linux-kernel - Re: [PATCH 1/2] socfpga: hotplug: put cpu1 in wfi

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Message-ID: <542D38D6.4030209@opensource.altera.com>
Date:	Thu, 2 Oct 2014 06:36:54 -0500
From:	Dinh Nguyen <dinguyen@...nsource.altera.com>
To:	Pavel Machek <pavel@...x.de>
CC:	atull <atull@...nsource.altera.com>, <linux@....linux.org.uk>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <delicious.quinoa@...il.com>,
	<yvanderv@...nsource.altera.com>
Subject: Re: [PATCH 1/2] socfpga: hotplug: put cpu1 in wfi



On 10/1/14, 6:16 PM, Pavel Machek wrote:
> On Wed 2014-10-01 11:07:18, Dinh Nguyen wrote:
>>
>>
>> On 10/1/14, 10:04 AM, Pavel Machek wrote:
>>> Hi!
>>>
>>>>>> +		__raw_writel(RSTMGR_MPUMODRST_CPU1,
>>>>>> +			     rst_manager_base_addr + 0x10);
>>>>>
>>>>> Would it be possible to copy reset manager description struct from
>>>>> u-boot and use it here, instead of raw offset?
>>>>
>>>> I will replace this 0x10 with a macro that reflects how the register is 
>>>> named in the register map.
>>>
>>> That would be better than 0x10, but even better would be just copying
>>>
>>> struct socfpga_reset_manager {
>>>         u32     status;
>>>         u32     ctrl;
>>>         u32     counts;
>>>         u32     padding1;
>>>         u32     mpu_mod_reset;
>>>         u32     per_mod_reset;
>>>         u32     per2_mod_reset;
>>>         u32     brg_mod_reset;
>>> };
>>>
>>> from u-boot. Unlike macros, structs have advantages that typos lead to
>>> easier-to-see failure modes... (And they are easier to read/parse,
>>> too).
>>>
>>
>> Copying from uboot sounds good, but I already know that the CPU reset
>> offset is different for our next SOC, Arria 10. The Arria 10 SOC should
>> still be able to use the same MSL as Cyclone5 and Arria5, but with a few
>> differences. One of them being, the CPU1 reset offset is at 0x20 instead
>> of 0x10. So I think having a macro for this one register is a bit
>> cleaner than having to define a whole new struct for Arria10.
> 
> I don't think "whole new struct" is a problem. At least it will be
> plain to see what changed (which will get easily lost in ifdefs.
> 
> struct cyclone5_reset_manager {
> 	struct socfpga_reset_manager common;
> 	u32 brg_mod_reset;
> }
> 
> struct aria10_reset_manager {
> 	struct socfpga_reset_manager common;
> 	char filler[0x10];
> 	u32 brg_mod_reset;
> }
> 
> if (of_machine_is_compatible("altr,socfpga-arria10"))
> 	__raw_writel(0, (struct cyclone5_reset_manager *) rst_manager_base_addr->brg_mod_reset));
> else
> 	__raw_writel(0, (struct aria10_reset_manager *) rst_manager_base_addr->brg_mod_reset));
> 
> ...does not sound that bad. (And you'll need some nice solution for
> u-boot, anyway...)
> 

That's fine.

Dinh
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