leon3/start/bspidle.S

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  * @file
0005  *
0006  * @ingroup RTEMSBSPsSPARCShared
0007  *
0008  * @brief This assembler source file contains the LEON3-specific
0009  *   bsp_idle_thread() implementation.
0010  */
0011
0012 /*
0013  *  Idle Thread Body
0014  *
0015  *  This routine puts LEON3 in power-down mode.
0016  *
0017  *  COPYRIGHT (c) 2004.
0018  *  Gaisler Research.
0019  *
0020  * Redistribution and use in source and binary forms, with or without
0021  * modification, are permitted provided that the following conditions
0022  * are met:
0023  * 1. Redistributions of source code must retain the above copyright
0024  *    notice, this list of conditions and the following disclaimer.
0025  * 2. Redistributions in binary form must reproduce the above copyright
0026  *    notice, this list of conditions and the following disclaimer in the
0027  *    documentation and/or other materials provided with the distribution.
0028  *
0029  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0030  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0031  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0032  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0033  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0034  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0035  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0036  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0037  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0038  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0039  * POSSIBILITY OF SUCH DAMAGE.
0040  */
0041
0042
0043
0044 #include <rtems/asm.h>
0045
0046 /*
0047  * LEON specific power-down function
0048  *
0049  * This implementation contains the workaround for the GR712RC
0050  * power-down errata described in GR712RC-UM, version 2.16, section
0051  * 1.7.8. The workaround is compatible with other LEON3 components.
0052  */
0053
0054         .align 4
0055         PUBLIC(bsp_idle_thread)
0056         PUBLIC(leon3_power_down_loop)
0057 SYM(bsp_idle_thread):
0058 SYM(leon3_power_down_loop):
0059 pwdloop:
0060           /*
0061            * Address 0xfffffff0 is the read-only AHB plug & play region at
0062            * least for the UT699, GR712RC, and GR740.
0063            */
0064           set     0xfffffff0, %o0
0065
0066           /*
0067            * Make sure the following two instructions are in one cache line.
0068            * This ensures that the instructions are fetched from the
0069            * instruction cache when the processor leaves power-down mode
0070            * (unless a SEU occurs in the instruction cache line).
0071            *
0072            * Use a load which bypasses the MMU and cache (ASI 0x1c).
0073            */
0074           .align 32
0075           mov     %g0, %asr19
0076           lda     [%o0] 0x1c, %g0
0077
0078           /*
0079            * Place the branch far enough away from the preceding load, to make
0080            * sure the preceding load is executed before the branch to prevent
0081            * an instruction fetch from memory.
0082            */
0083           .align 32
0084           ba,a    pwdloop
0085            nop