eswin sdhci driver

[br]

Summary

Add driver for Eswin SDHCI controller.

This one requires PHY initialization otherwise it does not start.

Sorry for some amount of crap -- I found it Linux/U-Boot.

Test Plan

Works on Premier P550.

No prior sdcard initialization needed in U-Boot (I think)

[mhorne]

I have never written or studied an sdhci driver in depth. Maybe @manu would like to look.

TODO: MMCCAM (?)

sys/riscv/eswin/eswin_sdhci.c

107

Better as either BIT_SHIFT or BIT_S.

139

This may as well be sorted next to irq_res.

187–200

This is the ugliness you mean? If you want to submit this, I don't mind, it is your driver. Presumably what lands in upstream linux/u-boot will be documented a little better, and I hope you can update this to match.

236

487

Ideally we would disable the clocks here too.

[mhorne]

sys/riscv/eswin/eswin_sdhci.c

412–417

This type of thing is more typical in an attach routine.

[manu]

In D47883#1091835, @mhorne wrote:

I have never written or studied an sdhci driver in depth. Maybe @manu would like to look.

TODO: MMCCAM (?)

mmccam should be covered as it's an sdhci subdriver.

[manu]

sys/riscv/eswin/eswin_sdhci.c

126

I can't find any doc on this one in linux master branch, is that a compatible from some vendor u-boot ?