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lib: utils/timer: Simplify MTIMER synchronization

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We simplify MTIMER synchronization as follows:

1) Detect MTIMER devices with unique (or non-shared) MTIME
   register at boot-time
2) Select first MTIMER device with no associated HART as our
   reference MTIMER device
3) Only synchronize MTIMER devices with unique (or non-shared)
   MTIME register using reference MTIMER device
4) Directly update the MTIME register at time of synchronization
   because MTIME is a read/write register.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
This commit is contained in:
Anup Patel
2021-07-24 10:35:01 +05:30
committed by Anup Patel
parent b35f7826b0
commit 7aa6c9aa96
3 changed files with 83 additions and 33 deletions
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42
lib/utils/timer/fdt_timer_mtimer.c
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@@ -17,19 +17,18 @@
static unsigned long mtimer_count = 0;
static struct aclint_mtimer_data mtimer[MTIMER_MAX_NR];
static struct aclint_mtimer_data *mt_reference = NULL;
static int timer_mtimer_cold_init(void *fdt, int nodeoff,
const struct fdt_match *match)
{
int rc;
int i, rc;
unsigned long offset, addr[2], size[2];
struct aclint_mtimer_data *mt, *mtmaster = NULL;
struct aclint_mtimer_data *mt;
if (MTIMER_MAX_NR <= mtimer_count)
return SBI_ENOSPC;
mt = &mtimer[mtimer_count];
if (0 < mtimer_count)
mtmaster = &mtimer[0];
rc = fdt_parse_aclint_node(fdt, nodeoff, true,
&addr[0], &size[0], &addr[1], &size[1],
@@ -37,6 +36,7 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
if (rc)
return rc;
mt->has_64bit_mmio = true;
mt->has_shared_mtime = false;
if (match->data) { /* SiFive CLINT */
/* Set CLINT addresses */
@@ -63,10 +63,42 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
mt->has_64bit_mmio = false;
}
rc = aclint_mtimer_cold_init(mt, mtmaster);
/* Check if MTIMER device has shared MTIME address */
mt->has_shared_mtime = false;
for (i = 0; i < mtimer_count; i++) {
if (mtimer[i].mtime_addr == mt->mtime_addr) {
mt->has_shared_mtime = true;
break;
}
}
/* Initialize the MTIMER device */
rc = aclint_mtimer_cold_init(mt, mt_reference);
if (rc)
return rc;
/*
* Select first MTIMER device with no associated HARTs as our
* reference MTIMER device. This is only a temporary strategy
* of selecting reference MTIMER device. In future, we might
* define an optional DT property or some other mechanism to
* help us select the reference MTIMER device.
*/
if (!mt->hart_count && !mt_reference) {
mt_reference = mt;
/*
* Set reference for already propbed MTIMER devices
* with non-shared MTIME
*/
for (i = 0; i < mtimer_count; i++)
if (!mtimer[i].has_shared_mtime)
aclint_mtimer_set_reference(&mtimer[i], mt);
}
/* Explicitly sync-up MTIMER devices not associated with any HARTs */
if (!mt->hart_count)
aclint_mtimer_sync(mt);
mtimer_count++;
return 0;
}