+++ /dev/null
-// crt0-app.S
-// Applications downloaded in RAM using a debug monitor (eg. XMON, RedBoot)
-// start here at _app_reset. Such applications don't have any vectors:
-// all exceptions are handled by the debug monitor.
-// Thus, this file essentially plays the role of the reset vector
-// to setup a few things before jumping to _start (in crt1*.S).
-
-// Copyright (c) 2005-2010 Tensilica Inc.
-//
-// Permission is hereby granted, free of charge, to any person obtaining
-// a copy of this software and associated documentation files (the
-// "Software"), to deal in the Software without restriction, including
-// without limitation the rights to use, copy, modify, merge, publish,
-// distribute, sublicense, and/or sell copies of the Software, and to
-// permit persons to whom the Software is furnished to do so, subject to
-// the following conditions:
-//
-// The above copyright notice and this permission notice shall be included
-// in all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-
-#include <xtensa/cacheattrasm.h>
-#include <xtensa/xt2000.h>
-#include <xtensa/coreasm.h>
-
-
-// Assumptions on entry to _app_reset:
-// - debug monitor handles all exceptions, has setup all vectors
-// - interrupt related state is initialized
-// (interrupts disabled or enabled for debug monitor's purposes)
-// - debug option related state is initialized (for debug monitor)
-// - any MMU related state is initialized (all handled by debug monitor)
-// - caches are initialized (cache attributes not necessarily correct)
-// - entire application is loaded (no unpacking needed here)
-
-// Assumptions on exit from _app_reset, ie. when jumping to _start:
-// - low (level-one) and medium priority interrupts are disabled
-// - C calling context not initialized:
-// - PS not fully initialized (eg. PS.WOE not set per ABI)
-// - SP not initialized
-// - the following are initialized:
-// - LITBASE, WindowBase, WindowStart, LCOUNT, CPENABLE, FP's FCR and FSR,
-// cache attributes
-
-/**************************************************************************/
-
- .text
- .global _app_reset
-_app_reset:
- /* _app_reset may be required to be located at the beginning of the text
- segment. However, the constant pool for _app_reset must be placed
- before the code. Jump over the constant pool to solve this. */
- j .LpastInitialConstants
-
- .literal_position // tells the assembler/linker to place literals here
-
-.LpastInitialConstants:
- // Keep a0 zero. It is used to initialize a few things.
- // It is also the return address, where zero indicates
- // that the frame used by _start is the bottommost frame.
- //
- movi a0, 0 // keep this register zero.
-
-#if XCHAL_HAVE_LOOPS
- wsr a0, LCOUNT // loop count = 0
-#endif /* XCHAL_HAVE_LOOPS */
-
- // Interrupts might be enabled, make sure at least medium and low priority
- // interrupts are disabled until WindowBase, WindowStart, SP, and the stack
- // are all properly setup (which will happen outside this file, after the
- // _start label). We leave loops enabled on new exception architecture.
-#if XCHAL_HAVE_EXCEPTIONS
- movi a2, XCHAL_EXCM_LEVEL
- wsr a2, PS // set PS.INTLEVEL=EXCM_LEVEL, PS.WOE=0, PS.EXCM=0
- rsync
-#endif
-
- // DO THIS FIRST: initialize the window start and base
- // before, so that windows don't move under us.
-#if XCHAL_HAVE_WINDOWED
- // We do this even if we are assembling for the
- // call0 abi, but it's not really needed.
- movi a2, 1
- wsr a2, WINDOWSTART // window start = 1
- wsr a0, WINDOWBASE // window base = 0
- rsync
-
- // NOTE: a0 may no longer be zero here, because
- // we wrote to WindowBase. So clear it again.
- movi a0, 0
-#endif
-
- // Now, BEFORE we do any L32R (or MOVI with non-immediate
- // range which results in an L32R), ensure LITBASE is set
- // correctly. This is necessary for RAM applications loaded
- // using a target-side debug monitor -- such applications
- // don't have a reset vector and start execution at _start.
- // (This part is unnecessary if running from a reset vector.)
- // The target-side debug monitor might have set LITBASE to
- // anything at all, so we cannot rely on its value here.
-#if XCHAL_HAVE_ABSOLUTE_LITERALS
- wsr a0, LITBASE // force PC-relative L32R
- rsync
-# if XSHAL_USE_ABSOLUTE_LITERALS
- .begin no-absolute-literals // use PC-rel L32R to load
- movi a2, _lit4_start + 0x40001 // address of absolute literals
- .end no-absolute-literals // (see handlers/ResetVector.S
- wsr a2, LITBASE // for explanation)
- rsync
-# endif
-#endif
-
-
- /*
- * Enable the caches correctly for this board.
- * We use the "safe" sequence.
- *
- * NOTE: We don't *initialize* the caches here, because the
- * target debugger agent (debug monitor) has initialized them for us.
- */
- movi a2, XTBOARD_CACHEATTR_DEFAULT
- cacheattr_set /* set CACHEATTR from a2 (clobbers a3-a8) */
-
-
-
- // Coprocessor option initialization
-#if XCHAL_HAVE_CP
- //movi a2, XCHAL_CP_MASK // enable existing CPs
- // To allow creating new coprocessors using TC that are not known
- // at GUI build time without having to explicitly enable them,
- // all CPENABLE bits must be set, even though they may not always
- // correspond to a coprocessor.
- movi a2, 0xFF // enable *all* bits, to allow dynamic TIE
- wsr a2, CPENABLE
-#endif
-
- // Floating point coprocessor option initialization
-#if XCHAL_HAVE_FP
-# define FCR 232 /* floating-point control register (user register number) */
-# define FSR 233 /* floating-point status register (user register number) */
- rsync /* wait for WSR to CPENABLE to complete before accessing FP coproc state */
- wur a0, FCR /* clear FCR (default rounding mode, round-nearest) */
- wur a0, FSR /* clear FSR */
-#endif
-
-
- /* NOTE: Future releases may clear BSS here rather than in the CRT1. */
-
-
- /*
- * Now jump to the application. This is typically the
- * C run-time initialization ("CRT") which in turn calls main():
- */
- movi a4, _start
- jx a4 // jump to _start
-
- .size _app_reset, . - _app_reset
-
projects / open-ath9k-htc-firmware.git / blobdiff