// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2017 Cadence
// Cadence PCIe endpoint controller driver.
// Author: Cyrille Pitchen <cyrille.pitchen@free-electrons.com>

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/pci-epc.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/sizes.h>

#include "pcie-cadence.h"

#define CDNS_PCIE_EP_MIN_APERTURE               128     /* 128 bytes */
#define CDNS_PCIE_EP_IRQ_PCI_ADDR_NONE          0x1
#define CDNS_PCIE_EP_IRQ_PCI_ADDR_LEGACY        0x3

/**
 * struct cdns_pcie_ep - private data for this PCIe endpoint controller driver
 * @pcie: Cadence PCIe controller
 * @max_regions: maximum number of regions supported by hardware
 * @ob_region_map: bitmask of mapped outbound regions
 * @ob_addr: base addresses in the AXI bus where the outbound regions start
 * @irq_phys_addr: base address on the AXI bus where the MSI/legacy IRQ
 *                 dedicated outbound regions is mapped.
 * @irq_cpu_addr: base address in the CPU space where a write access triggers
 *                the sending of a memory write (MSI) / normal message (legacy
 *                IRQ) TLP through the PCIe bus.
 * @irq_pci_addr: used to save the current mapping of the MSI/legacy IRQ
 *                dedicated outbound region.
 * @irq_pci_fn: the latest PCI function that has updated the mapping of
 *              the MSI/legacy IRQ dedicated outbound region.
 * @irq_pending: bitmask of asserted legacy IRQs.
 */
struct cdns_pcie_ep {
        struct cdns_pcie                pcie;
        u32                             max_regions;
        unsigned long                   ob_region_map;
        phys_addr_t                     *ob_addr;
        phys_addr_t                     irq_phys_addr;
        void __iomem                    *irq_cpu_addr;
        u64                             irq_pci_addr;
        u8                              irq_pci_fn;
        u8                              irq_pending;
};

static int cdns_pcie_ep_write_header(struct pci_epc *epc, u8 fn,
                                     struct pci_epf_header *hdr)
{
        struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
        struct cdns_pcie *pcie = &ep->pcie;

        cdns_pcie_ep_fn_writew(pcie, fn, PCI_DEVICE_ID, hdr->deviceid);
        cdns_pcie_ep_fn_writeb(pcie, fn, PCI_REVISION_ID, hdr->revid);
        cdns_pcie_ep_fn_writeb(pcie, fn, PCI_CLASS_PROG, hdr->progif_code);
        cdns_pcie_ep_fn_writew(pcie, fn, PCI_CLASS_DEVICE,
                               hdr->subclass_code | hdr->baseclass_code << 8);
        cdns_pcie_ep_fn_writeb(pcie, fn, PCI_CACHE_LINE_SIZE,
                               hdr->cache_line_size);
        cdns_pcie_ep_fn_writew(pcie, fn, PCI_SUBSYSTEM_ID, hdr->subsys_id);
        cdns_pcie_ep_fn_writeb(pcie, fn, PCI_INTERRUPT_PIN, hdr->interrupt_pin);

        /*
         * Vendor ID can only be modified from function 0, all other functions
         * use the same vendor ID as function 0.
         */
        if (fn == 0) {
                /* Update the vendor IDs. */
                u32 id = CDNS_PCIE_LM_ID_VENDOR(hdr->vendorid) |
                         CDNS_PCIE_LM_ID_SUBSYS(hdr->subsys_vendor_id);

                cdns_pcie_writel(pcie, CDNS_PCIE_LM_ID, id);
        }

        return 0;
}

static int cdns_pcie_ep_set_bar(struct pci_epc *epc, u8 fn,
                                struct pci_epf_bar *epf_bar)
{
        struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
        struct cdns_pcie *pcie = &ep->pcie;
        dma_addr_t bar_phys = epf_bar->phys_addr;
        enum pci_barno bar = epf_bar->barno;
        int flags = epf_bar->flags;
        u32 addr0, addr1, reg, cfg, b, aperture, ctrl;
        u64 sz;

