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For scalability and performance reasons, we want the tick broadcast IPIs to be handled as efficiently as possible. Fixed IPI messages are one of the most efficient mechanisms available - they are faster than the smp_call_function mechanism because the IPI handlers are fixed and hence they don't involve costly operations such as adding IPI handlers to the target CPU's function queue, acquiring locks for synchronization etc. Luckily we have an unused IPI message slot, so use that to implement tick broadcast IPIs efficiently. Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> [Functions renamed to tick_broadcast* and Changelog modified by Preeti U. Murthy<preeti@linux.vnet.ibm.com>] Signed-off-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com> Acked-by: Geoff Levand <geoff@infradead.org> [For the PS3 part] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
135 lines
3.1 KiB
C
135 lines
3.1 KiB
C
/*
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* PS3 SMP routines.
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*
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* Copyright (C) 2006 Sony Computer Entertainment Inc.
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* Copyright 2006 Sony Corp.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/kernel.h>
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#include <linux/smp.h>
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#include <asm/machdep.h>
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#include <asm/udbg.h>
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#include "platform.h"
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#if defined(DEBUG)
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#define DBG udbg_printf
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#else
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#define DBG pr_debug
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#endif
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/**
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* ps3_ipi_virqs - a per cpu array of virqs for ipi use
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*/
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#define MSG_COUNT 4
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static DEFINE_PER_CPU(unsigned int [MSG_COUNT], ps3_ipi_virqs);
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static void ps3_smp_message_pass(int cpu, int msg)
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{
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int result;
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unsigned int virq;
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if (msg >= MSG_COUNT) {
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DBG("%s:%d: bad msg: %d\n", __func__, __LINE__, msg);
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return;
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}
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virq = per_cpu(ps3_ipi_virqs, cpu)[msg];
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result = ps3_send_event_locally(virq);
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if (result)
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DBG("%s:%d: ps3_send_event_locally(%d, %d) failed"
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" (%d)\n", __func__, __LINE__, cpu, msg, result);
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}
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static int __init ps3_smp_probe(void)
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{
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int cpu;
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for (cpu = 0; cpu < 2; cpu++) {
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int result;
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unsigned int *virqs = per_cpu(ps3_ipi_virqs, cpu);
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int i;
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DBG(" -> %s:%d: (%d)\n", __func__, __LINE__, cpu);
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/*
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* Check assumptions on ps3_ipi_virqs[] indexing. If this
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* check fails, then a different mapping of PPC_MSG_
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* to index needs to be setup.
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*/
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BUILD_BUG_ON(PPC_MSG_CALL_FUNCTION != 0);
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BUILD_BUG_ON(PPC_MSG_RESCHEDULE != 1);
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BUILD_BUG_ON(PPC_MSG_TICK_BROADCAST != 2);
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BUILD_BUG_ON(PPC_MSG_DEBUGGER_BREAK != 3);
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for (i = 0; i < MSG_COUNT; i++) {
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result = ps3_event_receive_port_setup(cpu, &virqs[i]);
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if (result)
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continue;
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DBG("%s:%d: (%d, %d) => virq %u\n",
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__func__, __LINE__, cpu, i, virqs[i]);
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result = smp_request_message_ipi(virqs[i], i);
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if (result)
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virqs[i] = NO_IRQ;
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else
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ps3_register_ipi_irq(cpu, virqs[i]);
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}
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ps3_register_ipi_debug_brk(cpu, virqs[PPC_MSG_DEBUGGER_BREAK]);
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DBG(" <- %s:%d: (%d)\n", __func__, __LINE__, cpu);
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}
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return 2;
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}
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void ps3_smp_cleanup_cpu(int cpu)
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{
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unsigned int *virqs = per_cpu(ps3_ipi_virqs, cpu);
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int i;
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DBG(" -> %s:%d: (%d)\n", __func__, __LINE__, cpu);
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for (i = 0; i < MSG_COUNT; i++) {
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/* Can't call free_irq from interrupt context. */
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ps3_event_receive_port_destroy(virqs[i]);
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virqs[i] = NO_IRQ;
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}
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DBG(" <- %s:%d: (%d)\n", __func__, __LINE__, cpu);
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}
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static struct smp_ops_t ps3_smp_ops = {
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.probe = ps3_smp_probe,
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.message_pass = ps3_smp_message_pass,
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.kick_cpu = smp_generic_kick_cpu,
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};
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void smp_init_ps3(void)
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{
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DBG(" -> %s\n", __func__);
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smp_ops = &ps3_smp_ops;
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DBG(" <- %s\n", __func__);
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}
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