9 config SPL_DFU_NO_RESET
14 depends on SUPPORT_SPL
17 If you want to build SPL as well as the normal image, say Y.
20 bool "Support SPL based upon the common SPL framework"
24 Enable the SPL framework under common/spl/. This framework
25 supports MMC, NAND and YMODEM and other methods loading of U-Boot
26 and the Linux Kernel. If unsure, say Y.
29 hex "Maximum size of SPL image"
31 default 69632 if ARCH_MX6 && !MX6_OCRAM_256KB
32 default 200704 if ARCH_MX6 && MX6_OCRAM_256KB
35 Specifies the maximum length of the U-Boot SPL image.
36 If this value is zero, it is ignored.
38 config SPL_SIZE_LIMIT_SUBTRACT_GD
39 bool "SPL image size check: provide space for global data"
40 depends on SPL_SIZE_LIMIT > 0
42 If enabled, aligned size of global data is reserved in
43 SPL_SIZE_LIMIT check to ensure such an image does not overflow SRAM
44 if SPL_SIZE_LIMIT describes the size of SRAM available for SPL when
45 pre-reloc global data is put into this SRAM, too.
47 config SPL_SIZE_LIMIT_SUBTRACT_MALLOC
48 bool "SPL image size check: provide space for malloc() pool before relocation"
49 depends on SPL_SIZE_LIMIT > 0
51 If enabled, SPL_SYS_MALLOC_F_LEN is reserved in SPL_SIZE_LIMIT check
52 to ensure such an image does not overflow SRAM if SPL_SIZE_LIMIT
53 describes the size of SRAM available for SPL when pre-reloc malloc
54 pool is put into this SRAM, too.
56 config SPL_SIZE_LIMIT_PROVIDE_STACK
57 hex "SPL image size check: provide stack space before relocation"
58 depends on SPL_SIZE_LIMIT > 0
61 If set, this size is reserved in SPL_SIZE_LIMIT check to ensure such
62 an image does not overflow SRAM if SPL_SIZE_LIMIT describes the size
63 of SRAM available for SPL when the stack required before reolcation
66 config SPL_SYS_STACK_F_CHECK_BYTE
70 Constant used to check the stack
72 config SPL_SYS_REPORT_STACK_F_USAGE
73 depends on SPL_SIZE_LIMIT_PROVIDE_STACK != 0
74 bool "Check and report stack usage in SPL before relocation"
76 If this option is enabled, the initial SPL stack is filled with 0xaa
77 very early, up to the size configured with
78 SPL_SIZE_LIMIT_PROVIDE_STACK.
79 Later when SPL is done using this initial stack and switches to a
80 stack in DRAM, the actually used size of this initial stack is
81 reported by examining the memory and searching for the lowest
82 occurrence of non 0xaa bytes.
83 This default implementation works for stacks growing down only.
85 menu "PowerPC SPL Boot options"
86 depends on PPC && (SUPPORT_SPL && !SPL_FRAMEWORK)
89 bool "Load SPL from NAND flash"
92 bool "Load SPL from SD Card / eMMC"
95 bool "Load SPL from SPI flash"
98 bool "Create SPL in Freescale PBI format"
100 Create boot binary having SPL binary in PBI format concatenated with
106 bool "Pass hand-off information from SPL to U-Boot proper"
109 It is useful to be able to pass information from SPL to U-Boot
110 proper to preserve state that is known in SPL and is needed in U-Boot.
111 Enable this to locate the handoff information in U-Boot proper, early
112 in boot. It is available in gd->handoff. The state state is set up
113 in SPL (or TPL if that is being used).
118 bool "Pass hand-off information from SPL to U-Boot proper"
119 depends on HANDOFF && SPL_BLOBLIST
122 This option enables SPL to write handoff information. This can be
123 used to pass information like the size of SDRAM from SPL to U-Boot
124 proper. Also SPL can receive information from TPL in the same place
128 string "Linker script for the SPL stage"
129 default "arch/$(ARCH)/cpu/u-boot-spl.lds"
131 The SPL stage will usually require a different linker-script
132 (as it runs from a different memory region) than the regular
133 U-Boot stage. Set this to the path of the linker-script to
138 default ISW_ENTRY_ADDR if AM43XX || AM33XX || OMAP54XX || ARCH_KEYSTONE
139 default 0x10060 if MACH_SUN50I || MACH_SUN50I_H5 || MACH_SUN9I
140 default 0x20060 if MACH_SUN50I_H6
141 default 0x00060 if ARCH_SUNXI
142 default 0xfffc0000 if ARCH_ZYNQMP
145 The address in memory that SPL will be running from.
147 config SPL_BOARD_INIT
148 bool "Call board-specific initialization in SPL"
150 If this option is enabled, U-Boot will call the function
151 spl_board_init() from board_init_r(). This function should be
152 provided by the board.
154 config SPL_BOOTROM_SUPPORT
155 bool "Support returning to the BOOTROM"
157 Some platforms (e.g. the Rockchip RK3368) provide support in their
158 ROM for loading the next boot-stage after performing basic setup
161 Enable this option, to return to the BOOTROM through the
162 BOOT_DEVICE_BOOTROM (or fall-through to the next boot device in the
163 boot device list, if not implemented for a given board)
165 config SPL_BOOTCOUNT_LIMIT
166 bool "Support bootcount in SPL"
167 depends on SPL_ENV_SUPPORT
169 On some boards, which use 'falcon' mode, it is necessary to check
170 and increment the number of boot attempts. Such boards do not
171 use proper U-Boot for normal boot flow and hence needs those
172 adjustments to be done in the SPL.
174 config SPL_RAW_IMAGE_SUPPORT
175 bool "Support SPL loading and booting of RAW images"
176 default n if (ARCH_MX6 && (SPL_MMC_SUPPORT || SPL_SATA_SUPPORT))
177 default y if !TI_SECURE_DEVICE
179 SPL will support loading and booting a RAW image when this option
180 is y. If this is not set, SPL will move on to other available
181 boot media to find a suitable image.
183 config SPL_LEGACY_IMAGE_SUPPORT
184 bool "Support SPL loading and booting of Legacy images"
185 default y if !TI_SECURE_DEVICE && !SPL_LOAD_FIT
187 SPL will support loading and booting Legacy images when this option
188 is y. If this is not set, SPL will move on to other available
189 boot media to find a suitable image.
