/**
 * APM X-Gene PCIe Driver
 *
 * Copyright (c) 2014 Applied Micro Circuits Corporation.
 *
 * Author: Tanmay Inamdar <tinamdar@apm.com>.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/jiffies.h>
#include <linux/memblock.h>
#include <linux/init.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_pci.h>
#include <linux/pci.h>
#include <linux/pci-acpi.h>
#include <linux/pci-ecam.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#define PCIECORE_CTLANDSTATUS           0x50
#define PIM1_1L                         0x80
#define IBAR2                           0x98
#define IR2MSK                          0x9c
#define PIM2_1L                         0xa0
#define IBAR3L                          0xb4
#define IR3MSKL                         0xbc
#define PIM3_1L                         0xc4
#define OMR1BARL                        0x100
#define OMR2BARL                        0x118
#define OMR3BARL                        0x130
#define CFGBARL                         0x154
#define CFGBARH                         0x158
#define CFGCTL                          0x15c
#define RTDID                           0x160
#define BRIDGE_CFG_0                    0x2000
#define BRIDGE_CFG_4                    0x2010
#define BRIDGE_STATUS_0                 0x2600

#define LINK_UP_MASK                    0x00000100
#define AXI_EP_CFG_ACCESS               0x10000
#define EN_COHERENCY                    0xF0000000
#define EN_REG                          0x00000001
#define OB_LO_IO                        0x00000002
#define XGENE_PCIE_VENDORID             0x10E8
#define XGENE_PCIE_DEVICEID             0xE004
#define SZ_1T                           (SZ_1G*1024ULL)
#define PIPE_PHY_RATE_RD(src)           ((0xc000 & (u32)(src)) >> 0xe)

#define ROOT_CAP_AND_CTRL               0x5C

/* PCIe IP version */
#define XGENE_PCIE_IP_VER_UNKN          0
#define XGENE_PCIE_IP_VER_1             1
#define XGENE_PCIE_IP_VER_2             2

#if defined(CONFIG_PCI_XGENE) || (defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS))
struct xgene_pcie_port {
        struct device_node      *node;
        struct device           *dev;
        struct clk              *clk;
        void __iomem            *csr_base;
        void __iomem            *cfg_base;
        unsigned long           cfg_addr;
        bool                    link_up;
        u32                     version;
};

static u32 xgene_pcie_readl(struct xgene_pcie_port *port, u32 reg)
{
        return readl(port->csr_base + reg);
}

static void xgene_pcie_writel(struct xgene_pcie_port *port, u32 reg, u32 val)
{
        writel(val, port->csr_base + reg);
}

static inline u32 pcie_bar_low_val(u32 addr, u32 flags)
{
        return (addr & PCI_BASE_ADDRESS_MEM_MASK) | flags;
}

static inline struct xgene_pcie_port *pcie_bus_to_port(struct pci_bus *bus)
{
        struct pci_config_window *cfg;

        if (acpi_disabled)
                return (struct xgene_pcie_port *)(bus->sysdata);

        cfg = bus->sysdata;
        return (struct xgene_pcie_port *)(cfg->priv);
}

/*
 * When the address bit [17:16] is 2'b01, the Configuration access will be
 * treated as Type 1 and it will be forwarded to external PCIe device.
 */
static void __iomem *xgene_pcie_get_cfg_base(struct pci_bus *bus)
{
        struct xgene_pcie_port *port = pcie_bus_to_port(bus);

        if (bus->number >= (bus->primary + 1))
                return port->cfg_base + AXI_EP_CFG_ACCESS;

        return port->cfg_base;
}

/*
 * For Configuration request, RTDID register is used as Bus Number,
 * Device Number and Function number of the header fields.
 */
static void xgene_pcie_set_rtdid_reg(struct pci_bus *bus, uint devfn)
{
        struct xgene_pcie_port *port = pcie_bus_to_port(bus);
        unsigned int b, d, f;
        u32 rtdid_val = 0;

        b = bus->number;
        d = PCI_SLOT(devfn);
        f = PCI_FUNC(devfn);

        if (!pci_is_root_bus(bus))
                rtdid_val = (b << 8) | (d << 3) | f;

        xgene_pcie_writel(port, RTDID, rtdid_val);
        /* read the register back to ensure flush */
        xgene_pcie_readl(port, RTDID);
}