        /* BAR size is 2^(aperture + 7) */
        sz = max_t(size_t, epf_bar->size, CDNS_PCIE_EP_MIN_APERTURE);
        /*
         * roundup_pow_of_two() returns an unsigned long, which is not suited
         * for 64bit values.
         */
        sz = 1ULL << fls64(sz - 1);
        aperture = ilog2(sz) - 7; /* 128B -> 0, 256B -> 1, 512B -> 2, ... */

        if ((flags & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO) {
                ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_IO_32BITS;
        } else {
                bool is_prefetch = !!(flags & PCI_BASE_ADDRESS_MEM_PREFETCH);
                bool is_64bits = sz > SZ_2G;

                if (is_64bits && (bar & 1))
                        return -EINVAL;

                if (is_64bits && !(flags & PCI_BASE_ADDRESS_MEM_TYPE_64))
                        epf_bar->flags |= PCI_BASE_ADDRESS_MEM_TYPE_64;

                if (is_64bits && is_prefetch)
                        ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_PREFETCH_MEM_64BITS;
                else if (is_prefetch)
                        ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_PREFETCH_MEM_32BITS;
                else if (is_64bits)
                        ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_MEM_64BITS;
                else
                        ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_MEM_32BITS;
        }

        addr0 = lower_32_bits(bar_phys);
        addr1 = upper_32_bits(bar_phys);
        cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR0(fn, bar),
                         addr0);
        cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR1(fn, bar),
                         addr1);

        if (bar < BAR_4) {
                reg = CDNS_PCIE_LM_EP_FUNC_BAR_CFG0(fn);
                b = bar;
        } else {
                reg = CDNS_PCIE_LM_EP_FUNC_BAR_CFG1(fn);
                b = bar - BAR_4;
        }

        cfg = cdns_pcie_readl(pcie, reg);
        cfg &= ~(CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_APERTURE_MASK(b) |
                 CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_CTRL_MASK(b));
        cfg |= (CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_APERTURE(b, aperture) |
                CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_CTRL(b, ctrl));
        cdns_pcie_writel(pcie, reg, cfg);

        return 0;
}

static void cdns_pcie_ep_clear_bar(struct pci_epc *epc, u8 fn,
                                   struct pci_epf_bar *epf_bar)
{
        struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
        struct cdns_pcie *pcie = &ep->pcie;
        enum pci_barno bar = epf_bar->barno;
        u32 reg, cfg, b, ctrl;

        if (bar < BAR_4) {
                reg = CDNS_PCIE_LM_EP_FUNC_BAR_CFG0(fn);
                b = bar;
        } else {
                reg = CDNS_PCIE_LM_EP_FUNC_BAR_CFG1(fn);
                b = bar - BAR_4;
        }

        ctrl = CDNS_PCIE_LM_BAR_CFG_CTRL_DISABLED;
        cfg = cdns_pcie_readl(pcie, reg);
        cfg &= ~(CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_APERTURE_MASK(b) |
                 CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_CTRL_MASK(b));
        cfg |= CDNS_PCIE_LM_EP_FUNC_BAR_CFG_BAR_CTRL(b, ctrl);
        cdns_pcie_writel(pcie, reg, cfg);

        cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR0(fn, bar), 0);
        cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_EP_FUNC_BAR_ADDR1(fn, bar), 0);
}

static int cdns_pcie_ep_map_addr(struct pci_epc *epc, u8 fn, phys_addr_t addr,
                                 u64 pci_addr, size_t size)
{
        struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
        struct cdns_pcie *pcie = &ep->pcie;
        u32 r;

        r = find_first_zero_bit(&ep->ob_region_map,
                                sizeof(ep->ob_region_map) * BITS_PER_LONG);
        if (r >= ep->max_regions - 1) {
                dev_err(&epc->dev, "no free outbound region\n");
                return -EINVAL;
        }

        cdns_pcie_set_outbound_region(pcie, fn, r, false, addr, pci_addr, size);

        set_bit(r, &ep->ob_region_map);
        ep->ob_addr[r] = addr;

        return 0;
}

static void cdns_pcie_ep_unmap_addr(struct pci_epc *epc, u8 fn,
                                    phys_addr_t addr)
{
        struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
        struct cdns_pcie *pcie = &ep->pcie;
        u32 r;

        for (r = 0; r < ep->max_regions - 1; r++)
                if (ep->ob_addr[r] == addr)
                        break;

        if (r == ep->max_regions - 1)
                return;

        cdns_pcie_reset_outbound_region(pcie, r);

        ep->ob_addr[r] = 0;
        clear_bit(r, &ep->ob_region_map);
}

static int cdns_pcie_ep_set_msi(struct pci_epc *epc, u8 fn, u8 mmc)
{
        struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
        struct cdns_pcie *pcie = &ep->pcie;
        u32 cap = CDNS_PCIE_EP_FUNC_MSI_CAP_OFFSET;
        u16 flags;

