On Mon, Dec 15, 2025 at 10:56:49AM -0500, Frank Li wrote:

On Mon, Dec 15, 2025 at 05:41:43PM +0300, Dan Carpenter wrote:

quoted

The s32g devices have a GPR register region which holds a number of
miscellaneous registers.  Currently only the stmmac/dwmac-s32.c uses
anything from there and we just add a line to the device tree to
access that GMAC_0_CTRL_STS register:

                        reg = <0x4033c000 0x2000>, /* gmac IP */
                              <0x4007c004 0x4>;    /* GMAC_0_CTRL_STS */

We still have to maintain backwards compatibility to this format,
of course, but it would be better to access these through a syscon.
First of all, putting all the registers together is more organized
and shows how the hardware actually is implemented.  Secondly, in
some versions of this chipset those registers can only be accessed
via SCMI, if the registers aren't grouped together each driver will
have to create a whole lot of if then statements to access it via
IOMEM or via SCMI,

Does SCMI work as regmap? syscon look likes simple, but missed abstract
in overall.

The SCMI part of this is pretty complicated and needs discussion.  It
might be that it requires a vendor extension.  Right now, the out of
tree code uses a nvmem vendor extension but that probably won't get
merged upstream.

But in theory, it's fairly simple, you can write a regmap driver and
register it as a syscon and everything that was accessing nxp,phy-sel
accesses the same register but over SCMI.

You still use regmap by use MMIO. /* GMAC_0_CTRL_STS */

regmap = devm_regmap_init_mmio(dev, sts_offset, &regmap_config);

You can use have an MMIO syscon, or you can create a custom driver
and register it as a syscon using of_syscon_register_regmap().

So all code can use regmap function without if-then statements if SCMI work
as regmap.

regards,
dan carpenter