/*
 * X-Gene PCIe port uses BAR0-BAR1 of RC's configuration space as
 * the translation from PCI bus to native BUS.  Entire DDR region
 * is mapped into PCIe space using these registers, so it can be
 * reached by DMA from EP devices.  The BAR0/1 of bridge should be
 * hidden during enumeration to avoid the sizing and resource allocation
 * by PCIe core.
 */
static bool xgene_pcie_hide_rc_bars(struct pci_bus *bus, int offset)
{
        if (pci_is_root_bus(bus) && ((offset == PCI_BASE_ADDRESS_0) ||
                                     (offset == PCI_BASE_ADDRESS_1)))
                return true;

        return false;
}

static void __iomem *xgene_pcie_map_bus(struct pci_bus *bus, unsigned int devfn,
                              int offset)
{
        if ((pci_is_root_bus(bus) && devfn != 0) ||
            xgene_pcie_hide_rc_bars(bus, offset))
                return NULL;

        xgene_pcie_set_rtdid_reg(bus, devfn);
        return xgene_pcie_get_cfg_base(bus) + offset;
}

static int xgene_pcie_config_read32(struct pci_bus *bus, unsigned int devfn,
                                    int where, int size, u32 *val)
{
        struct xgene_pcie_port *port = pcie_bus_to_port(bus);

        if (pci_generic_config_read32(bus, devfn, where & ~0x3, 4, val) !=
            PCIBIOS_SUCCESSFUL)
                return PCIBIOS_DEVICE_NOT_FOUND;

        /*
         * The v1 controller has a bug in its Configuration Request
         * Retry Status (CRS) logic: when CRS is enabled and we read the
         * Vendor and Device ID of a non-existent device, the controller
         * fabricates return data of 0xFFFF0001 ("device exists but is not
         * ready") instead of 0xFFFFFFFF ("device does not exist").  This
         * causes the PCI core to retry the read until it times out.
         * Avoid this by not claiming to support CRS.
         */
        if (pci_is_root_bus(bus) && (port->version == XGENE_PCIE_IP_VER_1) &&
            ((where & ~0x3) == ROOT_CAP_AND_CTRL))
                *val &= ~(PCI_EXP_RTCAP_CRSVIS << 16);

        if (size <= 2)
                *val = (*val >> (8 * (where & 3))) & ((1 << (size * 8)) - 1);

        return PCIBIOS_SUCCESSFUL;
}
#endif

#if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS)
static int xgene_get_csr_resource(struct acpi_device *adev,
                                  struct resource *res)
{
        struct device *dev = &adev->dev;
        struct resource_entry *entry;
        struct list_head list;
        unsigned long flags;
        int ret;

        INIT_LIST_HEAD(&list);
        flags = IORESOURCE_MEM;
        ret = acpi_dev_get_resources(adev, &list,
                                     acpi_dev_filter_resource_type_cb,
                                     (void *) flags);
        if (ret < 0) {
                dev_err(dev, "failed to parse _CRS method, error code %d\n",
                        ret);
                return ret;
        }

        if (ret == 0) {
                dev_err(dev, "no IO and memory resources present in _CRS\n");
                return -EINVAL;
        }

        entry = list_first_entry(&list, struct resource_entry, node);
        *res = *entry->res;
        acpi_dev_free_resource_list(&list);
        return 0;
}

static int xgene_pcie_ecam_init(struct pci_config_window *cfg, u32 ipversion)
{
        struct device *dev = cfg->parent;
        struct acpi_device *adev = to_acpi_device(dev);
        struct xgene_pcie_port *port;
        struct resource csr;
        int ret;

