[Skiboot] [PATCH stable 5.1.x 1/3] xscom: Return OPAL_WRONG_STATE on XSCOM ops if CPU is asleep

[Vipin K Parashar]

From: Russell Currey <ruscur at russell.cc>

xscom_read and xscom_write return OPAL_SUCCESS if they worked, and
OPAL_HARDWARE if they didn't.  This doesn't provide information about why
the operation failed, such as if the CPU happens to be asleep.

This is specifically useful in error scanning, so if every CPU is being
scanned for errors, sleeping CPUs likely aren't the cause of failures.

So, return OPAL_WRONG_STATE in xscom_read and xscom_write if the CPU is
sleeping.

Signed-off-by: Russell Currey <ruscur at russell.cc>
Reviewed-by: Alistair Popple <alistair at popple.id.au>
Signed-off-by: Stewart Smith <stewart at linux.vnet.ibm.com>
(cherry picked from commit 9c2d82394fd2303847cac4a665dee62556ca528a)
Signed-off-by: Vipin K Parashar <vipin at linux.vnet.ibm.com>
---
 doc/opal-api/opal-xscom-read-write-65-66.txt |  5 +++++
 hw/xscom.c                                   | 29 +++++++++++++++++-----------
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/doc/opal-api/opal-xscom-read-write-65-66.txt b/doc/opal-api/opal-xscom-read-write-65-66.txt
index 92916df..4ed0134 100644
--- a/doc/opal-api/opal-xscom-read-write-65-66.txt
+++ b/doc/opal-api/opal-xscom-read-write-65-66.txt
@@ -10,3 +10,8 @@ each takes three parameters:
 
 int xscom_read(uint32_t partid, uint64_t pcb_addr, uint64_t *val)
 int xscom_write(uint32_t partid, uint64_t pcb_addr, uint64_t val)
+
+Returns:
+	OPAL_SUCCESS
+	OPAL_HARDWARE if operation failed
+	OPAL_WRONG_STATE if CPU is asleep
diff --git a/hw/xscom.c b/hw/xscom.c
index c8e13be..84f72f5 100644
--- a/hw/xscom.c
+++ b/hw/xscom.c
@@ -118,7 +118,7 @@ static void xscom_reset(uint32_t gcid)
 	 */
 }
 
-static bool xscom_handle_error(uint64_t hmer, uint32_t gcid, uint32_t pcb_addr,
+static int xscom_handle_error(uint64_t hmer, uint32_t gcid, uint32_t pcb_addr,
 			       bool is_write)
 {
 	unsigned int stat = GETFIELD(SPR_HMER_XSCOM_STATUS, hmer);
@@ -129,7 +129,10 @@ static bool xscom_handle_error(uint64_t hmer, uint32_t gcid, uint32_t pcb_addr,
 	switch(stat) {
 	/* XSCOM blocked, just retry */
 	case 1:
-		return true;
+		return OPAL_BUSY;
+	/* CPU is asleep, don't retry */
+	case 2:
+		return OPAL_WRONG_STATE;
 	}
 
 	/* XXX: Create error log entry ? */
@@ -141,7 +144,7 @@ static bool xscom_handle_error(uint64_t hmer, uint32_t gcid, uint32_t pcb_addr,
 	xscom_reset(gcid);
 
 	/* Non recovered ... just fail */
-	return false;
+	return OPAL_HARDWARE;
 }
 
 static void xscom_handle_ind_error(uint64_t data, uint32_t gcid,
@@ -175,6 +178,7 @@ static bool xscom_gcid_ok(uint32_t gcid)
 static int __xscom_read(uint32_t gcid, uint32_t pcb_addr, uint64_t *val)
 {
 	uint64_t hmer;
+	int64_t ret;
 
 	if (!xscom_gcid_ok(gcid)) {
 		prerror("%s: invalid XSCOM gcid 0x%x\n", __func__, gcid);
@@ -197,16 +201,18 @@ static int __xscom_read(uint32_t gcid, uint32_t pcb_addr, uint64_t *val)
 		if (!(hmer & SPR_HMER_XSCOM_FAIL))
 			break;
 
-		/* Handle error and eventually retry */
-		if (!xscom_handle_error(hmer, gcid, pcb_addr, false))
-			return OPAL_HARDWARE;
+		/* Handle error and possibly eventually retry */
+		ret = xscom_handle_error(hmer, gcid, pcb_addr, false);
+		if (ret == OPAL_HARDWARE || ret == OPAL_WRONG_STATE)
+			return ret;
 	}
-	return 0;
+	return OPAL_SUCCESS;
 }
 
 static int __xscom_write(uint32_t gcid, uint32_t pcb_addr, uint64_t val)
 {
 	uint64_t hmer;
+	int64_t ret;
 
 	if (!xscom_gcid_ok(gcid)) {
 		prerror("%s: invalid XSCOM gcid 0x%x\n", __func__, gcid);
@@ -229,11 +235,12 @@ static int __xscom_write(uint32_t gcid, uint32_t pcb_addr, uint64_t val)
 		if (!(hmer & SPR_HMER_XSCOM_FAIL))
 			break;
 
-		/* Handle error and eventually retry */
-		if (!xscom_handle_error(hmer, gcid, pcb_addr, true))
-			return OPAL_HARDWARE;
+		/* Handle error and possibly eventually retry */
+		ret = xscom_handle_error(hmer, gcid, pcb_addr, true);
+		if (ret == OPAL_HARDWARE || ret == OPAL_WRONG_STATE)
+			return ret;
 	}
-	return 0;
+	return OPAL_SUCCESS;
 }
 
 /*
-- 
2.7.4