LinuxKPI: Add pci_power querying for drm-kmod

[jfree]

Summary

Adds a few struct members and a function to get i915_runtime_pm_status()
to compile in drm-kmod.

[• hselasky]

sys/compat/linuxkpi/common/include/linux/pci.h

205

This must be declared in a C-file and extern keyword must be used here instead of static!

1585

Any range check on state?

[jfree]

• Added bound checking to pci_power_name()
• Made pci_power_names array external

[• hselasky]

sys/compat/linuxkpi/common/include/linux/pci.h

1590

return (pci_power_names[0]); ???

[• hselasky]

sys/compat/linuxkpi/common/include/linux/pci.h

1585

int pstate = state + 1;

1587

Can you do it like this, instead of hardcoding the array size?

if (pstate >= 0 && pstate < nitems(pci_power_names))

[jfree]

Various changes to pci_power_name() thanks to @hselasky

[manu]

sys/compat/linuxkpi/common/include/linux/device.h

127

If we add some member this change will break MFC, so if we do that could we add some padding members too for the futur ?

[bz]

sys/compat/linuxkpi/common/include/linux/device.h

127

I thought @imp had moved all allocation specifics into .c files so that if it is at the end it shouldn't be a problem or do I misremember incorrectly what https://reviews.freebsd.org/D34768 was trying to solve?

[manu]

sys/compat/linuxkpi/common/include/linux/device.h

127

Indeed, we should be ok by moving it at the end of the struct.

[jfree]

Moved struct dev_pm_info power member to bottom of struct device in <linux/device.h>