// Test case for XHCI buffer expansion regression
//
// 1) Compile this program:  gcc -o xhci_bug xhci_bug.c
// 2) Plug in a supported USB to serial device
// 3) Get the bus and device numbers from lsusb:
//    Bus 003 Device 015: ID 0403:6001 Future Technology Devices International, Ltd FT232 Serial (UART) IC
// 4) Run as root:  ./xhci_bug ftdi_sio 3 15 4096

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/usbdevice_fs.h>

#define URB_SIZE 64

struct Device {
    const char *driver;
    int         ep;
    const char *ep_debug;
};

static struct Device devices[] = {
    { "ftdi_sio", 0x81, "ep02" },
    { "pl2303",   0x83, "ep06" },
    { "cp210x",   0x82, "ep04" },
    { },
};

int main (int argc, char *argv[])
{
    // Parse command line
    if (argc < 4) {
        char drivers[255] = { };
        for (int i = 0; devices[i].driver; ++i) {
            strcat(drivers, devices[i].driver);
            if (devices[i+1].driver) strcat(drivers, "|");
        }

        printf("usage: xhci_bug <%s> BUS DEV NUM_URBS\n", drivers);
        return 1;
    }

    const char *driver = argv[1];
    int bus = atoi(argv[2]);
    int dev = atoi(argv[3]);
    int num_urbs = atoi(argv[4]);

    if (num_urbs > 4096)
        num_urbs = 4096;

    // Find the driver
    struct Device *device = NULL;
    for (int i = 0; devices[i].driver; ++i) {
        if (strcmp(devices[i].driver, driver) == 0) {
            device = &devices[i];
            break;
        }
    }

    if (device == NULL) {
        printf("error: driver %s not found\n", driver);
        return 1;
    }

    // Remove the driver
    char cmd[1024];
    sprintf(cmd, "lsmod | grep %s -q && rmmod %s", driver, driver);
    system(cmd);

    // Get the debug path
    char debug[256] = { };

    sprintf(
        cmd,
        "find /sys/kernel/debug/usb/xhci -name 'name' | "
        "while IFS= read -r line; do "
        "dir=$(dirname $line); "
        "sys=/sys/bus/usb/devices/$(cat $dir/name); "
        "grep -q '^%d$' $sys/busnum && "
        "grep -q '^%d$' $sys/devnum && "
        "echo $dir; "
        "done",
        bus, dev
    );

    FILE *fp = popen(cmd, "r");
    char *p = fgets(debug, sizeof(debug), fp);
    pclose(fp);

    if (p == NULL) {
        printf("error: debug path not found\n");
        return 1;
    }

    debug[strlen(debug)-1] = '\0';

    // Print the number of TRBs
    printf("Before URB submission:\n");
    sprintf(cmd, "wc -l %s/%s/trbs", debug, device->ep_debug);
    system(cmd);
    printf("\n");

    // Open the device
    char path[256];
    sprintf(path, "/dev/bus/usb/%03d/%03d", bus, dev);

    int fd = open(path, O_RDWR);
    if (fd < 0)
        return 1;

    int rc;

    int cfg = 1;
    rc = ioctl(fd, USBDEVFS_SETCONFIGURATION, &cfg);
    if (rc < 0 && errno != EBUSY) {
        printf("error: unable to set configuration\n");
        close(fd);
        return 1;
    }

    int ifce = 0;
    rc = ioctl(fd, USBDEVFS_CLAIMINTERFACE, &ifce);
    if (rc < 0) {
        printf("error: unable to claim interface\n");
        close(fd);
        return 1;
    }

    // Submit URBs
    printf("Submitting %d URBs\n\n", num_urbs);

    for (int i = 0; i < num_urbs; ++i) {
        struct usbdevfs_urb *ioctl_urb = calloc(1, sizeof(*ioctl_urb));

        ioctl_urb->type          = USBDEVFS_URB_TYPE_BULK;
        ioctl_urb->endpoint      = device->ep;
        ioctl_urb->buffer        = calloc(1, URB_SIZE);
        ioctl_urb->buffer_length = URB_SIZE;

        rc = ioctl(fd, USBDEVFS_SUBMITURB, ioctl_urb);
        if (rc < 0) {
            printf("error: could not submit urb #%d\n", i);
            return 1;
        }
    }

    // Print the number of TRBs
    printf("After URB submission:\n");
    system(cmd);
    printf("\n");

    // Close the device
    close(fd);
    return 0;
}