arch/arm64/kernel/smp_spin_table.c

Source file repositories/reference/linux-study-clean/arch/arm64/kernel/smp_spin_table.c

File Facts

System
Linux kernel
Corpus path
arch/arm64/kernel/smp_spin_table.c
Extension
.c
Size
3114 bytes
Lines
128
Domain
Architecture Layer
Bucket
arch/arm64
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
/*
 * Spin Table SMP initialisation
 *
 * Copyright (C) 2013 ARM Ltd.
 */

#include <linux/delay.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/smp.h>
#include <linux/types.h>
#include <linux/mm.h>

#include <asm/cacheflush.h>
#include <asm/cpu_ops.h>
#include <asm/cputype.h>
#include <asm/io.h>
#include <asm/smp_plat.h>

extern void secondary_holding_pen(void);
volatile unsigned long __section(".mmuoff.data.read")
secondary_holding_pen_release = INVALID_HWID;

static phys_addr_t cpu_release_addr[NR_CPUS];

/*
 * Write secondary_holding_pen_release in a way that is guaranteed to be
 * visible to all observers, irrespective of whether they're taking part
 * in coherency or not.  This is necessary for the hotplug code to work
 * reliably.
 */
static void write_pen_release(u64 val)
{
	void *start = (void *)&secondary_holding_pen_release;
	unsigned long size = sizeof(secondary_holding_pen_release);

	secondary_holding_pen_release = val;
	dcache_clean_inval_poc((unsigned long)start, (unsigned long)start + size);
}


static int smp_spin_table_cpu_init(unsigned int cpu)
{
	struct device_node *dn;
	int ret;

	dn = of_get_cpu_node(cpu, NULL);
	if (!dn)
		return -ENODEV;

	/*
	 * Determine the address from which the CPU is polling.
	 */
	ret = of_property_read_u64(dn, "cpu-release-addr",
				   &cpu_release_addr[cpu]);
	if (ret)
		pr_err("CPU %d: missing or invalid cpu-release-addr property\n",
		       cpu);

	of_node_put(dn);

	return ret;
}

static int smp_spin_table_cpu_prepare(unsigned int cpu)
{
	__le64 __iomem *release_addr;
	phys_addr_t pa_holding_pen = __pa_symbol(secondary_holding_pen);

	if (!cpu_release_addr[cpu])
		return -ENODEV;

	/*
	 * The cpu-release-addr may or may not be inside the linear mapping.
	 * As ioremap_cache will either give us a new mapping or reuse the
	 * existing linear mapping, we can use it to cover both cases. In
	 * either case the memory will be MT_NORMAL.
	 */
	release_addr = ioremap_cache(cpu_release_addr[cpu],
				     sizeof(*release_addr));
	if (!release_addr)
		return -ENOMEM;

	/*
	 * We write the release address as LE regardless of the native
	 * endianness of the kernel. Therefore, any boot-loaders that
	 * read this address need to convert this address to the
	 * boot-loader's endianness before jumping. This is mandated by
	 * the boot protocol.

Annotation

Implementation Notes