        port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
        if (!port)
                return -ENOMEM;

        ret = xgene_get_csr_resource(adev, &csr);
        if (ret) {
                dev_err(dev, "can't get CSR resource\n");
                kfree(port);
                return ret;
        }
        port->csr_base = devm_ioremap_resource(dev, &csr);
        if (IS_ERR(port->csr_base)) {
                kfree(port);
                return -ENOMEM;
        }

        port->cfg_base = cfg->win;
        port->version = ipversion;

        cfg->priv = port;
        return 0;
}

static int xgene_v1_pcie_ecam_init(struct pci_config_window *cfg)
{
        return xgene_pcie_ecam_init(cfg, XGENE_PCIE_IP_VER_1);
}

struct pci_ecam_ops xgene_v1_pcie_ecam_ops = {
        .bus_shift      = 16,
        .init           = xgene_v1_pcie_ecam_init,
        .pci_ops        = {
                .map_bus        = xgene_pcie_map_bus,
                .read           = xgene_pcie_config_read32,
                .write          = pci_generic_config_write,
        }
};

static int xgene_v2_pcie_ecam_init(struct pci_config_window *cfg)
{
        return xgene_pcie_ecam_init(cfg, XGENE_PCIE_IP_VER_2);
}

struct pci_ecam_ops xgene_v2_pcie_ecam_ops = {
        .bus_shift      = 16,
        .init           = xgene_v2_pcie_ecam_init,
        .pci_ops        = {
                .map_bus        = xgene_pcie_map_bus,
                .read           = xgene_pcie_config_read32,
                .write          = pci_generic_config_write,
        }
};
#endif

#if defined(CONFIG_PCI_XGENE)
static u64 xgene_pcie_set_ib_mask(struct xgene_pcie_port *port, u32 addr,
                                  u32 flags, u64 size)
{
        u64 mask = (~(size - 1) & PCI_BASE_ADDRESS_MEM_MASK) | flags;
        u32 val32 = 0;
        u32 val;

        val32 = xgene_pcie_readl(port, addr);
        val = (val32 & 0x0000ffff) | (lower_32_bits(mask) << 16);
        xgene_pcie_writel(port, addr, val);

        val32 = xgene_pcie_readl(port, addr + 0x04);
        val = (val32 & 0xffff0000) | (lower_32_bits(mask) >> 16);
        xgene_pcie_writel(port, addr + 0x04, val);

        val32 = xgene_pcie_readl(port, addr + 0x04);
        val = (val32 & 0x0000ffff) | (upper_32_bits(mask) << 16);
        xgene_pcie_writel(port, addr + 0x04, val);

        val32 = xgene_pcie_readl(port, addr + 0x08);
        val = (val32 & 0xffff0000) | (upper_32_bits(mask) >> 16);
        xgene_pcie_writel(port, addr + 0x08, val);

        return mask;
}

static void xgene_pcie_linkup(struct xgene_pcie_port *port,
                                   u32 *lanes, u32 *speed)
{
        u32 val32;

        port->link_up = false;
        val32 = xgene_pcie_readl(port, PCIECORE_CTLANDSTATUS);
        if (val32 & LINK_UP_MASK) {
                port->link_up = true;
                *speed = PIPE_PHY_RATE_RD(val32);
                val32 = xgene_pcie_readl(port, BRIDGE_STATUS_0);
                *lanes = val32 >> 26;
        }
}

static int xgene_pcie_init_port(struct xgene_pcie_port *port)
{
        struct device *dev = port->dev;
        int rc;

        port->clk = clk_get(dev, NULL);
        if (IS_ERR(port->clk)) {
                dev_err(dev, "clock not available\n");
                return -ENODEV;
        }

        rc = clk_prepare_enable(port->clk);
        if (rc) {
                dev_err(dev, "clock enable failed\n");
                return rc;
        }

        return 0;
}

static int xgene_pcie_map_reg(struct xgene_pcie_port *port,
                              struct platform_device *pdev)
{
        struct device *dev = port->dev;
        struct resource *res;

