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hw/mips: implement ITC Storage - P/V Sync and Try Views 

P/V Synchronized and Try Views can be used to access Semaphore cells.
Load returns current value and post-decrements the value in the cell
(until it reaches zero). Stores increment the value (until it saturates
at 0xFFFF).

P/V Synchronized View causes the issuing thread to block on read if value
is 0. P/V Try View does not block the thread, it returns 0 in this case.

Cell's Empty and Full bits are not modified.

Trap bit (i.e. Gating Storage exceptions) not implemented.

Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>
This commit is contained in:
Leon Alrae 2016-03-25 13:49:33 +00:00
parent 4051089d61
commit 40dc9dc339
1 changed files with 68 additions and 0 deletions
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68
hw/misc/mips_itu.c
View File

@ -33,6 +33,8 @@
#define ITC_SEMAPH_NUM_MAX 16
#define ITC_AM1_NUMENTRIES_OFS 20
#define ITC_CELL_PV_MAX_VAL 0xFFFF
#define ITC_CELL_TAG_FIFO_DEPTH 28
#define ITC_CELL_TAG_FIFO_PTR 18
#define ITC_CELL_TAG_FIFO 17
@ -284,6 +286,60 @@ static void view_ef_try_write(ITCStorageCell *c, uint64_t val)
view_ef_common_write(c, val, false);
}
/* ITC P/V View */
static uint64_t view_pv_common_read(ITCStorageCell *c, bool blocking)
{
uint64_t ret = c->data[0];
if (c->tag.FIFO) {
return 0;
}
if (c->data[0] > 0) {
c->data[0]--;
} else if (blocking) {
block_thread_and_exit(c);
}
return ret;
}
static uint64_t view_pv_sync_read(ITCStorageCell *c)
{
return view_pv_common_read(c, true);
}
static uint64_t view_pv_try_read(ITCStorageCell *c)
{
return view_pv_common_read(c, false);
}
static inline void view_pv_common_write(ITCStorageCell *c)
{
if (c->tag.FIFO) {
return;
}
if (c->data[0] < ITC_CELL_PV_MAX_VAL) {
c->data[0]++;
}
if (c->blocked_threads) {
wake_blocked_threads(c);
}
}
static void view_pv_sync_write(ITCStorageCell *c)
{
view_pv_common_write(c);
}
static void view_pv_try_write(ITCStorageCell *c)
{
view_pv_common_write(c);
}
static uint64_t itc_storage_read(void *opaque, hwaddr addr, unsigned size)
{
MIPSITUState *s = (MIPSITUState *)opaque;
@ -301,6 +357,12 @@ static uint64_t itc_storage_read(void *opaque, hwaddr addr, unsigned size)
case ITCVIEW_EF_TRY:
ret = view_ef_try_read(cell);
break;
case ITCVIEW_PV_SYNC:
ret = view_pv_sync_read(cell);
break;
case ITCVIEW_PV_TRY:
ret = view_pv_try_read(cell);
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"itc_storage_read: Bad ITC View %d\n", (int)view);
@ -327,6 +389,12 @@ static void itc_storage_write(void *opaque, hwaddr addr, uint64_t data,
case ITCVIEW_EF_TRY:
view_ef_try_write(cell, data);
break;
case ITCVIEW_PV_SYNC:
view_pv_sync_write(cell);
break;
case ITCVIEW_PV_TRY:
view_pv_try_write(cell);
break;
default:
qemu_log_mask(LOG_GUEST_ERROR,
"itc_storage_write: Bad ITC View %d\n", (int)view);