lib/iomap.c

Source file repositories/reference/linux-study-clean/lib/iomap.c

File Facts

System
Linux kernel
Corpus path
lib/iomap.c
Extension
.c
Size
11312 bytes
Lines
430
Domain
Kernel Services
Bucket
lib
Inferred role
Kernel Services: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Shared kernel service surface used by multiple subsystems, including helpers, cryptography, virtualization support, and async I/O infrastructure.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * Implement the default iomap interfaces
 *
 * (C) Copyright 2004 Linus Torvalds
 */
#include <linux/pci.h>
#include <linux/io.h>
#include <linux/kmsan-checks.h>

#include <linux/export.h>

/*
 * Read/write from/to an (offsettable) iomem cookie. It might be a PIO
 * access or a MMIO access, these functions don't care. The info is
 * encoded in the hardware mapping set up by the mapping functions
 * (or the cookie itself, depending on implementation and hw).
 *
 * The generic routines don't assume any hardware mappings, and just
 * encode the PIO/MMIO as part of the cookie. They coldly assume that
 * the MMIO IO mappings are not in the low address range.
 *
 * Architectures for which this is not true can't use this generic
 * implementation and should do their own copy.
 */

#ifndef HAVE_ARCH_PIO_SIZE
/*
 * We encode the physical PIO addresses (0-0xffff) into the
 * pointer by offsetting them with a constant (0x10000) and
 * assuming that all the low addresses are always PIO. That means
 * we can do some sanity checks on the low bits, and don't
 * need to just take things for granted.
 */
#define PIO_OFFSET	0x10000UL
#define PIO_MASK	0x0ffffUL
#define PIO_RESERVED	0x40000UL
#endif

static void bad_io_access(unsigned long port, const char *access)
{
	static int count = 10;
	if (count) {
		count--;
		WARN(1, KERN_ERR "Bad IO access at port %#lx (%s)\n", port, access);
	}
}

/*
 * Ugly macros are a way of life.
 */
#define IO_COND(addr, is_pio, is_mmio) do {			\
	unsigned long port = (unsigned long __force)addr;	\
	if (port >= PIO_RESERVED) {				\
		is_mmio;					\
	} else if (port > PIO_OFFSET) {				\
		port &= PIO_MASK;				\
		is_pio;						\
	} else							\
		bad_io_access(port, #is_pio );			\
} while (0)

#ifndef pio_read16be
#define pio_read16be(port) swab16(inw(port))
#define pio_read32be(port) swab32(inl(port))
#endif

#ifndef mmio_read16be
#define mmio_read16be(addr) swab16(readw(addr))
#define mmio_read32be(addr) swab32(readl(addr))
#define mmio_read64be(addr) swab64(readq(addr))
#endif

/*
 * Here and below, we apply __no_kmsan_checks to functions reading data from
 * hardware, to ensure that KMSAN marks their return values as initialized.
 */
__no_kmsan_checks
unsigned int ioread8(const void __iomem *addr)
{
	IO_COND(addr, return inb(port), return readb(addr));
	return 0xff;
}
__no_kmsan_checks
unsigned int ioread16(const void __iomem *addr)
{
	IO_COND(addr, return inw(port), return readw(addr));
	return 0xffff;
}
__no_kmsan_checks

Annotation

Implementation Notes