powerpc/eeh: Initialize EEH address cache earlier

The EEH address cache is currently initialized and populated by a
single function: eeh_addr_cache_build().  While the initial population
of the cache can only be done once resources are allocated,
initialization (just setting up a spinlock) could be done much
earlier.

So move the initialization step into a separate function and call it
from a core_initcall (rather than a subsys initcall).

This will allow future work to make use of the cache during boot time
PCI scanning.

Signed-off-by: Sam Bobroff <sbobroff@linux.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/0557206741bffee76cdfff042f65321f6f7a5b41.1565930772.git.sbobroff@linux.ibm.com

arch/powerpc/include/asm/eeh.h

@@ -274,6 +274,7 @@ int __init eeh_ops_register(struct eeh_ops *ops);
 int __exit eeh_ops_unregister(const char *name);
 int eeh_check_failure(const volatile void __iomem *token);
 int eeh_dev_check_failure(struct eeh_dev *edev);
+void eeh_addr_cache_init(void);
 void eeh_addr_cache_build(void);
 void eeh_add_device_early(struct pci_dn *);
 void eeh_add_device_tree_early(struct pci_dn *);
@@ -332,6 +333,8 @@ static inline int eeh_check_failure(const volatile void __iomem *token)
 
 #define eeh_dev_check_failure(x) (0)
 
+static inline void eeh_addr_cache_init(void) { }
+
 static inline void eeh_addr_cache_build(void) { }
 
 static inline void eeh_add_device_early(struct pci_dn *pdn) { }

arch/powerpc/kernel/eeh.c

@@ -1120,6 +1120,8 @@ static int eeh_init(void)
 	list_for_each_entry_safe(hose, tmp, &hose_list, list_node)
 		eeh_dev_phb_init_dynamic(hose);
 
+	eeh_addr_cache_init();
+
 	/* Initialize EEH event */
 	return eeh_event_init();
 }

arch/powerpc/kernel/eeh_cache.c

@@ -257,6 +257,17 @@ void eeh_addr_cache_rmv_dev(struct pci_dev *dev)
 	spin_unlock_irqrestore(&pci_io_addr_cache_root.piar_lock, flags);
 }
 
+/**
+ * eeh_addr_cache_init - Initialize a cache of I/O addresses
+ *
+ * Initialize a cache of pci i/o addresses.  This cache will be used to
+ * find the pci device that corresponds to a given address.
+ */
+void eeh_addr_cache_init(void)
+{
+	spin_lock_init(&pci_io_addr_cache_root.piar_lock);
+}
+
 /**
  * eeh_addr_cache_build - Build a cache of I/O addresses
  *
@@ -272,8 +283,6 @@ void eeh_addr_cache_build(void)
 	struct eeh_dev *edev;
 	struct pci_dev *dev = NULL;
 
-	spin_lock_init(&pci_io_addr_cache_root.piar_lock);
-
 	for_each_pci_dev(dev) {
 		pdn = pci_get_pdn_by_devfn(dev->bus, dev->devfn);
 		if (!pdn)