arch/arm/kernel/smp_scu.c

Source file repositories/reference/linux-study-clean/arch/arm/kernel/smp_scu.c

File Facts

System
Linux kernel
Corpus path
arch/arm/kernel/smp_scu.c
Extension
.c
Size
3043 bytes
Lines
125
Domain
Architecture Layer
Bucket
arch/arm
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/arm/kernel/smp_scu.c
 *
 *  Copyright (C) 2002 ARM Ltd.
 *  All Rights Reserved
 */
#include <linux/init.h>
#include <linux/io.h>

#include <asm/smp_plat.h>
#include <asm/smp_scu.h>
#include <asm/cacheflush.h>
#include <asm/cputype.h>

#define SCU_CTRL		0x00
#define SCU_ENABLE		(1 << 0)
#define SCU_STANDBY_ENABLE	(1 << 5)
#define SCU_CONFIG		0x04
#define SCU_CPU_STATUS		0x08
#define SCU_CPU_STATUS_MASK	GENMASK(1, 0)
#define SCU_INVALIDATE		0x0c
#define SCU_FPGA_REVISION	0x10

#ifdef CONFIG_SMP
/*
 * Get the number of CPU cores from the SCU configuration
 */
unsigned int __init scu_get_core_count(void __iomem *scu_base)
{
	unsigned int ncores = readl_relaxed(scu_base + SCU_CONFIG);
	return (ncores & 0x03) + 1;
}

/*
 * Enable the SCU
 */
void scu_enable(void __iomem *scu_base)
{
	u32 scu_ctrl;

#ifdef CONFIG_ARM_ERRATA_764369
	/* Cortex-A9 only */
	if ((read_cpuid_id() & 0xff0ffff0) == 0x410fc090) {
		scu_ctrl = readl_relaxed(scu_base + 0x30);
		if (!(scu_ctrl & 1))
			writel_relaxed(scu_ctrl | 0x1, scu_base + 0x30);
	}
#endif

	scu_ctrl = readl_relaxed(scu_base + SCU_CTRL);
	/* already enabled? */
	if (scu_ctrl & SCU_ENABLE)
		return;

	scu_ctrl |= SCU_ENABLE;

	/* Cortex-A9 earlier than r2p0 has no standby bit in SCU */
	if ((read_cpuid_id() & 0xff0ffff0) == 0x410fc090 &&
	    (read_cpuid_id() & 0x00f0000f) >= 0x00200000)
		scu_ctrl |= SCU_STANDBY_ENABLE;

	writel_relaxed(scu_ctrl, scu_base + SCU_CTRL);

	/*
	 * Ensure that the data accessed by CPU0 before the SCU was
	 * initialised is visible to the other CPUs.
	 */
	flush_cache_all();
}
#endif

static int scu_set_power_mode_internal(void __iomem *scu_base,
				       unsigned int logical_cpu,
				       unsigned int mode)
{
	unsigned int val;
	int cpu = MPIDR_AFFINITY_LEVEL(cpu_logical_map(logical_cpu), 0);

	if (mode > 3 || mode == 1 || cpu > 3)
		return -EINVAL;

	val = readb_relaxed(scu_base + SCU_CPU_STATUS + cpu);
	val &= ~SCU_CPU_STATUS_MASK;
	val |= mode;
	writeb_relaxed(val, scu_base + SCU_CPU_STATUS + cpu);

	return 0;
}

Annotation

Implementation Notes