How to implement common clk in multi function controller?

From: Masahiro Yamada
Date: Tue Nov 10 2015 - 22:16:51 EST


I am implementing clk and reset drivers for my SoCs.
(drivers/clk/uniphier/* and drivers/reset/uniphier/*)

In my SoCs, one hardware block contains various
registers for both clock and reset controlling.
(so, it is like a MFD system controller device).
I think it is a common case.

I am guessing my device tree would be like follows:
(one syscon device contains clk and rst devices under it)

syscon {
compatible = "socionext,uniphier-syscon",
"syscon", "simple-mfd";
reg = <... ...>;

clk_ctrl {
.compatible = "socionext,uniphier-clkctrl";
#clock-cells = <1>;

rst_ctrl {
.compatible = "socionext,uniphier-rstctrl";
#reset-cells = <1>;

One problem I noticed was,
we are supposed to use regmap for register access
if we use syscon.

OTOH, common clk APIs such as clk-gate, clk-divider
expect simple register access via writel()/readl().

Is it a good idea to expand such APIs to regmap?

Of course, I could my own uniphier/clk-gate.c
to use regmap as other SoCs do.

But, I think regmap is general demand, so
I am wondering if it could be supported in common parts.

Or, any other good solution exists?

Best Regards
Masahiro Yamada
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