = tpm_read_log_of(chip);
+
+	return rc;
+}
+
 int tpm_bios_log_setup(struct tpm_chip *chip)
 {
 	const char *name = dev_name(&chip->dev);
···
 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
 		return 0;
 
-	rc = read_log(chip);
+	rc = tpm_read_log(chip);
 	/*
 	 * read_log failure means event log is not supported except for ENOMEM.
 	 */

drivers/char/tpm/tpm_eventlog.h

···
 	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

drivers/char/tpm/tpm_of.c

···
  * Copyright 2012 IBM Corporation
  *
  * Author: Ashley Lai <[e-mail]>
+ *         Nayna Jain <[e-mail]>
  *
  * Maintained by: <[e-mail]>
  *
···
 #include "tpm.h"
 #include "tpm_eventlog.h"
 
-int read_log(struct tpm_chip *chip)
+int tpm_read_log_of(struct tpm_chip *chip)
 {
 	struct device_node *np;
 	const u32 *sizep;
···
 	struct tpm_bios_log *log;
 
 	log = &chip->log;
-	if (log->bios_event_log != NULL) {
-		pr_err("%s: ERROR - Eventlog already initialized\n", __func__);
-		return -EFAULT;
-	}
-
 	np = of_find_node_by_name(NULL, "vtpm");
 	if (!np) {
 		pr_err("%s: ERROR - IBMVTPM not supported\n", __func__);