Remove residual blank line at start of Makefile

This is a residual of the $FreeBSD$ removal.

MFC After: 3 days (though I'll just run the command on the branches)
Sponsored by: Netflix

sys: Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

MFHead @r350386

Sponsored by: The FreeBSD Foundation

enable ig4_acpi on aarch64

The already-listed APMC0D0F ID belongs to the Ampere eMAG aarch64
platform, but ACPI support was not even built on aarch64.

Submitted by: Greg V <greg_unrelenting.technol

enable ig4_acpi on aarch64

The already-listed APMC0D0F ID belongs to the Ampere eMAG aarch64
platform, but ACPI support was not even built on aarch64.

Submitted by: Greg V <greg_unrelenting.technology>
Differential Revision: https://reviews.freebsd.org/D21059

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sys/modules: normalize .CURDIR-relative paths to SRCTOP

This simplifies make output/logic

Tested with: `cd sys/modules; make ALL_MODULES=` on amd64
MFC after: 1 month
Sponsored by: Dell EMC Isilon

[ig4] Add ACPI platform support for ig4 driver

Add ACPI part for ig4 driver to make it work on Intel BayTrail SoC where
ig4 device is available only through ACPI

Reviewed by: avg
MFC after: 1 week

[ig4] Add ACPI platform support for ig4 driver

Add ACPI part for ig4 driver to make it work on Intel BayTrail SoC where
ig4 device is available only through ACPI

Reviewed by: avg
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D8742

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Merge ^/head r307736 through r308146.

add iic interface to ig4 driver, move isl and cyapa to iicbus

Summary:
The hardware does not expose a classic SMBus interface.
Instead it has a lower level interface that can express a far richer
I2

add iic interface to ig4 driver, move isl and cyapa to iicbus

Summary:
The hardware does not expose a classic SMBus interface.
Instead it has a lower level interface that can express a far richer
I2C protocol than what smbus offers. However, the interface does not
provide a way to explicitly generate the I2C stop and start conditions.
It's only possible to request that the stop condition is generated
after transferring the next byte in either direction. So, at least
one data byte must always be transferred.
Thus, some I2C sequences are impossible to generate, e.g., an equivalent
of smbus quick command (<start>-<slave addr>-<r/w bit>-<stop>).

At the same time isl(4) and cyapa(4) are moved to iicbus and now they use
iicbus_transfer for communication. Previously they used smbus_trans()
interface that is not defined by the SMBus protocol and was implemented
only by ig4(4). In fact, that interface was impossible to implement
for the typical SMBus controllers like intpm(4) or ichsmb(4) where
a type of the SMBus command must be programmed.

The plan is to remove smbus_trans() and all its uses.
As an aside, the smbus_trans() method deviates from the standard,
but perhaps backwards, FreeBSD convention of using 8-bit slave
addresses (shifted by 1 bit to the left). The method expects
7-bit addresses.

There is a user facing consequence of this change.
A user must now provide device hints for isl and cyapa that specify an iicbus to use
and a slave address on it.
On Chromebook hardware where isl and cyapa devices are commonly found
it is also possible to use a new chromebook_platform(4) driver that
automatically configures isl and cyapa devices. There is no need to
provide the device hints in that case,

Right now smbus(4) driver tries to discover all slaves on the bus.
That is very dangerous. Fortunately, the probing code uses smbus_trans()
to do its job, so it is really enabled for ig4 only.
The plan is to remove that auto-probing code and smbus_trans().

Tested by: grembo, Matthias Apitz <guru@unixarea.de> (w/o
chromebook_platform)
Discussed with: grembo, imp
Reviewed by: wblock (docs)
MFC after: 1 month
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D8172

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Catch up with HEAD (r280229-r284686).

Merge from head

Merge ^/head r283596 through r283770.

ig4 - Intel fourth gen integrated I2C SMBus driver.

Differential Revision: https://reviews.freebsd.org/D2372
Reviewed by: jhb, wblock, adrian
Approved by: jhb, wblock
Relnotes: yes