191 config SPL_LEGACY_IMAGE_CRC_CHECK
192 bool "Check CRC of Legacy images"
193 depends on SPL_LEGACY_IMAGE_SUPPORT
194 select SPL_CRC32_SUPPORT
196 Enable this to check the CRC of Legacy images. While this increases
197 reliability, it affects both code size and boot duration.
198 If disabled, Legacy images are booted if the image magic and size
199 are correct, without further integrity checks.
201 config SPL_SYS_MALLOC_SIMPLE
203 prompt "Only use malloc_simple functions in the SPL"
205 Say Y here to only use the *_simple malloc functions from
206 malloc_simple.c, rather then using the versions from dlmalloc.c;
207 this will make the SPL binary smaller at the cost of more heap
208 usage as the *_simple malloc functions do not re-use free-ed mem.
210 config TPL_SYS_MALLOC_SIMPLE
212 prompt "Only use malloc_simple functions in the TPL"
215 Say Y here to only use the *_simple malloc functions from
216 malloc_simple.c, rather then using the versions from dlmalloc.c;
217 this will make the TPL binary smaller at the cost of more heap
218 usage as the *_simple malloc functions do not re-use free-ed mem.
221 bool "Enable SDRAM location for SPL stack"
223 SPL starts off execution in SRAM and thus typically has only a small
224 stack available. Since SPL sets up DRAM while in its board_init_f()
225 function, it is possible for the stack to move there before
226 board_init_r() is reached. This option enables a special SDRAM
227 location for the SPL stack. U-Boot SPL switches to this after
228 board_init_f() completes, and before board_init_r() starts.
230 config SPL_STACK_R_ADDR
231 depends on SPL_STACK_R
232 hex "SDRAM location for SPL stack"
233 default 0x82000000 if ARCH_OMAP2PLUS
235 Specify the address in SDRAM for the SPL stack. This will be set up
236 before board_init_r() is called.
238 config SPL_STACK_R_MALLOC_SIMPLE_LEN
239 depends on SPL_STACK_R && SPL_SYS_MALLOC_SIMPLE
240 hex "Size of malloc_simple heap after switching to DRAM SPL stack"
243 Specify the amount of the stack to use as memory pool for
244 malloc_simple after switching the stack to DRAM. This may be set
245 to give board_init_r() a larger heap then the initial heap in
246 SRAM which is limited to SYS_MALLOC_F_LEN bytes.
248 config SPL_SEPARATE_BSS
249 bool "BSS section is in a different memory region from text"
251 Some platforms need a large BSS region in SPL and can provide this
252 because RAM is already set up. In this case BSS can be moved to RAM.
253 This option should then be enabled so that the correct device tree
254 location is used. Normally we put the device tree at the end of BSS
255 but with this option enabled, it goes at _image_binary_end.
257 config SPL_BANNER_PRINT
258 bool "Enable output of the SPL banner 'U-Boot SPL ...'"
261 If this option is enabled, SPL will print the banner with version
262 info. Disabling this option could be useful to reduce TPL boot time
263 (e.g. approx. 6 ms faster, when output on i.MX6 with 115200 baud).
265 config TPL_BANNER_PRINT
266 bool "Enable output of the TPL banner 'U-Boot TPL ...'"
270 If this option is enabled, SPL will not print the banner with version
271 info. Disabling this option could be useful to reduce SPL boot time
272 (e.g. approx. 6 ms faster, when output on i.MX6 with 115200 baud).
275 depends on ARM && !ARM64
276 bool "Allows initializing BSS early before entering board_init_f"
278 On some platform we have sufficient memory available early on to
279 allow setting up and using a basic BSS prior to entering
280 board_init_f. Activating this option will also de-activate the
281 clearing of BSS during the SPL relocation process, thus allowing
282 to carry state from board_init_f to board_init_r by way of BSS.
284 config SPL_DISPLAY_PRINT
285 bool "Display a board-specific message in SPL"
287 If this option is enabled, U-Boot will call the function
288 spl_display_print() immediately after displaying the SPL console
289 banner ("U-Boot SPL ..."). This function should be provided by
292 config SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR
293 bool "MMC raw mode: by sector"
294 default y if ARCH_SUNXI || ARCH_DAVINCI || ARCH_UNIPHIER || \
295 ARCH_MX6 || ARCH_MX7 || \
296 ARCH_ROCKCHIP || ARCH_MVEBU || ARCH_SOCFPGA || \
297 ARCH_AT91 || ARCH_ZYNQ || ARCH_KEYSTONE || OMAP34XX || \
298 OMAP44XX || OMAP54XX || AM33XX || AM43XX
300 Use sector number for specifying U-Boot location on MMC/SD in
303 config SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR
304 hex "Address on the MMC to load U-Boot from"
305 depends on SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR
306 default 0x50 if ARCH_SUNXI
307 default 0x75 if ARCH_DAVINCI
308 default 0x8a if ARCH_MX6 || ARCH_MX7
309 default 0x100 if ARCH_UNIPHIER
310 default 0x140 if ARCH_MVEBU
311 default 0x200 if ARCH_SOCFPGA || ARCH_AT91
312 default 0x300 if ARCH_ZYNQ || ARCH_KEYSTONE || OMAP34XX || OMAP44XX || \
313 OMAP54XX || AM33XX || AM43XX || ARCH_K3
314 default 0x4000 if ARCH_ROCKCHIP
316 Address on the MMC to load U-Boot from, when the MMC is being used
317 in raw mode. Units: MMC sectors (1 sector = 512 bytes).
319 config SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION
320 bool "MMC Raw mode: by partition"
322 Use a partition for loading U-Boot when using MMC/SD in raw mode.
324 config SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
325 hex "Partition to use to load U-Boot from"
326 depends on SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION
329 Partition on the MMC to load U-Boot from when the MMC is being
332 config SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION_TYPE
333 bool "MMC raw mode: by partition type"
334 depends on DOS_PARTITION && SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION
336 Use partition type for specifying U-Boot partition on MMC/SD in
337 raw mode. U-Boot will be loaded from the first partition of this
340 config SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION_TYPE
341 hex "Partition Type on the MMC to load U-Boot from"
342 depends on SYS_MMCSD_RAW_MODE_U_BOOT_USE_PARTITION_TYPE
344 Partition Type on the MMC to load U-Boot from, when the MMC is being
347 config SPL_CRC32_SUPPORT
349 default y if SPL_LEGACY_IMAGE_SUPPORT
351 Enable this to support CRC32 in uImages or FIT images within SPL.
352 This is a 32-bit checksum value that can be used to verify images.
353 For FIT images, this is the least secure type of checksum, suitable
354 for detected accidental image corruption. For secure applications you
355 should consider SHA1 or SHA256.
