[ig4] Convert polling loop from status-based to interrupt-based

INTR_STAT register exposes more useful informaton then STA register does
e.g. it exposes error and I2C bus STOP conditions. Make it a

[ig4] Convert polling loop from status-based to interrupt-based

INTR_STAT register exposes more useful informaton then STA register does
e.g. it exposes error and I2C bus STOP conditions. Make it a main source
of I2C transfer state.

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[ig4] Use interrupts for waiting for empty TX FIFO

[ig4] Convert last remaining usage of TX_NOTFULL status to TX_EMPTY

in ig4iic_read routine. It makes possible interrupt utilization while
waiting for empty space in TX FIFO.

[ig4] Rewrite ig4iic_write routine to use TX_EMPTY status flag

rather than TX_NOTFULL. It makes possible interrupt utilization while
waiting for empty space in TX FIFO.

[ig4] Remove dead code inherited from DragonflyBSD

[ig4] Add suspend/resume support

That is done with re-execution of controller initialization procedure
from resume handler.

PR: 238037

[ig4] Implement burst mode for data reads

In this mode DATA_CMD register reads and writes are performed in
TX/RX FIFO-sized bursts to increase I2C bus utilization.

That reduces read time from 60us

[ig4] Implement burst mode for data reads

In this mode DATA_CMD register reads and writes are performed in
TX/RX FIFO-sized bursts to increase I2C bus utilization.

That reduces read time from 60us to 30us per byte when read data is fit
in to RX FIFO buffer in FAST speed mode in my setup.

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[ig4] Set clock registers based on controller model

IC clock rates are varied between different controller models so we have
to adjust timing registers in each case individually. Borrow intresting
c

[ig4] Set clock registers based on controller model

IC clock rates are varied between different controller models so we have
to adjust timing registers in each case individually. Borrow intresting
constants and formulas from Intel specs, i2c-designware and lpss_intel
drivers and apply them to FreeBSD supported controller models.

Implement fetching of timing data via ACPI methods execution if available.

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[ig4] dump IG4_REG_COMP_PARAM1 and IG4_REG_COMP_VER registers unconditionally

They appeared to be supported (although undocumented) on SkyLakes+ too.

[ig4] Do not wait until interrupts are enabled at attach stage

as the driver is fully functional on a cold boot through utilization of
polled mode.

As a side effect, ig4 children probe and attach m

[ig4] Do not wait until interrupts are enabled at attach stage

as the driver is fully functional on a cold boot through utilization of
polled mode.

As a side effect, ig4 children probe and attach methods can be called
earlier in the boot sequence, so now it is up to the child drivers
to wait for a kernel initialization completion if it is required.

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[ig4] Allow enabling of polled mode from iicbus allocation callback

If controller is allocated with IIC_NOWAIT option ig4 enables polled mode
for a period of allocation that makes possible to start

[ig4] Allow enabling of polled mode from iicbus allocation callback

If controller is allocated with IIC_NOWAIT option ig4 enables polled mode
for a period of allocation that makes possible to start I2C transfers
from the contexts where sleeping is not allowed e.g. from ithreads or
callouts.

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[ig4] Add support for polled mode

Currently ig4 internally depends on it's own interrupts and uses mtx_sleep()
to wait for them. That means it can not be used from any context where
sleeping is disa

[ig4] Add support for polled mode

Currently ig4 internally depends on it's own interrupts and uses mtx_sleep()
to wait for them. That means it can not be used from any context where
sleeping is disallowed e.g. on cold boot, from DDB/KDB, from other device
driver's interrupt handlers and so on.

This change replaces sleeps with busy loops in cold boot and DDB cases.

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[ig4] disable controller before initialization of clock counters

It is required by controller specifications.

[ig4] Stop I2C controller after checking that it's kind of functional.

Obtained from: DragonfliBSD (0b3eedb)

[ig4] We actually need to set the Rx threshold register one smaller.

Setting the IG4_REG_RX_TL register to 1 was actually generating an
interrupt after 2 bytes were available in the Rx fifo. We need

[ig4] We actually need to set the Rx threshold register one smaller.

Setting the IG4_REG_RX_TL register to 1 was actually generating an
interrupt after 2 bytes were available in the Rx fifo. We need to set the
register to 0 to get an interrupt for 1 byte already.

Obtained from: DragonflyBSD (02f0bf2)

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[ig4] Ignore stray interrupts

[ig4] Reduce scope of io_lock

Now io_lock is used as condition variable to synchronize active process with
the interrupt handler. It is not used for tasks other than waiting for
interrupt and passin

[ig4] Reduce scope of io_lock

Now io_lock is used as condition variable to synchronize active process with
the interrupt handler. It is not used for tasks other than waiting for
interrupt and passing parameters to and from it's handler.

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[ig4] Do not wait for interrupts in set_controller() routine

Specs shows no dedicated interrupt firing on disable of the controller.

Remove io lock acquisitions around set_controller() calls as the

[ig4] Do not wait for interrupts in set_controller() routine

Specs shows no dedicated interrupt firing on disable of the controller.

Remove io lock acquisitions around set_controller() calls as they are
not needed anymore.

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[ig4] Drop driver's internal RX FIFO

There is no need to read all controller's RX FIFO data to clear RX_FULL
bit in interrupt handler as interrupts are masked permanently since
previous commit.

[ig4] Only enable interrupts when we want them. Otherwise keep mask at 0.

This avoids possible interrupt storms, depending on the state of the I2C
controller before the driver attached.

During atta

[ig4] Only enable interrupts when we want them. Otherwise keep mask at 0.

This avoids possible interrupt storms, depending on the state of the I2C
controller before the driver attached.

During attaching this clears the interrupt mask.

Revert r338215 as this change makes it no-op.

Obtained from: DragonflyBSD (d7c8555)

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[ig4] Handle controller startup errors

Fail the attach on controller startup errors. For some reason the
dell xps 13 says there's I2C controller, but the controller appears
to be permanente disable

[ig4] Handle controller startup errors

Fail the attach on controller startup errors. For some reason the
dell xps 13 says there's I2C controller, but the controller appears
to be permanente disabled and will refuse to enable.

Obtained from: DragonflyBSD (509820b)

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[ig4] Give common name to PCI and ACPI device drivers

They share common device driver code with different bus attachments

This commit starts a bunch of changes which have following properties:

Rev

[ig4] Give common name to PCI and ACPI device drivers

They share common device driver code with different bus attachments

This commit starts a bunch of changes which have following properties:

Reviewed by: imp (previous version)
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D22016

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Merge ^/head r352105 through r352307.

ig4(4): Fix SDA HOLD time set too low on Skylake controllers

Execution of "Soft reset" command (IG4_REG_RESETS_SKL) at controller init
stage sets SDA_HOLD register value to 0x0001 which is often too

ig4(4): Fix SDA HOLD time set too low on Skylake controllers

Execution of "Soft reset" command (IG4_REG_RESETS_SKL) at controller init
stage sets SDA_HOLD register value to 0x0001 which is often too low for
normal operation.

Set SDA_HOLD back to 28 after reset to restore controller functionality.

PR: 240339
Reported by: imp, GregV, et al.
MFC after: 3 days

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Merge ^/head r339015 through r339669.