// SPDX-License-Identifier: GPL-2.0
/*
 *	linux/arch/alpha/kernel/core_mcpcia.c
 *
 * Based on code written by David A Rusling (david.rusling@reo.mts.dec.com).
 *
 * Code common to all MCbus-PCI Adaptor core logic chipsets
 */

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

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

#include <asm/ptrace.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.
 */

/*
 * BIOS32-style PCI interface:
 */

#define DEBUG_CFG 0

#if DEBUG_CFG
# define DBG_CFG(args)	printk args
#else
# define DBG_CFG(args)
#endif

/*
 * Given a bus, device, and function number, compute resulting
 * configuration space address and setup the MCPCIA_HAXR2 register
 * accordingly.  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 unsigned int
conf_read(unsigned long addr, unsigned char type1,
	  struct pci_controller *hose)
{
	unsigned long flags;
	unsigned long mid = MCPCIA_HOSE2MID(hose->index);
	unsigned int stat0, value, cpu;

	cpu = smp_processor_id();

	local_irq_save(flags);

	DBG_CFG(("conf_read(addr=0x%lx, type1=%d, hose=%d)\n",
		 addr, type1, mid));

	/* Reset status register to avoid losing errors.  */
	stat0 = *(vuip)MCPCIA_CAP_ERR(mid);
	*(vuip)MCPCIA_CAP_ERR(mid) = stat0;
	mb();
	*(vuip)MCPCIA_CAP_ERR(mid);
	DBG_CFG(("conf_read: MCPCIA_CAP_ERR(%d) was 0x%x\n", mid, stat0));

	mb();
	draina();
	mcheck_expected(cpu) = 1;
	mcheck_taken(cpu) = 0;
	mcheck_extra(cpu) = mid;
	mb();

	/* Access configuration space.  */
	value = *((vuip)addr);
	mb();
	mb();  /* magic */

	if (mcheck_taken(cpu)) {
		mcheck_taken(cpu) = 0;
		value = 0xffffffffU;
		mb();
	}
	mcheck_expected(cpu) = 0;
	mb();

	DBG_CFG(("conf_read(): finished\n"));

	local_irq_restore(flags);
	return value;
}

static void
conf_write(unsigned long addr, unsigned int value, unsigned char type1,
	   struct pci_controller *hose)
{
	unsigned long flags;
	unsigned long mid = MCPCIA_HOSE2MID(hose->index);
	unsigned int stat0, cpu;

	cpu = smp_processor_id();

	local_irq_save(flags);	/* avoid getting hit by machine check */

	/* Reset status register to avoid losing errors.  */
	stat0 = *(vuip)MCPCIA_CAP_ERR(mid);
	*(vuip)MCPCIA_CAP_ERR(mid) = stat0; mb();
	*(vuip)MCPCIA_CAP_ERR(mid);
	DBG_CFG(("conf_write: MCPCIA CAP_ERR(%d) was 0x%x\n", mid, stat0));

	draina();
	mcheck_expected(cpu) = 1;
	mcheck_extra(cpu) = mid;
	mb();

	/* Access configuration space.  */
	*((vuip)addr) = value;
	mb();
	mb();  /* magic */
	*(vuip)MCPCIA_CAP_ERR(mid); /* read to force the write */
	mcheck_expected(cpu) = 0;
	mb();

	DBG_CFG(("conf_write(): finished\n"));
	local_irq_restore(flags);
}

static int
mk_conf_addr(struct pci_bus *pbus, unsigned int devfn, int where,
	     struct pci_controller *hose, unsigned long *pci_addr,
	     unsigned char *type1)
{
	u8 bus = pbus->number;
	unsigned long addr;

	DBG_CFG(("mk_conf_addr(bus=%d,devfn=0x%x,hose=%d,where=0x%x,"
		 " pci_addr=0x%p, type1=0x%p)\n",
		 bus, devfn, hose->index, where, pci_addr, type1));

	/* Type 1 configuration cycle for *ALL* busses.  */
	*type1 = 1;

	if (!pbus->parent) /* No parent means peer PCI bus. */
		bus = 0;
	addr = (bus << 16) | (devfn << 8) | (where);
	addr <<= 5; /* swizzle for SPARSE */
	addr |= hose->config_space_base;

	*pci_addr = addr;
	DBG_CFG(("mk_conf_addr: returning pci_addr 0x%lx\n", addr));
	return 0;
}

static int
mcpcia_read_config(struct pci_bus *bus, unsigned int devfn, int where,
		   int size, u32 *value)
{
	struct pci_controller *hose = bus->sysdata;
	unsigned long addr, w;
	unsigned char type1;

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

	addr |= (size - 1) * 8;
	w = conf_read(addr, type1, hose);
	switch (size) {
	case 1:
		*value = __kernel_extbl(w, where & 3);
		break;
	case 2:
		*value = __kernel_extwl(w, where & 3);
		break;
	case 4:
		*value = w;
		break;
	}
	return PCIBIOS_SUCCESSFUL;
}

static int
mcpcia_write_config(struct pci_bus *bus, unsigned int devfn, int where,
		    int size, u32 value)
{
	struct pci_controller *hose = bus->sysdata;
	unsigned long addr;
	unsigned char type1;

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

	addr |= (size - 1) * 8;
	value = __kernel_insql(value, where & 3);
	conf_write(addr, value, type1, hose);
	return PCIBIOS_SUCCESSFUL;
}

struct pci_ops mcpcia_pci_ops = 
{
	.read =		mcpcia_read_config,
	.write =	mcpcia_write_config,
};
