[PATCH 2/2] platform: sifive_fu740: fix reset when watchdog is running

[Anup Patel]

On Wed, Jan 5, 2022 at 12:52 PM Aurelien Jarno <aurelien at aurel32.net> wrote:
>
> When the watchdog is running the HiFive Unmatched board does not reboot
> properly and shuts down itself a few seconds after reboot, in the early
> stages of the u-boot loading. On a Linux kernel this happens when the
> da9063_wdt module is loaded. This does not happen if the module is
> unloaded before reboot or if the watchdog module is loaded with
> "stop_on_reboot=1".
>
> Fix that by stopping the watchdog before attempting to reset the board.
> This is done by zeroing the TWDSCALE field of CONTROL_D register, unless
> it was already set to 0.
>
> Reported-by: Tianon Gravi <tianon at debian.org>
> Signed-off-by: Aurelien Jarno <aurelien at aurel32.net>

Apologies for being slow on this patch.

Reviewed-by: Anup Patel <anup at brainfault.org>

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup

> ---
>  platform/generic/sifive_fu740.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
>
> diff --git a/platform/generic/sifive_fu740.c b/platform/generic/sifive_fu740.c
> index 866e924..f595c04 100644
> --- a/platform/generic/sifive_fu740.c
> +++ b/platform/generic/sifive_fu740.c
> @@ -22,6 +22,7 @@
>
>  #define DA9063_REG_PAGE_CON            0x00
>  #define DA9063_REG_CONTROL_A           0x0e
> +#define DA9063_REG_CONTROL_D           0x11
>  #define DA9063_REG_CONTROL_F           0x13
>  #define DA9063_REG_DEVICE_ID           0x81
>
> @@ -29,6 +30,8 @@
>  #define DA9063_CONTROL_A_M_POWER_EN    (1 << 5)
>  #define DA9063_CONTROL_A_STANDBY       (1 << 3)
>
> +#define DA9063_CONTROL_D_TWDSCALE_MASK 0x07
> +
>  #define DA9063_CONTROL_F_WAKEUP        (1 << 2)
>  #define DA9063_CONTROL_F_SHUTDOWN      (1 << 1)
>
> @@ -79,6 +82,27 @@ static inline int da9063_sanity_check(struct i2c_adapter *adap, uint32_t reg)
>         return 0;
>  }
>
> +static inline int da9063_stop_watchdog(struct i2c_adapter *adap, uint32_t reg)
> +{
> +       uint8_t val;
> +       int rc = i2c_adapter_reg_write(adap, reg,
> +                                       DA9063_REG_PAGE_CON, 0x00);
> +
> +       if (rc)
> +               return rc;
> +
> +       rc = i2c_adapter_reg_read(adap, reg, DA9063_REG_CONTROL_D, &val);
> +       if (rc)
> +               return rc;
> +
> +       if ((val & DA9063_CONTROL_D_TWDSCALE_MASK) == 0)
> +               return 0;
> +
> +       val &= ~DA9063_CONTROL_D_TWDSCALE_MASK;
> +
> +       return i2c_adapter_reg_write(adap, reg, DA9063_REG_CONTROL_D, val);
> +}
> +
>  static inline int da9063_shutdown(struct i2c_adapter *adap, uint32_t reg)
>  {
>         int rc = i2c_adapter_reg_write(adap, reg,
> @@ -133,6 +157,7 @@ static void da9063_system_reset(u32 type, u32 reason)
>                         break;
>                 case SBI_SRST_RESET_TYPE_COLD_REBOOT:
>                 case SBI_SRST_RESET_TYPE_WARM_REBOOT:
> +                       da9063_stop_watchdog(adap, reg);
>                         da9063_reset(adap, reg);
>                         break;
>                 }
> --
> 2.34.1
>
>
> --
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