dbgp.c

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/*
 * dbgp.c -- EHCI Debug Port device gadget
 *
 * Copyright (C) 2010 Stephane Duverger
 *
 * Released under the GPLv2.
 */

/* verbose messages */
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>

#ifdef CONFIG_USB_G_DBGP_SERIAL
#include "u_serial.c"
#endif

#define DRIVER_VENDOR_ID    0x0525 /* NetChip */
#define DRIVER_PRODUCT_ID   0xc0de /* undefined */

#define USB_DEBUG_MAX_PACKET_SIZE     8
#define DBGP_REQ_EP0_LEN              128
#define DBGP_REQ_LEN                  512

static struct dbgp {
    struct usb_gadget  *gadget;
    struct usb_request *req;
    struct usb_ep      *i_ep;
    struct usb_ep      *o_ep;
#ifdef CONFIG_USB_G_DBGP_SERIAL
    struct gserial     *serial;
#endif
} dbgp;

static struct usb_device_descriptor device_desc = {
    .bLength = sizeof device_desc,
    .bDescriptorType = USB_DT_DEVICE,
    .bcdUSB = __constant_cpu_to_le16(0x0200),
    .bDeviceClass = USB_CLASS_VENDOR_SPEC,
    .idVendor = __constant_cpu_to_le16(DRIVER_VENDOR_ID),
    .idProduct = __constant_cpu_to_le16(DRIVER_PRODUCT_ID),
    .bNumConfigurations = 1,
};

static struct usb_debug_descriptor dbg_desc = {
    .bLength = sizeof dbg_desc,
    .bDescriptorType = USB_DT_DEBUG,
};

static struct usb_endpoint_descriptor i_desc = {
    .bLength = USB_DT_ENDPOINT_SIZE,
    .bDescriptorType = USB_DT_ENDPOINT,
    .bmAttributes = USB_ENDPOINT_XFER_BULK,
    .bEndpointAddress = USB_DIR_IN,
};

static struct usb_endpoint_descriptor o_desc = {
    .bLength = USB_DT_ENDPOINT_SIZE,
    .bDescriptorType = USB_DT_ENDPOINT,
    .bmAttributes = USB_ENDPOINT_XFER_BULK,
    .bEndpointAddress = USB_DIR_OUT,
};

#ifdef CONFIG_USB_G_DBGP_PRINTK
static int dbgp_consume(char *buf, unsigned len)
{
    char c;

    if (!len)
        return 0;

    c = buf[len-1];
    if (c != 0)
        buf[len-1] = 0;

    printk(KERN_NOTICE "%s%c", buf, c);
    return 0;
}

static void __disable_ep(struct usb_ep *ep)
{
    if (ep && ep->driver_data == dbgp.gadget) {
        usb_ep_disable(ep);
        ep->driver_data = NULL;
    }
}

static void dbgp_disable_ep(void)
{
    __disable_ep(dbgp.i_ep);
    __disable_ep(dbgp.o_ep);
}

static void dbgp_complete(struct usb_ep *ep, struct usb_request *req)
{
    int stp;
    int err = 0;
    int status = req->status;

    if (ep == dbgp.i_ep) {
        stp = 1;
        goto fail;
    }

    if (status != 0) {
        stp = 2;
        goto release_req;
    }

    dbgp_consume(req->buf, req->actual);

    req->length = DBGP_REQ_LEN;
    err = usb_ep_queue(ep, req, GFP_ATOMIC);
    if (err < 0) {
        stp = 3;
        goto release_req;
    }

    return;

release_req:
    kfree(req->buf);
    usb_ep_free_request(dbgp.o_ep, req);
    dbgp_disable_ep();
fail:
    dev_dbg(&dbgp.gadget->dev,
        "complete: failure (%d:%d) ==> %d\n", stp, err, status);
}

static int dbgp_enable_ep_req(struct usb_ep *ep)
{
    int err, stp;
    struct usb_request *req;

    req = usb_ep_alloc_request(ep, GFP_KERNEL);
    if (!req) {
        err = -ENOMEM;
        stp = 1;
        goto fail_1;
    }

    req->buf = kmalloc(DBGP_REQ_LEN, GFP_KERNEL);
    if (!req->buf) {
        err = -ENOMEM;
        stp = 2;
        goto fail_2;
    }

