powerpc/powernv Platform dump interface

This enables support for userspace to fetch and initiate FSP and
Platform dumps from the service processor (via firmware) through sysfs.

Based on original patch from Vasant Hegde <hegdevasant@linux.vnet.ibm.com>

Flow:
  - We register for OPAL notification events.
  - OPAL sends new dump available notification.
  - We make information on dump available via sysfs
  - Userspace requests dump contents
  - We retrieve the dump via OPAL interface
  - User copies the dump data
  - userspace sends ack for dump
  - We send ACK to OPAL.

sysfs files:
  - We add the /sys/firmware/opal/dump directory
  - echoing 1 (well, anything, but in future we may support
    different dump types) to /sys/firmware/opal/dump/initiate_dump
    will initiate a dump.
  - Each dump that we've been notified of gets a directory
    in /sys/firmware/opal/dump/ with a name of the dump type and ID (in hex,
    as this is what's used elsewhere to identify the dump).
  - Each dump has files: id, type, dump and acknowledge
    dump is binary and is the dump itself.
    echoing 'ack' to acknowledge (currently any string will do) will
    acknowledge the dump and it will soon after disappear from sysfs.

OPAL APIs:
  - opal_dump_init()
  - opal_dump_info()
  - opal_dump_read()
  - opal_dump_ack()
  - opal_dump_resend_notification()

Currently we are only ever notified for one dump at a time (until
the user explicitly acks the current dump, then we get a notification
of the next dump), but this kernel code should "just work" when OPAL
starts notifying us of all the dumps present.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Documentation/ABI/stable/sysfs-firmware-opal-dump

@@ -0,0 +1,41 @@
+What:		/sys/firmware/opal/dump
+Date:		Feb 2014
+Contact:	Stewart Smith <stewart@linux.vnet.ibm.com>
+Description:
+		This directory exposes interfaces for interacting with
+		the FSP and platform dumps through OPAL firmware interface.
+
+		This is only for the powerpc/powernv platform.
+
+		initiate_dump:	When '1' is written to it,
+				we will initiate a dump.
+				Read this file for supported commands.
+
+		0xXX-0xYYYY:	A directory for dump of type 0xXX and
+				id 0xYYYY (in hex). The name of this
+				directory should not be relied upon to
+				be in this format, only that it's unique
+				among all dumps. For determining the type
+				and ID of the dump, use the id and type files.
+				Do not rely on any particular size of dump
+				type or dump id.
+
+		Each dump has the following files:
+		id:		An ASCII representation of the dump ID
+				in hex (e.g. '0x01')
+		type:		An ASCII representation of the type of
+				dump in the format "0x%x %s" with the ID
+				in hex and a description of the dump type
+				(or 'unknown').
+				Type '0xffffffff unknown' is used when
+				we could not get the type from firmware.
+				e.g. '0x02 System/Platform Dump'
+		dump:		A binary file containing the dump.
+				The size of the dump is the size of this file.
+		acknowledge:	When 'ack' is written to this, we will
+				acknowledge that we've retrieved the
+				dump to the service processor. It will
+				then remove it, making the dump
+				inaccessible.
+				Reading this file will get a list of
+				supported actions.

arch/powerpc/include/asm/opal.h

@@ -159,9 +159,15 @@ extern int opal_enter_rtas(struct rtas_args *args,
 #define OPAL_FLASH_VALIDATE			76
 #define OPAL_FLASH_MANAGE			77
 #define OPAL_FLASH_UPDATE			78
+#define OPAL_DUMP_INIT				81
+#define OPAL_DUMP_INFO				82
+#define OPAL_DUMP_READ				83
+#define OPAL_DUMP_ACK				84
 #define OPAL_GET_MSG				85
 #define OPAL_CHECK_ASYNC_COMPLETION		86
+#define OPAL_DUMP_RESEND			91
 #define OPAL_SYNC_HOST_REBOOT			87
+#define OPAL_DUMP_INFO2				94
 
 #ifndef __ASSEMBLY__
 
@@ -242,6 +248,7 @@ enum OpalPendingState {
 	OPAL_EVENT_EPOW			= 0x80,
 	OPAL_EVENT_LED_STATUS		= 0x100,
 	OPAL_EVENT_PCI_ERROR		= 0x200,
+	OPAL_EVENT_DUMP_AVAIL		= 0x400,
 	OPAL_EVENT_MSG_PENDING		= 0x800,
 };
 
@@ -838,6 +845,12 @@ void opal_resend_pending_logs(void);
 int64_t opal_validate_flash(uint64_t buffer, uint32_t *size, uint32_t *result);
 int64_t opal_manage_flash(uint8_t op);
 int64_t opal_update_flash(uint64_t blk_list);
+int64_t opal_dump_init(uint8_t dump_type);
+int64_t opal_dump_info(uint32_t *dump_id, uint32_t *dump_size);
+int64_t opal_dump_info2(uint32_t *dump_id, uint32_t *dump_size, uint32_t *dump_type);
+int64_t opal_dump_read(uint32_t dump_id, uint64_t buffer);
+int64_t opal_dump_ack(uint32_t dump_id);
+int64_t opal_dump_resend_notification(void);
 
 int64_t opal_get_msg(uint64_t buffer, size_t size);
 int64_t opal_check_completion(uint64_t buffer, size_t size, uint64_t token);
@@ -876,6 +889,7 @@ extern unsigned long opal_get_boot_time(void);
 extern void opal_nvram_init(void);
 extern void opal_flash_init(void);
 extern int opal_elog_init(void);
+extern void opal_platform_dump_init(void);
 
 extern int opal_machine_check(struct pt_regs *regs);
 extern bool opal_mce_check_early_recovery(struct pt_regs *regs);

arch/powerpc/platforms/powernv/Makefile

@@ -1,6 +1,6 @@
 obj-y			+= setup.o opal-takeover.o opal-wrappers.o opal.o
 obj-y			+= opal-rtc.o opal-nvram.o opal-lpc.o opal-flash.o
-obj-y			+= rng.o opal-elog.o
+obj-y			+= rng.o opal-elog.o opal-dump.o
 
 obj-$(CONFIG_SMP)	+= smp.o
 obj-$(CONFIG_PCI)	+= pci.o pci-p5ioc2.o pci-ioda.o