2

私はUSB http://www.linuxforu.com/2011/12/data-transfers-to-from-usb-devices/でレッスンを試みていますが、問題に悩まされています-読み取り中にusb_bulk_msgがエラー22を返します-無効な引数。書き込み操作は成功します。

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/usb.h>

#define MIN(a,b) (((a) <= (b)) ? (a) : (b))
#define BULK_EP_OUT 0x01
#define BULK_EP_IN 0x82
#define MAX_PKT_SIZE 512

static struct usb_device *device;
static struct usb_class_driver class;
static unsigned char bulk_buf[MAX_PKT_SIZE];

static int pen_open(struct inode *i, struct file *f)
{
    return 0;
}
static int pen_close(struct inode *i, struct file *f)
{
    return 0;
}
static ssize_t pen_read(struct file *f, char __user *buf, size_t cnt, loff_t *off)
{
    int retval;
    int read_cnt;

    /* Read the data from the bulk endpoint */
    retval = usb_bulk_msg(device, usb_rcvbulkpipe(device, BULK_EP_IN),
            bulk_buf, MAX_PKT_SIZE, &read_cnt, 5000);
    if (retval)
    {
        printk(KERN_ERR "Bulk message returned %d\n", retval);
        return retval;
    }
    if (copy_to_user(buf, bulk_buf, MIN(cnt, read_cnt)))
    {
        return -EFAULT;
    }

    return MIN(cnt, read_cnt);
}
static ssize_t pen_write(struct file *f, const char __user *buf, size_t cnt, loff_t *off)
{
    int retval;
    int wrote_cnt = MIN(cnt, MAX_PKT_SIZE);

    if (copy_from_user(bulk_buf, buf, MIN(cnt, MAX_PKT_SIZE)))
    {
        return -EFAULT;
    }

    /* Write the data into the bulk endpoint */
    retval = usb_bulk_msg(device, usb_sndbulkpipe(device, BULK_EP_OUT),
            bulk_buf, MIN(cnt, MAX_PKT_SIZE), &wrote_cnt, 5000);
    if (retval)
    {
        printk(KERN_ERR "Bulk message returned %d\n", retval);
        return retval;
    }

    return wrote_cnt;
}

static struct file_operations fops =
{
    .open = pen_open,
    .release = pen_close,
    .read = pen_read,
    .write = pen_write,
};

static int pen_probe(struct usb_interface *interface, const struct usb_device_id *id)
{
    int retval;

    device = interface_to_usbdev(interface);

    class.name = "usb/pen%d";
    class.fops = &fops;
    if ((retval = usb_register_dev(interface, &class)) < 0)
    {
        /* Something prevented us from registering this driver */
        err("Not able to get a minor for this device.");
    }
    else
    {
        printk(KERN_INFO "Minor obtained: %d\n", interface->minor);
    }

    return retval;
}

static void pen_disconnect(struct usb_interface *interface)
{
    usb_deregister_dev(interface, &class);
}

/* Table of devices that work with this driver */
static struct usb_device_id pen_table[] =
{
    { USB_DEVICE(0x058F, 0x6387) },
    {} /* Terminating entry */
};
MODULE_DEVICE_TABLE (usb, pen_table);

static struct usb_driver pen_driver =
{
    .name = "pen_driver",
    .probe = pen_probe,
    .disconnect = pen_disconnect,
    .id_table = pen_table,
};

static int __init pen_init(void)
{
    int result;

    /* Register this driver with the USB subsystem */
    if ((result = usb_register(&pen_driver)))
    {
        err("usb_register failed. Error number %d", result);
    }
    return result;
}

static void __exit pen_exit(void)
{
    /* Deregister this driver with the USB subsystem */
    usb_deregister(&pen_driver);
}

module_init(pen_init);
module_exit(pen_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anil Kumar Pugalia <email_at_sarika-pugs_dot_com>");
MODULE_DESCRIPTION("USB Pen Device Driver");
4

2 に答える 2

0

このエラーには多くの理由が考えられますが、私の場合は BULK_EP アドレスが間違っていました。ハードコーディングするのではなく、プローブ機能でエンドポイント アドレスを設定することをお勧めします。以下のコードを参照して、一括エンドポイント アドレスを設定してください。

static void
set_bulk_address (
    struct my_device *dev,
    struct usb_interface *interface)
{
    struct usb_endpoint_descriptor *endpoint;
    struct usb_host_interface *iface_desc;
    int i;

    iface_desc = interface->cur_altsetting;
    for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
        endpoint = &iface_desc->endpoint[i].desc;

        /* check for bulk endpoint */
        if ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) 
            == USB_ENDPOINT_XFER_BULK){

            /* bulk in */
            if(endpoint->bEndpointAddress & USB_DIR_IN) {
                dev->bulk_in_add = endpoint->bEndpointAddress;
                dev->bulk_in_size = endpoint->wMaxPacketSize;
                dev->bulk_in_buffer = kmalloc(dev->bulk_in_size,
                                GFP_KERNEL);
                if (!dev->bulk_in_buffer)
                    print("Could not allocate bulk buffer");
            }

            /* bulk out */
            else
                dev->bulk_out_add = endpoint->bEndpointAddress; 
        }
    }
}

お気づきかもしれませんが、エンドポイント情報を保持するために独自のデバイス構造体を定義しました。ここに私の構造体定義があります

struct my_device {
    struct usb_device   *udev;      /* usb device for this device */
    struct usb_interface    *interface; /* interface for this device */
    unsigned char       minor;      /* minor value */
    unsigned char *     bulk_in_buffer; /* the buffer to in data */
    size_t          bulk_in_size;   /* the size of the in buffer */
    __u8            bulk_in_add;    /* bulk in endpoint address */
    __u8            bulk_out_add;   /* bulk out endpoint address */
    struct kref     kref;       /* module references counter */
};
于 2014-08-16T20:34:14.853 に答える