From 5de1d3240f9163de95bc6803fb4100a77d65ab6b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Beno=C3=AEt=20Monin?= Date: Fri, 7 Nov 2025 11:46:57 +0100 Subject: [PATCH] lib: utils/timer: mtimer: Select the reference mtimer from a DT property MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Anup Patel Link: https://lore.kernel.org/r/20251107-p8700-aclint-v3-1-93eabb17d54e@bootlin.com Signed-off-by: Anup Patel --- lib/utils/timer/fdt_timer_mtimer.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/lib/utils/timer/fdt_timer_mtimer.c b/lib/utils/timer/fdt_timer_mtimer.c index e1fd0519..1f29f3a2 100644 --- a/lib/utils/timer/fdt_timer_mtimer.c +++ b/lib/utils/timer/fdt_timer_mtimer.c @@ -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