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

[Jagan Teki]

On Mon, Oct 30, 2017 at 4:24 PM, Marek Vasut <marex at denx.de> wrote:
> On 10/30/2017 07:04 AM, Jagan Teki wrote:
>> On Sat, Oct 28, 2017 at 5:09 PM, Marek Vasut <marex at denx.de> wrote:
>>> On 10/27/2017 03:54 PM, Eugeniy Paltsev wrote:
>>>> On Tue, 2017-10-24 at 15:22 +0530, Jagan Teki wrote:
>>>>> On Tue, Oct 24, 2017 at 11:38 AM, Marek Vasut <marex at denx.de> wrote:
>>>>>> 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.
>>>>>
>>>>> I would rather like to see some check on clock manager itself whether
>>>>> CONFIG_IS_ENABLED(CLK) is using or not? this can tends not to use
>>>>> __weak as well soc #ifdefs in driver.
>>>>>
>>>>
>>>> Actually I don't understand what do you mean.
>>>> Even if I add any #ifdefs to the clock_manager.h I still need to wrap clock_manager.h
>>>> include with #ifdefs as clock_manager.h is defined only for two
>>>> targets - SOCFPGA_GEN5 and SOCFPGA_ARRIA10.
>>>>
>>>> #if defined(CONFIG_TARGET_SOCFPGA_GEN5) || defined(CONFIG_TARGET_SOCFPGA_ARRIA10)
>>>> #include <asm/arch/clock_manager.h>
>>>> #endif
>>>>
>>>> And I think it is better to add this #ifdef in driver than create empty
>>>> clock_manager.h file for every new target which uses this driver.
>>
>> Check CLK in clock-manager like below, of-course cm_get_l4_noc_hz used
>> in other IP's as well. we need to carefully adding these check and if
>> require add CLK for remaining drivers as well. the reason for adding
>> checks in clock-manager is it may be removable code if all use CLK.
>
> I do not understand what you're trying to tell me, but the patch below
> makes no sense. What I would like to see is a weak function in the
> driver and that function be overriden in the socfpga clock manager.

I'm trying to avoid __weak or #ifdef on driver instead make changes in
clock manager which will remove in future(once all moved with CLK)

thanks!
-- 
Jagan Teki
Free Software Engineer | www.openedev.com
U-Boot, Linux | Upstream Maintainer
Hyderabad, India.