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diff --git a/doc/bsp_howto/target.t b/doc/bsp_howto/target.t deleted file mode 100644 index b2ccfe7ffc..0000000000 --- a/doc/bsp_howto/target.t +++ /dev/null @@ -1,236 +0,0 @@ -@c -@c COPYRIGHT (c) 1988-2002. -@c On-Line Applications Research Corporation (OAR). -@c All rights reserved. - -@chapter Target Dependent Files - -RTEMS has a multi-layered approach to portability. This is done to -maximize the amount of software that can be reused. Much of the -RTEMS source code can be reused on all RTEMS platforms. Other parts -of the executive are specific to hardware in some sense. -RTEMS classifies target dependent code based upon its dependencies -into one of the following categories. - -@itemize @bullet -@item CPU dependent -@item Board dependent -@item Peripheral dependent -@end itemize - -@section CPU Dependent - -This class of code includes the foundation -routines for the executive proper such as the context switch and -the interrupt subroutine implementations. Sources for the supported -processor families can be found in @code{cpukit/score/cpu}. -A good starting point for a new family of processors is the -@code{no_cpu} directory, which holds both prototypes and -descriptions of each needed CPU dependent function. - -CPU dependent code is further subcategorized if the implementation is -dependent on a particular CPU model. For example, the MC68000 and MC68020 -processors are both members of the m68k CPU family but there are significant -differences between these CPU models which RTEMS must take into account. - -The source code found in the @code{cpukit/score/cpu} is required to -only depend upon the CPU model variations that GCC distinguishes -for the purposes of multilib'ing. Multilib is the term the GNU -community uses to refer to building a single library source multiple -times with different compiler options so the binary code generated -is compatible. As an example, from GCC's perspective, many PowerPC -CPU models are just a PPC603e. Remember that GCC only cares about -the CPU code itself and need not be aware of any peripherals. In -the embedded community, we are exposed to thousands of CPU models -which are all based upon only a relative small number of CPU cores. - -Similarly for the SPARC/ERC32 BSP, the @code{RTEMS_CPU} is specified as -@code{erc32} which is the name of the CPU model and BSP for this SPARC V7 -system on chip. But the multilib variant used is actually @code{v7} -which indicates the ERC32 CPU core is a SPARC V7. - -@section Board Dependent - -This class of code provides the most specific glue between RTEMS and -a particular board. This code is represented by the Board Support Packages -and associated Device Drivers. Sources for the BSPs included in the -RTEMS distribution are located in the directory @code{c/src/lib/libbsp}. -The BSP source directory is further subdivided based on the CPU family -and BSP. - -Some BSPs may support multiple board models within a single board family. -This is necessary when the board supports multiple variants on a -single base board. For example, the Motorola MVME162 board family has a -fairly large number of variations based upon the particular CPU model -and the peripherals actually placed on the board. - -@section Peripheral Dependent - -This class of code provides a reusable library of peripheral device -drivers which can be tailored easily to a particular board. The -libchip library is a collection of reusable software objects that -correspond to standard controllers. Just as the hardware engineer -chooses a standard controller when designing a board, the goal of -this library is to let the software engineer do the same thing. - -The source code for the reusable peripheral driver library may be found -in the directory @code{c/src/lib/libchip}. The source code is further -divided based upon the class of hardware. Example classes include serial -communications controllers, real-time clocks, non-volatile memory, and -network controllers. - -@section Questions to Ask - -When evaluating what is required to support RTEMS applications on -a particular target board, the following questions should be asked: - -@itemize @bullet - -@item Does a BSP for this board exist? - -@item Does a BSP for a similar board exists? - -@item Is the board's CPU supported? - -@end itemize - -If there is already a BSP for the board, then things may already be ready -to start developing application software. All that remains is to verify -that the existing BSP provides device drivers for all the peripherals -on the board that the application will be using. For example, the application -in question may require that the board's Ethernet controller be used and -the existing BSP may not support this. - -If the BSP does