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "csr");
        port->csr_base = devm_ioremap_resource(dev, res);
        if (IS_ERR(port->csr_base))
                return PTR_ERR(port->csr_base);

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "cfg");
        port->cfg_base = devm_ioremap_resource(dev, res);
        if (IS_ERR(port->cfg_base))
                return PTR_ERR(port->cfg_base);
        port->cfg_addr = res->start;

        return 0;
}

static void xgene_pcie_setup_ob_reg(struct xgene_pcie_port *port,
                                    struct resource *res, u32 offset,
                                    u64 cpu_addr, u64 pci_addr)
{
        struct device *dev = port->dev;
        resource_size_t size = resource_size(res);
        u64 restype = resource_type(res);
        u64 mask = 0;
        u32 min_size;
        u32 flag = EN_REG;

        if (restype == IORESOURCE_MEM) {
                min_size = SZ_128M;
        } else {
                min_size = 128;
                flag |= OB_LO_IO;
        }

        if (size >= min_size)
                mask = ~(size - 1) | flag;
        else
                dev_warn(dev, "res size 0x%llx less than minimum 0x%x\n",
                         (u64)size, min_size);

        xgene_pcie_writel(port, offset, lower_32_bits(cpu_addr));
        xgene_pcie_writel(port, offset + 0x04, upper_32_bits(cpu_addr));
        xgene_pcie_writel(port, offset + 0x08, lower_32_bits(mask));
        xgene_pcie_writel(port, offset + 0x0c, upper_32_bits(mask));
        xgene_pcie_writel(port, offset + 0x10, lower_32_bits(pci_addr));
        xgene_pcie_writel(port, offset + 0x14, upper_32_bits(pci_addr));
}

static void xgene_pcie_setup_cfg_reg(struct xgene_pcie_port *port)
{
        u64 addr = port->cfg_addr;

        xgene_pcie_writel(port, CFGBARL, lower_32_bits(addr));
        xgene_pcie_writel(port, CFGBARH, upper_32_bits(addr));
        xgene_pcie_writel(port, CFGCTL, EN_REG);
}

static int xgene_pcie_map_ranges(struct xgene_pcie_port *port,
                                 struct list_head *res,
                                 resource_size_t io_base)
{
        struct resource_entry *window;
        struct device *dev = port->dev;
        int ret;

        resource_list_for_each_entry(window, res) {
                struct resource *res = window->res;
                u64 restype = resource_type(res);

                dev_dbg(dev, "%pR\n", res);

                switch (restype) {
                case IORESOURCE_IO:
                        xgene_pcie_setup_ob_reg(port, res, OMR3BARL, io_base,
                                                res->start - window->offset);
                        ret = pci_remap_iospace(res, io_base);
                        if (ret < 0)
                                return ret;
                        break;
                case IORESOURCE_MEM:
                        if (res->flags & IORESOURCE_PREFETCH)
                                xgene_pcie_setup_ob_reg(port, res, OMR2BARL,
                                                        res->start,
                                                        res->start -
                                                        window->offset);
                        else
                                xgene_pcie_setup_ob_reg(port, res, OMR1BARL,
                                                        res->start,
                                                        res->start -
                                                        window->offset);
                        break;
                case IORESOURCE_BUS:
                        break;
                default:
                        dev_err(dev, "invalid resource %pR\n", res);
                        return -EINVAL;
                }
        }
        xgene_pcie_setup_cfg_reg(port);
        return 0;
}

static void xgene_pcie_setup_pims(struct xgene_pcie_port *port, u32 pim_reg,
                                  u64 pim, u64 size)
{
        xgene_pcie_writel(port, pim_reg, lower_32_bits(pim));
        xgene_pcie_writel(port, pim_reg + 0x04,
                          upper_32_bits(pim) | EN_COHERENCY);
        xgene_pcie_writel(port, pim_reg + 0x10, lower_32_bits(size));
        xgene_pcie_writel(port, pim_reg + 0x14, upper_32_bits(size));
}