    req->complete = dbgp_complete;
    req->length = DBGP_REQ_LEN;
    err = usb_ep_queue(ep, req, GFP_ATOMIC);
    if (err < 0) {
        stp = 3;
        goto fail_3;
    }

    return 0;

fail_3:
    kfree(req->buf);
fail_2:
    usb_ep_free_request(dbgp.o_ep, req);
fail_1:
    dev_dbg(&dbgp.gadget->dev,
        "enable ep req: failure (%d:%d)\n", stp, err);
    return err;
}

static int __enable_ep(struct usb_ep *ep, struct usb_endpoint_descriptor *desc)
{
    int err;
    ep->desc = desc;
    err = usb_ep_enable(ep);
    ep->driver_data = dbgp.gadget;
    return err;
}

static int dbgp_enable_ep(void)
{
    int err, stp;

    err = __enable_ep(dbgp.i_ep, &i_desc);
    if (err < 0) {
        stp = 1;
        goto fail_1;
    }

    err = __enable_ep(dbgp.o_ep, &o_desc);
    if (err < 0) {
        stp = 2;
        goto fail_2;
    }

    err = dbgp_enable_ep_req(dbgp.o_ep);
    if (err < 0) {
        stp = 3;
        goto fail_3;
    }

    return 0;

fail_3:
    __disable_ep(dbgp.o_ep);
fail_2:
    __disable_ep(dbgp.i_ep);
fail_1:
    dev_dbg(&dbgp.gadget->dev, "enable ep: failure (%d:%d)\n", stp, err);
    return err;
}
#endif

static void dbgp_disconnect(struct usb_gadget *gadget)
{
#ifdef CONFIG_USB_G_DBGP_PRINTK
    dbgp_disable_ep();
#else
    gserial_disconnect(dbgp.serial);
#endif
}

static void dbgp_unbind(struct usb_gadget *gadget)
{
#ifdef CONFIG_USB_G_DBGP_SERIAL
    kfree(dbgp.serial);
#endif
    if (dbgp.req) {
        kfree(dbgp.req->buf);
        usb_ep_free_request(gadget->ep0, dbgp.req);
    }

    gadget->ep0->driver_data = NULL;
}

static int __init dbgp_configure_endpoints(struct usb_gadget *gadget)
{
    int stp;

    usb_ep_autoconfig_reset(gadget);

    dbgp.i_ep = usb_ep_autoconfig(gadget, &i_desc);
    if (!dbgp.i_ep) {
        stp = 1;
        goto fail_1;
    }

    dbgp.i_ep->driver_data = gadget;
    i_desc.wMaxPacketSize =
        __constant_cpu_to_le16(USB_DEBUG_MAX_PACKET_SIZE);

    dbgp.o_ep = usb_ep_autoconfig(gadget, &o_desc);
    if (!dbgp.o_ep) {
        dbgp.i_ep->driver_data = NULL;
        stp = 2;
        goto fail_2;
    }

    dbgp.o_ep->driver_data = gadget;
    o_desc.wMaxPacketSize =
        __constant_cpu_to_le16(USB_DEBUG_MAX_PACKET_SIZE);

    dbg_desc.bDebugInEndpoint = i_desc.bEndpointAddress;
    dbg_desc.bDebugOutEndpoint = o_desc.bEndpointAddress;

#ifdef CONFIG_USB_G_DBGP_SERIAL
    dbgp.serial->in = dbgp.i_ep;
    dbgp.serial->out = dbgp.o_ep;

    dbgp.serial->in->desc = &i_desc;
    dbgp.serial->out->desc = &o_desc;

    if (gserial_setup(gadget, 1) < 0) {
        stp = 3;
        goto fail_3;
    }

    return 0;

fail_3:
    dbgp.o_ep->driver_data = NULL;
#else
    return 0;
#endif
fail_2:
    dbgp.i_ep->driver_data = NULL;
fail_1:
    dev_dbg(&dbgp.gadget->dev, "ep config: failure (%d)\n", stp);
    return -ENODEV;
}

static int __init dbgp_bind(struct usb_gadget *gadget,
        struct usb_gadget_driver *driver)
{
    int err, stp;

    dbgp.gadget = gadget;

    dbgp.req = usb_ep_alloc_request(gadget->ep0, GFP_KERNEL);
    if (!dbgp.req) {
        err = -ENOMEM;
        stp = 1;
        goto fail;
    }

    dbgp.req->buf = kmalloc(DBGP_REQ_EP0_LEN, GFP_KERNEL);
    if (!dbgp.req->buf) {
        err = -ENOMEM;
        stp = 2;
        goto fail;
    }

    dbgp.req->length = DBGP_REQ_EP0_LEN;
    gadget->ep0->driver_data = gadget;

