powerpc/eeh: pseries platform EEH operations

There're 4 EEH operations that are covered by the dedicated RTAS
call <ibm,set-eeh-option>: enable or disable EEH, enable MMIO and
enable DMA. At early stage of system boot, the EEH would be tried
to enable on PCI device related device node. MMIO and DMA for
particular PE should be enabled when doing recovery on EEH errors
so that the PE could function properly again.

The patch implements it and abstract that through struct
eeh_ops::set_eeh. It would be help for EEH to support multiple
platforms in future.

Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/eeh.h

@@ -38,6 +38,10 @@ struct device_node;
  * platform should register its own EEH operation callback
  * functions before any EEH further operations.
  */
+#define EEH_OPT_DISABLE		0	/* EEH disable	*/
+#define EEH_OPT_ENABLE		1	/* EEH enable	*/
+#define EEH_OPT_THAW_MMIO	2	/* MMIO enable	*/
+#define EEH_OPT_THAW_DMA	3	/* DMA enable	*/
 struct eeh_ops {
 	char *name;
 	int (*init)(void);