[PATCH 2/7] uart: pl011: Add proper DM clock support

Linus Walleij linus.walleij at linaro.org
Thu Mar 26 23:34:08 CET 2020


On Wed, Mar 25, 2020 at 3:47 PM Andre Przywara <andre.przywara at arm.com> wrote:

> Even though the PL011 UART driver claims to be DM compliant, it does not
> really a good job with parsing DT nodes. U-Boot seems to adhere to a
> non-standard binding, either requiring to have a "skip-init" property in
> the node, or to have an extra "clock" property holding the base
> *frequency* value for the baud rate generator.
> DTs in the U-Boot tree seem to have been hacked to match this
> requirement.
>
> The official binding does not mention any of these properties, instead
> recommends a standard "clocks" property to point to the baud base clock.
>
> Some boards use simple "fixed-clock" providers, which U-Boot readily
> supports, so let's add some simple DM clock code to the PL011 driver to
> learn the rate of the first clock, as described by the official binding.
>
> These clock nodes seem to be not ready very early in the boot process,
> so provide a fallback value, by re-using the already existing
> CONFIG_PL011_CLOCK variable.
>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>

A good start for other platforms to follow.
Reviewed-by: Linus Walleij <linus.walleij at linaro.org>

Yours,
Linus Walleij


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