357 config SPL_MD5_SUPPORT
361 Enable this to support MD5 in FIT images within SPL. An MD5
362 checksum is a 128-bit hash value used to check that the image
363 contents have not been corrupted. Note that MD5 is not considered
364 secure as it is possible (with a brute-force attack) to adjust the
365 image while still retaining the same MD5 hash value. For secure
366 applications where images may be changed maliciously, you should
367 consider SHA1 or SHA256.
369 config SPL_SHA1_SUPPORT
374 Enable this to support SHA1 in FIT images within SPL. A SHA1
375 checksum is a 160-bit (20-byte) hash value used to check that the
376 image contents have not been corrupted or maliciously altered.
377 While SHA1 is fairly secure it is coming to the end of its life
378 due to the expanding computing power available to brute-force
379 attacks. For more security, consider SHA256.
381 config SPL_SHA256_SUPPORT
382 bool "Support SHA256"
386 Enable this to support SHA256 in FIT images within SPL. A SHA256
387 checksum is a 256-bit (32-byte) hash value used to check that the
388 image contents have not been corrupted. SHA256 is recommended for
389 use in secure applications since (as at 2016) there is no known
390 feasible attack that could produce a 'collision' with differing
391 input data. Use this for the highest security. Note that only the
392 SHA256 variant is supported: SHA512 and others are not currently
395 config SPL_FIT_IMAGE_TINY
396 bool "Remove functionality from SPL FIT loading to reduce size"
398 default y if MACH_SUN50I || MACH_SUN50I_H5 || MACH_SUN50I_H6
399 default y if ARCH_IMX8M
401 Enable this to reduce the size of the FIT image loading code
402 in SPL, if space for the SPL binary is very tight.
404 This removes the detection of image types (which forces the
405 first image to be treated as having a U-Boot style calling
406 convention) and skips the recording of each loaded payload
407 (i.e. loadable) into the FDT (modifying the loaded FDT to
408 ensure this information is available to the next image
411 config SPL_CPU_SUPPORT
412 bool "Support CPU drivers"
414 Enable this to support CPU drivers in SPL. These drivers can set
415 up CPUs and provide information about them such as the model and
416 name. This can be useful in SPL since setting up the CPUs earlier
417 may improve boot performance. Enable this option to build the
418 drivers in drivers/cpu as part of an SPL build.
420 config SPL_CRYPTO_SUPPORT
421 bool "Support crypto drivers"
423 Enable crypto drivers in SPL. These drivers can be used to
424 accelerate secure boot processing in secure applications. Enable
425 this option to build the drivers in drivers/crypto as part of an
428 config SPL_HASH_SUPPORT
429 bool "Support hashing drivers"
433 Enable hashing drivers in SPL. These drivers can be used to
434 accelerate secure boot processing in secure applications. Enable
435 this option to build system-specific drivers for hash acceleration
436 as part of an SPL build.
438 config TPL_HASH_SUPPORT
439 bool "Support hashing drivers in TPL"
444 Enable hashing drivers in SPL. These drivers can be used to
445 accelerate secure boot processing in secure applications. Enable
446 this option to build system-specific drivers for hash acceleration
447 as part of an SPL build.
449 config SPL_DMA_SUPPORT
450 bool "Support DMA drivers"
452 Enable DMA (direct-memory-access) drivers in SPL. These drivers
453 can be used to handle memory-to-peripheral data transfer without
454 the CPU moving the data. Enable this option to build the drivers
455 in drivers/dma as part of an SPL build.
457 config SPL_DRIVERS_MISC_SUPPORT
458 bool "Support misc drivers"
460 Enable miscellaneous drivers in SPL. These drivers perform various
461 tasks that don't fall nicely into other categories, Enable this
462 option to build the drivers in drivers/misc as part of an SPL
463 build, for those that support building in SPL (not all drivers do).
465 config SPL_ENV_SUPPORT
466 bool "Support an environment"
468 Enable environment support in SPL. The U-Boot environment provides
469 a number of settings (essentially name/value pairs) which can
470 control many aspects of U-Boot's operation. Normally this is not
471 needed in SPL as it has a much simpler task with less
472 configuration. But some boards use this to support 'Falcon' boot
473 on EXT2 and FAT, where SPL boots directly into Linux without
474 starting U-Boot first. Enabling this option will make env_get()
475 and env_set() available in SPL.
478 bool "Support save environment"
479 depends on SPL_ENV_SUPPORT
480 select SPL_MMC_WRITE if ENV_IS_IN_MMC
482 Enable save environment support in SPL after setenv. By default
483 the saveenv option is not provided in SPL, but some boards need
484 this support in 'Falcon' boot, where SPL need to boot from
485 different images based on environment variable set by OS. For
486 example OS may set "reboot_image" environment variable to
487 "recovery" inorder to boot recovery image by SPL. The SPL read
488 "reboot_image" and act accordingly and change the reboot_image
489 to default mode using setenv and save the environment.
491 config SPL_ETH_SUPPORT
492 bool "Support Ethernet"
493 depends on SPL_ENV_SUPPORT
495 Enable access to the network subsystem and associated Ethernet
496 drivers in SPL. This permits SPL to load U-Boot over an Ethernet
497 link rather than from an on-board peripheral. Environment support
498 is required since the network stack uses a number of environment
499 variables. See also SPL_NET_SUPPORT.
502 bool "Support EXT filesystems"
504 Enable support for EXT2/3/4 filesystems with SPL. This permits
505 U-Boot (or Linux in Falcon mode) to be loaded from an EXT
506 filesystem from within SPL. Support for the underlying block
507 device (e.g. MMC or USB) must be enabled separately.
510 bool "Support FAT filesystems"
513 Enable support for FAT and VFAT filesystems with SPL. This
514 permits U-Boot (or Linux in Falcon mode) to be loaded from a FAT
515 filesystem from within SPL. Support for the underlying block
516 device (e.g. MMC or USB) must be enabled separately.
