Am 15.08.2019 um 19:07 schrieb Marek Vasut:
On 8/15/19 6:57 PM, Simon Goldschmidt wrote:
Am 15.08.2019 um 18:34 schrieb Marek Vasut:
On 8/15/19 6:22 PM, Simon Goldschmidt wrote:
Hi Marek,

Am 24.07.2019 um 09:45 schrieb Simon Goldschmidt:
On Wed, Jul 24, 2019 at 9:31 AM Marek Vasut <ma...@denx.de> wrote:

On 7/23/19 10:27 PM, Simon Goldschmidt wrote:
This adds clk-gen5 as a readonly DM_CLK driver that can return
clocks for
the peripherals.

Further changes are:
- select DM_CLK for gen5 U-Boot and SPL
- add SPL tags to clock nodes in socfpga-common-u-boot.dtsi
- adjust socfpga.dtsi to provide missing src selection registers
- start 'handoff.dtsi' file for socrates (conatains clock speeds for
now)

These should likely be separate patches then ?

Well, in the end, yes. Especially the handoff.dtsi is required for
*all*
socfpga_gen5 boards, so I'll need to adapt the 'qts-filter.sh'
script to
generate it.

I'll change that script and separate these patches in v2.

I'm in the process of moving all of the 'qts' header files to devicetree
handoff.dtsi files. CLK and DDR are already working (pinmux/iocsr not
yet) - but I need to work a bit on DM memory consumption.

So now I'm faced with a question: in which driver do I implement the
pinmux control? From a DM point of view, it could be a UCLASS_PINCTRL
driver in 'drivers/pinctrl', but since it's more or less read-only
unless we'd get more details about the hardware, I'm a bit hesistant to
do it that way.

Also, the registers are in 'sysmgr', which is handled by the standard
"syscon" driver right now, so it could well get a UCLASS_SYSCON driver?

What do we need read-only pinmux driver for ? I would expect pinmux to
be more write-only, from the hardware perspective that is.

Well, I don't know. I just need a driver that can parse its dts subtree
for the config instead of loading from the qts wrapper file. Then this
driver needs to be probed at the appropriate place in SPL so that the
pins are initialized.

Sounds more like misc driver or something along those lines.

Hmm, probing UCLASS_MISC in SPL to get the pinmux initializes sounds a bit strange, but that's probably OK.


My future plan is then that such a driver could be re-probed after
loading some kind of dts overlay matching an FPGA image to be programmed
(as that FPGA image can contain different pin settings, e.g. when using
loan IO).

But then it becomes a PINMUX driver.

Well, what I'm writing *is* a writeonly driver controlling the pins. However, since we don't know anything about the iocsr part, we can't implement all the functions in 'struct pinctrl_ops' (just write the given scan chain and that's it). I think PINMUX would fit best, but see below...


I'm just not familiar enough with pinctrl drivers or syscon drivers and
could need some input on which direction to take this...

Does a syscon driver for that purpose sound better?

Isn't syscon driver for system controllers, which provide e.g. regmaps
to subdevices ? I think the altera pinmux shouldn't be syscon.

The thing is that 'sysmgr' already *is* a syscon driver: it provides access to various control bits (e.g. used by the ethernet driver in Linux) but also pinmux registers.

Of course, I could add "scanmgr@0xfff02000" as a new node in the devicetree that would be the PINMUX driver which accesses the pinmux registers in sysmgr via sysycon... That would keep sysmgr's syscon behaviour working (for other drivers).

Regards,
Simon

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