        /*
         * Set the Multiple Message Capable bitfield into the Message Control
         * register.
         */
        flags = cdns_pcie_ep_fn_readw(pcie, fn, cap + PCI_MSI_FLAGS);
        flags = (flags & ~PCI_MSI_FLAGS_QMASK) | (mmc << 1);
        flags |= PCI_MSI_FLAGS_64BIT;
        flags &= ~PCI_MSI_FLAGS_MASKBIT;
        cdns_pcie_ep_fn_writew(pcie, fn, cap + PCI_MSI_FLAGS, flags);

        return 0;
}

static int cdns_pcie_ep_get_msi(struct pci_epc *epc, u8 fn)
{
        struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
        struct cdns_pcie *pcie = &ep->pcie;
        u32 cap = CDNS_PCIE_EP_FUNC_MSI_CAP_OFFSET;
        u16 flags, mme;

        /* Validate that the MSI feature is actually enabled. */
        flags = cdns_pcie_ep_fn_readw(pcie, fn, cap + PCI_MSI_FLAGS);
        if (!(flags & PCI_MSI_FLAGS_ENABLE))
                return -EINVAL;

        /*
         * Get the Multiple Message Enable bitfield from the Message Control
         * register.
         */
        mme = (flags & PCI_MSI_FLAGS_QSIZE) >> 4;

        return mme;
}

static void cdns_pcie_ep_assert_intx(struct cdns_pcie_ep *ep, u8 fn,
                                     u8 intx, bool is_asserted)
{
        struct cdns_pcie *pcie = &ep->pcie;
        u32 offset;
        u16 status;
        u8 msg_code;

        intx &= 3;

        /* Set the outbound region if needed. */
        if (unlikely(ep->irq_pci_addr != CDNS_PCIE_EP_IRQ_PCI_ADDR_LEGACY ||
                     ep->irq_pci_fn != fn)) {
                /* First region was reserved for IRQ writes. */
                cdns_pcie_set_outbound_region_for_normal_msg(pcie, fn, 0,
                                                             ep->irq_phys_addr);
                ep->irq_pci_addr = CDNS_PCIE_EP_IRQ_PCI_ADDR_LEGACY;
                ep->irq_pci_fn = fn;
        }

        if (is_asserted) {
                ep->irq_pending |= BIT(intx);
                msg_code = MSG_CODE_ASSERT_INTA + intx;
        } else {
                ep->irq_pending &= ~BIT(intx);
                msg_code = MSG_CODE_DEASSERT_INTA + intx;
        }

        status = cdns_pcie_ep_fn_readw(pcie, fn, PCI_STATUS);
        if (((status & PCI_STATUS_INTERRUPT) != 0) ^ (ep->irq_pending != 0)) {
                status ^= PCI_STATUS_INTERRUPT;
                cdns_pcie_ep_fn_writew(pcie, fn, PCI_STATUS, status);
        }

        offset = CDNS_PCIE_NORMAL_MSG_ROUTING(MSG_ROUTING_LOCAL) |
                 CDNS_PCIE_NORMAL_MSG_CODE(msg_code) |
                 CDNS_PCIE_MSG_NO_DATA;
        writel(0, ep->irq_cpu_addr + offset);
}

static int cdns_pcie_ep_send_legacy_irq(struct cdns_pcie_ep *ep, u8 fn, u8 intx)
{
        u16 cmd;

        cmd = cdns_pcie_ep_fn_readw(&ep->pcie, fn, PCI_COMMAND);
        if (cmd & PCI_COMMAND_INTX_DISABLE)
                return -EINVAL;

        cdns_pcie_ep_assert_intx(ep, fn, intx, true);
        /*
         * The mdelay() value was taken from dra7xx_pcie_raise_legacy_irq()
         * from drivers/pci/dwc/pci-dra7xx.c
         */
        mdelay(1);
        cdns_pcie_ep_assert_intx(ep, fn, intx, false);
        return 0;
}

static int cdns_pcie_ep_send_msi_irq(struct cdns_pcie_ep *ep, u8 fn,
                                     u8 interrupt_num)
{
        struct cdns_pcie *pcie = &ep->pcie;
        u32 cap = CDNS_PCIE_EP_FUNC_MSI_CAP_OFFSET;
        u16 flags, mme, data, data_mask;
        u8 msi_count;
        u64 pci_addr, pci_addr_mask = 0xff;

