Customize pinmux (per-pin SFIO / direction / state)

Overview

The Tegra pinmux spreadsheet (.xlsm) is the ground truth for every CVM ball: SoC pin name, supported SFIOs, customer-selected function, direction, and initial state. This skill parses that XLSM, runs a per-pin Q1–Q6 interactive loop, and emits the three BCT DTSIs (pinmux, gpio, padvoltage) in one shot into the overlay tracker at <source.root_path>/Linux_for_Tegra/bootloader/.

Unlike sibling skills jetson-customize-uphy / jetson-customize-pcie / jetson-customize-camera, pinmux has no kernel-DT overlay surface and no ODMDATA edit. The XLSM is the source of truth; the three emitted DTSIs land at flash time via the carrier conf's PINMUX_CONFIG= / GPIOINT_CONFIG= / PMC_CONFIG= references (which /jetson-derive-carrier set up).