dtoc: Tidy up more Python style in dtb_platdata

[u-boot.git] / doc / README.SPL

diff --git a/doc/README.SPL b/doc/README.SPL
index 536858664726e076d18d0654f32d62b6817a3964..2beb6d8f11b54fcf5c07814f846fed088b061c56 100644 (file)
--- a/doc/README.SPL
+++ b/doc/README.SPL
@@ -13,34 +13,29 @@ can be reused. No code duplication or symlinking is necessary anymore.
 How it works
 ------------
 
-There is a new directory TOPDIR/spl which contains only a Makefile.
-The object files are built separately for SPL and placed in this directory.
+The object files for SPL are built separately and placed in the "spl" directory.
 The final binaries which are generated are u-boot-spl, u-boot-spl.bin and
 u-boot-spl.map.
 
-During the SPL build a variable named CONFIG_SPL_BUILD is exported
-in the make environment and also appended to CPPFLAGS with -DCONFIG_SPL_BUILD.
+A config option named CONFIG_SPL_BUILD is enabled by Kconfig for SPL.
 Source files can therefore be compiled for SPL with different settings.
-ARM-based boards have previously used the option CONFIG_PRELOADER for it.
 
 For example:
 
 ifeq ($(CONFIG_SPL_BUILD),y)
-COBJS-y += board_spl.o
+obj-y += board_spl.o
 else
-COBJS-y += board.o
+obj-y += board.o
 endif
 
-COBJS-$(CONFIG_SPL_BUILD) += foo.o
+obj-$(CONFIG_SPL_BUILD) += foo.o
 
 #ifdef CONFIG_SPL_BUILD
        foo();
 #endif
 
 
-The building of SPL images can be with:
-
-#define CONFIG_SPL
+The building of SPL images can be enabled by CONFIG_SPL option in Kconfig.
 
 Because SPL images normally have a different text base, one has to be
 configured by defining CONFIG_SPL_TEXT_BASE. The linker script has to be
@@ -58,27 +53,35 @@ CONFIG_SPL_MMC_SUPPORT (drivers/mmc/libmmc.o)
 CONFIG_SPL_SERIAL_SUPPORT (drivers/serial/libserial.o)
 CONFIG_SPL_SPI_FLASH_SUPPORT (drivers/mtd/spi/libspi_flash.o)
 CONFIG_SPL_SPI_SUPPORT (drivers/spi/libspi.o)
-CONFIG_SPL_FAT_SUPPORT (fs/fat/libfat.o)
+CONFIG_SPL_FS_FAT (fs/fat/libfat.o)
+CONFIG_SPL_FS_EXT4
 CONFIG_SPL_LIBGENERIC_SUPPORT (lib/libgeneric.o)
 CONFIG_SPL_POWER_SUPPORT (drivers/power/libpower.o)
-CONFIG_SPL_NAND_SUPPORT (drivers/mtd/nand/libnand.o)
-CONFIG_SPL_DMA_SUPPORT (drivers/dma/libdma.o)
+CONFIG_SPL_NAND_SUPPORT (drivers/mtd/nand/raw/libnand.o)
+CONFIG_SPL_DRIVERS_MISC_SUPPORT (drivers/misc)
+CONFIG_SPL_DMA (drivers/dma/libdma.o)
 CONFIG_SPL_POST_MEM_SUPPORT (post/drivers/memory.o)
-CONFIG_SPL_NAND_LOAD (drivers/mtd/nand/nand_spl_load.o)
+CONFIG_SPL_NAND_LOAD (drivers/mtd/nand/raw/nand_spl_load.o)
 CONFIG_SPL_SPI_LOAD (drivers/mtd/spi/spi_spl_load.o)
-
-
-Normally CPU is assumed to be the same between the SPL and normal
-u-boot build.  However it is possible to specify a different CPU for
-the SPL build for cases where the SPL is expected to run on a
-different CPU model from the main u-boot.  This is done by specifying
-an SPL CPU in boards.cfg as follows:
-
-       normal_cpu:spl_cpu
-
-This this case CPU will be set to "normal_cpu" during the main u-boot
-build and "spl_cpu" during the SPL build.
-
+CONFIG_SPL_RAM_DEVICE (common/spl/spl.c)
+CONFIG_SPL_WATCHDOG_SUPPORT (drivers/watchdog/libwatchdog.o)
+
+Device tree
+-----------
+The U-Boot device tree is filtered by the fdtgrep tools during the build
+process to generate a much smaller device tree used in SPL (spl/u-boot-spl.dtb)
+with:
+- the mandatory nodes (/alias, /chosen, /config)
+- the nodes with one pre-relocation property:
+  'u-boot,dm-pre-reloc' or 'u-boot,dm-spl'
+
+fdtgrep is also used to remove:
+- the properties defined in CONFIG_OF_SPL_REMOVE_PROPS
+- all the pre-relocation properties
+  ('u-boot,dm-pre-reloc', 'u-boot,dm-spl' and 'u-boot,dm-tpl')
+
+All the nodes remaining in the SPL devicetree are bound
+(see doc/driver-model/design.rst).
 
 Debugging
 ---------