#ifdef CONFIG_USB_G_DBGP_SERIAL
    dbgp.serial = kzalloc(sizeof(struct gserial), GFP_KERNEL);
    if (!dbgp.serial) {
        stp = 3;
        err = -ENOMEM;
        goto fail;
    }
#endif
    err = dbgp_configure_endpoints(gadget);
    if (err < 0) {
        stp = 4;
        goto fail;
    }

    dev_dbg(&dbgp.gadget->dev, "bind: success\n");
    return 0;

fail:
    dev_dbg(&gadget->dev, "bind: failure (%d:%d)\n", stp, err);
    dbgp_unbind(gadget);
    return err;
}

static void dbgp_setup_complete(struct usb_ep *ep,
                struct usb_request *req)
{
    dev_dbg(&dbgp.gadget->dev, "setup complete: %d, %d/%d\n",
        req->status, req->actual, req->length);
}

static int dbgp_setup(struct usb_gadget *gadget,
              const struct usb_ctrlrequest *ctrl)
{
    struct usb_request *req = dbgp.req;
    u8 request = ctrl->bRequest;
    u16 value = le16_to_cpu(ctrl->wValue);
    u16 length = le16_to_cpu(ctrl->wLength);
    int err = -EOPNOTSUPP;
    void *data = NULL;
    u16 len = 0;

    gadget->ep0->driver_data = gadget;

    if (request == USB_REQ_GET_DESCRIPTOR) {
        switch (value>>8) {
        case USB_DT_DEVICE:
            dev_dbg(&dbgp.gadget->dev, "setup: desc device\n");
            len = sizeof device_desc;
            data = &device_desc;
            device_desc.bMaxPacketSize0 = gadget->ep0->maxpacket;
            break;
        case USB_DT_DEBUG:
            dev_dbg(&dbgp.gadget->dev, "setup: desc debug\n");
            len = sizeof dbg_desc;
            data = &dbg_desc;
            break;
        default:
            goto fail;
        }
        err = 0;
    } else if (request == USB_REQ_SET_FEATURE &&
           value == USB_DEVICE_DEBUG_MODE) {
        dev_dbg(&dbgp.gadget->dev, "setup: feat debug\n");
#ifdef CONFIG_USB_G_DBGP_PRINTK
        err = dbgp_enable_ep();
#else
        err = gserial_connect(dbgp.serial, 0);
#endif
        if (err < 0)
            goto fail;
    } else
        goto fail;

    req->length = min(length, len);
    req->zero = len < req->length;
    if (data && req->length)
        memcpy(req->buf, data, req->length);

    req->complete = dbgp_setup_complete;
    return usb_ep_queue(gadget->ep0, req, GFP_ATOMIC);

fail:
    dev_dbg(&dbgp.gadget->dev,
        "setup: failure req %x v %x\n", request, value);
    return err;
}

static __refdata struct usb_gadget_driver dbgp_driver = {
    .function = "dbgp",
    .max_speed = USB_SPEED_HIGH,
    .bind = dbgp_bind,
    .unbind = dbgp_unbind,
    .setup = dbgp_setup,
    .disconnect = dbgp_disconnect,
    .driver = {
        .owner = THIS_MODULE,
        .name = "dbgp"
    },
};

static int __init dbgp_init(void)
{
    return usb_gadget_probe_driver(&dbgp_driver);
}

static void __exit dbgp_exit(void)
{
    usb_gadget_unregister_driver(&dbgp_driver);
#ifdef CONFIG_USB_G_DBGP_SERIAL
    gserial_cleanup();
#endif
}

MODULE_AUTHOR("Stephane Duverger");
MODULE_LICENSE("GPL");
module_init(dbgp_init);
module_exit(dbgp_exit);