519 bool "Support write for FAT filesystems"
521 Enable write support for FAT and VFAT filesystems with SPL.
522 Support for the underlying block device (e.g. MMC or USB) must be
525 config SPL_FPGA_SUPPORT
528 Enable support for FPGAs in SPL. Field-programmable Gate Arrays
529 provide software-configurable hardware which is typically used to
530 implement peripherals (such as UARTs, LCD displays, MMC) or
531 accelerate custom processing functions, such as image processing
532 or machine learning. Sometimes it is useful to program the FPGA
533 as early as possible during boot, and this option can enable that
536 config SPL_GPIO_SUPPORT
537 bool "Support GPIO in SPL"
539 Enable support for GPIOs (General-purpose Input/Output) in SPL.
540 GPIOs allow U-Boot to read the state of an input line (high or
541 low) and set the state of an output line. This can be used to
542 drive LEDs, control power to various system parts and read user
543 input. GPIOs can be useful in SPL to enable a 'sign-of-life' LED,
544 for example. Enable this option to build the drivers in
545 drivers/gpio as part of an SPL build.
547 config SPL_I2C_SUPPORT
550 Enable support for the I2C (Inter-Integrated Circuit) bus in SPL.
551 I2C works with a clock and data line which can be driven by a
552 one or more masters or slaves. It is a fairly complex bus but is
553 widely used as it only needs two lines for communication. Speeds of
554 400kbps are typical but up to 3.4Mbps is supported by some
555 hardware. I2C can be useful in SPL to configure power management
556 ICs (PMICs) before raising the CPU clock speed, for example.
557 Enable this option to build the drivers in drivers/i2c as part of
560 config SPL_LIBCOMMON_SUPPORT
561 bool "Support common libraries"
563 Enable support for common U-Boot libraries within SPL. These
564 libraries include common code to deal with U-Boot images,
565 environment and USB, for example. This option is enabled on many
566 boards. Enable this option to build the code in common/ as part of
569 config SPL_LIBDISK_SUPPORT
570 bool "Support disk partitions"
573 Enable support for disk partitions within SPL. 'Disk' is something
574 of a misnomer as it includes non-spinning media such as flash (as
575 used in MMC and USB sticks). Partitions provide a way for a disk
576 to be split up into separate regions, with a partition table placed
577 at the start or end which describes the location and size of each
578 'partition'. These partitions are typically uses as individual block
579 devices, typically with an EXT2 or FAT filesystem in each. This
580 option enables whatever partition support has been enabled in
581 U-Boot to also be used in SPL. It brings in the code in disk/.
583 config SPL_LIBGENERIC_SUPPORT
584 bool "Support generic libraries"
586 Enable support for generic U-Boot libraries within SPL. These
587 libraries include generic code to deal with device tree, hashing,
588 printf(), compression and the like. This option is enabled on many
589 boards. Enable this option to build the code in lib/ as part of an
592 config SPL_DM_MAILBOX
593 bool "Support Mailbox"
595 Enable support for Mailbox within SPL. This enable the inter
596 processor communication protocols tobe used within SPL. Enable
597 this option to build the drivers in drivers/mailbox as part of
600 config SPL_MMC_SUPPORT
603 select HAVE_BLOCK_DEVICE
605 Enable support for MMC (Multimedia Card) within SPL. This enables
606 the MMC protocol implementation and allows any enabled drivers to
607 be used within SPL. MMC can be used with or without disk partition
608 support depending on the application (SPL_LIBDISK_SUPPORT). Enable
609 this option to build the drivers in drivers/mmc as part of an SPL
612 config SPL_FORCE_MMC_BOOT
613 bool "Force SPL booting from MMC"
614 depends on SPL_MMC_SUPPORT
617 Force SPL to use MMC device for Linux kernel booting even when the
618 SoC ROM recognized boot medium is not eMMC/SD. This is crucial for
619 factory or 'falcon mode' booting.
622 bool "Tiny MMC framework in SPL"
623 depends on SPL_MMC_SUPPORT
626 Enable MMC framework tinification support. This option is useful if
627 if your SPL is extremely size constrained. Heed the warning, enable
628 this option if and only if you know exactly what you are doing, if
629 you are reading this help text, you most likely have no idea :-)
631 The MMC framework is reduced to bare minimum to be useful. No malloc
632 support is needed for the MMC framework operation with this option
633 enabled. The framework supports exactly one MMC device and exactly
634 one MMC driver. The MMC driver can be adjusted to avoid any malloc
635 operations too, which can remove the need for malloc support in SPL
636 and thus further reduce footprint.
639 bool "MMC/SD/SDIO card support for write operations in SPL"
640 depends on SPL_MMC_SUPPORT
643 Enable write access to MMC and SD Cards in SPL
646 config SPL_MPC8XXX_INIT_DDR_SUPPORT
647 bool "Support MPC8XXX DDR init"
649 Enable support for DDR-SDRAM (double-data-rate synchronous dynamic
650 random-access memory) on the MPC8XXX family within SPL. This
651 allows DRAM to be set up before loading U-Boot into that DRAM,
654 config SPL_MTD_SUPPORT
655 bool "Support MTD drivers"
657 Enable support for MTD (Memory Technology Device) within SPL. MTD
658 provides a block interface over raw NAND and can also be used with
659 SPI flash. This allows SPL to load U-Boot from supported MTD
660 devices. See SPL_NAND_SUPPORT and SPL_ONENAND_SUPPORT for how
661 to enable specific MTD drivers.
663 config SPL_MUSB_NEW_SUPPORT
664 bool "Support new Mentor Graphics USB"
666 Enable support for Mentor Graphics USB in SPL. This is a new
667 driver used by some boards. Enable this option to build
668 the drivers in drivers/usb/musb-new as part of an SPL build. The
669 old drivers are in drivers/usb/musb.
671 config SPL_NAND_SUPPORT
672 bool "Support NAND flash"
674 Enable support for NAND (Negative AND) flash in SPL. NAND flash
675 can be used to allow SPL to load U-Boot from supported devices.
676 This enables the drivers in drivers/mtd/nand/raw as part of an SPL
682 Enable support for loading payloads from UBI. See
683 README.ubispl for more info.
686 config SPL_UBI_LOAD_BY_VOLNAME
687 bool "Support loading volumes by name"
689 This enables support for loading UBI volumes by name. When this
690 is set, CONFIG_SPL_UBI_LOAD_MONITOR_VOLNAME can be used to
691 configure the volume name from which to load U-Boot.
