hw/phb4: Prevent register accesses when in reset
[ Upstream commit b310e8f79e6817e18bd0e3c606da50a00b425ef0 ]
While the the ETU is in reset we cannot access any of the PHB registers.
If a PHB register is accessed via the XSCOM indirect interface then
we'll cause an ETU reset error which may prevent the PHB from being
re-initialised once the reset is lifted.
Prevent register accesses while in reset by adding a flag that is set
while the ETU reset bit is high and checking that flag in the XSCOM
(ASB) backdoor register access path.
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
diff --git a/hw/phb4.c b/hw/phb4.c
index 83c0fc0..06ad18f 100644
--- a/hw/phb4.c
+++ b/hw/phb4.c
@@ -225,6 +225,10 @@
static uint64_t phb4_read_reg(struct phb4 *p, uint32_t offset)
{
+ /* No register accesses are permitted while in reset */
+ if (p->flags & PHB4_ETU_IN_RESET)
+ return -1ull;
+
if (p->flags & PHB4_CFG_USE_ASB)
return phb4_read_reg_asb(p, offset);
else
@@ -233,6 +237,10 @@
static void phb4_write_reg(struct phb4 *p, uint32_t offset, uint64_t val)
{
+ /* No register accesses are permitted while in reset */
+ if (p->flags & PHB4_ETU_IN_RESET)
+ return;
+
if (p->flags & PHB4_CFG_USE_ASB)
phb4_write_reg_asb(p, offset, val);
else
@@ -3268,6 +3276,7 @@
phb4_err_clear(p);
/* Actual reset */
+ p->flags |= PHB4_ETU_IN_RESET;
xscom_write(p->chip_id, p->pci_stk_xscom + XPEC_PCI_STK_ETU_RESET,
0x8000000000000000UL);
@@ -3321,6 +3330,7 @@
/* Clear PHB from reset */
xscom_write(p->chip_id,
p->pci_stk_xscom + XPEC_PCI_STK_ETU_RESET, 0x0);
+ p->flags &= ~PHB4_ETU_IN_RESET;
pci_slot_set_state(slot, PHB4_SLOT_CRESET_REINIT);
/* After lifting PHB reset, wait while logic settles */
diff --git a/include/phb4.h b/include/phb4.h
index c52a840..dc84fca 100644
--- a/include/phb4.h
+++ b/include/phb4.h
@@ -166,6 +166,7 @@
#define PHB4_CFG_BLOCKED 0x00000004
#define PHB4_CAPP_RECOVERY 0x00000008
#define PHB4_CAPP_DISABLE 0x00000010
+#define PHB4_ETU_IN_RESET 0x00000020
struct phb4 {
unsigned int index; /* 0..5 index inside p9 */
