[PATCH v2 2/2] lib: utils/timer: mtimer: add MIPS P8700 compatible

[Benoît Monin]

The MTIMER of the MIPS P8700 is compliant with the ACLINT specification,
so add a compatible string for it.

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, add a quirk to look
up an optional device tree property that indicate which MTIMER to use.
For the MIPS P8700, the property is "mips,reference-mtimer".

Signed-off-by: Benoît Monin <benoit.monin at bootlin.com>
---
 lib/utils/timer/fdt_timer_mtimer.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/lib/utils/timer/fdt_timer_mtimer.c b/lib/utils/timer/fdt_timer_mtimer.c
index e1fd051..e98c99f 100644
--- a/lib/utils/timer/fdt_timer_mtimer.c
+++ b/lib/utils/timer/fdt_timer_mtimer.c
@@ -20,6 +20,7 @@ struct timer_mtimer_quirks {
 	unsigned int	clint_mtime_offset;
 	bool		clint_without_mtime;
 	bool		has_64bit_mmio;
+	const char	*dt_ref_prop;
 };
 
 struct timer_mtimer_node {
@@ -39,6 +40,7 @@ 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 +112,18 @@ 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 (quirks && quirks->dt_ref_prop) {
+		if (fdt_getprop(fdt, nodeoff, quirks->dt_ref_prop, 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
@@ -152,6 +159,10 @@ static const struct timer_mtimer_quirks thead_aclint_quirks = {
 	.has_64bit_mmio		= false,
 };
 
+static const struct timer_mtimer_quirks mips_aclint_quirks = {
+	.dt_ref_prop		= "mips,reference-mtimer",
+};
+
 static const struct fdt_match timer_mtimer_match[] = {
 	{ .compatible = "riscv,clint0", .data = &sifive_clint_quirks },
 	{ .compatible = "sifive,clint0", .data = &sifive_clint_quirks },
@@ -159,6 +170,8 @@ static const struct fdt_match timer_mtimer_match[] = {
 	{ .compatible = "thead,c900-clint", .data = &thead_clint_quirks },
 	{ .compatible = "thead,c900-aclint-mtimer",
 	  .data = &thead_aclint_quirks },
+	{ .compatible = "mips,p8700-aclint-mtimer",
+	  .data = &mips_aclint_quirks },
 	{ .compatible = "riscv,aclint-mtimer" },
 	{ },
 };

-- 
2.51.1