693 config SPL_UBI_MAX_VOL_LEBS
694 int "Maximum number of LEBs per volume"
697 The maximum number of logical eraseblocks which a static volume
698 to load can contain. Used for sizing the scan data structure.
700 config SPL_UBI_MAX_PEB_SIZE
701 int "Maximum PEB size"
704 The maximum physical erase block size.
706 config SPL_UBI_MAX_PEBS
707 int "Maximum number of PEBs"
710 The maximum physical erase block size. If not overridden by
711 board code, this value will be used as the actual number of PEBs.
713 config SPL_UBI_PEB_OFFSET
714 int "Offset to first UBI PEB"
717 The offset in number of PEBs from the start of flash to the first
718 PEB part of the UBI image.
720 config SPL_UBI_VID_OFFSET
721 int "Offset to VID header"
724 config SPL_UBI_LEB_START
725 int "Offset to LEB in PEB"
728 The offset in bytes to the LEB within a PEB.
730 config SPL_UBI_INFO_ADDR
731 hex "Address to place UBI scan info"
734 Address for ubispl to place the scan info. Read README.ubispl to
735 determine the required size
737 config SPL_UBI_VOL_IDS
738 int "Maximum volume id"
741 The maximum volume id which can be loaded. Used for sizing the
744 config SPL_UBI_LOAD_MONITOR_ID
745 int "id of U-Boot volume"
748 The UBI volume id from which to load U-Boot
750 config SPL_UBI_LOAD_MONITOR_VOLNAME
751 string "volume name of U-Boot volume"
752 depends on SPL_UBI_LOAD_BY_VOLNAME
754 The UBI volume name from which to load U-Boot
756 config SPL_UBI_LOAD_KERNEL_ID
757 int "id of kernel volume"
758 depends on SPL_OS_BOOT && SPL_UBI
760 The UBI volume id from which to load the kernel
762 config SPL_UBI_LOAD_ARGS_ID
763 int "id of kernel args volume"
764 depends on SPL_OS_BOOT && SPL_UBI
766 The UBI volume id from which to load the device tree
768 config UBI_SPL_SILENCE_MSG
769 bool "silence UBI SPL messages"
772 Disable messages from UBI SPL. This leaves warnings
777 config SPL_NET_SUPPORT
778 bool "Support networking"
780 Enable support for network devices (such as Ethernet) in SPL.
781 This permits SPL to load U-Boot over a network link rather than
782 from an on-board peripheral. Environment support is required since
783 the network stack uses a number of environment variables. See also
787 config SPL_NET_VCI_STRING
788 string "BOOTP Vendor Class Identifier string sent by SPL"
790 As defined by RFC 2132 the vendor class identifier field can be
791 sent by the client to identify the vendor type and configuration
792 of a client. This is often used in practice to allow for the DHCP
793 server to specify different files to load depending on if the ROM,
794 SPL or U-Boot itself makes the request
795 endif # if SPL_NET_SUPPORT
797 config SPL_NO_CPU_SUPPORT
798 bool "Drop CPU code in SPL"
800 This is specific to the ARM926EJ-S CPU. It disables the standard
801 start.S start-up code, presumably so that a replacement can be
802 used on that CPU. You should not enable it unless you know what
805 config SPL_NOR_SUPPORT
806 bool "Support NOR flash"
808 Enable support for loading U-Boot from memory-mapped NOR (Negative
809 OR) flash in SPL. NOR flash is slow to write but fast to read, and
810 a memory-mapped device makes it very easy to access. Loading from
811 NOR is typically achieved with just a memcpy().
813 config SPL_XIP_SUPPORT
817 Enable support for execute in place of U-Boot or kernel image. There
818 is no need to copy image from flash to ram if flash supports execute
819 in place. Its very useful in systems having enough flash but not
820 enough ram to load the image.
822 config SPL_ONENAND_SUPPORT
823 bool "Support OneNAND flash"
825 Enable support for OneNAND (Negative AND) flash in SPL. OneNAND is
826 a type of NAND flash and therefore can be used to allow SPL to
827 load U-Boot from supported devices. This enables the drivers in
828 drivers/mtd/onenand as part of an SPL build.
831 bool "Activate Falcon Mode"
832 depends on !TI_SECURE_DEVICE
835 Enable booting directly to an OS from SPL.
836 for more info read doc/README.falcon
840 hex "addr, where OS is found"
841 depends on SPL_NOR_SUPPORT
843 Specify the address, where the OS image is found, which
850 default "tpl/u-boot-with-tpl.bin" if TPL
853 Payload for SPL boot. For backward compatibility, default to
854 u-boot.bin, i.e. RAW image without any header. In case of
855 TPL, tpl/u-boot-with-tpl.bin. For new boards, suggest to
859 bool "Support PCI drivers"
861 Enable support for PCI in SPL. For platforms that need PCI to boot,
862 or must perform some init using PCI in SPL, this provides the
863 necessary driver support. This enables the drivers in drivers/pci
864 as part of an SPL build.
866 config SPL_PCH_SUPPORT
867 bool "Support PCH drivers"
869 Enable support for PCH (Platform Controller Hub) devices in SPL.
870 These are used to set up GPIOs and the SPI peripheral early in
871 boot. This enables the drivers in drivers/pch as part of an SPL
874 config SPL_POST_MEM_SUPPORT
875 bool "Support POST drivers"
877 Enable support for POST (Power-on Self Test) in SPL. POST is a
878 procedure that checks that the hardware (CPU or board) appears to
879 be functionally correctly. It is a sanity check that can be
880 performed before booting. This enables the drivers in post/drivers
881 as part of an SPL build.
884 bool "Support reset drivers"
887 Enable support for reset control in SPL.
888 That can be useful in SPL to handle IP reset in driver, as in U-Boot,
889 by using the generic reset API provided by driver model.
890 This enables the drivers in drivers/reset as part of an SPL build.
892 config SPL_POWER_SUPPORT
893 bool "Support power drivers"
895 Enable support for power control in SPL. This includes support
896 for PMICs (Power-management Integrated Circuits) and some of the
897 features provided by PMICs. In particular, voltage regulators can
898 be used to enable/disable power and vary its voltage. That can be
899 useful in SPL to turn on boot peripherals and adjust CPU voltage
900 so that the clock speed can be increased. This enables the drivers
901 in drivers/power, drivers/power/pmic and drivers/power/regulator
902 as part of an SPL build.