/*
 * X-Gene PCIe support maximum 3 inbound memory regions
 * This function helps to select a region based on size of region
 */
static int xgene_pcie_select_ib_reg(u8 *ib_reg_mask, u64 size)
{
        if ((size > 4) && (size < SZ_16M) && !(*ib_reg_mask & (1 << 1))) {
                *ib_reg_mask |= (1 << 1);
                return 1;
        }

        if ((size > SZ_1K) && (size < SZ_1T) && !(*ib_reg_mask & (1 << 0))) {
                *ib_reg_mask |= (1 << 0);
                return 0;
        }

        if ((size > SZ_1M) && (size < SZ_1T) && !(*ib_reg_mask & (1 << 2))) {
                *ib_reg_mask |= (1 << 2);
                return 2;
        }

        return -EINVAL;
}

static void xgene_pcie_setup_ib_reg(struct xgene_pcie_port *port,
                                    struct of_pci_range *range, u8 *ib_reg_mask)
{
        void __iomem *cfg_base = port->cfg_base;
        struct device *dev = port->dev;
        void *bar_addr;
        u32 pim_reg;
        u64 cpu_addr = range->cpu_addr;
        u64 pci_addr = range->pci_addr;
        u64 size = range->size;
        u64 mask = ~(size - 1) | EN_REG;
        u32 flags = PCI_BASE_ADDRESS_MEM_TYPE_64;
        u32 bar_low;
        int region;

        region = xgene_pcie_select_ib_reg(ib_reg_mask, range->size);
        if (region < 0) {
                dev_warn(dev, "invalid pcie dma-range config\n");
                return;
        }

        if (range->flags & IORESOURCE_PREFETCH)
                flags |= PCI_BASE_ADDRESS_MEM_PREFETCH;

        bar_low = pcie_bar_low_val((u32)cpu_addr, flags);
        switch (region) {
        case 0:
                xgene_pcie_set_ib_mask(port, BRIDGE_CFG_4, flags, size);
                bar_addr = cfg_base + PCI_BASE_ADDRESS_0;
                writel(bar_low, bar_addr);
                writel(upper_32_bits(cpu_addr), bar_addr + 0x4);
                pim_reg = PIM1_1L;
                break;
        case 1:
                xgene_pcie_writel(port, IBAR2, bar_low);
                xgene_pcie_writel(port, IR2MSK, lower_32_bits(mask));
                pim_reg = PIM2_1L;
                break;
        case 2:
                xgene_pcie_writel(port, IBAR3L, bar_low);
                xgene_pcie_writel(port, IBAR3L + 0x4, upper_32_bits(cpu_addr));
                xgene_pcie_writel(port, IR3MSKL, lower_32_bits(mask));
                xgene_pcie_writel(port, IR3MSKL + 0x4, upper_32_bits(mask));
                pim_reg = PIM3_1L;
                break;
        }

        xgene_pcie_setup_pims(port, pim_reg, pci_addr, ~(size - 1));
}

static int pci_dma_range_parser_init(struct of_pci_range_parser *parser,
                                     struct device_node *node)
{
        const int na = 3, ns = 2;
        int rlen;

        parser->node = node;
        parser->pna = of_n_addr_cells(node);
        parser->np = parser->pna + na + ns;

        parser->range = of_get_property(node, "dma-ranges", &rlen);
        if (!parser->range)
                return -ENOENT;
        parser->end = parser->range + rlen / sizeof(__be32);

        return 0;
}

static int xgene_pcie_parse_map_dma_ranges(struct xgene_pcie_port *port)
{
        struct device_node *np = port->node;
        struct of_pci_range range;
        struct of_pci_range_parser parser;
        struct device *dev = port->dev;
        u8 ib_reg_mask = 0;

        if (pci_dma_range_parser_init(&parser, np)) {
                dev_err(dev, "missing dma-ranges property\n");
                return -EINVAL;
        }

