// 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;