[PATCH v2 1/3] imx8mp-evk: Add support for booting via USB

[Ahmad Fatoum]

On 13.08.21 22:20, Lucas Stach wrote:
> Am Freitag, dem 13.08.2021 um 21:26 +0200 schrieb Ahmad Fatoum:
>> On 13.08.21 17:22, Uwe Kleine-König wrote:
>>
>> S-o-b missing.
>>
>>> ---
>>>  arch/arm/boards/nxp-imx8mp-evk/lowlevel.c | 27 +++++++++++++++++++++++
>>>  arch/arm/mach-imx/boot.c                  |  4 +++-
>>>  include/asm-generic/sections.h            |  1 +
>>>  3 files changed, 31 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/arm/boards/nxp-imx8mp-evk/lowlevel.c b/arch/arm/boards/nxp-imx8mp-evk/lowlevel.c
>>> index 3298ded5866d..1fb7899198d6 100644
>>> --- a/arch/arm/boards/nxp-imx8mp-evk/lowlevel.c
>>> +++ b/arch/arm/boards/nxp-imx8mp-evk/lowlevel.c
>>> @@ -99,6 +99,30 @@ static int power_init_board(void)
>>>  	return 0;
>>>  }
>>>  
>>> +/* read piggydata via a bootrom callback and place it behind our copy in SDRAM */
>>> +static int imx8m_bootrom_load_image(void)
>>> +{
>>> +	int (*download_image)(u8 *dest, u32 offset, u32 size, u32 xor) = *(void **)0x988;
>>
>> Would be nice to have this in a header, e.g.
>>
>> extern struct imx8mp_bootrom_ops {
>> 	/* ... */
>> 	int (*download_image)(u8 *dest, u32 offset, u32 size, u32 xor);
>> } *imx8mp_bootrom_ops = (void *)0x988;
>>
>>> +	size_t count = __piggydata_end - __piggydata_start;
>>> +	char *p = (char *)MX8M_ATF_BL33_BASE_ADDR + (__piggydata_start - __image_start);
>>> +
>>> +	while (count) {
>>> +		size_t chunksize = min(count, (size_t)1024);
>>> +		int ret;
>>> +
>>> +		ret = download_image(p, 0, chunksize, (uintptr_t)p ^ chunksize);
>>> +		if (ret != 0xf0) {
>>> +			pr_err("Failed to load piggy data (ret = %x)\n", ret);
>>> +			return -EIO;
>>> +		}
>>> +
>>> +		p += chunksize;
>>> +		count -= chunksize;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
> This shouldn't be in board code, but in some location where it is
> reusable by other i.MX8MP boards.
> 
>>>  extern struct dram_timing_info imx8mp_evk_dram_timing;
>>>  
>>>  static void start_atf(void)
>>> @@ -125,6 +149,9 @@ static void start_atf(void)
>>>  	case BOOTSOURCE_MMC:
>>>  		imx8mp_esdhc_load_image(instance, false);
>>>  		break;
>>> +	case BOOTSOURCE_SERIAL:
>>> +		imx8m_bootrom_load_image();
>>> +		break;
>>>  	default:
>>>  		printf("Unhandled bootsource BOOTSOURCE_%d\n", src);
>>>  		hang();
>>> diff --git a/arch/arm/mach-imx/boot.c b/arch/arm/mach-imx/boot.c
>>> index 2b66bbf71eb1..7c1d49291045 100644
>>> --- a/arch/arm/mach-imx/boot.c
>>> +++ b/arch/arm/mach-imx/boot.c
>>> @@ -495,10 +495,12 @@ static void __imx7_get_boot_source(enum bootsource *src, int *instance,
>>>  	case 5:
>>>  		*src = BOOTSOURCE_NOR;
>>>  		break;
>>> -	case 15:
>>> +	case 14: /* observed on i.MX8MP for USB "serial" booting */
>>> +	case 15: /* observed on i.MX8MM for USB "serial" booting */
>>>  		*src = BOOTSOURCE_SERIAL;
>>>  		break;
>>>  	default:
>>> +		*src = BOOTSOURCE_UNKNOWN;
>>>  		break;
>>>  	}
>>>  }
>>> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
>>> index 870bff21f668..597c4951ea5e 100644
>>> --- a/include/asm-generic/sections.h
>>> +++ b/include/asm-generic/sections.h
>>> @@ -9,6 +9,7 @@ extern char _end[];
>>>  extern char __image_start[];
>>>  extern char __image_end[];
>>>  extern char __piggydata_start[];
>>> +extern char __piggydata_end[];
>>
>> Other code normally uses __image_end, but it seems __piggydata_end should be
>> equal to it. I'd prefer __image_end, because conceptually, you want to copy
>> off the rest of the image (which happens to be just the piggy data)
>>
>> @Rouven, The sha sum is at the end of the image, right?
>> Would this be included this way?
> 
> The checksum is built into the PBL, as it is used to authenticate the
> piggydata, as the BootROM will only authenticate the initial loaded
> part of the image, i.e. the PBL.

Of course. Excuse the brain fart.

> 
> Regards,
> Lucas
> 
> 


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