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watchdog: qcom: Add max timeout check to prevent overflow

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Added a check to ensure the requested timeout does not exceed the
hardware's maximum supported value. This prevents register overflow
and ensures watchdog reliability.

So, added a check in qcom_wdt_start() to ensure the requested timeout
does not exceed the hardware-supported maximum value. If the requested
value exceeds the maximum value, then the timeout is clamped
at maximum value.

The timeout is first converted to watchdog ticks and then compared
against QCOM_WDT_MAX_TIMEOUT. This helps prevent misconfiguration
and potential watchdog misbehavior due to overflow.

QCOM_WDT_MAX_TIMEOUT is set to 0xFFFFF, as Qualcomm SoCs typically
use 20 bits to store bark/bite timeout values.

This work builds upon the previous submission:
https://lore.kernel.org/u-boot/20250527124926.128413-1-balaji.selvanathan@oss.qualcomm.com/

Signed-off-by: Gopinath Sekar <gopinath.sekar@oss.qualcomm.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Link: https://patch.msgid.link/20250625094607.1348494-1-gopinath.sekar@oss.qualcomm.com
Signed-off-by: Casey Connolly <casey.connolly@linaro.org>
This commit is contained in:
Gopinath Sekar
2025-06-25 15:16:07 +05:30
committed by Casey Connolly
parent d503633a36
commit b2446a2314
1 changed files with 21 additions and 2 deletions
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23
drivers/watchdog/qcom-wdt.c
View File

@@ -17,6 +17,9 @@
#include <asm/io.h>
/* Maximum allowed timeout value in Qcom SoCs*/
#define QCOM_WDT_MAX_TIMEOUT 0xfffff
enum wdt_reg {
WDT_RST,
WDT_EN,
@@ -55,8 +58,24 @@ static void __iomem *wdt_addr(struct qcom_wdt *wdt, enum wdt_reg reg)
int qcom_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
{
struct qcom_wdt *wdt = dev_get_priv(dev);
ulong bark_timeout_s = ((timeout_ms - 1) * wdt->clk_rate) / 1000;
ulong bite_timeout_s = (timeout_ms * wdt->clk_rate) / 1000;
u64 tmp_timeout;
u32 bark_timeout_s, bite_timeout_s;
/* Compute timeout in watchdog ticks */
tmp_timeout = (timeout_ms * (u64)wdt->clk_rate) / 1000;
if (tmp_timeout > QCOM_WDT_MAX_TIMEOUT) {
dev_warn(dev,
"Requested timeout (%llu ms) exceeds maximum allowed value (%llu ms). "
"Using max timeout instead.\n",
timeout_ms,
((u64)QCOM_WDT_MAX_TIMEOUT * 1000) / wdt->clk_rate);
tmp_timeout = (u32)QCOM_WDT_MAX_TIMEOUT;
timeout_ms = (tmp_timeout * 1000) / wdt->clk_rate;
}
bite_timeout_s = (u32)tmp_timeout;
tmp_timeout = ((timeout_ms - 1) * (u64)wdt->clk_rate) / 1000;
bark_timeout_s = (u32)tmp_timeout;
writel(0, wdt_addr(wdt, WDT_EN));
writel(BIT(0), wdt_addr(wdt, WDT_RST));