        /* Get the dma-ranges from DT */
        for_each_of_pci_range(&parser, &range) {
                u64 end = range.cpu_addr + range.size - 1;

                dev_dbg(dev, "0x%08x 0x%016llx..0x%016llx -> 0x%016llx\n",
                        range.flags, range.cpu_addr, end, range.pci_addr);
                xgene_pcie_setup_ib_reg(port, &range, &ib_reg_mask);
        }
        return 0;
}

/* clear BAR configuration which was done by firmware */
static void xgene_pcie_clear_config(struct xgene_pcie_port *port)
{
        int i;

        for (i = PIM1_1L; i <= CFGCTL; i += 4)
                xgene_pcie_writel(port, i, 0);
}

static int xgene_pcie_setup(struct xgene_pcie_port *port,
                            struct list_head *res,
                            resource_size_t io_base)
{
        struct device *dev = port->dev;
        u32 val, lanes = 0, speed = 0;
        int ret;

        xgene_pcie_clear_config(port);

        /* setup the vendor and device IDs correctly */
        val = (XGENE_PCIE_DEVICEID << 16) | XGENE_PCIE_VENDORID;
        xgene_pcie_writel(port, BRIDGE_CFG_0, val);

        ret = xgene_pcie_map_ranges(port, res, io_base);
        if (ret)
                return ret;

        ret = xgene_pcie_parse_map_dma_ranges(port);
        if (ret)
                return ret;

        xgene_pcie_linkup(port, &lanes, &speed);
        if (!port->link_up)
                dev_info(dev, "(rc) link down\n");
        else
                dev_info(dev, "(rc) x%d gen-%d link up\n", lanes, speed + 1);
        return 0;
}

static struct pci_ops xgene_pcie_ops = {
        .map_bus = xgene_pcie_map_bus,
        .read = xgene_pcie_config_read32,
        .write = pci_generic_config_write32,
};

static int xgene_pcie_probe_bridge(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *dn = dev->of_node;
        struct xgene_pcie_port *port;
        resource_size_t iobase = 0;
        struct pci_bus *bus;
        int ret;
        LIST_HEAD(res);

        port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
        if (!port)
                return -ENOMEM;

        port->node = of_node_get(dn);
        port->dev = dev;

        port->version = XGENE_PCIE_IP_VER_UNKN;
        if (of_device_is_compatible(port->node, "apm,xgene-pcie"))
                port->version = XGENE_PCIE_IP_VER_1;

        ret = xgene_pcie_map_reg(port, pdev);
        if (ret)
                return ret;

        ret = xgene_pcie_init_port(port);
        if (ret)
                return ret;

        ret = of_pci_get_host_bridge_resources(dn, 0, 0xff, &res, &iobase);
        if (ret)
                return ret;

        ret = devm_request_pci_bus_resources(dev, &res);
        if (ret)
                goto error;

        ret = xgene_pcie_setup(port, &res, iobase);
        if (ret)
                goto error;

        bus = pci_create_root_bus(dev, 0, &xgene_pcie_ops, port, &res);
        if (!bus) {
                ret = -ENOMEM;
                goto error;
        }

        pci_scan_child_bus(bus);
        pci_assign_unassigned_bus_resources(bus);
        pci_bus_add_devices(bus);
        return 0;

error:
        pci_free_resource_list(&res);
        return ret;
}

static const struct of_device_id xgene_pcie_match_table[] = {
        {.compatible = "apm,xgene-pcie",},
        {},
};

static struct platform_driver xgene_pcie_driver = {
        .driver = {
                   .name = "xgene-pcie",
                   .of_match_table = of_match_ptr(xgene_pcie_match_table),
        },
        .probe = xgene_pcie_probe_bridge,
};
builtin_platform_driver(xgene_pcie_driver);
#endif