[Skiboot] [PATCH v1] PCI: pci should throw error on platform PCI devices not being detected

[Mamatha Inamdar]

Problem Description: Sometimes system boots to petitboot and get into a state where
only the PHBs were detected and *no* other PCI devices.

Fix: This patch is to check the detected PCI devices against the PCI slot 
table in the platform definition and display an error if they don't match 
and commit an errorlog.

Test Results:
After testing the patch, we see following traces on the SOL console.
[8212824503,5] PCI: Check for a present device...
[8212921065,3] Slot3 PCI: No device found
[8212987391,5] Device Found in SLOT= Backplane PLX
[8213085726,3] Slot4 PCI: No device found 

Signed-off-by: Mamatha Inamdar <mamatha4 at linux.vnet.ibm.com>
---
 core/pci.c         |   33 +++++++++++++++++++++++++++++++++
 include/errorlog.h |    3 ++-
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/core/pci.c b/core/pci.c
index 9b238d0..f7ca477 100644
--- a/core/pci.c
+++ b/core/pci.c
@@ -20,6 +20,7 @@
 #include <pci-cfg.h>
 #include <timebase.h>
 #include <device.h>
+#include <errorlog.h>
 #include <fsp.h>
 
 #define MAX_PHB_ID	256
@@ -47,6 +48,9 @@ int last_phb_id = 0;
 	      ((_bdfn) >> 8) & 0xff,			\
 	      ((_bdfn) >> 3) & 0x1f, (_bdfn) & 0x7, ## a)
 
+DEFINE_LOG_ENTRY(OPAL_RC_PCI_DETECT_DEV, OPAL_PLATFORM_ERR_EVT, OPAL_PCI,
+		OPAL_MISC_SUBSYSTEM,OPAL_PREDICTIVE_ERR_GENERAL,
+		OPAL_NA);
 /*
  * Generic PCI utilities
  */
@@ -1510,6 +1514,28 @@ static void pci_do_jobs(void (*fn)(void *))
 	free(jobs);
 }
 
+static void scan_present_device(struct phb *phb)
+{
+	int64_t rc;
+	struct pci_device *pd;
+
+	/*
+	for PCI/PCI-X, we get the slot info and heck
+	if the PHB has anything connected to it
+	*/
+	while ((pd = list_pop(&phb->devices, struct pci_device, link)) != NULL) {
+		if (platform.pci_get_slot_info)
+			platform.pci_get_slot_info(phb, pd);
+
+		rc = phb->ops->presence_detect(phb);
+		if (rc != OPAL_SHPC_DEV_PRESENT)
+			log_simple_error(&e_info(OPAL_RC_PCI_DETECT_DEV), "%s "
+			"PCI: No device found\n", pd->slot_info->label);
+		else
+			prlog(PR_NOTICE, "Device Found in SLOT= %s\n", pd->slot_info->label);
+	}
+}
+
 void pci_init_slots(void)
 {
 	unsigned int i;
@@ -1538,6 +1564,13 @@ void pci_init_slots(void)
 
 		phbs[i]->ops->phb_final_fixup(phbs[i]);
 	}
+
+	prlog(PR_NOTICE, "PCI: Check for a present device...\n");
+	for (i = 0; i < ARRAY_SIZE(phbs); i++) {
+		if (!phbs[i])
+			continue;
+		scan_present_device(phbs[i]);
+	}
 }
 
 /*
diff --git a/include/errorlog.h b/include/errorlog.h
index b8fca7d..d6f18d1 100644
--- a/include/errorlog.h
+++ b/include/errorlog.h
@@ -280,7 +280,8 @@ enum opal_reasoncode {
 	OPAL_RC_PCI_INIT_SLOT   = OPAL_PC | 0x10,
 	OPAL_RC_PCI_ADD_SLOT    = OPAL_PC | 0x11,
 	OPAL_RC_PCI_SCAN        = OPAL_PC | 0x12,
-	OPAL_RC_PCI_RESET_PHB   = OPAL_PC | 0x10,
+	OPAL_RC_PCI_RESET_PHB   = OPAL_PC | 0x13,
+	OPAL_RC_PCI_DETECT_DEV  = OPAL_PC | 0x14,
 /* ATTN */
 	OPAL_RC_ATTN		= OPAL_AT | 0x10,
 /* MEM_ERR */