        /* Check whether the MSI feature has been enabled by the PCI host. */
        flags = cdns_pcie_ep_fn_readw(pcie, fn, cap + PCI_MSI_FLAGS);
        if (!(flags & PCI_MSI_FLAGS_ENABLE))
                return -EINVAL;

        /* Get the number of enabled MSIs */
        mme = (flags & PCI_MSI_FLAGS_QSIZE) >> 4;
        msi_count = 1 << mme;
        if (!interrupt_num || interrupt_num > msi_count)
                return -EINVAL;

        /* Compute the data value to be written. */
        data_mask = msi_count - 1;
        data = cdns_pcie_ep_fn_readw(pcie, fn, cap + PCI_MSI_DATA_64);
        data = (data & ~data_mask) | ((interrupt_num - 1) & data_mask);

        /* Get the PCI address where to write the data into. */
        pci_addr = cdns_pcie_ep_fn_readl(pcie, fn, cap + PCI_MSI_ADDRESS_HI);
        pci_addr <<= 32;
        pci_addr |= cdns_pcie_ep_fn_readl(pcie, fn, cap + PCI_MSI_ADDRESS_LO);
        pci_addr &= GENMASK_ULL(63, 2);

        /* Set the outbound region if needed. */
        if (unlikely(ep->irq_pci_addr != (pci_addr & ~pci_addr_mask) ||
                     ep->irq_pci_fn != fn)) {
                /* First region was reserved for IRQ writes. */
                cdns_pcie_set_outbound_region(pcie, fn, 0,
                                              false,
                                              ep->irq_phys_addr,
                                              pci_addr & ~pci_addr_mask,
                                              pci_addr_mask + 1);
                ep->irq_pci_addr = (pci_addr & ~pci_addr_mask);
                ep->irq_pci_fn = fn;
        }
        writel(data, ep->irq_cpu_addr + (pci_addr & pci_addr_mask));

        return 0;
}

static int cdns_pcie_ep_raise_irq(struct pci_epc *epc, u8 fn,
                                  enum pci_epc_irq_type type,
                                  u16 interrupt_num)
{
        struct cdns_pcie_ep *ep = epc_get_drvdata(epc);

        switch (type) {
        case PCI_EPC_IRQ_LEGACY:
                return cdns_pcie_ep_send_legacy_irq(ep, fn, 0);

        case PCI_EPC_IRQ_MSI:
                return cdns_pcie_ep_send_msi_irq(ep, fn, interrupt_num);

        default:
                break;
        }

        return -EINVAL;
}

static int cdns_pcie_ep_start(struct pci_epc *epc)
{
        struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
        struct cdns_pcie *pcie = &ep->pcie;
        struct pci_epf *epf;
        u32 cfg;

        /*
         * BIT(0) is hardwired to 1, hence function 0 is always enabled
         * and can't be disabled anyway.
         */
        cfg = BIT(0);
        list_for_each_entry(epf, &epc->pci_epf, list)
                cfg |= BIT(epf->func_no);
        cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, cfg);

        return 0;
}

static const struct pci_epc_features cdns_pcie_epc_features = {
        .linkup_notifier = false,
        .msi_capable = true,
        .msix_capable = false,
};

static const struct pci_epc_features*
cdns_pcie_ep_get_features(struct pci_epc *epc, u8 func_no)
{
        return &cdns_pcie_epc_features;
}

static const struct pci_epc_ops cdns_pcie_epc_ops = {
        .write_header   = cdns_pcie_ep_write_header,
        .set_bar        = cdns_pcie_ep_set_bar,
        .clear_bar      = cdns_pcie_ep_clear_bar,
        .map_addr       = cdns_pcie_ep_map_addr,
        .unmap_addr     = cdns_pcie_ep_unmap_addr,
        .set_msi        = cdns_pcie_ep_set_msi,
        .get_msi        = cdns_pcie_ep_get_msi,
        .raise_irq      = cdns_pcie_ep_raise_irq,
        .start          = cdns_pcie_ep_start,
        .get_features   = cdns_pcie_ep_get_features,
};

static const struct of_device_id cdns_pcie_ep_of_match[] = {
        { .compatible = "cdns,cdns-pcie-ep" },

