[PATCH 2/2] ARM: imx: Pick correct eMMC boot partition from ROM log

[Teresa Remmet]

Hello Marek,

Am Donnerstag, den 01.07.2021, 01:08 +0200 schrieb Marek Vasut:
> In case the iMX8M boot from eMMC boot partition and the primary image
> is corrupted, the BootROM is capable of starting a secondary image in
> the other eMMC boot partition as a fallback.

I would like to ask a more general question. As I could not find
information about that. What are the criteria for the BootROM to
consider a image as corrupted? 
I remember on other platforms with NAND where it was a erased page or
too many bitflips. What is it here with eMMC?

Thanks,
Teresa

> 
> However, the BootROM leaves the eMMC BOOT_PARTITION_ENABLE setting as
> it was, i.e. pointing to the boot partition containing the corrupted
> image, and the BootROM does not provide any indication that this sort
> of fallback occured.
> 
> According to AN12853 i.MX ROMs Log Events, Rev. 0, May 2020, it is
> possible to determine whether fallback event occurred by parsing the
> ROM event log. In case ROM event ID 0x51 is present, fallback event
> did occur.
> 
> This patch implements ROM event log parsing and search for event ID
> 0x51 for all iMX8M SoCs, and based on that corrects the eMMC boot
> partition selection. This way, the SPL loads the remaining boot
> components from the same eMMC boot partition from which it was
> started, even in case of the fallback.
> 
> Signed-off-by: Marek Vasut <marex at denx.de>
> Cc: Faiz Abbas <faiz_abbas at ti.com>
> Cc: Harald Seiler <hws at denx.de>
> Cc: Lokesh Vutla <lokeshvutla at ti.com>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Fabio Estevam <festevam at gmail.com>
> Cc: Peng Fan <peng.fan at nxp.com>
> Cc: Stefano Babic <sbabic at denx.de>
> Cc: Ye Li <ye.li at nxp.com>
> ---
>  arch/arm/mach-imx/imx8m/soc.c | 61
> +++++++++++++++++++++++++++++++++++
>  1 file changed, 61 insertions(+)
> 
> diff --git a/arch/arm/mach-imx/imx8m/soc.c b/arch/arm/mach-
> imx/imx8m/soc.c
> index 0c44022a6dc..92a71b6ba29 100644
> --- a/arch/arm/mach-imx/imx8m/soc.c
> +++ b/arch/arm/mach-imx/imx8m/soc.c
> @@ -571,6 +571,67 @@ enum boot_device get_boot_device(void)
>  }
>  #endif
>  
> +#if defined(CONFIG_IMX8M)
> +#include <spl.h>
> +int spl_mmc_emmc_boot_partition(struct mmc *mmc)
> +{
> +	u32 *rom_log_addr = (u32 *)0x9e0;
> +	u32 *rom_log;
> +	u8 event_id;
> +	int i, part;
> +
> +	part = default_spl_mmc_emmc_boot_partition(mmc);
> +
> +	/* If the ROM event log pointer is not valid. */
> +	if (*rom_log_addr < 0x900000 || *rom_log_addr >= 0xb00000 ||
> +	    *rom_log_addr & 0x3)
> +		return part;
> +
> +	/* Parse the ROM event ID version 2 log */
> +	rom_log = (u32 *)(uintptr_t)(*rom_log_addr);
> +	for (i = 0; i < 128; i++) {
> +		event_id = rom_log[i] >> 24;
> +		switch (event_id) {
> +		case 0x00: /* End of list */
> +			break;
> +		/* Log entries with 1 parameter, skip 1 */
> +		case 0x80: /* Start to perform the device
> initialization */
> +		case 0x81: /* The boot device initialization completes
> */
> +		case 0x8f: /* The boot device initialization fails */
> +		case 0x90: /* Start to read data from boot device */
> +		case 0x91: /* Reading data from boot device completes
> */
> +		case 0x9f: /* Reading data from boot device fails */
> +			i += 1;
> +			continue;
> +		/* Log entries with 2 parameters, skip 2 */
> +		case 0xa0: /* Image authentication result */
> +		case 0xc0: /* Jump to the boot image soon */
> +			i += 2;
> +			continue;
> +		/* Boot from the secondary boot image */
> +		case 0x51:
> +			/*
> +			 * Swap the eMMC boot partitions in case there
> was a
> +			 * fallback event (i.e. primary image was
> corrupted
> +			 * and that corruption was recognized by the
> BootROM),
> +			 * so the SPL loads the rest of the U-Boot from
> the
> +			 * correct eMMC boot partition, since the
> BootROM
> +			 * leaves the boot partition set to the
> corrupted one.
> +			 */
> +			if (part == 1)
> +				part = 2;
> +			else if (part == 2)
> +				part = 1;
> +			continue;
> +		default:
> +			continue;
> +		}
> +	}
> +
> +	return part;
> +}
> +#endif
> +
>  bool is_usb_boot(void)
>  {
>  	return get_boot_device() == USB_BOOT;