Hi Peter.
On 5 November 2013 14:54, Peter Maydell <
address@hidden> wrote:
>
> On 5 November 2013 11:41, Jan Petrouš <
address@hidden> wrote:
> > Linux kernel from version 3.4 requires CM_REFCNT register for sched timer
> > for Integrator/CP board (integrator_defconfig).
> >
> > See
> >
http://infocenter.arm.com/help/topic/com.arm.doc.dui0138e/ch04s06s11.html
> >
> > Signed-off-by: Jan Petrous <
address@hidden>
>
> Hi; thanks for this patch. (I have to wonder why on earth
> people are still messing with kernel functionality for such
> an ancient devboard :-)).
>
Hehe, duno, but when I started learning QEMU the Integrator devboard
looked for me the nice start-up point = very simple to understand
and only very basic, but still core, device list. And when I moved
from precompiled kernels (downloaded from internet) to my own
ones I found the issue with default kernel configuration. And because
it can help to not fool somebody later I decided to release patch :)
>
> > diff --git a/hw/arm/integratorcp.c b/hw/arm/integratorcp.c
> > index c44b2a4..f419764 100644
> > --- a/hw/arm/integratorcp.c
> > +++ b/hw/arm/integratorcp.c
> > @@ -83,8 +83,11 @@ static uint64_t integratorcm_read(void *opaque, hwaddr
> > offset,
> > case 9: /* CM_INIT */
> > return s->cm_init;
> > case 10: /* CM_REFCT */
>
> could you fix this comment to add the 'N' to CM_REFCNT while
> you're changing this bit of code, please?
Done.
>
>
> > - /* ??? High frequency timer. */
> > - hw_error("integratorcm_read: CM_REFCT");
> > + /* This register, CM_REFCNT, provides a 32-bit count value.
> > + * The count increments at the fixed reference clock frequency of 24MHz
> > + * and can be used as a real-time counter.
> > + */
>
> The indent here doesn't look right, I think you have
> hardcoded tabs here rather than spaces. If you run your
> patch through scripts/
checkpatch.pl it should catch this
> sort of mistake.
>
Yes, you are right. My fault. Fixed now.
>
> > + return muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), 24, 1000);
> > case 12: /* CM_FLAGS */
> > return s->cm_flags;
> > case 14: /* CM_NVFLAGS */
>
> The spec says that this register resets to zero, so I think
> it would be good to implement that: put a uint32_t cm_refcnt_offset
> in the IntegratorCMState struct, initialize it with the initial
> value of muldiv64(etc) in integratorcm_init(), and then in
> integratorcm_read() return (uint32_t)muldiv64(etc) - cm_refcnt_offset
> for the register read.
>
Added too.
>
> (We don't actually implement a proper reset function in this device
> at the moment, but putting in the offset field gives us a marker
> for doing it right if/when we add a reset function later on.)
>
> thanks
> -- PMM
Here is my next version:
Linux kernel from version 3.4 requires CM_REFCNT register for sched timer
for Integrator/CP board (integrator_defconfig).
---
hw/arm/integratorcp.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/hw/arm/integratorcp.c b/hw/arm/integratorcp.c
index c44b2a4..a759689 100644
--- a/hw/arm/integratorcp.c
+++ b/hw/arm/integratorcp.c
@@ -36,6 +36,7 @@ typedef struct IntegratorCMState {
uint32_t cm_init;
uint32_t cm_flags;
uint32_t cm_nvflags;
+ uint32_t cm_refcnt_offset;
uint32_t int_level;
uint32_t irq_enabled;
uint32_t fiq_enabled;
@@ -82,9 +83,13 @@ static uint64_t integratorcm_read(void *opaque, hwaddr offset,
return s->cm_sdram;
case 9: /* CM_INIT */
return s->cm_init;
- case 10: /* CM_REFCT */
- /* ??? High frequency timer. */
- hw_error("integratorcm_read: CM_REFCT");
+ case 10: /* CM_REFCNT */
+ /* This register, CM_REFCNT, provides a 32-bit count value.
+ * The count increments at the fixed reference clock frequency of 24MHz
+ * and can be used as a real-time counter.
+ */
+ return (uint32_t)muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), 24,
+ 1000) - s->cm_refcnt_offset;
case 12: /* CM_FLAGS */
return s->cm_flags;
case 14: /* CM_NVFLAGS */
@@ -257,6 +262,8 @@ static int integratorcm_init(SysBusDevice *dev)
}
memcpy(integrator_spd + 73, "QEMU-MEMORY", 11);
s->cm_init = 0x00000112;
+ s->cm_refcnt_offset = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), 24,
+ 1000);
memory_region_init_ram(&s->flash, OBJECT(s), "integrator.flash", 0x100000);
vmstate_register_ram_global(&s->flash);
--
1.7.11.3
0001-integrator-cp-add-support-for-REFCNT-register.patch