xref: /kernel/linux/linux-5.10/arch/mips/pci/ops-msc.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 1999, 2000, 2004, 2005	 MIPS Technologies, Inc.
 *    All rights reserved.
 *    Authors: Carsten Langgaard <carstenl@mips.com>
 *	       Maciej W. Rozycki <macro@mips.com>
 * Copyright (C) 2005 Ralf Baechle (ralf@linux-mips.org)
 *
 * MIPS boards specific PCI support.
 */
#include <linux/types.h>
#include <linux/pci.h>
#include <linux/kernel.h>

#include <asm/mips-boards/msc01_pci.h>

#define PCI_ACCESS_READ	 0
#define PCI_ACCESS_WRITE 1

/*
 *  PCI configuration cycle AD bus definition
 */
/* Type 0 */
#define PCI_CFG_TYPE0_REG_SHF		0
#define PCI_CFG_TYPE0_FUNC_SHF		8

/* Type 1 */
#define PCI_CFG_TYPE1_REG_SHF		0
#define PCI_CFG_TYPE1_FUNC_SHF		8
#define PCI_CFG_TYPE1_DEV_SHF		11
#define PCI_CFG_TYPE1_BUS_SHF		16

static int msc_pcibios_config_access(unsigned char access_type,
	struct pci_bus *bus, unsigned int devfn, int where, u32 * data)
{
	unsigned char busnum = bus->number;
	u32 intr;

	/* Clear status register bits. */
	MSC_WRITE(MSC01_PCI_INTSTAT,
		  (MSC01_PCI_INTCFG_MA_BIT | MSC01_PCI_INTCFG_TA_BIT));

	MSC_WRITE(MSC01_PCI_CFGADDR,
		  ((busnum << MSC01_PCI_CFGADDR_BNUM_SHF) |
		   (PCI_SLOT(devfn) << MSC01_PCI_CFGADDR_DNUM_SHF) |
		   (PCI_FUNC(devfn) << MSC01_PCI_CFGADDR_FNUM_SHF) |
		   ((where / 4) << MSC01_PCI_CFGADDR_RNUM_SHF)));

	/* Perform access */
	if (access_type == PCI_ACCESS_WRITE)
		MSC_WRITE(MSC01_PCI_CFGDATA, *data);
	else
		MSC_READ(MSC01_PCI_CFGDATA, *data);

	/* Detect Master/Target abort */
	MSC_READ(MSC01_PCI_INTSTAT, intr);
	if (intr & (MSC01_PCI_INTCFG_MA_BIT | MSC01_PCI_INTCFG_TA_BIT)) {
		/* Error occurred */

		/* Clear bits */
		MSC_WRITE(MSC01_PCI_INTSTAT,
			  (MSC01_PCI_INTCFG_MA_BIT | MSC01_PCI_INTCFG_TA_BIT));

		return -1;
	}

	return 0;
}


/*
 * We can't address 8 and 16 bit words directly.  Instead we have to
 * read/write a 32bit word and mask/modify the data we actually want.
 */
static int msc_pcibios_read(struct pci_bus *bus, unsigned int devfn,
			     int where, int size, u32 * val)
{
	u32 data = 0;

	if ((size == 2) && (where & 1))
		return PCIBIOS_BAD_REGISTER_NUMBER;
	else if ((size == 4) && (where & 3))
		return PCIBIOS_BAD_REGISTER_NUMBER;

	if (msc_pcibios_config_access(PCI_ACCESS_READ, bus, devfn, where,
				      &data))
		return -1;

	if (size == 1)
		*val = (data >> ((where & 3) << 3)) & 0xff;
	else if (size == 2)
		*val = (data >> ((where & 3) << 3)) & 0xffff;
	else
		*val = data;

	return PCIBIOS_SUCCESSFUL;
}

static int msc_pcibios_write(struct pci_bus *bus, unsigned int devfn,
			      int where, int size, u32 val)
{
	u32 data = 0;

	if ((size == 2) && (where & 1))
		return PCIBIOS_BAD_REGISTER_NUMBER;
	else if ((size == 4) && (where & 3))
		return PCIBIOS_BAD_REGISTER_NUMBER;

	if (size == 4)
		data = val;
	else {
		if (msc_pcibios_config_access(PCI_ACCESS_READ, bus, devfn,
					      where, &data))
			return -1;

		if (size == 1)
			data = (data & ~(0xff << ((where & 3) << 3))) |
				(val << ((where & 3) << 3));
		else if (size == 2)
			data = (data & ~(0xffff << ((where & 3) << 3))) |
				(val << ((where & 3) << 3));
	}

	if (msc_pcibios_config_access(PCI_ACCESS_WRITE, bus, devfn, where,
				       &data))
		return -1;

	return PCIBIOS_SUCCESSFUL;
}

struct pci_ops msc_pci_ops = {
	.read = msc_pcibios_read,
	.write = msc_pcibios_write
};