[PATCH] PPC64 Use newer RTAS call when available

[Paul Mackerras]

This patch is from Nathan Fontenot <nfont at austin.ibm.com> originally.

The PPC64 EEH code needs a small update to start using the
ibm,read-slot-reset-state2 rtas call if available.  The currently
used ibm,read-slot-reset-state call will be going away on future
machines.

This patch attempts to use the newer rtas call if available and falls
back the older version otherwise.  This will maintain EEH slot checking
capabilities on all future and current firmware levels.

Signed-off-by: Nathan Fontenot <nfont at austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus at samba.org>

diff -urN base-2.6/arch/ppc64/kernel/eeh.c test/arch/ppc64/kernel/eeh.c
--- base-2.6/arch/ppc64/kernel/eeh.c	2005-01-05 14:29:58.333466400 +1100
+++ test/arch/ppc64/kernel/eeh.c	2005-01-05 15:04:59.937483424 +1100
@@ -96,6 +96,7 @@
 static int ibm_set_eeh_option;
 static int ibm_set_slot_reset;
 static int ibm_read_slot_reset_state;
+static int ibm_read_slot_reset_state2;
 static int ibm_slot_error_detail;
 
 static int eeh_subsystem_enabled;
@@ -408,6 +409,27 @@
 }
 
 /**
+ * read_slot_reset_state - Read the reset state of a device node's slot
+ * @dn: device node to read
+ * @rets: array to return results in
+ */
+static int read_slot_reset_state(struct device_node *dn, int rets[])
+{
+	int token, outputs;
+
+	if (ibm_read_slot_reset_state2 != RTAS_UNKNOWN_SERVICE) {
+		token = ibm_read_slot_reset_state2;
+		outputs = 4;
+	} else {
+		token = ibm_read_slot_reset_state;
+		outputs = 3;
+	}
+	
+	return rtas_call(token, 3, outputs, rets, dn->eeh_config_addr, 
+			 BUID_HI(dn->phb->buid), BUID_LO(dn->phb->buid));
+}
+
+/**
  * eeh_panic - call panic() for an eeh event that cannot be handled.
  * The philosophy of this routine is that it is better to panic and
  * halt the OS than it is to risk possible data corruption by
@@ -509,7 +531,7 @@
 int eeh_dn_check_failure(struct device_node *dn, struct pci_dev *dev)
 {
 	int ret;
-	int rets[2];
+	int rets[3];
 	unsigned long flags;
 	int rc, reset_state;
 	struct eeh_event  *event;
@@ -540,11 +562,8 @@
 		atomic_inc(&eeh_fail_count);
 		if (atomic_read(&eeh_fail_count) >= EEH_MAX_FAILS) {
 			/* re-read the slot reset state */
-			rets[0] = -1;
-			rtas_call(ibm_read_slot_reset_state, 3, 3, rets,
-				  dn->eeh_config_addr,
-				  BUID_HI(dn->phb->buid),
-				  BUID_LO(dn->phb->buid));
+			if (read_slot_reset_state(dn, rets) != 0)
+				rets[0] = -1;	/* reset state unknown */
 			eeh_panic(dev, rets[0]);
 		}
 		return 0;
@@ -557,10 +576,7 @@
 	 * function zero of a multi-function device.
 	 * In any case they must share a common PHB.
 	 */
-	ret = rtas_call(ibm_read_slot_reset_state, 3, 3, rets,
-			dn->eeh_config_addr, BUID_HI(dn->phb->buid),
-			BUID_LO(dn->phb->buid));
-
+	ret = read_slot_reset_state(dn, rets);
 	if (!(ret == 0 && rets[1] == 1 && (rets[0] == 2 || rets[0] == 4))) {
 		__get_cpu_var(false_positives)++;
 		return 0;
@@ -756,6 +772,7 @@
 
 	ibm_set_eeh_option = rtas_token("ibm,set-eeh-option");
 	ibm_set_slot_reset = rtas_token("ibm,set-slot-reset");
+	ibm_read_slot_reset_state2 = rtas_token("ibm,read-slot-reset-state2");
 	ibm_read_slot_reset_state = rtas_token("ibm,read-slot-reset-state");
 	ibm_slot_error_detail = rtas_token("ibm,slot-error-detail");