[U-Boot] [PATCH v1 1/2] sunxi (sun50i): support i2c on A64 (pin-config, clocking)

[Dr. Philipp Tomsich]

> On 18 Feb 2017, at 02:15, André Przywara <andre.przywara at arm.com> wrote:
> 
>> diff --git a/board/sunxi/board.c b/board/sunxi/board.c
>> index bba9b7c..a47b113 100644
>> --- a/board/sunxi/board.c
>> +++ b/board/sunxi/board.c
>> @@ -485,90 +485,108 @@ int board_mmc_init(bd_t *bis)
>> void i2c_init_board(void)
>> {
>> #ifdef CONFIG_I2C0_ENABLE
>> #if defined(CONFIG_MACH_SUN4I) || defined(CONFIG_MACH_SUN5I) || defined(CONFIG_MACH_SUN7I)
>> 	sunxi_gpio_set_cfgpin(SUNXI_GPB(0), SUN4I_GPB_TWI0);
>> 	sunxi_gpio_set_cfgpin(SUNXI_GPB(1), SUN4I_GPB_TWI0);
>> 	clock_twi_onoff(0, 1);
>> #elif defined(CONFIG_MACH_SUN6I)
>> 	sunxi_gpio_set_cfgpin(SUNXI_GPH(14), SUN6I_GPH_TWI0);
>> 	sunxi_gpio_set_cfgpin(SUNXI_GPH(15), SUN6I_GPH_TWI0);
>> 	clock_twi_onoff(0, 1);
>> #elif defined(CONFIG_MACH_SUN8I)
>> 	sunxi_gpio_set_cfgpin(SUNXI_GPH(2), SUN8I_GPH_TWI0);
>> 	sunxi_gpio_set_cfgpin(SUNXI_GPH(3), SUN8I_GPH_TWI0);
>> 	clock_twi_onoff(0, 1);
>> +#elif defined(CONFIG_MACH_SUN50I)
>> +	sunxi_gpio_set_cfgpin(SUNXI_GPH(0), SUN50I_GPH_TWI0);
>> +	sunxi_gpio_set_cfgpin(SUNXI_GPH(1), SUN50I_GPH_TWI0);
>> +	/* The A64-uQ7 doesn't have external pull-ups for I2C[01]. */
>> +	sunxi_gpio_set_pull(SUNXI_GPH(0), SUNXI_GPIO_PULL_UP);
>> +	sunxi_gpio_set_pull(SUNXI_GPH(1), SUNXI_GPIO_PULL_UP);
> 
> Is this specific to your board?

No. This is board-specific for any board.
Every I2C bus will need pull-ups, but it’s not defined where on the bus these
should/will be located.  There’s even a few I2C peripherals that have the
pull-ups integrated.

In other words: this was one of many things that triggered me going after
support DM (and it was the one change that caused me to look at the size
of the SPL and whether there’s still space available for DM drivers when
using OF_PLATDATA … but we both know the conclusion).

> Which isn't officially supported yet?

I can send patches with the board-specific DTS and defconfig, if that helps ;-)

Just wanted until we get dual-IO SPI reads validated (and the DM changes
merged), so it can be a single changeset instead of relying on multiple updates
to the same files.

If you think it’s worthwhile to send out a defconfig that doesn’t depend on DM
together with the DTS (without the gpiobank-entries), let me know.

> And having a DM conversion would make this easily fixable via DT, I guess?

Yes. But that will still leave the SPL/TPL discussion for another day, as the
SPL still depends on these programmatic settings.

Our board’s early-stage normally shouldn't need to do anything on this I2C
bus, but customer boards may come up with a use for it (image this going
towards battery/power managing circuitry on a baseboard).

Regards,
Philipp.