Gabe Black has submitted this change. (
https://gem5-review.googlesource.com/c/public/gem5/+/55283 )
(
3 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the
submitted one.
)Change subject: arch-x86: Implement count latching with the PIT read back
command.
......................................................................
arch-x86: Implement count latching with the PIT read back command.
This command can trigger count latching for any of the PIT channels
together with a single command, and can also latch a status byte. The
status byte is not implemented here, but there is already functionality
for latching the count which this can use.
Change-Id: Ic2ad7c73d0c521fdd6fe5f62cb478c6718f3b90c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55283
Reviewed-by: Gabe Black <[email protected]>
Maintainer: Gabe Black <[email protected]>
Tested-by: kokoro <[email protected]>
---
M src/dev/intel_8254_timer.cc
M src/dev/intel_8254_timer.hh
2 files changed, 46 insertions(+), 4 deletions(-)
Approvals:
Gabe Black: Looks good to me, approved; Looks good to me, approved
kokoro: Regressions pass
diff --git a/src/dev/intel_8254_timer.cc b/src/dev/intel_8254_timer.cc
index c0fc773..f64c0fe 100644
--- a/src/dev/intel_8254_timer.cc
+++ b/src/dev/intel_8254_timer.cc
@@ -58,12 +58,24 @@
{
int sel = data.sel;
- if (sel == ReadBackCommand)
- panic("PITimer Read-Back Command is not implemented.\n");
+ if (sel == ReadBackCommand) {
+ ReadBackCommandVal rb_val = static_cast<uint8_t>(data);
- if (data.rw == LatchCommand)
+ panic_if(!rb_val.status,
+ "Latching the PIT status byte is not implemented.");
+
+ if (!rb_val.count) {
+ for (auto &cnt: counter) {
+ if (bits((uint8_t)rb_val.select, cnt->index()))
+ cnt->latchCount();
+ }
+ }
+ return;
+ }
+
+ if (data.rw == LatchCommand) {
counter[sel]->latchCount();
- else {
+ } else {
counter[sel]->setRW(data.rw);
counter[sel]->setMode(data.mode);
counter[sel]->setBCD(data.bcd);
diff --git a/src/dev/intel_8254_timer.hh b/src/dev/intel_8254_timer.hh
index 9876d13..e02a4cc 100644
--- a/src/dev/intel_8254_timer.hh
+++ b/src/dev/intel_8254_timer.hh
@@ -53,6 +53,16 @@
Bitfield<0> bcd;
EndBitUnion(CtrlReg)
+ BitUnion8(ReadBackCommandVal)
+ Bitfield<4> status; // Active low.
+ Bitfield<5> count; // Active low.
+ SubBitUnion(select, 3, 1)
+ Bitfield<3> cnt2;
+ Bitfield<2> cnt1;
+ Bitfield<1> cnt0;
+ EndSubBitUnion(select)
+ EndBitUnion(ReadBackCommandVal)
+
enum SelectVal
{
SelectCounter0,
@@ -152,6 +162,8 @@
public:
Counter(Intel8254Timer *p, const std::string &name, unsigned int
num);
+ unsigned int index() const { return num; }
+
/** Latch the current count (if one is not already latched) */
void latchCount();
--
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: Ic2ad7c73d0c521fdd6fe5f62cb478c6718f3b90c
Gerrit-Change-Number: 55283
Gerrit-PatchSet: 5
Gerrit-Owner: Gabe Black <[email protected]>
Gerrit-Reviewer: Bradford Beckmann <[email protected]>
Gerrit-Reviewer: Gabe Black <[email protected]>
Gerrit-Reviewer: Matt Sinclair <[email protected]>
Gerrit-Reviewer: Matthew Poremba <[email protected]>
Gerrit-Reviewer: kokoro <[email protected]>
Gerrit-MessageType: merged
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