[PATCH 19/28] ARM: at91: add helpers for chain-loading barebox from SD-card

[Sascha Hauer]

On Mon, Jul 06, 2020 at 12:35:30AM +0200, Ahmad Fatoum wrote:
> 
> 
> On 7/5/20 8:42 PM, Sascha Hauer wrote:
> > On Wed, Jul 01, 2020 at 11:11:13AM +0200, Ahmad Fatoum wrote:
> >> +static void at91_fat_start_image(struct pbl_bio *bio,
> >> +				 void *buf, unsigned int len,
> >> +				 u32 r4)
> >> +{
> >> +	void __noreturn (*bb)(void);
> >> +	int ret;
> >> +
> >> +	ret = pbl_fat_load(bio, "barebox.bin", buf, len);
> >> +	if (ret < 0) {
> >> +		pr_err("pbl_fat_load: error %d\n", ret);
> >> +		return;
> >> +	}
> >> +
> >> +	bb = buf;
> >> +
> >> +	sync_caches_for_execution();
> >> +
> >> +	xload_bb(bb, r4);
> >> +}
> >> +
> >> +static const struct sdhci_instance {
> >> +	void __iomem *base;
> >> +	unsigned id;
> >> +	u8 periph;
> >> +	s8 pins[15];
> >> +} sdhci_instances[] = {
> >> +	[0] = { SAMA5D2_BASE_SDHC0, SAMA5D2_ID_SDMMC0, AT91_MUX_PERIPH_A,
> >> +		{ 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 13, 10, 11, 12, -1 } },
> >> +	[1] = { SAMA5D2_BASE_SDHC1, SAMA5D2_ID_SDMMC1, AT91_MUX_PERIPH_E,
> >> +		{ 18, 19, 20, 21, 22, 28, 30, -1 } },
> >> +};
> > 
> > Can we use C99 initializer here please?
> 
> Can do
> 
> > 
> >> +
> >> +/**
> >> + * sama5d2_sdhci_start_image - Load and start an image from FAT-formatted SDHCI
> >> + * @r4: value of r4 passed by BootROM
> >> + *
> >> + * Return: If successul, this function does not return. A negative error
> > 
> > s/successul/successful/
> > 
> >> + * code is returned when this function fails.
> > 
> > This is not true, the function panics on error.
> 
> It did when I first wrote the comment :D.
> Will reply with a fixup.
> 
> > 
> >> + */
> >> +void __noreturn sama5d2_sdhci_start_image(u32 r4)
> >> +{
> >> +	void *buf = (void *)SAMA5_DDRCS;
> >> +	const struct sdhci_instance *instance;
> >> +	struct pbl_bio bio;
> >> +	const s8 *pin;
> >> +	int ret;
> >> +
> >> +	instance = &sdhci_instances[!!sama5_bootsource_instance(r4)];
> > 
> > Why "!!"? sama5_bootsource_instance() should return exactly 0 or 1 here.
> 
> SAMA5_BOOTSOURCE_INSTANCE is GENMASK(7, 4). While it should only be 0 or 1
> on the sama5d2, better be on the safe side and force it to either 0 or 1.

"safe" would be to only accept 0 and 1 and refuse other values.
Interpreting everything != 0 as 1 is IMO not safe.

Sascha

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