Older hisilicon chipsets

[arnd@arndb.de (Arnd Bergmann)]

On Saturday, August 27, 2016 1:53:25 PM CEST Marty Plummer wrote:
> On 08/27/2016 10:04 AM, Jason Cooper wrote:
> > 
> > Ah, yes.  The same device we were discussing on #mvlinux?
> > 
> Indeed, the very same
> > 
> > Note that I have no experience with HiSilicon. :-)  However, I think
> > it's correct to add it mach-hisi/.   A quick grep shows that there is
> > devicetree support for hisilicon SoCs (arch/arm/boot/dts/).  So that
> > means there's a *lot* less code to add under mach-hisi/.
> > 
> The issue here is that mach-hisi/Kconfig and CONFIG_ARCH_HISI require
> ARMv7, whereas the hi3520 has an arm1176/arm926 core, thereby being
> ARMv6/v5

No problem, just modify the dependency list for the top-level option.

> > Ideally, most of it will be a devicetree.  Assuming we have code for the
> > SoC and associated drivers.
> > 
> Yes, I've been doing some work on that already, but as I've said, unsure
> where one should/would insert all these different things.

start with getting the serial console working. debug_ll is useful for
early bringup and should only need a patch to arch/arm/Kconfig.debug.

Later you would typically use earlycon (using a stdout-path property
in DT to point to the UART and configuration). The approximate order
in which you need other drivers is:

* drivers/irqchip (often a standard VIC or GIC)
* drivers/clocksource
* drivers/tty/serial/
* drivers/clk
* drivers/pinctrl (or drivers/gpio for simpler I/O pins)
* drivers/mmc
* drivers/net/ethernet
* drivers/spi/
* drivers/i2c/
* drivers/mtd/

In each case, look for a driver that works on your hardware first,
or create one based on the old source if that doesn't exist upstream.

> > I've added GregKH to the Cc to see if he knows of anyone currently
> > working with Hisilicon.
> > 
> Thanks, mayhaps someone can get even a response from Hisilicon, as I've
> yet to recieve even that.

I expect that Xu Wei will pick up the patches once they are ready to
go in, but he probably won't have a lot of comments for your patches.

	Arnd