// SPDX-License-Identifier: GPL-2.0
/*
 *	linux/arch/alpha/kernel/core_cia.c
 *
 * Written by David A Rusling (david.rusling@reo.mts.dec.com).
 * December 1995.
 *
 *	Copyright (C) 1995  David A Rusling
 *	Copyright (C) 1997, 1998  Jay Estabrook
 *	Copyright (C) 1998, 1999, 2000  Richard Henderson
 *
 * Code common to all CIA core logic chips.
 */

#define __EXTERN_INLINE inline
#include <asm/io.h>
#include <asm/core_cia.h>
#undef __EXTERN_INLINE

#include <linux/types.h>
#include <linux/pci.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/memblock.h>

#include <asm/ptrace.h>
#include <asm/mce.h>

#include "proto.h"
#include "pci_impl.h"


/*
 * NOTE: Herein lie back-to-back mb instructions.  They are magic. 
 * One plausible explanation is that the i/o controller does not properly
 * handle the system transaction.  Another involves timing.  Ho hum.
 */

#define DEBUG_CONFIG 0
#if DEBUG_CONFIG
# define DBGC(args)	printk args
#else
# define DBGC(args)
#endif

#define vip	volatile int  *

/*
 * Given a bus, device, and function number, compute resulting
 * configuration space address.  It is therefore not safe to have
 * concurrent invocations to configuration space access routines, but
 * there really shouldn't be any need for this.
 *
 * Type 0:
 *
 *  3 3|3 3 2 2|2 2 2 2|2 2 2 2|1 1 1 1|1 1 1 1|1 1 
 *  3 2|1 0 9 8|7 6 5 4|3 2 1 0|9 8 7 6|5 4 3 2|1 0 9 8|7 6 5 4|3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | | |D|D|D|D|D|D|D|D|D|D|D|D|D|D|D|D|D|D|D|D|D|F|F|F|R|R|R|R|R|R|0|0|
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 *	31:11	Device select bit.
 * 	10:8	Function number
 * 	 7:2	Register number
 *
 * Type 1:
 *
 *  3 3|3 3 2 2|2 2 2 2|2 2 2 2|1 1 1 1|1 1 1 1|1 1 
 *  3 2|1 0 9 8|7 6 5 4|3 2 1 0|9 8 7 6|5 4 3 2|1 0 9 8|7 6 5 4|3 2 1 0
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * | | | | | | | | | | |B|B|B|B|B|B|B|B|D|D|D|D|D|F|F|F|R|R|R|R|R|R|0|1|
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 *	31:24	reserved
 *	23:16	bus number (8 bits = 128 possible buses)
 *	15:11	Device number (5 bits)
 *	10:8	function number
 *	 7:2	register number
 *  
 * Notes:
 *	The function number selects which function of a multi-function device 
 *	(e.g., SCSI and Ethernet).
 * 
 *	The register selects a DWORD (32 bit) register offset.  Hence it
 *	doesn't get shifted by 2 bits as we want to "drop" the bottom two
 *	bits.
 */

static int
mk_conf_addr(struct pci_bus *bus_dev, unsigned int device_fn, int where,
	     unsigned long *pci_addr, unsigned char *type1)
{
	u8 bus = bus_dev->number;

	*type1 = (bus != 0);
	*pci_addr = (bus << 16) | (device_fn << 8) | where;

	DBGC(("mk_conf_addr(bus=%d ,device_fn=0x%x, where=0x%x,"
	      " returning address 0x%p\n"
	      bus, device_fn, where, *pci_addr));

	return 0;
}

static unsigned int
conf_read(unsigned long addr, unsigned char type1)
{
	unsigned long flags;
	int stat0, value;
	int cia_cfg = 0;

	DBGC(("conf_read(addr=0x%lx, type1=%d) ", addr, type1));
	local_irq_save(flags);

