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lib: utils/timer: mtimer: Select the reference mtimer from a DT property

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The current selection of the reference MTIMER may fail in some setup.
In a multi-cluster configuration, there is one MTIMER per cluster, each
associated with the HARTS of the cluster. So we do not have a MTIMER
with no associated HARTs to use as our reference.

To be able to select a reference MTIMER in that case, look up an optional
device tree property named "riscv,reference-mtimer" that indicate which
MTIMER is the reference.

Signed-off-by: Benoît Monin <benoit.monin@bootlin.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20251107-p8700-aclint-v3-1-93eabb17d54e@bootlin.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Benoît Monin
2025-11-07 11:46:57 +01:00
committed by Anup Patel
parent 38a6106b10
commit 5de1d3240f
1 changed files with 10 additions and 6 deletions
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16
lib/utils/timer/fdt_timer_mtimer.c
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@@ -39,6 +39,7 @@ static int timer_mtimer_cold_init(const void *fdt, int nodeoff,
struct aclint_mtimer_data *mt;
const struct timer_mtimer_quirks *quirks = match->data;
bool is_clint = quirks && quirks->is_clint;
bool is_ref = false;
mtn = sbi_zalloc(sizeof(*mtn));
if (!mtn)
@@ -110,13 +111,16 @@ static int timer_mtimer_cold_init(const void *fdt, int nodeoff,
}
/*
* 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 we have a DT property to indicate which MTIMER is the reference,
* select the first MTIMER device that has it. Otherwise, select the
* first MTIMER device with no associated HARTs as our reference.
*/
if (!mt->hart_count && !mt_reference) {
if (fdt_getprop(fdt, nodeoff, "riscv,reference-mtimer", NULL))
is_ref = true;
else if (!mt->hart_count)
is_ref = true;
if (is_ref && !mt_reference) {
mt_reference = mt;
/*
* Set reference for already propbed MTIMER devices