arch/sh/drivers/pci/ops-sh4.c

Source file repositories/reference/linux-study-clean/arch/sh/drivers/pci/ops-sh4.c

File Facts

System
Linux kernel
Corpus path
arch/sh/drivers/pci/ops-sh4.c
Extension
.c
Size
2385 bytes
Lines
106
Domain
Architecture Layer
Bucket
arch/sh
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
/*
 * Generic SH-4 / SH-4A PCIC operations (SH7751, SH7780).
 *
 * Copyright (C) 2002 - 2009  Paul Mundt
 */
#include <linux/pci.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <asm/addrspace.h>
#include "pci-sh4.h"

/*
 * Direct access to PCI hardware...
 */
#define CONFIG_CMD(bus, devfn, where) \
	(0x80000000 | (bus->number << 16) | (devfn << 8) | (where & ~3))

/*
 * Functions for accessing PCI configuration space with type 1 accesses
 */
static int sh4_pci_read(struct pci_bus *bus, unsigned int devfn,
			   int where, int size, u32 *val)
{
	struct pci_channel *chan = bus->sysdata;
	unsigned long flags;
	u32 data;

	/*
	 * PCIPDR may only be accessed as 32 bit words,
	 * so we must do byte alignment by hand
	 */
	raw_spin_lock_irqsave(&pci_config_lock, flags);
	pci_write_reg(chan, CONFIG_CMD(bus, devfn, where), SH4_PCIPAR);
	data = pci_read_reg(chan, SH4_PCIPDR);
	raw_spin_unlock_irqrestore(&pci_config_lock, flags);

	switch (size) {
	case 1:
		*val = (data >> ((where & 3) << 3)) & 0xff;
		break;
	case 2:
		*val = (data >> ((where & 2) << 3)) & 0xffff;
		break;
	case 4:
		*val = data;
		break;
	default:
		return PCIBIOS_FUNC_NOT_SUPPORTED;
	}

	return PCIBIOS_SUCCESSFUL;
}

/*
 * Since SH4 only does 32bit access we'll have to do a read,
 * mask,write operation.
 * We'll allow an odd byte offset, though it should be illegal.
 */
static int sh4_pci_write(struct pci_bus *bus, unsigned int devfn,
			 int where, int size, u32 val)
{
	struct pci_channel *chan = bus->sysdata;
	unsigned long flags;
	int shift;
	u32 data;

	raw_spin_lock_irqsave(&pci_config_lock, flags);
	pci_write_reg(chan, CONFIG_CMD(bus, devfn, where), SH4_PCIPAR);
	data = pci_read_reg(chan, SH4_PCIPDR);
	raw_spin_unlock_irqrestore(&pci_config_lock, flags);

	switch (size) {
	case 1:
		shift = (where & 3) << 3;
		data &= ~(0xff << shift);
		data |= ((val & 0xff) << shift);
		break;
	case 2:
		shift = (where & 2) << 3;
		data &= ~(0xffff << shift);
		data |= ((val & 0xffff) << shift);
		break;
	case 4:
		data = val;
		break;
	default:
		return PCIBIOS_FUNC_NOT_SUPPORTED;
	}

Annotation

Implementation Notes