[U-Boot] [PATCH 2/5] arm64: mvebu: a8k: Add support for NAND clock get

[Konstantin Porotchkin]

Hi, Stefan,

On 03/30/2017 04:15 PM, Stefan Roese wrote:
> On 28.03.2017 17:16, kostap at marvell.com wrote:
>> From: Konstantin Porotchkin <kostap at marvell.com>
>>
>> Implement mvebu_get_nand_clock call for A8K family.
>> This function is used by PXA3XX NAND driver.
>>
>> Signed-off-by: Konstantin Porotchkin <kostap at marvell.com>
>> Cc: Stefan Roese <sr at denx.de>
>> Cc: Igal Liberman <igall at marvell.com>
>> Cc: Nadav Haklai <nadavh at marvell.com>
>> ---
>>  arch/arm/mach-mvebu/armada8k/cpu.c | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>>
>> diff --git a/arch/arm/mach-mvebu/armada8k/cpu.c
>> b/arch/arm/mach-mvebu/armada8k/cpu.c
>> index 2325e9a..e18ca6b 100644
>> --- a/arch/arm/mach-mvebu/armada8k/cpu.c
>> +++ b/arch/arm/mach-mvebu/armada8k/cpu.c
>> @@ -110,3 +110,19 @@ void reset_cpu(ulong ignored)
>>      reg &= ~(1 << RFU_SW_RESET_OFFSET);
>>      writel(reg, RFU_GLOBAL_SW_RST);
>>  }
>> +
>> +#ifdef CONFIG_NAND_PXA3XX
>
> Do we really need to have this code conditionally compiled here?
I can remove it, just wanted not to increase the code size if not 
needed. Do you think it is excessive?
>
>> +/* Return NAND clock in Hz */
>> +u32 mvebu_get_nand_clock(void)
>> +{
>> +    unsigned long NAND_FLASH_CLK_CTRL = 0xF2440700UL;
>
> I know that some of this code is historically done this way. But
> with DT available now, isn't it possible to at least get the base
> address of such registers from the DT instead of hardcoding it?
I see what you saying and I agree it is not as elegant as it could be. 
The only problem is that the NAND clock register is not part of the SoC 
NAND unit, so the IO base taken from DTS entry for NAND device is not 
really useful here. NAND unit and its clock configuration register are 
only sharing the CP0 base - 0xF2000000.

>
> Thanks,
> Stefan