[PATCH v2 1/4] ACPI: GTDT: Generate platform devices for MMIO timers

From: Marc Zyngier
Date: Thu Aug 14 2025 - 11:53:55 EST


In preparation for the MMIO timer support code becoming an actual
driver, mimic what is done for the SBSA watchdog and expose
a synthetic device for each MMIO timer block.

Tested-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>
Link: https://lore.kernel.org/r/20250807160243.1970533-2-maz@xxxxxxxxxx
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
drivers/acpi/arm64/gtdt.c | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/acpi/arm64/gtdt.c b/drivers/acpi/arm64/gtdt.c
index 70f8290b659de..fd995a1d3d248 100644
--- a/drivers/acpi/arm64/gtdt.c
+++ b/drivers/acpi/arm64/gtdt.c
@@ -388,11 +388,11 @@ static int __init gtdt_import_sbsa_gwdt(struct acpi_gtdt_watchdog *wd,
return 0;
}

-static int __init gtdt_sbsa_gwdt_init(void)
+static int __init gtdt_platform_timer_init(void)
{
void *platform_timer;
struct acpi_table_header *table;
- int ret, timer_count, gwdt_count = 0;
+ int ret, timer_count, gwdt_count = 0, mmio_timer_count = 0;

if (acpi_disabled)
return 0;
@@ -414,20 +414,41 @@ static int __init gtdt_sbsa_gwdt_init(void)
goto out_put_gtdt;

for_each_platform_timer(platform_timer) {
+ ret = 0;
+
if (is_non_secure_watchdog(platform_timer)) {
ret = gtdt_import_sbsa_gwdt(platform_timer, gwdt_count);
if (ret)
- break;
+ continue;
gwdt_count++;
+ } else if (is_timer_block(platform_timer)) {
+ struct arch_timer_mem atm = {};
+ struct platform_device *pdev;
+
+ ret = gtdt_parse_timer_block(platform_timer, &atm);
+ if (ret)
+ continue;
+
+ pdev = platform_device_register_data(NULL, "gtdt-arm-mmio-timer",
+ gwdt_count, &atm,
+ sizeof(atm));
+ if (IS_ERR(pdev)) {
+ pr_err("Can't register timer %d\n", gwdt_count);
+ continue;
+ }
+
+ mmio_timer_count++;
}
}

if (gwdt_count)
pr_info("found %d SBSA generic Watchdog(s).\n", gwdt_count);
+ if (mmio_timer_count)
+ pr_info("found %d Generic MMIO timer(s).\n", mmio_timer_count);

out_put_gtdt:
acpi_put_table(table);
return ret;
}

-device_initcall(gtdt_sbsa_gwdt_init);
+device_initcall(gtdt_platform_timer_init);
--
2.39.2