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

[Marek Vasut]

On 10/23/2017 01:43 PM, Eugeniy Paltsev wrote:
> On Thu, 2017-10-19 at 13:20 -0500, Dinh Nguyen wrote:
>>
>> 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 at 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
> 
> Yep, thanks for your comments.
> 
> So, Jagan, 
> given Dinh's reply, could you please apply this patch?

I'd really hate it to start seeing soc-specific ifdefs in drivers,
that's IMO not acceptable. A __weak override might be a temporary
solution I'd be willing to live with though.

-- 
Best regards,
Marek Vasut