904 config SPL_POWER_DOMAIN
905 bool "Support power domain drivers"
907 Enable support for power domain control in SPL. Many SoCs allow
908 power to be applied to or removed from portions of the SoC (power
909 domains). This may be used to save power. This API provides the
910 means to control such power management hardware. This enables
911 the drivers in drivers/power/domain as part of a SPL build.
913 config SPL_RAM_SUPPORT
914 bool "Support booting from RAM"
915 default y if MICROBLAZE || ARCH_SOCFPGA || TEGRA || ARCH_ZYNQ
917 Enable booting of an image in RAM. The image can be preloaded or
918 it can be loaded by SPL directly into RAM (e.g. using USB).
920 config SPL_RAM_DEVICE
921 bool "Support booting from preloaded image in RAM"
922 depends on SPL_RAM_SUPPORT
923 default y if MICROBLAZE || ARCH_SOCFPGA || TEGRA || ARCH_ZYNQ
925 Enable booting of an image already loaded in RAM. The image has to
926 be already in memory when SPL takes over, e.g. loaded by the boot
929 config SPL_REMOTEPROC
930 bool "Support REMOTEPROCS"
932 Enable support for REMOTEPROCs in SPL. This permits to load
933 a remote processor firmware in SPL.
935 config SPL_RTC_SUPPORT
936 bool "Support RTC drivers"
938 Enable RTC (Real-time Clock) support in SPL. This includes support
939 for reading and setting the time. Some RTC devices also have some
940 non-volatile (battery-backed) memory which is accessible if
941 needed. This enables the drivers in drivers/rtc as part of an SPL
944 config SPL_SATA_SUPPORT
945 bool "Support loading from SATA"
947 Enable support for SATA (Serial AT attachment) in SPL. This allows
948 use of SATA devices such as hard drives and flash drivers for
949 loading U-Boot. SATA is used in higher-end embedded systems and
950 can provide higher performance than MMC , at somewhat higher
951 expense and power consumption. This enables loading from SATA
952 using a configured device.
954 config SPL_SATA_RAW_U_BOOT_USE_SECTOR
955 bool "SATA raw mode: by sector"
956 depends on SPL_SATA_SUPPORT
958 Use sector number for specifying U-Boot location on SATA disk in
961 config SPL_SATA_RAW_U_BOOT_SECTOR
962 hex "Sector on the SATA disk to load U-Boot from"
963 depends on SPL_SATA_RAW_U_BOOT_USE_SECTOR
965 Sector on the SATA disk to load U-Boot from, when the SATA disk is being
966 used in raw mode. Units: SATA disk sectors (1 sector = 512 bytes).
968 config SPL_SERIAL_SUPPORT
969 bool "Support serial"
973 Enable support for serial in SPL. This allows use of a serial UART
974 for displaying messages while SPL is running. It also brings in
975 printf() and panic() functions. This should normally be enabled
976 unless there are space reasons not to. Even then, consider
977 enabling SPL_USE_TINY_PRINTF which is a small printf() version.
979 config SPL_SPI_FLASH_SUPPORT
980 bool "Support SPI flash drivers"
982 Enable support for using SPI flash in SPL, and loading U-Boot from
983 SPI flash. SPI flash (Serial Peripheral Bus flash) is named after
984 the SPI bus that is used to connect it to a system. It is a simple
985 but fast bidirectional 4-wire bus (clock, chip select and two data
986 lines). This enables the drivers in drivers/mtd/spi as part of an
987 SPL build. This normally requires SPL_SPI_SUPPORT.
989 if SPL_SPI_FLASH_SUPPORT
991 config SPL_SPI_FLASH_TINY
992 bool "Enable low footprint SPL SPI Flash support"
993 depends on !SPI_FLASH_BAR
994 default y if SPI_FLASH
996 Enable lightweight SPL SPI Flash support that supports just reading
997 data/images from flash. No support to write/erase flash. Enable
998 this if you have SPL size limitations and don't need full
999 fledged SPI flash support.
1001 config SPL_SPI_FLASH_SFDP_SUPPORT
1002 bool "SFDP table parsing support for SPI NOR flashes"
1003 depends on !SPI_FLASH_BAR && !SPL_SPI_FLASH_TINY
1005 Enable support for parsing and auto discovery of parameters for
1006 SPI NOR flashes using Serial Flash Discoverable Parameters (SFDP)
1007 tables as per JESD216 standard in SPL.
1010 bool "Support loading from SPI flash"
1012 Enable support for loading next stage, U-Boot or otherwise, from
1013 SPI NOR in U-Boot SPL.
1015 endif # SPL_SPI_FLASH_SUPPORT
1017 config SYS_SPI_U_BOOT_OFFS
1018 hex "address of u-boot payload in SPI flash"
1020 depends on SPL_SPI_LOAD || SPL_SPI_SUNXI
1022 Address within SPI-Flash from where the u-boot payload is fetched
1025 config SPL_SPI_SUPPORT
1026 bool "Support SPI drivers"
1028 Enable support for using SPI in SPL. This is used for connecting
1029 to SPI flash for loading U-Boot. See SPL_SPI_FLASH_SUPPORT for
1030 more details on that. The SPI driver provides the transport for
1031 data between the SPI flash and the CPU. This option can be used to
1032 enable SPI drivers that are needed for other purposes also, such
1036 bool "Driver support for thermal devices"
1038 Enable support for temperature-sensing devices. Some SoCs have on-chip
1039 temperature sensors to permit warnings, speed throttling or even
1040 automatic power-off when the temperature gets too high or low. Other
1041 devices may be discrete but connected on a suitable bus.
1043 config SPL_USB_HOST_SUPPORT
1044 bool "Support USB host drivers"
1045 select HAVE_BLOCK_DEVICE
1047 Enable access to USB (Universal Serial Bus) host devices so that
1048 SPL can load U-Boot from a connected USB peripheral, such as a USB
1049 flash stick. While USB takes a little longer to start up than most
1050 buses, it is very flexible since many different types of storage
1051 device can be attached. This option enables the drivers in
1052 drivers/usb/host as part of an SPL build.
1054 config SPL_USB_STORAGE
1055 bool "Support loading from USB"
1056 depends on SPL_USB_HOST_SUPPORT && !(BLK && !DM_USB)
1058 Enable support for USB devices in SPL. This allows use of USB
1059 devices such as hard drives and flash drivers for loading U-Boot.