        { },
};

static int cdns_pcie_ep_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct cdns_pcie_ep *ep;
        struct cdns_pcie *pcie;
        struct pci_epc *epc;
        struct resource *res;
        int ret;
        int phy_count;

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

        pcie = &ep->pcie;
        pcie->is_rc = false;

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "reg");
        pcie->reg_base = devm_ioremap_resource(dev, res);
        if (IS_ERR(pcie->reg_base)) {
                dev_err(dev, "missing \"reg\"\n");
                return PTR_ERR(pcie->reg_base);
        }

        res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mem");
        if (!res) {
                dev_err(dev, "missing \"mem\"\n");
                return -EINVAL;
        }
        pcie->mem_res = res;

        ret = of_property_read_u32(np, "cdns,max-outbound-regions",
                                   &ep->max_regions);
        if (ret < 0) {
                dev_err(dev, "missing \"cdns,max-outbound-regions\"\n");
                return ret;
        }
        ep->ob_addr = devm_kcalloc(dev,
                                   ep->max_regions, sizeof(*ep->ob_addr),
                                   GFP_KERNEL);
        if (!ep->ob_addr)
                return -ENOMEM;

        ret = cdns_pcie_init_phy(dev, pcie);
        if (ret) {
                dev_err(dev, "failed to init phy\n");
                return ret;
        }
        platform_set_drvdata(pdev, pcie);
        pm_runtime_enable(dev);
        ret = pm_runtime_get_sync(dev);
        if (ret < 0) {
                dev_err(dev, "pm_runtime_get_sync() failed\n");
                goto err_get_sync;
        }

        /* Disable all but function 0 (anyway BIT(0) is hardwired to 1). */
        cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, BIT(0));

        epc = devm_pci_epc_create(dev, &cdns_pcie_epc_ops);
        if (IS_ERR(epc)) {
                dev_err(dev, "failed to create epc device\n");
                ret = PTR_ERR(epc);
                goto err_init;
        }

        epc_set_drvdata(epc, ep);

        if (of_property_read_u8(np, "max-functions", &epc->max_functions) < 0)
                epc->max_functions = 1;

        ret = pci_epc_mem_init(epc, pcie->mem_res->start,
                               resource_size(pcie->mem_res));
        if (ret < 0) {
                dev_err(dev, "failed to initialize the memory space\n");
                goto err_init;
        }

        ep->irq_cpu_addr = pci_epc_mem_alloc_addr(epc, &ep->irq_phys_addr,
                                                  SZ_128K);
        if (!ep->irq_cpu_addr) {
                dev_err(dev, "failed to reserve memory space for MSI\n");
                ret = -ENOMEM;
                goto free_epc_mem;
        }
        ep->irq_pci_addr = CDNS_PCIE_EP_IRQ_PCI_ADDR_NONE;
        /* Reserve region 0 for IRQs */
        set_bit(0, &ep->ob_region_map);

        return 0;

 free_epc_mem:
        pci_epc_mem_exit(epc);

 err_init:
        pm_runtime_put_sync(dev);

 err_get_sync:
        pm_runtime_disable(dev);
        cdns_pcie_disable_phy(pcie);
        phy_count = pcie->phy_count;
        while (phy_count--)
                device_link_del(pcie->link[phy_count]);

        return ret;
}

static void cdns_pcie_ep_shutdown(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct cdns_pcie *pcie = dev_get_drvdata(dev);
        int ret;

        ret = pm_runtime_put_sync(dev);
        if (ret < 0)
                dev_dbg(dev, "pm_runtime_put_sync failed\n");

        pm_runtime_disable(dev);

        cdns_pcie_disable_phy(pcie);
}

static struct platform_driver cdns_pcie_ep_driver = {
        .driver = {
                .name = "cdns-pcie-ep",
                .of_match_table = cdns_pcie_ep_of_match,
                .pm     = &cdns_pcie_pm_ops,
        },
        .probe = cdns_pcie_ep_probe,
        .shutdown = cdns_pcie_ep_shutdown,
};
builtin_platform_driver(cdns_pcie_ep_driver);