On EEH events the kernel will print a dump of relevant registers.
If EEH is unavailable (i.e. CONFIG_EEH is disabled, a new platform
doesn't have EEH support, etc) this information isn't readily available.

Add a new debugfs handler to trigger a PHB register dump, so that this
information can be made available on demand.

Signed-off-by: Russell Currey <rus...@russell.cc>
---
V2 changes:
        - use a simple attribute instead of full fops thanks to mpe
        - miscellanous fixes thanks to Gavin
        - rename from "regdump" to "dump_regs"
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 43 ++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c 
b/arch/powerpc/platforms/powernv/pci-ioda.c
index 891fc4a..2b9f114 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -3018,6 +3018,42 @@ static void pnv_ioda_setup_pe_seg(struct pnv_ioda_pe *pe)
        }
 }
 
+#ifdef CONFIG_DEBUG_FS
+static int pnv_pci_diag_data_set(void *data, u64 val)
+{
+       struct pci_controller *hose;
+       struct pnv_phb *phb;
+       int ret;
+
+       if (val != 1)
+               return -EINVAL;
+
+       hose = (struct pci_controller *)data;
+       if (!hose)
+               return -EFAULT;
+
+       phb = hose->private_data;
+       if (!phb)
+               return -EFAULT;
+
+       /* Retrieve the diag data from firmware */
+       ret = opal_pci_get_phb_diag_data2(phb->opal_id, phb->diag.blob,
+                                         PNV_PCI_DIAG_BUF_SIZE);
+       if (ret != OPAL_SUCCESS)
+               return -EIO;
+
+       /* Print the diag data to the kernel log */
+       pnv_pci_dump_phb_diag_data(phb->hose, phb->diag.blob);
+       return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(pnv_pci_diag_data_fops,
+                       NULL,
+                       pnv_pci_diag_data_set,
+                       "%llu\n");
+
+#endif /* CONFIG_DEBUG_FS */
+
 static void pnv_pci_ioda_create_dbgfs(void)
 {
 #ifdef CONFIG_DEBUG_FS
@@ -3033,9 +3069,14 @@ static void pnv_pci_ioda_create_dbgfs(void)
 
                sprintf(name, "PCI%04x", hose->global_number);
                phb->dbgfs = debugfs_create_dir(name, powerpc_debugfs_root);
-               if (!phb->dbgfs)
+               if (!phb->dbgfs) {
                        pr_warning("%s: Error on creating debugfs on PHB#%x\n",
                                __func__, hose->global_number);
+                       continue;
+               }
+
+               debugfs_create_file("dump_regs", 0200, phb->dbgfs, hose,
+                                   &pnv_pci_diag_data_fops);
        }
 #endif /* CONFIG_DEBUG_FS */
 }
-- 
2.9.0

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