On Thu, Sep 21, 2023 at 02:02:36AM -0700, Darren Hart wrote:
> Commit abd3ac7902fb ("watchdog: sbsa: Support architecture version 1")
> introduced new timer math for watchdog revision 1 with the 48 bit offset
> register.
>
> The gwdt->clk and timeout are u32, but the argument being calculated is
> u64. Without a cast, the compiler performs u32 operations, truncating
> intermediate steps, resulting in incorrect values.
>
> A watchdog revision 1 implementation with a gwdt->clk of 1GHz and a
> timeout of 600s writes 3647256576 to the one shot watchdog instead of
> 300000000000, resulting in the watchdog firing in 3.6s instead of 600s.
>
> Force u64 math by casting the first argument (gwdt->clk) as a u64. Make
> the order of operations explicit with parenthesis.
>
> Fixes: abd3ac7902fb ("watchdog: sbsa: Support architecture version 1")
> Reported-by: Vanshidhar Konda <vanshikonda@xxxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Darren Hart <darren@xxxxxxxxxxxxxxxxxxxxxx>
> Cc: Wim Van Sebroeck <wim@xxxxxxxxxxxxxxxxxx>
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> Cc: linux-watchdog@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: <stable@xxxxxxxxxxxxxxx> # 5.14.x
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> drivers/watchdog/sbsa_gwdt.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/sbsa_gwdt.c b/drivers/watchdog/sbsa_gwdt.c
> index fd3cfdda4949..76527324b63c 100644
> --- a/drivers/watchdog/sbsa_gwdt.c
> +++ b/drivers/watchdog/sbsa_gwdt.c
> @@ -153,14 +153,14 @@ static int sbsa_gwdt_set_timeout(struct watchdog_device *wdd,
> timeout = clamp_t(unsigned int, timeout, 1, wdd->max_hw_heartbeat_ms / 1000);
>
> if (action)
> - sbsa_gwdt_reg_write(gwdt->clk * timeout, gwdt);
> + sbsa_gwdt_reg_write((u64)gwdt->clk * timeout, gwdt);
> else
> /*
> * In the single stage mode, The first signal (WS0) is ignored,
> * the timeout is (WOR * 2), so the WOR should be configured
> * to half value of timeout.
> */
> - sbsa_gwdt_reg_write(gwdt->clk / 2 * timeout, gwdt);
> + sbsa_gwdt_reg_write(((u64)gwdt->clk / 2) * timeout, gwdt);
>
> return 0;
> }
> --
> 2.41.0
>
