/*
 * Copyright (C) 2011       Citrix Ltd.
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 */

#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/cutils.h"
#include "hw/xen/xen-legacy-backend.h"
#include "hw/xen/xen-bus-helper.h"
#include "xen-host-pci-device.h"

#define XEN_HOST_PCI_MAX_EXT_CAP \
    ((PCIE_CONFIG_SPACE_SIZE - PCI_CONFIG_SPACE_SIZE) / (PCI_CAP_SIZEOF + 4))

#ifdef XEN_HOST_PCI_DEVICE_DEBUG
#  define XEN_HOST_PCI_LOG(f, a...) fprintf(stderr, "%s: " f, __func__, ##a)
#else
#  define XEN_HOST_PCI_LOG(f, a...) (void)0
#endif

/*
 * from linux/ioport.h
 * IO resources have these defined flags.
 */
#define IORESOURCE_BITS         0x000000ff      /* Bus-specific bits */

#define IORESOURCE_TYPE_BITS    0x00000f00      /* Resource type */
#define IORESOURCE_IO           0x00000100
#define IORESOURCE_MEM          0x00000200

#define IORESOURCE_PREFETCH     0x00001000      /* No side effects */
#define IORESOURCE_MEM_64       0x00100000

/*
 * Non-passthrough (dom0) accesses are local PCI devices and use the given BDF
 * Passthough (stubdom) accesses are through PV frontend PCI device.  Those
 * either have a BDF identical to the backend's BDF (xen-backend.passthrough=1)
 * or a local virtual BDF (xen-backend.passthrough=0)
 *
 * We are always given the backend's BDF and need to lookup the appropriate
 * local BDF for sysfs access.
 */
static void xen_host_pci_fill_local_addr(XenHostPCIDevice *d, Error **errp)
{
    unsigned int num_devs, len, i;
    unsigned int domain, bus, dev, func;
    char *be_path = NULL;
    char path[16];

    be_path = qemu_xen_xs_read(xenstore, 0, "device/pci/0/backend", &len);
    if (!be_path) {
        error_setg(errp, "Failed to read device/pci/0/backend");
        goto out;
    }

    if (xs_node_scanf(xenstore, 0, be_path, "num_devs", NULL,
                      "%d", &num_devs) != 1) {
        error_setg(errp, "Failed to read or parse %s/num_devs", be_path);
        goto out;
    }

    for (i = 0; i < num_devs; i++) {
        snprintf(path, sizeof(path), "dev-%d", i);
        if (xs_node_scanf(xenstore, 0, be_path, path, NULL,
                          "%x:%x:%x.%x", &domain, &bus, &dev, &func) != 4) {
            error_setg(errp, "Failed to read or parse %s/%s", be_path, path);
            goto out;
        }
        if (domain != d->domain ||
                bus != d->bus ||
                dev != d->dev ||
                func != d->func)
            continue;
        snprintf(path, sizeof(path), "vdev-%d", i);
        if (xs_node_scanf(xenstore, 0, be_path, path, NULL,
                          "%x:%x:%x.%x", &domain, &bus, &dev, &func) != 4) {
            error_setg(errp, "Failed to read or parse %s/%s", be_path, path);
            goto out;
        }
        d->local_domain = domain;
        d->local_bus = bus;
        d->local_dev = dev;
        d->local_func = func;
        goto out;
    }
    error_setg(errp, "Failed to find PCI device %x:%x:%x.%x in xenstore",
               d->domain, d->bus, d->dev, d->func);

out:
    free(be_path);
}

static void xen_host_pci_sysfs_path(const XenHostPCIDevice *d,
                                    const char *name, char *buf, ssize_t size)
{
    int rc;

    rc = snprintf(buf, size, "/sys/bus/pci/devices/%04x:%02x:%02x.%d/%s",
                  d->local_domain, d->local_bus, d->local_dev, d->local_func,
                  name);
    assert(rc >= 0 && rc < size);
}


/* This size should be enough to read the first 7 lines of a resource file */
#define XEN_HOST_PCI_RESOURCE_BUFFER_SIZE 400
static void xen_host_pci_get_resource(XenHostPCIDevice *d, Error **errp)
{
    int i, rc, fd;
    char path[PATH_MAX];
    char buf[XEN_HOST_PCI_RESOURCE_BUFFER_SIZE];
    unsigned long long start, end, flags, size;
    char *endptr, *s;
    uint8_t type;

    xen_host_pci_sysfs_path(d, "resource", path, sizeof(path));

    fd = open(path, O_RDONLY);
    if (fd == -1) {
        error_setg_file_open(errp, errno, path);
        return;
    }

