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arm, dev: add basic support for GICC_BPR register

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The Binary Point Register (BPR) specifies which bits belong to the
group priority field (which are used for preemption) and which to the
subpriority field (which are ignored for preemption).

Change-Id: If51e669d23b49047b69b82ab363dd01a936cc93b
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/2443
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Weiping Liao <weipingliao@google.com>
This commit is contained in:
Curtis Dunham 2017-03-09 17:30:59 +00:00 committed by Andreas Sandberg
parent 2f14baaabc
commit 60075068ea
2 changed files with 26 additions and 5 deletions
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26
src/dev/arm/gic_pl390.cc
View file

@ -83,7 +83,7 @@ Pl390::Pl390(const Params *p)
iccrpr[x] = 0xff;
cpuEnabled[x] = false;
cpuPriority[x] = 0xff;
cpuBpr[x] = 0;
cpuBpr[x] = GICC_BPR_MINIMUM;
// Initialize cpu highest int
cpuHighestInt[x] = SPURIOUS_INT;
postIntEvent[x] = new PostIntEvent(*this, x);
@ -538,9 +538,13 @@ Pl390::writeCpu(ContextID ctx, Addr daddr, uint32_t data)
case GICC_PMR:
cpuPriority[ctx] = data;
break;
case GICC_BPR:
cpuBpr[ctx] = data;
case GICC_BPR: {
auto bpr = data & 0x7;
if (bpr < GICC_BPR_MINIMUM)
bpr = GICC_BPR_MINIMUM;
cpuBpr[ctx] = bpr;
break;
}
case GICC_EOIR: {
const IAR iar = data;
if (iar.ack_id < SGI_MAX) {
@ -666,6 +670,17 @@ Pl390::genSwiMask(int cpu)
return ULL(0x0101010101010101) << cpu;
}
uint8_t
Pl390::getCpuPriority(unsigned cpu)
{
// see Table 3-2 in IHI0048B.b (GICv2)
// mask some low-order priority bits per BPR value
// NB: the GIC prioritization scheme is upside down:
// lower values are higher priority; masking off bits
// actually creates a higher priority, not lower.
return cpuPriority[cpu] & (0xff00 >> (7 - cpuBpr[cpu]));
}
void
Pl390::updateIntState(int hint)
{
@ -676,7 +691,7 @@ Pl390::updateIntState(int hint)
/*@todo use hint to do less work. */
int highest_int = SPURIOUS_INT;
// Priorities below that set in GICC_PMR can be ignored
uint8_t highest_pri = cpuPriority[cpu];
uint8_t highest_pri = getCpuPriority(cpu);
// Check SGIs
for (int swi = 0; swi < SGI_MAX; swi++) {
@ -733,7 +748,8 @@ Pl390::updateIntState(int hint)
/* @todo make this work for more than one cpu, need to handle 1:N, N:N
* models */
if (enabled && cpuEnabled[cpu] && (highest_pri < cpuPriority[cpu]) &&
if (enabled && cpuEnabled[cpu] &&
(highest_pri < getCpuPriority(cpu)) &&
!(getActiveInt(cpu, intNumToWord(highest_int))
& (1 << intNumToBit(highest_int)))) {

5
src/dev/arm/gic_pl390.hh
View file

@ -111,6 +111,10 @@ class Pl390 : public BaseGic
static const int INT_LINES_MAX = 1020;
static const int GLOBAL_INT_LINES = INT_LINES_MAX - SGI_MAX - PPI_MAX;
/** minimum value for Binary Point Register ("IMPLEMENTATION DEFINED");
chosen for consistency with Linux's in-kernel KVM GIC model */
static const int GICC_BPR_MINIMUM = 2;
BitUnion32(SWI)
Bitfield<3,0> sgi_id;
Bitfield<23,16> cpu_list;
@ -276,6 +280,7 @@ class Pl390 : public BaseGic
/** CPU priority */
uint8_t cpuPriority[CPU_MAX];
uint8_t getCpuPriority(unsigned cpu); // BPR-adjusted priority value
/** Binary point registers */
uint8_t cpuBpr[CPU_MAX];