This is the bulk of GPIO changes for the v4.21 kernel series: Core changes: - Some core changes are already in outside of this pull request as they came through the regulator tree, most notably devm_gpiod_unhinge() that removes devres refcount management from a GPIO descriptor. This is needed in subsystems such as regulators where the regulator core need to take over the reference counting and lifecycle management for a GPIO descriptor. - We dropped devm_gpiochip_remove() and devm_gpio_chip_match() as nothing needs it. We can bring it back if need be. - Add a global TODO so people see where we are going. This helps setting the direction now that we are two GPIO maintainers. - Handle the MMC CD/WP properties in the device tree core. (The bulk of patches activating this code is already merged through the MMC/SD tree.) - Augment gpiochip_request_own_desc() to pass a flag so we as gpiochips can request lines as active low or open drain etc even from ourselves. New drivers: - New driver for Cadence GPIO blocks. - New driver for Atmel SAMA5D2 PIOBU GPIO lines. Driver improvements: - A major refactoring of the PCA953x driver - this driver has been around for ages, and is now modernized to reduce code duplication that has stacked up and is using regmap to read write and cache registers. - Intel drivers are now maintained in a separate tree and start with a round of cleanups and unifications.