[U-Boot] [PATCH v2] DW SPI: Get clock value from Device Tree

[Dinh Nguyen <dinguyen@kernel.org>]

On 10/19/2017 10:51 AM, Marek Vasut wrote:
> On 10/19/2017 05:36 PM, Eugeniy Paltsev wrote:
>> On Tue, 2017-10-17 at 20:32 +0530, Jagan Teki wrote:
>>> On Tue, Oct 17, 2017 at 8:27 PM, Alexey Brodkin
>>> <Alexey.Brodkin@synopsys.com> wrote:
>>>> Hi Jagan,
>>>>
>>>>> -----Original Message-----
>>>>> From: Eugeniy Paltsev [mailto:paltsev at synopsys.com]
>>>>> Sent: Tuesday, October 17, 2017 4:33 PM
>>>>> To: jagannadh.teki at gmail.com
>>>>> Cc: u-boot at lists.denx.de; uboot-snps-arc at synopsys.com
>>>>> Subject: [uboot-snps-arc] Re: [PATCH v2] DW SPI: Get clock value from Device Tree
>>>>>>
>>>>>> How hard it is to make others to use clock manager? do you have any list?
>>>>>
>>>>> clock_manager.h is an old (and non-generic) way to deal with different clocks.
>>>>> For example in SOCFPGA_GEN5 and SOCFPGA_ARRIA10 clock_manager.h provides
>>>>> cm_get_spi_controller_clk_hz function to deal with spi controller clock.
>>>>>
>>>>> But today we have another, linux-like alternative: to bind clocks via device tree
>>>>> and manipulate with clocks via generic functions provided by clk.h
>>>>>
>>>>> In this patch I added option to get clock via device tree using standard bindings
>>>>> and restrict clock_manager.h functions usage only to targets which still use it,
>>>>> so new targets can simply bind clock via device tree and they do not need to
>>>>> implement/define something in clock_manager.h
>>>>>
>>>>> So we don't need to make others to use clock manager :)
>>>>
>>>> Maybe it worth trying the other way around and think about switching SOCFPGA platforms to
>>>> generic clk framework?
>>>
>>> Yes, ie what exactly I thought of, thanks!
>>
>> I checked cm_get_spi_controller_clk_hz implementation in SOCFPGA_GEN5 and
>> SOCFPGA_ARRIA10: we can't simply replace it with "fixed-clock" driver as it 
>> manipulate with real hardware.
>> The only way to do it is to replace SOCFPGA* clock manager functions by real
>> clock driver.
>>
>> And given I don't have mentioned hardware so I barely can help with
>> those improvements on SOCFPGA. That said if there're no short-term plans to
>> switch SOCFPGA to clk framework maybe we'll be OK with my workaround with #ifdefs?
> 
> Wait for Dinh's reply ...
> 

Honestly, I don't have too much time to work on this right now. So I
really don't when it can get done. But it'll go on my to-do list.

Dinh