[siddarth-nexthop]

Pre-submission checklist

• I've ran the linters locally and fixed lint errors related to the files I modified in this PR. You can install the linters by running pip install -r requirements-dev.txt && pre-commit install
• pre-commit run

Summary

Enable the kernel config needed for interrupt-driven FPGA I2C support.

• CONFIG_GPIO_PCI_IDIO_16=m: pulls in REGMAP_IRQ transitively, which is used by the parent PCI driver to demultiplex MSI vectors into per-controller Linux IRQs.

Test Plan

• Built an image with this config change.

• Verified on test hardware that the running kernel has the expected config and exports the required REGMAP_IRQ symbols.

Kernel config check:

grep -E "CONFIG_REGMAP_IRQ|CONFIG_GPIO_PCI_IDIO_16" /boot/config-$(uname -r)

Output:

CONFIG_REGMAP_IRQ=y
CONFIG_GPIO_PCI_IDIO_16=m

Exported symbols check:

grep -E " __ksymtab_(regmap_irq_get_virq|devm_regmap_add_irq_chip)$" /proc/kallsyms

Output:

__ksymtab_devm_regmap_add_irq_chip
__ksymtab_regmap_irq_get_virq

Hardware-tested with the built image on four platforms. The systems imaged successfully, booted into FBOSS, and platform bring-up completed successfully. Every FPGA I2C controller came up interrupt-driven, and BSP and platform hw tests passed.