not exist and the board's CPU model is supported, then -examine the reusable chip library and existing BSPs for a close match. -Other BSPs and libchip provide starting points for the development -of a new BSP. It is often possible to copy existing components in -the reusable chip library or device drivers from BSPs from different -CPU families as the starting point for a new device driver. -This will help reduce the development effort required. - -If the board's CPU family is supported but the particular CPU model on -that board is not, then the RTEMS port to that CPU family will have to -be augmented. After this is done, development of the new BSP can proceed. - -Otherwise both CPU dependent code and the BSP will have to be written. - -This type of development often requires specialized skills. If -you need help in making these modifications to RTEMS, please -consider using one of the RTEMS Service Providers. The current -list of these is at @uref{@value{RTEMSHTTPURL}/support.html}. - -@section CPU Dependent Executive Files - -The CPU dependent files in the RTEMS executive source code are found -in the following directory: - -@example -cpukit/score/cpu/@i{CPU} -@end example - -where @i{CPU} is replaced with the CPU family name. - -Within each CPU dependent directory inside the executive proper is a -file named @code{@i{CPU}.h} which contains information about each of the -supported CPU models within that family. - -@section CPU Dependent Support Files - -The CPU dependent support files contain routines which aid in the development -of applications using that CPU family. For example, the support routines -may contain standard trap handlers for alignment or floating point exceptions -or device drivers for peripheral controllers found on the CPU itself. -This class of code may be found in the following directory: - -@example -c/src/lib/libcpu/@i{CPU} -@end example - -CPU model dependent support code is found in the following directory: - -@example -c/src/lib/libcpu/@i{CPU}/@i{CPU_MODEL} -@end example - -@i{CPU_MODEL} may be a specific CPU model name or a name indicating a CPU -core or a set of related CPU models. The file @code{configure.ac} in each -@code{c/src/lib/libcpu/@i{CPU}} directory contains the logic which enables -the appropriate subdirectories for the specific CPU model your BSP has. - -@section Board Support Package Structure - -The BSPs are all under the @code{c/src/lib/libbsp} directory. Below this -directory, there is a subdirectory for each CPU family. Each BSP -is found under the subdirectory for the appropriate processor -family (m68k, powerpc, etc.). In addition, there is source code -available which may be shared across all BSPs regardless of -the CPU family or just across BSPs within a single CPU family. This -results in a BSP using the following directories: - -@example -c/src/lib/libbsp/shared -c/src/lib/libbsp/@i{CPU}/shared -c/src/lib/libbsp/@i{CPU}/@i{BSP} -@end example - -Under each BSP specific directory, there is a collection of -subdirectories. For commonly provided functionality, the BSPs -follow a convention on subdirectory naming. The following list -describes the commonly found subdirectories under each BSP. - -@itemize @bullet - -@item @b{console}: -is technically the serial driver for the BSP rather -than just a console driver, it deals with the board -UARTs (i.e. serial devices). - -@item @b{clock}: -support for the clock tick -- a regular time basis to the kernel. - -@item @b{timer}: -support of timer devices. - -@item @b{rtc} or @code{tod}: -support for the hardware real-time clock. - -@item @b{nvmem}: -support for non-volatile memory such as EEPROM or Flash. - -@item @b{network}: -the Ethernet driver. - -@item @b{shmsupp}: -support of shared memory driver MPCI layer in a multiprocessor system, - -@item @b{include}: -include files for this BSP. - -@item @b{gnatsupp}: -BSP specific support for the GNU Ada run-time. Each BSP that wishes -to have the possibility to map faults or exceptions into Ada language -exceptions or hardware interrupts into Ada interrupt tasks must provide -this support. - -@end itemize - -There may be other directories in the BSP tree and the name should -be indicative of the functionality of the code within that directory. - -The build order of the BSP is determined by the Makefile structure. -This structure is discussed in more detail in the @ref{Makefiles} -chapter. - -@b{NOTE:} This manual refers to the gen68340 BSP for numerous concrete -examples. You should have a copy of the gen68340 BSP available while -reading this piece of documentation. This BSP is located in the -following directory: - -@example -c/src/lib/libbsp/m68k/gen68340 -@end example - -Later in this document, the $BSP340_ROOT label will be used -to refer to this directory. - |