[Qemu-devel] [PATCH V2 1/2] ARM: PL061: Clear PL061 device state after reset

[Wei Huang]

Current QEMU doesn't clear PL061 state after reset. This causes a
weird issue with guest reboot via GPIO. Here is the device state
description with two reboot requests:

  (PL061State fields)           data   old_in_data   istate
VM boot                         0      0             0
After 1st ACPI reboot request   8      8             8
After VM PL061 driver ACK       8      8             0
After VM reboot                 8      8             0
------------------------------------------------------------
2nd ACPI reboot request         8

In the second reboot request above, because old_in_data field is 8,
QEMU decides that there is a pending edge IRQ already (see
pl061_update()) in input; so it doesn't raise up IRQ again. As a result
the second reboot request is lost. The correct way is to clear PL061
device state after reset.

NOTE: The reset state is found from the following documentation:
 - PL061 Technical Reference Manual
 - Stellaris LM3S8962 Microcontroller Data Sheet
 - Stellaris LM3S5P31 Microcontroller Data Sheet

Signed-off-by: Wei Huang <address@hidden>
---
 hw/gpio/pl061.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/hw/gpio/pl061.c b/hw/gpio/pl061.c
index e5a696e..342a70d 100644
--- a/hw/gpio/pl061.c
+++ b/hw/gpio/pl061.c
@@ -284,8 +284,35 @@ static void pl061_write(void *opaque, hwaddr offset,
 
 static void pl061_reset(PL061State *s)
 {
-  s->locked = 1;
-  s->cr = 0xff;
+    /* reset values from PL061 TRM, Stellaris LM3S5P31 & LM3S8962 Data Sheet */
+    s->data = 0;
+    s->old_out_data = 0;
+    s->old_in_data = 0;
+    s->dir = 0;
+    s->isense = 0;
+    s->ibe = 0;
+    s->iev = 0;
+    s->im = 0;
+    s->istate = 0;
+    s->afsel = 0;
+    s->dr2r = 0xff;
+    s->dr4r = 0;
+    s->dr8r = 0;
+    s->odr = 0;
+    s->pur = 0;
+    s->pdr = 0;
+    s->slr = 0;
+    s->den = 0;
+    s->locked = 1;
+    s->cr = 0xff;
+    s->amsel = 0;
+}
+
+static void pl061_state_reset(DeviceState *dev)
+{
+    PL061State *s = PL061(dev);
+
+    pl061_reset(s);
 }
 
 static void pl061_set_irq(void * opaque, int irq, int level)
@@ -343,6 +370,7 @@ static void pl061_class_init(ObjectClass *klass, void *data)
 
     k->init = pl061_initfn;
     dc->vmsd = &vmstate_pl061;
+    dc->reset = &pl061_state_reset;
 }
 
 static const TypeInfo pl061_info = {
-- 
1.8.3.1