    do {
        rc = read(fd, &buf, sizeof(buf) - 1);
        if (rc < 0 && errno != EINTR) {
            error_setg_errno(errp, errno, "read err");
            goto out;
        }
    } while (rc < 0);
    buf[rc] = 0;

    s = buf;
    for (i = 0; i < PCI_NUM_REGIONS; i++) {
        type = 0;

        start = strtoll(s, &endptr, 16);
        if (*endptr != ' ' || s == endptr) {
            break;
        }
        s = endptr + 1;
        end = strtoll(s, &endptr, 16);
        if (*endptr != ' ' || s == endptr) {
            break;
        }
        s = endptr + 1;
        flags = strtoll(s, &endptr, 16);
        if (*endptr != '\n' || s == endptr) {
            break;
        }
        s = endptr + 1;

        if (start) {
            size = end - start + 1;
        } else {
            size = 0;
        }

        if (flags & IORESOURCE_IO) {
            type |= XEN_HOST_PCI_REGION_TYPE_IO;
        }
        if (flags & IORESOURCE_MEM) {
            type |= XEN_HOST_PCI_REGION_TYPE_MEM;
        }
        if (flags & IORESOURCE_PREFETCH) {
            type |= XEN_HOST_PCI_REGION_TYPE_PREFETCH;
        }
        if (flags & IORESOURCE_MEM_64) {
            type |= XEN_HOST_PCI_REGION_TYPE_MEM_64;
        }

        if (i < PCI_ROM_SLOT) {
            d->io_regions[i].base_addr = start;
            d->io_regions[i].size = size;
            d->io_regions[i].type = type;
            d->io_regions[i].bus_flags = flags & IORESOURCE_BITS;
        } else {
            d->rom.base_addr = start;
            d->rom.size = size;
            d->rom.type = type;
            d->rom.bus_flags = flags & IORESOURCE_BITS;
        }
    }

    if (i != PCI_NUM_REGIONS) {
        error_setg(errp, "Invalid format or input too short: %s", buf);
    }

out:
    close(fd);
}

/* This size should be enough to read a long from a file */
#define XEN_HOST_PCI_GET_VALUE_BUFFER_SIZE 22
static void xen_host_pci_get_value(XenHostPCIDevice *d, const char *name,
                                   unsigned int *pvalue, int base, Error **errp)
{
    char path[PATH_MAX];
    char buf[XEN_HOST_PCI_GET_VALUE_BUFFER_SIZE];
    int fd, rc;
    unsigned long value;
    const char *endptr;

    xen_host_pci_sysfs_path(d, name, path, sizeof(path));

    fd = open(path, O_RDONLY);
    if (fd == -1) {
        error_setg_file_open(errp, errno, path);
        return;
    }

    do {
        rc = read(fd, &buf, sizeof(buf) - 1);
        if (rc < 0 && errno != EINTR) {
            error_setg_errno(errp, errno, "read err");
            goto out;
        }
    } while (rc < 0);

    buf[rc] = 0;
    rc = qemu_strtoul(buf, &endptr, base, &value);
    if (!rc) {
        assert(value <= UINT_MAX);
        *pvalue = value;
    } else {
        error_setg_errno(errp, -rc, "failed to parse value '%s'", buf);
    }

out:
    close(fd);
}

static inline void xen_host_pci_get_hex_value(XenHostPCIDevice *d,
                                              const char *name,
                                              unsigned int *pvalue,
                                              Error **errp)
{
    xen_host_pci_get_value(d, name, pvalue, 16, errp);
}

static inline void xen_host_pci_get_dec_value(XenHostPCIDevice *d,
                                              const char *name,
                                              unsigned int *pvalue,
                                              Error **errp)
{
    xen_host_pci_get_value(d, name, pvalue, 10, errp);
}

static bool xen_host_pci_dev_is_virtfn(XenHostPCIDevice *d)
{
    char path[PATH_MAX];
    struct stat buf;

    xen_host_pci_sysfs_path(d, "physfn", path, sizeof(path));

    return !stat(path, &buf);
}

static void xen_host_pci_config_open(XenHostPCIDevice *d, Error **errp)
{
    char path[PATH_MAX];

    xen_host_pci_sysfs_path(d, "config", path, sizeof(path));

    d->config_fd = open(path, O_RDWR);
    if (d->config_fd == -1) {
        error_setg_file_open(errp, errno, path);
    }
}

static int xen_host_pci_config_read(XenHostPCIDevice *d,
                                    int pos, void *buf, int len)
{
    int rc;

    do {
        rc = pread(d->config_fd, buf, len, pos);
    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
    if (rc != len) {
        return -errno;
    }
    return 0;
}

static int xen_host_pci_config_write(XenHostPCIDevice *d,
                                     int pos, const void *buf, int len)
{
    int rc;

