// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2006 PA Semi, Inc
 *
 * Authors: Kip Walker, PA Semi
 *	    Olof Johansson, PA Semi
 *
 * Maintained by: Olof Johansson <olof@lixom.net>
 *
 * Based on arch/powerpc/platforms/maple/pci.c
 */


#include <linux/kernel.h>
#include <linux/pci.h>

#include <asm/pci-bridge.h>
#include <asm/isa-bridge.h>
#include <asm/machdep.h>

#include <asm/ppc-pci.h>

#include "pasemi.h"

#define PA_PXP_CFA(bus, devfn, off) (((bus) << 20) | ((devfn) << 12) | (off))

static inline int pa_pxp_offset_valid(u8 bus, u8 devfn, int offset)
{
	/* Device 0 Function 0 is special: It's config space spans function 1 as
	 * well, so allow larger offset. It's really a two-function device but the
	 * second function does not probe.
	 */
	if (bus == 0 && devfn == 0)
		return offset < 8192;
	else
		return offset < 4096;
}

static void volatile __iomem *pa_pxp_cfg_addr(struct pci_controller *hose,
				       u8 bus, u8 devfn, int offset)
{
	return hose->cfg_data + PA_PXP_CFA(bus, devfn, offset);
}

static inline int is_root_port(int busno, int devfn)
{
	return ((busno == 0) && (PCI_FUNC(devfn) < 4) &&
		 ((PCI_SLOT(devfn) == 16) || (PCI_SLOT(devfn) == 17)));
}

static inline int is_5945_reg(int reg)
{
	return (((reg >= 0x18) && (reg < 0x34)) ||
		((reg >= 0x158) && (reg < 0x178)));
}

static int workaround_5945(struct pci_bus *bus, unsigned int devfn,
			   int offset, int len, u32 *val)
{
	struct pci_controller *hose;
	void volatile __iomem *addr, *dummy;
	int byte;
	u32 tmp;

	if (!is_root_port(bus->number, devfn) || !is_5945_reg(offset))
		return 0;

	hose = pci_bus_to_host(bus);

	addr = pa_pxp_cfg_addr(hose, bus->number, devfn, offset & ~0x3);
	byte = offset & 0x3;

	/* Workaround bug 5945: write 0 to a dummy register before reading,
	 * and write back what we read. We must read/write the full 32-bit
	 * contents so we need to shift and mask by hand.
	 */
	dummy = pa_pxp_cfg_addr(hose, bus->number, devfn, 0x10);
	out_le32(dummy, 0);
	tmp = in_le32(addr);
	out_le32(addr, tmp);

	switch (len) {
	case 1:
		*val = (tmp >> (8*byte)) & 0xff;
		break;
	case 2:
		if (byte == 0)
			*val = tmp & 0xffff;
		else
			*val = (tmp >> 16) & 0xffff;
		break;
	default:
		*val = tmp;
		break;
	}

	return 1;
}

#ifdef CONFIG_PPC_PASEMI_NEMO
#define PXP_ERR_CFG_REG	0x4
#define PXP_IGNORE_PCIE_ERRORS	0x800
#define SB600_BUS 5

static void sb600_set_flag(int bus)
{
	static void __iomem *iob_mapbase = NULL;
	struct resource res;
	struct device_node *dn;
	int err;

	if (iob_mapbase == NULL) {
		dn = of_find_compatible_node(NULL, "isa", "pasemi,1682m-iob");
		if (!dn) {
			pr_crit("NEMO SB600 missing iob node\n");
			return;
		}

		err = of_address_to_resource(dn, 0, &res);
		of_node_put(dn);

		if (err) {
			pr_crit("NEMO SB600 missing resource\n");
			return;
		}

		pr_info("NEMO SB600 IOB base %08llx\n",res.start);

		iob_mapbase = ioremap(res.start + 0x100, 0x94);
	}

	if (iob_mapbase != NULL) {
		if (bus == SB600_BUS) {
			/*
			 * This is the SB600's bus, tell the PCI-e root port
			 * to allow non-zero devices to enumerate.
			 */
			out_le32(iob_mapbase + PXP_ERR_CFG_REG, in_le32(iob_mapbase + PXP_ERR_CFG_REG) | PXP_IGNORE_PCIE_ERRORS);
		} else {
			/*
			 * Only scan device 0 on other busses
			 */
			out_le32(iob_mapbase + PXP_ERR_CFG_REG, in_le32(iob_mapbase + PXP_ERR_CFG_REG) & ~PXP_IGNORE_PCIE_ERRORS);
		}
	}
}