1060 The actual drivers are enabled separately using the normal U-Boot
1061 config options. This enables loading from USB using a configured
1064 config SPL_USB_GADGET
1065 bool "Suppport USB Gadget drivers"
1067 Enable USB Gadget API which allows to enable USB device functions
1072 config SPL_USB_ETHER
1073 bool "Support USB Ethernet drivers"
1075 Enable access to the USB network subsystem and associated
1076 drivers in SPL. This permits SPL to load U-Boot over a
1077 USB-connected Ethernet link (such as a USB Ethernet dongle) rather
1078 than from an onboard peripheral. Environment support is required
1079 since the network stack uses a number of environment variables.
1080 See also SPL_NET_SUPPORT and SPL_ETH_SUPPORT.
1083 bool "Support DFU (Device Firmware Upgrade)"
1084 select SPL_HASH_SUPPORT
1085 select SPL_DFU_NO_RESET
1086 depends on SPL_RAM_SUPPORT
1088 This feature enables the DFU (Device Firmware Upgrade) in SPL with
1089 RAM memory device support. The ROM code will load and execute
1090 the SPL built with dfu. The user can load binaries (u-boot/kernel) to
1091 selected device partition from host-pc using dfu-utils.
1092 This feature is useful to flash the binaries to factory or bare-metal
1093 boards using USB interface.
1096 bool "DFU device selection"
1101 depends on SPL_DFU && SPL_RAM_SUPPORT
1103 select RAM/DDR memory device for loading binary images
1104 (u-boot/kernel) to the selected device partition using
1105 DFU and execute the u-boot/kernel from RAM.
1109 config SPL_USB_SDP_SUPPORT
1110 bool "Support SDP (Serial Download Protocol)"
1112 Enable Serial Download Protocol (SDP) device support in SPL. This
1113 allows to download images into memory and execute (jump to) them
1114 using the same protocol as implemented by the i.MX family's boot ROM.
1117 config SPL_WATCHDOG_SUPPORT
1118 bool "Support watchdog drivers"
1119 imply SPL_WDT if !HW_WATCHDOG
1121 Enable support for watchdog drivers in SPL. A watchdog is
1122 typically a hardware peripheral which can reset the system when it
1123 detects no activity for a while (such as a software crash). This
1124 enables the drivers in drivers/watchdog as part of an SPL build.
1126 config SPL_YMODEM_SUPPORT
1127 bool "Support loading using Ymodem"
1128 depends on SPL_SERIAL_SUPPORT
1130 While loading from serial is slow it can be a useful backup when
1131 there is no other option. The Ymodem protocol provides a reliable
1132 means of transmitting U-Boot over a serial line for using in SPL,
1133 with a checksum to ensure correctness.
1136 bool "Support ARM Trusted Firmware"
1139 ATF(ARM Trusted Firmware) is a component for ARM AArch64 which
1140 is loaded by SPL (which is considered as BL2 in ATF terminology).
1141 More detail at: https://github.com/ARM-software/arm-trusted-firmware
1143 config SPL_ATF_NO_PLATFORM_PARAM
1144 bool "Pass no platform parameter"
1147 While we expect to call a pointer to a valid FDT (or NULL)
1148 as the platform parameter to an ATF, some ATF versions are
1149 not U-Boot aware and have an insufficiently robust parameter
1150 validation to gracefully reject a FDT being passed.
1152 If this option is enabled, the spl_atf os-type handler will
1153 always pass NULL for the platform parameter.
1155 If your ATF is affected, say Y.
1157 config SPL_AM33XX_ENABLE_RTC32K_OSC
1158 bool "Enable the RTC32K OSC on AM33xx based platforms"
1161 Enable access to the AM33xx RTC and select the external 32kHz clock
1165 bool "Support OP-TEE Trusted OS"
1168 OP-TEE is an open source Trusted OS which is loaded by SPL.
1169 More detail at: https://github.com/OP-TEE/optee_os
1172 bool "Support RISC-V OpenSBI"
1173 depends on RISCV && SPL_RISCV_MMODE && RISCV_SMODE
1175 OpenSBI is an open-source implementation of the RISC-V Supervisor Binary
1176 Interface (SBI) specification. U-Boot supports the OpenSBI FW_DYNAMIC
1177 firmware. It is loaded and started by U-Boot SPL.
1179 More details are available at https://github.com/riscv/opensbi and
1180 https://github.com/riscv/riscv-sbi-doc
1182 config SPL_OPENSBI_LOAD_ADDR
1183 hex "OpenSBI load address"
1184 depends on SPL_OPENSBI
1186 Load address of the OpenSBI binary.
1190 depends on SUPPORT_TPL
1193 If you want to build TPL as well as the normal image and SPL, say Y.
1198 bool "Pass hand-off information from TPL to SPL and U-Boot proper"
1199 depends on HANDOFF && TPL_BLOBLIST
1202 This option enables TPL to write handoff information. This can be
1203 used to pass information like the size of SDRAM from TPL to U-Boot
1204 proper. The information is also available to SPL if it is useful
1207 config TPL_BOARD_INIT
1208 bool "Call board-specific initialization in TPL"
1210 If this option is enabled, U-Boot will call the function
1211 spl_board_init() from board_init_r(). This function should be
1212 provided by the board.
1215 string "Linker script for the TPL stage"
1217 default "arch/arm/cpu/armv8/u-boot-spl.lds" if ARM64
1218 default "arch/$(ARCH)/cpu/u-boot-spl.lds"
1220 The TPL stage will usually require a different linker-script
1221 (as it runs from a different memory region) than the regular
1222 U-Boot stage. Set this to the path of the linker-script to
1225 May be left empty to trigger the Makefile infrastructure to
1226 fall back to the linker-script used for the SPL stage.
1228 config TPL_NEEDS_SEPARATE_TEXT_BASE
1229 bool "TPL needs a separate text-base"
1233 Enable, if the TPL stage should not inherit its text-base
1234 from the SPL stage. When enabled, a base address for the
1235 .text sections of the TPL stage has to be set below.
1237 config TPL_NEEDS_SEPARATE_STACK
1238 bool "TPL needs a separate initial stack-pointer"
1242 Enable, if the TPL stage should not inherit its initial
1243 stack-pointer from the settings for the SPL stage.
