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- /*
- * Copyright (c) 2009 Openmoko Inc.
- *
- * Authors Daniel Mack <daniel@caiaq.de>
- * Holger Hans Peter Freyther <zecke@openmoko.com>
- *
- * This program 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.
- *
- * This program 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/>.
- */
- 1) CONCEPT
- Mahatma is our mini-kernel. Is is in fact not even worth the name 'kernel',
- as it is not more than a thin abstraction layer and some calls to wiki-lib,
- the library which has all the core functionality.
- In short, the flow thru the system from Mahatma's point of view is as
- follows:
- * The kernel sets up the hardware and trap tables
- * wikilib_init() and guilib_init() are called to let the libraries do their
- neccessary initialisations
- * As of calling wikilib_run(), the kernel gives control to wikilib's
- application logic. This function does never return
- * Wikilib calls wl_input_wait() after some time to wait for new event so
- arrive, this is where the kernel gets back control
- * As all possible input event will cause an interrupt to occur, Mahatma
- makes the CPU enter HALT state and lets the interrupt controller do the
- rest
- * The interrupt service routine for each IRQ handels the hardware
- * After that, each subsystem which is able to create input events is polled
- once. If there was an incoming event, control is given back to wikilib to
- handle it. Otherwise, Mahatma goes to sleep again so the game starts over.
- 2) MEMORY MAP
- Because we want to switch off the external SDRAM during HALT mode, code
- doing that and calling __asm__("halt") must be located outside the RAM
- area mapped to external components. Mahatma's linker script stores routines
- which are involved in interrupt handling and system suspend/resume to the
- DST RAM section. In particular, all symbols and functions from traps.c and
- suspend.c are handled like that.
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