powerpc/pseries/eeh: Allow zero to be a valid PE configuration address

[linux-2.6-microblaze.git] / arch / powerpc / platforms / pseries / eeh_pseries.c

diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
index 4b88b48..f8b5461 100644 (file)
--- a/arch/powerpc/platforms/pseries/eeh_pseries.c
+++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
@@ -87,21 +87,20 @@ void pseries_pcibios_bus_add_device(struct pci_dev *pdev)
  * pseries_eeh_get_pe_config_addr - Find the pe_config_addr for a device
  * @pdn: pci_dn of the input device
  *
- * Retrieve the assocated config address. Actually, there're 2 RTAS
- * function calls dedicated for the purpose. We need implement
- * it through the new function and then the old one. Besides,
- * you should make sure the config address is figured out from
- * FDT node before calling the function.
+ * The EEH RTAS calls use a tuple consisting of: (buid_hi, buid_lo,
+ * pe_config_addr) as a handle to a given PE. This function finds the
+ * pe_config_addr based on the device's config addr.
  *
- * It's notable that zero'ed return value means invalid PE config
- * address.
+ * Keep in mind that the pe_config_addr *might* be numerically identical to the
+ * device's config addr, but the two are conceptually distinct.
+ *
+ * Returns the pe_config_addr, or a negative error code.
  */
 static int pseries_eeh_get_pe_config_addr(struct pci_dn *pdn)
 {
        int config_addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
        struct pci_controller *phb = pdn->phb;
-       int ret = 0;
-       int rets[3];
+       int ret, rets[3];
 
        if (ibm_get_config_addr_info2 != RTAS_UNKNOWN_SERVICE) {
                /*
@@ -112,16 +111,16 @@ static int pseries_eeh_get_pe_config_addr(struct pci_dn *pdn)
                                config_addr, BUID_HI(phb->buid),
                                BUID_LO(phb->buid), 1);
                if (ret || (rets[0] == 0))
-                       return 0;
+                       return -ENOENT;
 
-               /* Retrieve the associated PE config address */
+               /* Retrieve the associated PE config address with function 0 */
                ret = rtas_call(ibm_get_config_addr_info2, 4, 2, rets,
                                config_addr, BUID_HI(phb->buid),
                                BUID_LO(phb->buid), 0);
                if (ret) {
                        pr_warn("%s: Failed to get address for PHB#%x-PE#%x\n",
                                __func__, phb->global_number, config_addr);
-                       return 0;
+                       return -ENXIO;
                }
 
                return rets[0];
@@ -134,13 +133,20 @@ static int pseries_eeh_get_pe_config_addr(struct pci_dn *pdn)
                if (ret) {
                        pr_warn("%s: Failed to get address for PHB#%x-PE#%x\n",
                                __func__, phb->global_number, config_addr);
-                       return 0;
+                       return -ENXIO;
                }
 
                return rets[0];
        }
 
-       return ret;
+       /*
+        * PAPR does describe a process for finding the pe_config_addr that was
+        * used before the ibm,get-config-addr-info calls were added. However,
+        * I haven't found *any* systems that don't have that RTAS call
+        * implemented. If you happen to find one that needs the old DT based
+        * process, patches are welcome!
+        */
+       return -ENOENT;
 }
 
 /**
@@ -417,7 +423,7 @@ void pseries_eeh_init_edev(struct pci_dn *pdn)
 
        /* first up, find the pe_config_addr for the PE containing the device */
        addr = pseries_eeh_get_pe_config_addr(pdn);
-       if (addr == 0) {
+       if (addr < 0) {
                eeh_edev_dbg(edev, "Unable to find pe_config_addr\n");
                goto err;
        }
@@ -897,7 +903,7 @@ static int __init eeh_pseries_init(void)
                        config_addr = pseries_eeh_get_pe_config_addr(pdn);
 
                        /* invalid PE config addr */
-                       if (config_addr == 0)
+                       if (config_addr < 0)
                                continue;
 
                        pseries_eeh_phb_reset(phb, config_addr, EEH_RESET_FUNDAMENTAL);