arch/powerpc/sysdev/mmio_nvram.c

Source file repositories/reference/linux-study-clean/arch/powerpc/sysdev/mmio_nvram.c

File Facts

System
Linux kernel
Corpus path
arch/powerpc/sysdev/mmio_nvram.c
Extension
.c
Size
3177 bytes
Lines
146
Domain
Architecture Layer
Bucket
arch/powerpc
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-or-later
/*
 * memory mapped NVRAM
 *
 * (C) Copyright IBM Corp. 2005
 *
 * Authors : Utz Bacher <utz.bacher@de.ibm.com>
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/of_address.h>
#include <linux/spinlock.h>
#include <linux/types.h>

#include <asm/machdep.h>
#include <asm/nvram.h>

static void __iomem *mmio_nvram_start;
static long mmio_nvram_len;
static DEFINE_SPINLOCK(mmio_nvram_lock);

static ssize_t mmio_nvram_read(char *buf, size_t count, loff_t *index)
{
	unsigned long flags;

	if (*index >= mmio_nvram_len)
		return 0;
	if (*index + count > mmio_nvram_len)
		count = mmio_nvram_len - *index;

	spin_lock_irqsave(&mmio_nvram_lock, flags);

	memcpy_fromio(buf, mmio_nvram_start + *index, count);

	spin_unlock_irqrestore(&mmio_nvram_lock, flags);
	
	*index += count;
	return count;
}

static unsigned char mmio_nvram_read_val(int addr)
{
	unsigned long flags;
	unsigned char val;

	if (addr >= mmio_nvram_len)
		return 0xff;

	spin_lock_irqsave(&mmio_nvram_lock, flags);

	val = ioread8(mmio_nvram_start + addr);

	spin_unlock_irqrestore(&mmio_nvram_lock, flags);

	return val;
}

static ssize_t mmio_nvram_write(char *buf, size_t count, loff_t *index)
{
	unsigned long flags;

	if (*index >= mmio_nvram_len)
		return 0;
	if (*index + count > mmio_nvram_len)
		count = mmio_nvram_len - *index;

	spin_lock_irqsave(&mmio_nvram_lock, flags);

	memcpy_toio(mmio_nvram_start + *index, buf, count);

	spin_unlock_irqrestore(&mmio_nvram_lock, flags);
	
	*index += count;
	return count;
}

static void mmio_nvram_write_val(int addr, unsigned char val)
{
	unsigned long flags;

	if (addr < mmio_nvram_len) {
		spin_lock_irqsave(&mmio_nvram_lock, flags);

		iowrite8(val, mmio_nvram_start + addr);

		spin_unlock_irqrestore(&mmio_nvram_lock, flags);
	}
}

Annotation

Implementation Notes