u-boot/drivers/core/Kconfig

config DM
	bool "Enable Driver Model"
	help
	  This config option enables Driver Model. This brings in the core
	  support, including scanning of platform data on start-up. If
	  CONFIG_OF_CONTROL is enabled, the device tree will be scanned also
	  when available.

config SPL_DM
	bool "Enable Driver Model for SPL"
	depends on DM && SPL
	help
	  Enable driver model in SPL. You will need to provide a
	  suitable malloc() implementation. If you are not using the
	  full malloc() enabled by CONFIG_SYS_SPL_MALLOC_START,
	  consider using CONFIG_SYS_MALLOC_SIMPLE. In that case you
	  must provide CONFIG_SYS_MALLOC_F_LEN to set the size.
	  In most cases driver model will only allocate a few uclasses
	  and devices in SPL, so 1KB should be enable. See
	  CONFIG_SYS_MALLOC_F_LEN for more details on how to enable it.

config DM_WARN
	bool "Enable warnings in driver model"
	depends on DM
	default y
	help
	  The dm_warn() function can use up quite a bit of space for its
	  strings. By default this is disabled for SPL builds to save space.
	  This will cause dm_warn() to be compiled out - it will do nothing
	  when called.

config DM_DEVICE_REMOVE
	bool "Support device removal"
	depends on DM
	default y
	help
	  We can save some code space by dropping support for removing a
	  device. This is not normally required in SPL, so by default this
	  option is disabled for SPL.

	  Note that this may have undesirable results in the USB subsystem as
	  it causes unplugged devices to linger around in the dm-tree, and it
	  causes USB host controllers to not be stopped when booting the OS.

config DM_STDIO
	bool "Support stdio registration"
	depends on DM
	default y
	help
	  Normally serial drivers register with stdio so that they can be used
	  as normal output devices. In SPL we don't normally use stdio, so
	  we can omit this feature.

config DM_SEQ_ALIAS
	bool "Support numbered aliases in device tree"
	depends on DM
	default y
	help
	  Most boards will have a '/aliases' node containing the path to
	  numbered devices (e.g. serial0 = &serial0). This feature can be
	  disabled if it is not required, to save code space in SPL.

config REGMAP
	bool "Support register maps"
	depends on DM
	help
	  Hardware peripherals tend to have one or more sets of registers
	  which can be accessed to control the hardware. A register map
	  models this with a simple read/write interface. It can in principle
	  support any bus type (I2C, SPI) but so far this only supports
	  direct memory access.

config SYSCON
	bool "Support system controllers"
	depends on REGMAP
	help
	  Many SoCs have a number of system controllers which are dealt with
	  as a group by a single driver. Some common functionality is provided
	  by this uclass, including accessing registers via regmap and
	  assigning a unique number to each.

config DEVRES
	bool "Managed device resources"
	depends on DM
	help
	  This option enables the Managed device resources core support.
	  Device resources managed by the devres framework are automatically
	  released whether initialization fails half-way or the device gets
	  detached.

	  If this option is disabled, devres functions fall back to
	  non-managed variants.  For example, devres_alloc() to kzalloc(),
	  devm_kmalloc() to kmalloc(), etc.

config DEBUG_DEVRES
	bool "Managed device resources verbose debug messages"
	depends on DEVRES
	help
	  If this option is enabled, devres debug messages are printed.
	  Select this if you are having a problem with devres or want to
	  debug resource management for a managed device.

	  If you are unsure about this, Say N here.