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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
---
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes ChibiOS/RT, without being obliged to provide
the source code for any proprietary components. See the file exception.txt
for full details of how and when the exception can be applied.
*/
/**
* @defgroup PPC Power Architecture
* @details Power Architecture port for the GCC compiler.
*
* @section PPC_INTRO Introduction
* This port supports cores implementing a 32 bits Power Architecture.
*
* @section PPC_STATES Mapping of the System States in the Power Architecture port
* The ChibiOS/RT logical @ref system_states are mapped as follow in the
* PowerPC port:
* - <b>Init</b>. This state is represented by the startup code and the
* initialization code before @p chSysInit() is executed. It has not a
* special hardware state associated.
* - <b>Normal</b>. This is the state the system has after executing
* @p chSysInit(). Interrupts are enabled.
* - <b>Suspended</b>. Interrupts are disabled.
* - <b>Disabled</b>. Interrupts are disabled. This state is equivalent to the
* Suspended state because there are no fast interrupts in this architecture.
* - <b>Sleep</b>. This state is entered with the execution of the specific
* instruction @p <b>wait</b>.
* - <b>S-Locked</b>. Interrupts are disabled.
* - <b>I-Locked</b>. This state is equivalent to the SRI state, the
* @p chSysLockI() and @p chSysUnlockI() APIs do nothing (still use them in
* order to formally change state because this may change).
* - <b>Serving Regular Interrupt</b>. Normal interrupt service code.
* - <b>Serving Fast Interrupt</b>. Not present in this architecture.
* - <b>Serving Non-Maskable Interrupt</b>. The PowerPC has several non
* maskable interrupt sources that can be associated to this state.
* - <b>Halted</b>. Implemented as an infinite loop with interrupts disabled.
* .
* @section PPC_NOTES The PowerPC port notes
* The PowerPC port is organized as follow:
* - The @p main() function is invoked in privileged mode.
* - Each thread has a private stack with extra storage for interrupts
* servicing.
* - The Book-E Decrementer Timer, mapped on IVOR10, is used for system tick.
* - Interrupt nesting is not currently supported.
* .
* @ingroup gcc
*/
/**
* @defgroup PPC_CONF Configuration Options
* @details PowerPC Configuration Options. The PowerPC port allows some
* architecture-specific configurations settings that can be overridden by
* redefining them in @p chconf.h. Usually there is no need to change the
* default values.
* - @p INT_REQUIRED_STACK, this value represent the amount of stack space used
* by an interrupt handler between the @p extctx and @p intctx
* structures.
* The default for this value is @p 128 bytes, this space is allocated for
* each thread so be careful in order to not waste precious RAM space.
* - @p IDLE_THREAD_STACK_SIZE, stack area size to be assigned to the IDLE
* thread. Usually there is no need to change this value unless inserting
* code in the IDLE thread hook macro.
* - @p ENABLE_WFI_IDLE, if set to @p TRUE enables the use of the @p <b>wait</b>
* instruction from within the idle loop. This is defaulted to 0 because
* it can create problems with some debuggers. Setting this option to 1
* reduces the system power requirements.
* .
* @ingroup PPC
*/
/**
* @defgroup PPC_CORE Core Port Implementation
* @brief PowerPC specific port code, structures and macros.
*
* @ingroup PPC
*/
/**
* @defgroup PPC_STARTUP Startup Support
* @brief
* @details PPC startup code support. ChibiOS/RT provides its own generic
* startup file for the PowerPC port.
* Of course it is not mandatory to use it but care should be taken about the
* startup phase details.
*
* @section PPC_STARTUP_1 Startup Process
* The startup process, as implemented, is the following:
* -# The stacks pointer is initialized into the area defined in the linker
* script.
* -# The IVPR register is setup according to the linker script.
* -# The R2 and R13 registers are set to pointer to the SDA areas according
* to the EABI specification.
* -# An early initialization routine @p hwinit0 is invoked, if the symbol is
* not defined then an empty default routine is executed (weak symbol).
* -# DATA and BSS segments are initialized.
* -# A late initialization routine @p hwinit1 is invoked, if the symbol not
* defined then an empty default routine is executed (weak symbol).<br>
* This late initialization function is also the proper place for a
* @a bootloader, if your application requires one.
* -# The @p main() function is invoked with the parameters @p argc and @p argv
* set to zero.
* -# Should the @p main() function return a branch is performed to the weak
* symbol @p _main_exit_handler. The default code is an endless empty loop.
* .
* @section PPC_STARTUP_2 Expected linker symbols
* The startup code starts at the symbol @p _boot_address and expects the
* following symbols to be defined in the linker script:
* - @p __ram_end__ RAM end location +1.
* - @p __sdata2_start__ small constants data area
* - @p __sdata_start__ small variables data area
* - @p __romdata_start__ address of the data segment source read only data.
* - @p __data_start__ data segment start location.
* - @p __data_end__ data segment end location +1.
* - @p __bss_start__ BSS start location.
* - @p __bss_end__ BSS end location +1.
* - @p __ivpr_base__ IVPR register initialization address.
* .
* @ingroup PPC
*/
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