1245 config TPL_TEXT_BASE
1246 hex "Base address for the .text section of the TPL stage"
1247 depends on TPL_NEEDS_SEPARATE_TEXT_BASE
1249 The base address for the .text section of the TPL stage.
1252 int "Maximum size (in bytes) for the TPL stage"
1256 The maximum size (in bytes) of the TPL stage.
1259 hex "Address of the initial stack-pointer for the TPL stage"
1260 depends on TPL_NEEDS_SEPARATE_STACK
1262 The address of the initial stack-pointer for the TPL stage.
1263 Usually this will be the (aligned) top-of-stack.
1265 config TPL_BOOTROM_SUPPORT
1266 bool "Support returning to the BOOTROM (from TPL)"
1268 Some platforms (e.g. the Rockchip RK3368) provide support in their
1269 ROM for loading the next boot-stage after performing basic setup
1272 Enable this option, to return to the BOOTROM through the
1273 BOOT_DEVICE_BOOTROM (or fall-through to the next boot device in the
1274 boot device list, if not implemented for a given board)
1276 config TPL_DRIVERS_MISC_SUPPORT
1277 bool "Support misc drivers in TPL"
1279 Enable miscellaneous drivers in TPL. These drivers perform various
1280 tasks that don't fall nicely into other categories, Enable this
1281 option to build the drivers in drivers/misc as part of an TPL
1282 build, for those that support building in TPL (not all drivers do).
1284 config TPL_ENV_SUPPORT
1285 bool "Support an environment"
1287 Enable environment support in TPL. See SPL_ENV_SUPPORT for details.
1289 config TPL_GPIO_SUPPORT
1290 bool "Support GPIO in TPL"
1292 Enable support for GPIOs (General-purpose Input/Output) in TPL.
1293 GPIOs allow U-Boot to read the state of an input line (high or
1294 low) and set the state of an output line. This can be used to
1295 drive LEDs, control power to various system parts and read user
1296 input. GPIOs can be useful in TPL to enable a 'sign-of-life' LED,
1297 for example. Enable this option to build the drivers in
1298 drivers/gpio as part of an TPL build.
1300 config TPL_I2C_SUPPORT
1303 Enable support for the I2C bus in TPL. See SPL_I2C_SUPPORT for
1306 config TPL_LIBCOMMON_SUPPORT
1307 bool "Support common libraries"
1309 Enable support for common U-Boot libraries within TPL. See
1310 SPL_LIBCOMMON_SUPPORT for details.
1312 config TPL_LIBGENERIC_SUPPORT
1313 bool "Support generic libraries"
1315 Enable support for generic U-Boot libraries within TPL. See
1316 SPL_LIBGENERIC_SUPPORT for details.
1318 config TPL_MPC8XXX_INIT_DDR_SUPPORT
1319 bool "Support MPC8XXX DDR init"
1321 Enable support for DDR-SDRAM on the MPC8XXX family within TPL. See
1322 SPL_MPC8XXX_INIT_DDR_SUPPORT for details.
1324 config TPL_MMC_SUPPORT
1328 Enable support for MMC within TPL. See SPL_MMC_SUPPORT for details.
1330 config TPL_NAND_SUPPORT
1331 bool "Support NAND flash"
1333 Enable support for NAND in TPL. See SPL_NAND_SUPPORT for details.
1336 bool "Support PCI drivers"
1338 Enable support for PCI in TPL. For platforms that need PCI to boot,
1339 or must perform some init using PCI in SPL, this provides the
1340 necessary driver support. This enables the drivers in drivers/pci
1341 as part of a TPL build.
1343 config TPL_PCH_SUPPORT
1344 bool "Support PCH drivers"
1346 Enable support for PCH (Platform Controller Hub) devices in TPL.
1347 These are used to set up GPIOs and the SPI peripheral early in
1348 boot. This enables the drivers in drivers/pch as part of a TPL
1351 config TPL_RAM_SUPPORT
1352 bool "Support booting from RAM"
1354 Enable booting of an image in RAM. The image can be preloaded or
1355 it can be loaded by TPL directly into RAM (e.g. using USB).
1357 config TPL_RAM_DEVICE
1358 bool "Support booting from preloaded image in RAM"
1359 depends on TPL_RAM_SUPPORT
1361 Enable booting of an image already loaded in RAM. The image has to
1362 be already in memory when TPL takes over, e.g. loaded by the boot
1365 config TPL_RTC_SUPPORT
1366 bool "Support RTC drivers"
1368 Enable RTC (Real-time Clock) support in TPL. This includes support
1369 for reading and setting the time. Some RTC devices also have some
1370 non-volatile (battery-backed) memory which is accessible if
1371 needed. This enables the drivers in drivers/rtc as part of an TPL
1374 config TPL_SERIAL_SUPPORT
1375 bool "Support serial"
1379 Enable support for serial in TPL. See SPL_SERIAL_SUPPORT for
1382 config TPL_SPI_FLASH_SUPPORT
1383 bool "Support SPI flash drivers"
1385 Enable support for using SPI flash in TPL. See SPL_SPI_FLASH_SUPPORT
1389 bool "Support loading from SPI flash"
1390 depends on TPL_SPI_FLASH_SUPPORT
1392 Enable support for loading next stage, U-Boot or otherwise, from
1393 SPI NOR in U-Boot TPL.
1395 config TPL_SPI_SUPPORT
1396 bool "Support SPI drivers"
1398 Enable support for using SPI in TPL. See SPL_SPI_SUPPORT for
1401 config TPL_YMODEM_SUPPORT
1402 bool "Support loading using Ymodem"
1403 depends on TPL_SERIAL_SUPPORT
1405 While loading from serial is slow it can be a useful backup when
1406 there is no other option. The Ymodem protocol provides a reliable
1407 means of transmitting U-Boot over a serial line for using in TPL,
1408 with a checksum to ensure correctness.
1412 config SPL_AT91_MCK_BYPASS
1413 bool "Use external clock signal as a source of main clock for AT91 platforms"
1414 depends on ARCH_AT91
1417 Use external 8 to 24 Mhz clock signal as source of main clock instead
1418 of an external crystal oscillator.
1419 This option disables the internal driving on the XOUT pin.
1420 The external source has to provide a stable clock on the XIN pin.
1421 If this option is disabled, the SoC expects a crystal oscillator
1422 that needs driving on both XIN and XOUT lines.