    do {
        rc = pwrite(d->config_fd, buf, len, pos);
    } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
    if (rc != len) {
        return -errno;
    }
    return 0;
}


int xen_host_pci_get_byte(XenHostPCIDevice *d, int pos, uint8_t *p)
{
    uint8_t buf;
    int rc = xen_host_pci_config_read(d, pos, &buf, 1);
    if (!rc) {
        *p = buf;
    }
    return rc;
}

int xen_host_pci_get_word(XenHostPCIDevice *d, int pos, uint16_t *p)
{
    uint16_t buf;
    int rc = xen_host_pci_config_read(d, pos, &buf, 2);
    if (!rc) {
        *p = le16_to_cpu(buf);
    }
    return rc;
}

int xen_host_pci_get_long(XenHostPCIDevice *d, int pos, uint32_t *p)
{
    uint32_t buf;
    int rc = xen_host_pci_config_read(d, pos, &buf, 4);
    if (!rc) {
        *p = le32_to_cpu(buf);
    }
    return rc;
}

int xen_host_pci_get_block(XenHostPCIDevice *d, int pos, uint8_t *buf, int len)
{
    return xen_host_pci_config_read(d, pos, buf, len);
}

int xen_host_pci_set_byte(XenHostPCIDevice *d, int pos, uint8_t data)
{
    return xen_host_pci_config_write(d, pos, &data, 1);
}

int xen_host_pci_set_word(XenHostPCIDevice *d, int pos, uint16_t data)
{
    data = cpu_to_le16(data);
    return xen_host_pci_config_write(d, pos, &data, 2);
}

int xen_host_pci_set_long(XenHostPCIDevice *d, int pos, uint32_t data)
{
    data = cpu_to_le32(data);
    return xen_host_pci_config_write(d, pos, &data, 4);
}

int xen_host_pci_set_block(XenHostPCIDevice *d, int pos, uint8_t *buf, int len)
{
    return xen_host_pci_config_write(d, pos, buf, len);
}

int xen_host_pci_find_ext_cap_offset(XenHostPCIDevice *d, uint32_t cap)
{
    uint32_t header = 0;
    int max_cap = XEN_HOST_PCI_MAX_EXT_CAP;
    int pos = PCI_CONFIG_SPACE_SIZE;

    do {
        if (xen_host_pci_get_long(d, pos, &header)) {
            break;
        }
        /*
         * If we have no capabilities, this is indicated by cap ID,
         * cap version and next pointer all being 0.
         */
        if (header == 0) {
            break;
        }

        if (PCI_EXT_CAP_ID(header) == cap) {
            return pos;
        }

        pos = PCI_EXT_CAP_NEXT(header);
        if (pos < PCI_CONFIG_SPACE_SIZE) {
            break;
        }

        max_cap--;
    } while (max_cap > 0);

    return -1;
}

void xen_host_pci_device_get(XenHostPCIDevice *d, uint16_t domain,
                             uint8_t bus, uint8_t dev, uint8_t func,
                             Error **errp)
{
    ERRP_GUARD();
    unsigned int v;

    d->config_fd = -1;
    d->domain = domain;
    d->bus = bus;
    d->dev = dev;
    d->func = func;

    if (xen_is_stubdomain) {
        xen_host_pci_fill_local_addr(d, errp);
        if (*errp) {
            goto error;
        }
    } else {
        d->local_domain = d->domain;
        d->local_bus = d->bus;
        d->local_dev = d->dev;
        d->local_func = d->func;
    }

    xen_host_pci_config_open(d, errp);
    if (*errp) {
        goto error;
    }

    xen_host_pci_get_resource(d, errp);
    if (*errp) {
        goto error;
    }

    xen_host_pci_get_hex_value(d, "vendor", &v, errp);
    if (*errp) {
        goto error;
    }
    d->vendor_id = v;

    xen_host_pci_get_hex_value(d, "device", &v, errp);
    if (*errp) {
        goto error;
    }
    d->device_id = v;

    xen_host_pci_get_dec_value(d, "irq", &v, errp);
    if (*errp) {
        goto error;
    }
    d->irq = v;

    xen_host_pci_get_hex_value(d, "class", &v, errp);
    if (*errp) {
        goto error;
    }
    d->class_code = v;

    d->is_virtfn = xen_host_pci_dev_is_virtfn(d);

    return;

error:

    if (d->config_fd >= 0) {
        close(d->config_fd);
        d->config_fd = -1;
    }
}

bool xen_host_pci_device_closed(XenHostPCIDevice *d)
{
    return d->config_fd == -1;
}

void xen_host_pci_device_put(XenHostPCIDevice *d)
{
    if (d->config_fd >= 0) {
        close(d->config_fd);
        d->config_fd = -1;
    }
}