	/* Reset status register to avoid losing errors.  */
	stat0 = *(vip)CIA_IOC_CIA_ERR;
	*(vip)CIA_IOC_CIA_ERR = stat0;
	mb();
	*(vip)CIA_IOC_CIA_ERR; /* re-read to force write */

	/* If Type1 access, must set CIA CFG. */
	if (type1) {
		cia_cfg = *(vip)CIA_IOC_CFG;
		*(vip)CIA_IOC_CFG = (cia_cfg & ~3) | 1;
		mb();
		*(vip)CIA_IOC_CFG;
	}

	mb();
	draina();
	mcheck_expected(0) = 1;
	mcheck_taken(0) = 0;
	mb();

	/* Access configuration space.  */
	value = *(vip)addr;
	mb();
	mb();  /* magic */
	if (mcheck_taken(0)) {
		mcheck_taken(0) = 0;
		value = 0xffffffff;
		mb();
	}
	mcheck_expected(0) = 0;
	mb();

	/* If Type1 access, must reset IOC CFG so normal IO space ops work.  */
	if (type1) {
		*(vip)CIA_IOC_CFG = cia_cfg;
		mb();
		*(vip)CIA_IOC_CFG;
	}

	local_irq_restore(flags);
	DBGC(("done\n"));

	return value;
}

static void
conf_write(unsigned long addr, unsigned int value, unsigned char type1)
{
	unsigned long flags;
	int stat0, cia_cfg = 0;

	DBGC(("conf_write(addr=0x%lx, type1=%d) ", addr, type1));
	local_irq_save(flags);

	/* Reset status register to avoid losing errors.  */
	stat0 = *(vip)CIA_IOC_CIA_ERR;
	*(vip)CIA_IOC_CIA_ERR = stat0;
	mb();
	*(vip)CIA_IOC_CIA_ERR; /* re-read to force write */

	/* If Type1 access, must set CIA CFG.  */
	if (type1) {
		cia_cfg = *(vip)CIA_IOC_CFG;
		*(vip)CIA_IOC_CFG = (cia_cfg & ~3) | 1;
		mb();
		*(vip)CIA_IOC_CFG;
	}

	mb();
	draina();
	mcheck_expected(0) = 1;
	mcheck_taken(0) = 0;
	mb();

	/* Access configuration space.  */
	*(vip)addr = value;
	mb();
	*(vip)addr; /* read back to force the write */

	mcheck_expected(0) = 0;
	mb();

	/* If Type1 access, must reset IOC CFG so normal IO space ops work.  */
	if (type1) {
		*(vip)CIA_IOC_CFG = cia_cfg;
		mb();
		*(vip)CIA_IOC_CFG;
	}

	local_irq_restore(flags);
	DBGC(("done\n"));
}

static int 
cia_read_config(struct pci_bus *bus, unsigned int devfn, int where, int size,
		u32 *value)
{
	unsigned long addr, pci_addr;
	long mask;
	unsigned char type1;
	int shift;

	if (mk_conf_addr(bus, devfn, where, &pci_addr, &type1))
		return PCIBIOS_DEVICE_NOT_FOUND;

	mask = (size - 1) * 8;
	shift = (where & 3) * 8;
	addr = (pci_addr << 5) + mask + CIA_CONF;
	*value = conf_read(addr, type1) >> (shift);
	return PCIBIOS_SUCCESSFUL;
}

static int 
cia_write_config(struct pci_bus *bus, unsigned int devfn, int where, int size,
		 u32 value)
{
	unsigned long addr, pci_addr;
	long mask;
	unsigned char type1;

	if (mk_conf_addr(bus, devfn, where, &pci_addr, &type1))
		return PCIBIOS_DEVICE_NOT_FOUND;

	mask = (size - 1) * 8;
	addr = (pci_addr << 5) + mask + CIA_CONF;
	conf_write(addr, value << ((where & 3) * 8), type1);
	return PCIBIOS_SUCCESSFUL;
}

struct pci_ops cia_pci_ops = 
{
	.read = 	cia_read_config,
	.write =	cia_write_config,
};
