forked from Imagelibrary/rtems
9964895866
Adjust build support files to new directory layout. This patch is a part of the BSP source reorganization. Update #3285.
107 lines
3.0 KiB
C
107 lines
3.0 KiB
C
/*
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* ppc_idle.c
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*
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* Authorship
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* ----------
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* This software was created by
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* Till Straumann <strauman@slac.stanford.edu>, 2010,
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* Stanford Linear Accelerator Center, Stanford University.
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*
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* Acknowledgement of sponsorship
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* ------------------------------
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* This software was produced by
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* the Stanford Linear Accelerator Center, Stanford University,
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* under Contract DE-AC03-76SFO0515 with the Department of Energy.
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*
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* Government disclaimer of liability
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* ----------------------------------
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* Neither the United States nor the United States Department of Energy,
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* nor any of their employees, makes any warranty, express or implied, or
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* assumes any legal liability or responsibility for the accuracy,
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* completeness, or usefulness of any data, apparatus, product, or process
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* disclosed, or represents that its use would not infringe privately owned
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* rights.
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*
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* Stanford disclaimer of liability
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* --------------------------------
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* Stanford University makes no representations or warranties, express or
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* implied, nor assumes any liability for the use of this software.
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*
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* Stanford disclaimer of copyright
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* --------------------------------
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* Stanford University, owner of the copyright, hereby disclaims its
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* copyright and all other rights in this software. Hence, anyone may
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* freely use it for any purpose without restriction.
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*
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* Maintenance of notices
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* ----------------------
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* In the interest of clarity regarding the origin and status of this
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* SLAC software, this and all the preceding Stanford University notices
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* are to remain affixed to any copy or derivative of this software made
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* or distributed by the recipient and are to be affixed to any copy of
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* software made or distributed by the recipient that contains a copy or
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* derivative of this software.
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*
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* ------------------ SLAC Software Notices, Set 4 OTT.002a, 2004 FEB 03
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*/
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#include <bsp.h>
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#include <stdint.h>
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#ifdef BSP_IDLE_TASK_BODY
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/* Provide an idle-task body which switches the
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* CPU into power-save mode when idle. Any exception
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* (including an interrupt/external-exception)
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* wakes it up.
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*
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* IIRC - this cannot be used on real hardware due
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* to errata on many chips which is a real
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* pity. However, when used under qemu it
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* saves host-CPU cycles.
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* While qemu-0.12.4 needed to be patched
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* (would otherwise hang because an exception
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* didn't clear MSR_POW) qemu-0.14.1 seems
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* to work fine.
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*/
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#include <rtems/powerpc/registers.h>
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#include <libcpu/cpuIdent.h>
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#include <libcpu/spr.h>
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SPR_RW(HID0)
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void *
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bsp_ppc_idle_task_body(uintptr_t ignored)
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{
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uint32_t msr;
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switch ( current_ppc_cpu ) {
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case PPC_7400:
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case PPC_7455:
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case PPC_7457:
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/* Must enable NAP mode in HID0 for MSR_POW to work */
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_write_HID0( _read_HID0() | HID0_NAP );
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break;
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default:
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break;
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}
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for ( ;; ) {
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_CPU_MSR_GET(msr);
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msr |= MSR_POW;
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asm volatile(
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"1: sync \n"
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" mtmsr %0 \n"
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" isync \n"
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" b 1b \n"
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::"r"(msr)
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);
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}
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return 0;
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}
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#endif
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