[U-Boot] Socfpga: configure FPGA to SDRAM interface without reprogramming the FPGA

[Jan Siegmund]

Am 20.12.2017 um 10:35 schrieb Marek Vasut:
> On 12/20/2017 12:29 AM, Jan Siegmund wrote:
>> Am 18.12.2017 um 22:05 schrieb Marek Vasut:
>>> On 12/18/2017 09:44 PM, Jan Siegmund wrote:
>>
>> Hi Marek,
> 
> Hi,
> 

Hi Marek,

>>>> Hi all,
>>>
>>> Hi,
>>>
>>>> Here is another question on the FPGA to SDRAM interface of the Cyclone V SoC.
>>>> Is is possible to configure the the interface in U-Boot or SPL,
>>>
>>> What is "the interface" ?
>>
>> I am sorry I did not specify it further. I meant the FPGA-to-HPS SDRAM interface
>> [2], sometimes called FPGA2SDRAM bridge.
> 
> Oh OK. The F2S bridge is a bit special indeed.
> 
>>> If you mean DRAM, then yes, the CV/AV do _not_ configure the FPGA in SPL
>>> at all. They just configure the IOMUX/clock rings, but that's all.
>>>
>>
>> I know the FPGA is not configured in SPL, but does the FPGA need to be
>> configured in SPL or U-Boot, to use the FPGA-to-HPS SDRAM interface?
> 
> No
> 
>> Would it be
>> possible to just preset the registers for later configuration?
> 
> Yes
> 
>> My preferred usecase would be configuring the registers in the table below in
>> SPL and configuring the FPGA in Linux, with a design using the FPGA-to-HPS SDRAM
>> interface.
>>
>> For example, the last bits in the portcfg register define whether the
>> FPGA-to-HPS SDRAM interface's protocol is AXI or Avalon MM. The problem is, that
>> this register can't be written to in U-Boot, even though it is specified as rw
>> [3]. Can this register just be set by programming the FPGA?
> 
> You might need to regenerate the SPL if you changed those kinds of
> settings. The SPL programs these based on the handoff files IIRC.

I generated the headers using the bsp-editor from Quartus 17 and converted them
using the qts-filter.sh script in U-Boot. Since then, I did not change any settings.

sdram.h in board/.../qts and mach-socfpga/

	#define CONFIG_HPS_SDR_CTRLCFG_PORTCFG_AUTOPCHEN	0

	#define SDR_CTRLGRP_PORTCFG_AUTOPCHEN_LSB		10

wrap_sdram_config.c
	.port_cfg =
		(CONFIG_HPS_SDR_CTRLCFG_PORTCFG_AUTOPCHEN <<
			SDR_CTRLGRP_PORTCFG_AUTOPCHEN_LSB),

sdram.c
	debug("Configuring PORTCFG\n");
	writel(cfg->port_cfg, &sdr_ctrl->port_cfg);

When I add some debug printing around the code shown above, SPL console shows this:

U-Boot SPL 2018.01-rc1-00129-ga8548b9-dirty (Dec 18 2017 - 14:13:21)
Content of ffc2507c is 3f
Wrote 0 to ffc2507c
Content of ffc2507c is 3f
drivers/ddr/altera/sequencer.c: Preparing to start memory calibration
drivers/ddr/altera/sequencer.c: CALIBRATION PASSED
drivers/ddr/altera/sequencer.c: Calibration complete
Trying to boot from MMC1

Maybe the portprotocol part of portcfg is just a status register. But then
again, why would it be specified as rw?

Do you have any idea what I might be missing, to get the f2s running without
programming the FPGA?

> 
>>>> without reprogramming the FPGA? Maybe through the usage of the generated
>>>> header files from the Quartus synthesis?
>>>> The SDRAM controller's registers only differ in eight entries in Linux when the
>>>> FPGA is programmed or not.
>>>>
>>>> +----------+-------------+------------+----------------+
>>>> | address  |    name     | programmed | not programmed |
>>>> +----------+-------------+------------+----------------+
>>>> | FFC25064 |             | 00044003   | 00044FFF       |
>>>> | FFC25068 |             | 2C000000   | 2C03FFFF       |
>>>> | FFC2506c |             | 00B00000   | 00B3FFFF       |
>>>> | FFC25070 |             | 00760000   | 0076FFFF       |
>>>> | FFC25074 |             | 00980000   | 0098FFFF       |
>>>> | FFC25078 |             | 0005A003   | 0005AFFF       |
>>>> | FFC2507c | portcfg     | 00000000   | 0000003F       |
>>>> | FFC25080 | fpgaportrst | 000001FF   | 00000000       |
>>>> +----------+-------------+------------+----------------+
>>>>
>>>> The registers 0xFFC25064-0xFFC25078 don't show up on the HPS' memory map
>>>> [1], so are they even intended to be configured?
>>>>
>>>> Thanks
>>>>
>>>>
>>>>
>>>> [1]
>>>> https://www.altera.com/hps/cyclone-v/hps.html#topic/sfo1411577380716.html#sfo1411577380716
>>>>
>>>
>>>
>>
>> Best regards,
>> Jan
>>
>> [2]
>> https://www.altera.com/documentation/sfo1410143707420.html#sfo1411577336440__section_N10012_N1000F_N10001
>>
>>
>> [3] https://www.altera.com/hps/cyclone-v/hps.html#topic/sfo1411577375739.html
>>
> 
> 

Best regards,
Jan