Expand OpenFirmware API with ofw_bus_node_status_okay method

[mw_semihalf.com]

Summary

Method could be used before we can access device_t structure.
As per simple phandle_t handle we can access FDT to check
if specified node has been enabled.
It will be used in Marvell's common configuration code.

[zbb]

This is a useful change. +1

[mmel]

We have fdt_is_enabled() function, why you want new, duplicated, one?
Also note that 'ok' is also valid value for 'status' property (but yes, fdt_is_enabled() have same issue).

[andrew]

fdt_is_enabled is deprecated and should be removed as soon as there is an appropriate OpenFirmware function.

[mw_semihalf.com]

It was also decided to implement new OFW function, because fdt_is_enabled would be used by Marvell platforms at an early stage and it simply fails there with:

panic: pmap_fault: pm_pt1 abort
cpuid = 0
Uptime: 1s

because malloc is not yet available.

[mw_semihalf.com]

So, once a check for 'status = "ok"' is added, are there any objections to patch?

[mmel]

No, of course, not. And sorry for late response.
But remember, /sys/dev/ofw is under Nathan's jurisdiction. So you still needs his positive review.

[imp]

Love the concept, have issues with the implementation. :)

sys/dev/ofw/ofw_bus_subr.c

189–191

So if the property doesn't exist, we assume it's OK?

194

Wouldn't it be better to do something like:

if (len == 4 and bcmp(status, "okay", len) == 0)

since this will match 'o', 'ok' and 'oka' which isn't quite right. And properties aren't 'C' strings so bcmp would be better, no?

[mw_semihalf.com]

sys/dev/ofw/ofw_bus_subr.c

189–191

Yes. Node is enabled in 3 cases:

• lack of status property
• status = "ok"
• status = "okay"

194

Im ok with both fixing len and bcmp instead of strncmp.

[mw_semihalf.com]

• Add checking 'status = "ok"' and 'status = "okay"' with fixed lenght argument.
• Also use brcmp instead of strncmp.