driver: add PPI support in tpm driver

The Physical Presence Interface enables the OS and the BIOS to cooperate and
provides a simple and straightforward platform user experience for
administering the TPM without sacrificing security.

V2: separate the patch out in a separate source file,
    add #ifdef CONFIG_ACPI so it compiles out on ppc,
    use standard error instead of ACPI error as return code of show/store fns.
V3: move #ifdef CONFIG_ACPI from .c file to .h file.
V4: move tpm_ppi code from tpm module to tpm_bios module.
V5: modify sys_add_ppi() so that ppi_attr_grp doesn't need to be exported
Signed-off-by: Xiaoyan Zhang <xiaoyan.zhang@intel.com>
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>

drivers/char/tpm/Makefile

@@ -4,7 +4,7 @@
 obj-$(CONFIG_TCG_TPM) += tpm.o
 ifdef CONFIG_ACPI
 	obj-$(CONFIG_TCG_TPM) += tpm_bios.o
-	tpm_bios-objs += tpm_eventlog.o tpm_acpi.o
+	tpm_bios-objs += tpm_eventlog.o tpm_acpi.o tpm_ppi.o
 else
 ifdef CONFIG_TCG_IBMVTPM
 	obj-$(CONFIG_TCG_TPM) += tpm_bios.o

drivers/char/tpm/tpm.c

@@ -1476,6 +1476,11 @@ struct tpm_chip *tpm_register_hardware(struct device *dev,
 		goto put_device;
 	}
 
+	if (sys_add_ppi(&dev->kobj)) {
+		misc_deregister(&chip->vendor.miscdev);
+		goto put_device;
+	}
+
 	chip->bios_dir = tpm_bios_log_setup(devname);
 
 	/* Make chip available */

drivers/char/tpm/tpm.h

@@ -327,3 +327,12 @@ extern int tpm_pm_suspend(struct device *);
 extern int tpm_pm_resume(struct device *);
 extern int wait_for_tpm_stat(struct tpm_chip *, u8, unsigned long,
 			     wait_queue_head_t *);
+
+#ifdef CONFIG_ACPI
+extern ssize_t sys_add_ppi(struct kobject *parent);
+#else
+static inline ssize_t sys_add_ppi(struct kobject *parent)
+{
+	return 0;
+}
+#endif