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iicbus(4): Add support for ACPI-based children enumeration

Description

iicbus(4): Add support for ACPI-based children enumeration

When iicbus is attached as child of Designware I2C controller it scans all
ACPI nodes for "I2C Serial Bus Connection Resource Descriptor" described
in section 19.6.57 of ACPI specs.
If such a descriptor is found, I2C child is added to iicbus, it's I2C
address, IRQ resource and ACPI handle are added to ivars. Existing
ACPI bus-hosted child is deleted afterwards.

The driver also installs so called "I2C address space handler" which is
disabled by default as nontested.
Set hw.iicbus.enable_acpi_space_handler loader tunable to 1 to enable it.

Reviewed by: markj
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D22901

Details

Provenance
wulfAuthored on Mar 9 2020, 8:31 PM
Parents
rGddf8c230b1f2: acpi: Export functions required by upcoming acpi_iicbus driver.
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