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diff --git a/Documentation/sh/new-machine.txt b/Documentation/sh/new-machine.txt deleted file mode 100644 index e0961a66130b..000000000000 --- a/Documentation/sh/new-machine.txt +++ /dev/null @@ -1,270 +0,0 @@ - - Adding a new board to LinuxSH - ================================ - - Paul Mundt <lethal@linux-sh.org> - -This document attempts to outline what steps are necessary to add support -for new boards to the LinuxSH port under the new 2.5 and 2.6 kernels. This -also attempts to outline some of the noticeable changes between the 2.4 -and the 2.5/2.6 SH backend. - -1. New Directory Structure -========================== - -The first thing to note is the new directory structure. Under 2.4, most -of the board-specific code (with the exception of stboards) ended up -in arch/sh/kernel/ directly, with board-specific headers ending up in -include/asm-sh/. For the new kernel, things are broken out by board type, -companion chip type, and CPU type. Looking at a tree view of this directory -hierarchy looks like the following: - -Board-specific code: - -. -|-- arch -| `-- sh -| `-- boards -| |-- adx -| | `-- board-specific files -| |-- bigsur -| | `-- board-specific files -| | -| ... more boards here ... -| -`-- include - `-- asm-sh - |-- adx - | `-- board-specific headers - |-- bigsur - | `-- board-specific headers - | - .. more boards here ... - -Next, for companion chips: -. -`-- arch - `-- sh - `-- cchips - `-- hd6446x - `-- hd64461 - `-- cchip-specific files - -... and so on. Headers for the companion chips are treated the same way as -board-specific headers. Thus, include/asm-sh/hd64461 is home to all of the -hd64461-specific headers. - -Finally, CPU family support is also abstracted: -. -|-- arch -| `-- sh -| |-- kernel -| | `-- cpu -| | |-- sh2 -| | | `-- SH-2 generic files -| | |-- sh3 -| | | `-- SH-3 generic files -| | `-- sh4 -| | `-- SH-4 generic files -| `-- mm -| `-- This is also broken out per CPU family, so each family can -| have their own set of cache/tlb functions. -| -`-- include - `-- asm-sh - |-- cpu-sh2 - | `-- SH-2 specific headers - |-- cpu-sh3 - | `-- SH-3 specific headers - `-- cpu-sh4 - `-- SH-4 specific headers - -It should be noted that CPU subtypes are _not_ abstracted. Thus, these still -need to be dealt with by the CPU family specific code. - -2. Adding a New Board -===================== - -The first thing to determine is whether the board you are adding will be -isolated, or whether it will be part of a family of boards that can mostly -share the same board-specific code with minor differences. - -In the first case, this is just a matter of making a directory for your -board in arch/sh/boards/ and adding rules to hook your board in with the -build system (more on this in the next section). However, for board families -it makes more sense to have a common top-level arch/sh/boards/ directory -and then populate that with sub-directories for each member of the family. -Both the Solution Engine and the hp6xx boards are an example of this. - -After you have setup your new arch/sh/boards/ directory, remember that you -should also add a directory in include/asm-sh for headers localized to this -board (if there are going to be more than one). In order to interoperate -seamlessly with the build system, it's best to have this directory the same -as the arch/sh/boards/ directory name, though if your board is again part of -a family, the build system has ways of dealing with this (via incdir-y -overloading), and you can feel free to name the directory after the family -member itself. - -There are a few things that each board is required to have, both in the -arch/sh/boards and the include/asm-sh/ hierarchy. In order to better -explain this, we use some examples for adding an imaginary board. For -setup code, we're required at the very least to provide definitions for -get_system_type() and platform_setup(). For our imaginary board, this -might look something like: - -/* - * arch/sh/boards/vapor/setup.c - Setup code for imaginary board - */ -#include <linux/init.h> - -const char *get_system_type(void) -{ - return "FooTech Vaporboard"; -} - -int __init platform_setup(void) -{ - /* - * If our hardware actually existed, we would do real - * setup here. Though it's also sane to leave this empty - * if there's no real init work that has to be done for - * this board. - */ - - /* Start-up imaginary PCI ... */ - - /* And whatever else ... */ - - return 0; -} - -Our new imaginary board will also have to tie into the machvec in order for it -to be of any use. - -machvec functions fall into a number of categories: - - - I/O functions to IO memory (inb etc) and PCI/main memory (readb etc). - - I/O mapping functions (ioport_map, ioport_unmap, etc). - - a 'heartbeat' function. - - PCI and IRQ initialization routines. - - Consistent allocators (for boards that need special allocators, - particularly for allocating out of some board-specific SRAM for DMA - handles). - -There