[U-Boot] Add support for imxrt

[Giulio Benetti]

Hi Fabio,

On 10/9/19 6:03 PM, Fabio Estevam wrote:
> Hi Giulio,
> 
> On Wed, Oct 9, 2019 at 12:59 PM Giulio Benetti
> <giulio.benetti at benettiengineering.com> wrote:
>>
>> Hi Fabio and Stefano,
>>
>> On 9/29/19 9:40 PM, Fabio Estevam wrote:
>>> We try to use DM in U-Boot proper as much as possible, but using DM in
>>> SPL is currently not a requirement, especially due to internal RAM
>>> size constraints.
>> IOMUXC and LPUART(using 24Mhz clock) work correctly using DM.
>>
>> About clk drivers, I've seen all around that they are very shrinked
>> Linux's version drivers. Would it make sense to add complete clk driver
>> in u-boot starting from Linux one(i.e. vf610) or it would only grow
>> size? I mean, after adding initial support I would like to add Lcd
>> controller driver etc. etc. so a complete driver would be useful.
>> Instead what I see on IMX6 clk driver is only a subsection of all PLLs
>> and ref_sel to start Linux up.
> 
> Yes, since you are adding this from scratch, I would suggest adding a
> complete clock driver, which is close to the Linux driver.

With this you mean adding every single mux, divider, gate, fixed_factor 
and pfd(i.e. linux/drivers/clk/imx/clk-imxq6.c)?

Or only a shrinked version of that?
I mean, is it ok if I list everything during imxrt_clk_probe()?

Thanks in advance
-- 
Giulio Benetti
Benetti Engineering sas