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89b3098703
Current arch_cpu_idle() is called with IRQs disabled, but will return with IRQs enabled. However, the very first thing the generic code does after calling arch_cpu_idle() is raw_local_irq_disable(). This means that architectures that can idle with IRQs disabled end up doing a pointless 'enable-disable' dance. Therefore, push this IRQ disabling into the idle function, meaning that those architectures can avoid the pointless IRQ state flipping. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Tony Lindgren <tony@atomide.com> Tested-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com> Acked-by: Mark Rutland <mark.rutland@arm.com> [arm64] Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Guo Ren <guoren@kernel.org> Acked-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20230112195540.618076436@infradead.org
98 lines
2.3 KiB
C
98 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* leon_pmc.c: LEON Power-down cpu_idle() handler
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*
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* Copyright (C) 2011 Daniel Hellstrom (daniel@gaisler.com) Aeroflex Gaisler AB
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*/
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#include <linux/init.h>
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#include <linux/pm.h>
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#include <asm/leon_amba.h>
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#include <asm/cpu_type.h>
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#include <asm/leon.h>
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#include <asm/processor.h>
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/* List of Systems that need fixup instructions around power-down instruction */
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static unsigned int pmc_leon_fixup_ids[] = {
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AEROFLEX_UT699,
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GAISLER_GR712RC,
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LEON4_NEXTREME1,
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0
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};
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static int pmc_leon_need_fixup(void)
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{
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unsigned int systemid = amba_system_id >> 16;
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unsigned int *id;
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id = &pmc_leon_fixup_ids[0];
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while (*id != 0) {
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if (*id == systemid)
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return 1;
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id++;
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}
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return 0;
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}
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/*
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* CPU idle callback function for systems that need some extra handling
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* See .../arch/sparc/kernel/process.c
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*/
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static void pmc_leon_idle_fixup(void)
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{
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/* Prepare an address to a non-cachable region. APB is always
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* none-cachable. One instruction is executed after the Sleep
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* instruction, we make sure to read the bus and throw away the
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* value by accessing a non-cachable area, also we make sure the
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* MMU does not get a TLB miss here by using the MMU BYPASS ASI.
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*/
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register unsigned int address = (unsigned int)leon3_irqctrl_regs;
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/* Interrupts need to be enabled to not hang the CPU */
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raw_local_irq_enable();
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__asm__ __volatile__ (
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"wr %%g0, %%asr19\n"
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"lda [%0] %1, %%g0\n"
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:
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: "r"(address), "i"(ASI_LEON_BYPASS));
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raw_local_irq_disable();
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}
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/*
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* CPU idle callback function
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* See .../arch/sparc/kernel/process.c
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*/
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static void pmc_leon_idle(void)
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{
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/* Interrupts need to be enabled to not hang the CPU */
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raw_local_irq_enable();
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/* For systems without power-down, this will be no-op */
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__asm__ __volatile__ ("wr %g0, %asr19\n\t");
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raw_local_irq_disable();
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}
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/* Install LEON Power Down function */
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static int __init leon_pmc_install(void)
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{
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if (sparc_cpu_model == sparc_leon) {
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/* Assign power management IDLE handler */
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if (pmc_leon_need_fixup())
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sparc_idle = pmc_leon_idle_fixup;
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else
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sparc_idle = pmc_leon_idle;
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printk(KERN_INFO "leon: power management initialized\n");
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}
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return 0;
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}
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/* This driver is not critical to the boot process, don't care
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* if initialized late.
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*/
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late_initcall(leon_pmc_install);
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