#else

static void sb600_set_flag(int bus)
{
}
#endif

static int pa_pxp_read_config(struct pci_bus *bus, unsigned int devfn,
			      int offset, int len, u32 *val)
{
	struct pci_controller *hose;
	void volatile __iomem *addr;

	hose = pci_bus_to_host(bus);
	if (!hose)
		return PCIBIOS_DEVICE_NOT_FOUND;

	if (!pa_pxp_offset_valid(bus->number, devfn, offset))
		return PCIBIOS_BAD_REGISTER_NUMBER;

	if (workaround_5945(bus, devfn, offset, len, val))
		return PCIBIOS_SUCCESSFUL;

	addr = pa_pxp_cfg_addr(hose, bus->number, devfn, offset);

	sb600_set_flag(bus->number);

	/*
	 * Note: the caller has already checked that offset is
	 * suitably aligned and that len is 1, 2 or 4.
	 */
	switch (len) {
	case 1:
		*val = in_8(addr);
		break;
	case 2:
		*val = in_le16(addr);
		break;
	default:
		*val = in_le32(addr);
		break;
	}

	return PCIBIOS_SUCCESSFUL;
}

static int pa_pxp_write_config(struct pci_bus *bus, unsigned int devfn,
			       int offset, int len, u32 val)
{
	struct pci_controller *hose;
	void volatile __iomem *addr;

	hose = pci_bus_to_host(bus);
	if (!hose)
		return PCIBIOS_DEVICE_NOT_FOUND;

	if (!pa_pxp_offset_valid(bus->number, devfn, offset))
		return PCIBIOS_BAD_REGISTER_NUMBER;

	addr = pa_pxp_cfg_addr(hose, bus->number, devfn, offset);

	sb600_set_flag(bus->number);

	/*
	 * Note: the caller has already checked that offset is
	 * suitably aligned and that len is 1, 2 or 4.
	 */
	switch (len) {
	case 1:
		out_8(addr, val);
		break;
	case 2:
		out_le16(addr, val);
		break;
	default:
		out_le32(addr, val);
		break;
	}
	return PCIBIOS_SUCCESSFUL;
}

static struct pci_ops pa_pxp_ops = {
	.read = pa_pxp_read_config,
	.write = pa_pxp_write_config,
};

static void __init setup_pa_pxp(struct pci_controller *hose)
{
	hose->ops = &pa_pxp_ops;
	hose->cfg_data = ioremap(0xe0000000, 0x10000000);
}

static int __init pas_add_bridge(struct device_node *dev)
{
	struct pci_controller *hose;

	pr_debug("Adding PCI host bridge %pOF\n", dev);

	hose = pcibios_alloc_controller(dev);
	if (!hose)
		return -ENOMEM;

	hose->first_busno = 0;
	hose->last_busno = 0xff;
	hose->controller_ops = pasemi_pci_controller_ops;

	setup_pa_pxp(hose);

	pr_info("Found PA-PXP PCI host bridge.\n");

	/* Interpret the "ranges" property */
	pci_process_bridge_OF_ranges(hose, dev, 1);

	/*
	 * Scan for an isa bridge. This is needed to find the SB600 on the nemo
	 * and does nothing on machines without one.
	 */
	isa_bridge_find_early(hose);

	return 0;
}

void __init pas_pci_init(void)
{
	struct device_node *np, *root;
	int res;

	root = of_find_node_by_path("/");
	if (!root) {
		pr_crit("pas_pci_init: can't find root of device tree\n");
		return;
	}

	pci_set_flags(PCI_SCAN_ALL_PCIE_DEVS);

	np = of_find_compatible_node(root, NULL, "pasemi,rootbus");
	if (np) {
		res = pas_add_bridge(np);
		of_node_put(np);
	}
}

void __iomem *pasemi_pci_getcfgaddr(struct pci_dev *dev, int offset)
{
	struct pci_controller *hose;

	hose = pci_bus_to_host(dev->bus);

	return (void __iomem *)pa_pxp_cfg_addr(hose, dev->bus->number, dev->devfn, offset);
}

struct pci_controller_ops pasemi_pci_controller_ops;