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watchdog: wdat_wdt: map registers that fall inside ACPI NVS

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Some firmwares describe WDAT registers inside memory ranges marked as
ACPI NVS in the E820 map, failing with -EBUSY during probe, leaving the
hardware watchdog unserviced and triggering periodic system resets.

This issue was observed on a OnLogic Karbon 524 device (when watchdog is
enabled in BIOS):

wdat_wdt wdat_wdt: error -EBUSY: can't request region for resource [mem 0x63df7a98]
wdat_wdt wdat_wdt: probe with driver wdat_wdt failed with error -16

Check whether the region falls inside ACPI NVS before requesting it and,
if so, map it without reservation.

Signed-off-by: Renê de Souza Pinto <rene@renesp.com.br>
Link: https://lore.kernel.org/r/20260804103958.3684195-1-rene@renesp.com.br
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Renê de Souza Pinto
2026-08-04 12:39:57 +02:00
committed by Guenter Roeck
parent 80141041bd
commit 0ab46a83fa
1 changed files with 26 additions and 1 deletions
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27
drivers/watchdog/wdat_wdt.c
View File

@@ -7,7 +7,9 @@
*/
#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
@@ -309,6 +311,29 @@ static struct watchdog_ops wdat_wdt_ops = {
.set_timeout = wdat_wdt_set_timeout,
};
static void __iomem *wdat_wdt_map_mem(struct device *dev, struct resource *res)
{
resource_size_t size = resource_size(res);
void *addr;
/* Map memory region without reserving it if it falls inside ACPI NVS */
if (region_intersects(res->start, size, IORESOURCE_MEM,
IORES_DESC_ACPI_NV_STORAGE) == REGION_INTERSECTS) {
dev_warn(dev, "%pR is inside ACPI NVS, mapping without reservation\n",
res);
addr = devm_memremap(dev, res->start, size, MEMREMAP_WB);
if (IS_ERR(addr)) {
dev_err(dev, "failed to map resource %pR\n", res);
return IOMEM_ERR_PTR(PTR_ERR(addr));
}
return (void __iomem __force *)addr;
}
return devm_ioremap_resource(dev, res);
}
static int wdat_wdt_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
@@ -362,7 +387,7 @@ static int wdat_wdt_probe(struct platform_device *pdev)
res = &pdev->resource[i];
if (resource_type(res) == IORESOURCE_MEM) {
reg = devm_ioremap_resource(dev, res);
reg = wdat_wdt_map_mem(dev, res);
if (IS_ERR(reg)) {
ret = PTR_ERR(reg);
goto out_put_table;