[PATCH rtems-libbsd] rtemsbsd/arasan_sd: Prevent disabled device probe

[Chris Johns]

On 16/9/22 6:16 am, Kinsey Moore wrote:
> Probing a SDIO/SDHCI interface that has been disabled by system init via
> holding it in reset can cause a CPU hang. This prevents probing of
> devices that have been disabled in such a manner on ZynqMP systems.> ---
>  rtemsbsd/sys/dev/sdhci/arasan_sdhci.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/rtemsbsd/sys/dev/sdhci/arasan_sdhci.c b/rtemsbsd/sys/dev/sdhci/arasan_sdhci.c
> index ccdcb09b..6332260a 100644
> --- a/rtemsbsd/sys/dev/sdhci/arasan_sdhci.c
> +++ b/rtemsbsd/sys/dev/sdhci/arasan_sdhci.c
> @@ -246,6 +246,31 @@ arasan_sdhci_attach(device_t dev)
>  		goto fail;
>  	}
>  
> +	/*
> +	 * These devices may be disabled by being held in reset. If this is the
> +	 * case, a read attempt in its register range will result in a CPU hang.
> +	 * Detect this situation and avoid probing the device in this situation.
> +	 */
> +#if defined(LIBBSP_AARCH64_XILINX_ZYNQMP_BSP_H)
> +	volatile uint32_t *RST_LPD_IOU2_ptr = (uint32_t*)0xFF5E0238;
> +	uint32_t RST_LPD_IOU2 = *RST_LPD_IOU2_ptr;
> +	uint32_t SDIO0_disabled = RST_LPD_IOU2 & (1 << 5);
> +	uint32_t SDIO1_disabled = RST_LPD_IOU2 & (1 << 6);
> +	if ( sc->mem_res == 0xFF160000 ) {
> +		if ( SDIO0_disabled != 0 ) {
> +			device_printf(dev, "SDIO0 disabled\n");
> +			err = ENXIO;
> +			goto fail;
> +		}
> +	} else {
> +		if ( SDIO1_disabled != 0 ) {
> +			device_printf(dev, "SDIO1 disabled\n");
> +			err = ENXIO;
> +			goto fail;
> +		}
> +	}
> +#endif

This is fine given it is specific to the ZynqMP. If we find anything common
between the various families it can be updated.

Chris