are machvec functions added and removed over time, so always be sure to -consult include/asm-sh/machvec.h for the current state of the machvec. - -The kernel will automatically wrap in generic routines for undefined function -pointers in the machvec at boot time, as machvec functions are referenced -unconditionally throughout most of the tree. Some boards have incredibly -sparse machvecs (such as the dreamcast and sh03), whereas others must define -virtually everything (rts7751r2d). - -Adding a new machine is relatively trivial (using vapor as an example): - -If the board-specific definitions are quite minimalistic, as is the case for -the vast majority of boards, simply having a single board-specific header is -sufficient. - - - add a new file include/asm-sh/vapor.h which contains prototypes for - any machine specific IO functions prefixed with the machine name, for - example vapor_inb. These will be needed when filling out the machine - vector. - - Note that these prototypes are generated automatically by setting - __IO_PREFIX to something sensible. A typical example would be: - - #define __IO_PREFIX vapor - #include <asm/io_generic.h> - - somewhere in the board-specific header. Any boards being ported that still - have a legacy io.h should remove it entirely and switch to the new model. - - - Add machine vector definitions to the board's setup.c. At a bare minimum, - this must be defined as something like: - - struct sh_machine_vector mv_vapor __initmv = { - .mv_name = "vapor", - }; - ALIAS_MV(vapor) - - - finally add a file arch/sh/boards/vapor/io.c, which contains definitions of - the machine specific io functions (if there are enough to warrant it). - -3. Hooking into the Build System -================================ - -Now that we have the corresponding directories setup, and all of the -board-specific code is in place, it's time to look at how to get the -whole mess to fit into the build system. - -Large portions of the build system are now entirely dynamic, and merely -require the proper entry here and there in order to get things done. - -The first thing to do is to add an entry to arch/sh/Kconfig, under the -"System type" menu: - -config SH_VAPOR - bool "Vapor" - help - select Vapor if configuring for a FooTech Vaporboard. - -next, this has to be added into arch/sh/Makefile. All boards require a -machdir-y entry in order to be built. This entry needs to be the name of -the board directory as it appears in arch/sh/boards, even if it is in a -sub-directory (in which case, all parent directories below arch/sh/boards/ -need to be listed). For our new board, this entry can look like: - -machdir-$(CONFIG_SH_VAPOR) += vapor - -provided that we've placed everything in the arch/sh/boards/vapor/ directory. - -Next, the build system assumes that your include/asm-sh directory will also -be named the same. If this is not the case (as is the case with multiple -boards belonging to a common family), then the directory name needs to be -implicitly appended to incdir-y. The existing code manages this for the -Solution Engine and hp6xx boards, so see these for an example. - -Once that is taken care of, it's time to add an entry for the mach type. -This is done by adding an entry to the end of the arch/sh/tools/mach-types -list. The method for doing this is self explanatory, and so we won't waste -space restating it here. After this is done, you will be able to use -implicit checks for your board if you need this somewhere throughout the -common code, such as: - - /* Make sure we're on the FooTech Vaporboard */ - if (!mach_is_vapor()) - return -ENODEV; - -also note that the mach_is_boardname() check will be implicitly forced to -lowercase, regardless of the fact that the mach-types entries are all -uppercase. You can read the script if you really care, but it's pretty ugly, -so you probably don't want to do that. - -Now all that's left to do is providing a defconfig for your new board. This -way, other people who end up with this board can simply use this config -for reference instead of trying to guess what settings are supposed to be -used on it. - -Also, as soon as you have copied over a sample .config for your new board -(assume arch/sh/configs/vapor_defconfig), you can also use this directly as a -build target, and it will be implicitly listed as such in the help text. - -Looking at the 'make help' output, you should now see something like: - -Architecture specific targets (sh): - zImage - Compressed kernel image (arch/sh/boot/zImage) - adx_defconfig - Build for adx - cqreek_defconfig - Build for cqreek - dreamcast_defconfig - Build for dreamcast -... - vapor_defconfig - Build for vapor - -which then allows you to do: - -$ make ARCH=sh CROSS_COMPILE=sh4-linux- vapor_defconfig vmlinux - -which will in turn copy the defconfig for this board, run it through -oldconfig (prompting you for any new options since the time of creation), -and start you on your way to having a functional kernel for your new -board. |