--- /dev/null
+FastBoot  Version  0.4
+----------------------
+
+The fastboot protocol is a mechanism for communicating with bootloaders
+over USB.  It is designed to be very straightforward to implement, to
+allow it to be used across a wide range of devices and from hosts running
+Linux, Windows, or OSX.
+
+
+Basic Requirements
+------------------
+
+* Two bulk endpoints (in, out) are required
+* Max packet size must be 64 bytes for full-speed and 512 bytes for
+  high-speed USB
+* The protocol is entirely host-driven and synchronous (unlike the
+  multi-channel, bi-directional, asynchronous ADB protocol)
+
+
+Transport and Framing
+---------------------
+
+1. Host sends a command, which is an ascii string in a single
+   packet no greater than 64 bytes.
+
+2. Client response with a single packet no greater than 64 bytes.
+   The first four bytes of the response are "OKAY", "FAIL", "DATA",
+   or "INFO".  Additional bytes may contain an (ascii) informative
+   message.
+
+   a. INFO -> the remaining 60 bytes are an informative message
+      (providing progress or diagnostic messages).  They should
+      be displayed and then step #2 repeats
+
+   b. FAIL -> the requested command failed.  The remaining 60 bytes
+      of the response (if present) provide a textual failure message
+      to present to the user.  Stop.
+
+   c. OKAY -> the requested command completed successfully.  Go to #5
+
+   d. DATA -> the requested command is ready for the data phase.
+      A DATA response packet will be 12 bytes long, in the form of
+      DATA00000000 where the 8 digit hexidecimal number represents
+      the total data size to transfer.
+
+3. Data phase.  Depending on the command, the host or client will
+   send the indicated amount of data.  Short packets are always
+   acceptable and zero-length packets are ignored.  This phase continues
+   until the client has sent or received the number of bytes indicated
+   in the "DATA" response above.
+
+4. Client responds with a single packet no greater than 64 bytes.
+   The first four bytes of the response are "OKAY", "FAIL", or "INFO".
+   Similar to #2:
+
+   a. INFO -> display the remaining 60 bytes and return to #4
+
+   b. FAIL -> display the remaining 60 bytes (if present) as a failure
+      reason and consider the command failed.  Stop.
+
+   c. OKAY -> success.  Go to #5
+
+5. Success.  Stop.
+
+
+Example Session
+---------------
+
+Host:    "getvar:version"        request version variable
+
+Client:  "OKAY0.4"               return version "0.4"
+
+Host:    "getvar:nonexistant"    request some undefined variable
+
+Client:  "OKAY"                  return value ""
+
+Host:    "download:00001234"     request to send 0x1234 bytes of data
+
+Client:  "DATA00001234"          ready to accept data
+
+Host:    < 0x1234 bytes >        send data
+
+Client:  "OKAY"                  success
+
+Host:    "flash:bootloader"      request to flash the data to the bootloader
+
+Client:  "INFOerasing flash"     indicate status / progress
+         "INFOwriting flash"
+         "OKAY"                  indicate success
+
+Host:    "powerdown"             send a command
+
+Client:  "FAILunknown command"   indicate failure
+
+
+Command Reference
+-----------------
+
+* Command parameters are indicated by printf-style escape sequences.
+
+* Commands are ascii strings and sent without the quotes (which are
+  for illustration only here) and without a trailing 0 byte.
+
+* Commands that begin with a lowercase letter are reserved for this
+  specification.  OEM-specific commands should not begin with a
+  lowercase letter, to prevent incompatibilities with future specs.
+
+ "getvar:%s"           Read a config/version variable from the bootloader.
+                       The variable contents will be returned after the
+                       OKAY response.
+
+ "download:%08x"       Write data to memory which will be later used
+                       by "boot", "ramdisk", "flash", etc.  The client
+                       will reply with "DATA%08x" if it has enough
+                       space in RAM or "FAIL" if not.  The size of
+                       the download is remembered.
+
+  "verify:%08x"        Send a digital signature to verify the downloaded
+                       data.  Required if the bootloader is "secure"
+                       otherwise "flash" and "boot" will be ignored.
+
+  "flash:%s"           Write the previously downloaded image to the
+                       named partition (if possible).
+
+  "erase:%s"           Erase the indicated partition (clear to 0xFFs)
+
+  "boot"               The previously downloaded data is a boot.img
+                       and should be booted according to the normal
+                       procedure for a boot.img
+
+  "continue"           Continue booting as normal (if possible)
+
+  "reboot"             Reboot the device.
+
+  "reboot-bootloader"  Reboot back into the bootloader.
+                       Useful for upgrade processes that require upgrading
+                       the bootloader and then upgrading other partitions
+                       using the new bootloader.
+
+  "powerdown"          Power off the device.
+
+
+
+Client Variables
+----------------
+
+The "getvar:%s" command is used to read client variables which
+represent various information about the device and the software
+on it.
+
+The various currently defined names are:
+
+  version             Version of FastBoot protocol supported.
+                      It should be "0.3" for this document.
+
+  version-bootloader  Version string for the Bootloader.
+
+  version-baseband    Version string of the Baseband Software
+
+  product             Name of the product
+
+  serialno            Product serial number
+
+  secure              If the value is "yes", this is a secure
+                      bootloader requiring a signature before
+                      it will install or boot images.
+
+Names starting with a lowercase character are reserved by this
+specification.  OEM-specific names should not start with lowercase
+characters.
 
--- /dev/null
+/*
+ * (C) Copyright 2008 - 2009
+ * Windriver, <www.windriver.com>
+ * Tom Rix <Tom.Rix@windriver.com>
+ *
+ * Copyright 2011 Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+ *
+ * Copyright 2014 Linaro, Ltd.
+ * Rob Herring <robh@kernel.org>
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+#include <common.h>
+#include <errno.h>
+#include <malloc.h>
+#include <linux/usb/ch9.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/composite.h>
+#include <linux/compiler.h>
+#include <version.h>
+#include <g_dnl.h>
+
+#define FASTBOOT_VERSION               "0.4"
+
+#define FASTBOOT_INTERFACE_CLASS       0xff
+#define FASTBOOT_INTERFACE_SUB_CLASS   0x42
+#define FASTBOOT_INTERFACE_PROTOCOL    0x03
+
+#define RX_ENDPOINT_MAXIMUM_PACKET_SIZE_2_0  (0x0200)
+#define RX_ENDPOINT_MAXIMUM_PACKET_SIZE_1_1  (0x0040)
+#define TX_ENDPOINT_MAXIMUM_PACKET_SIZE      (0x0040)
+
+/* The 64 defined bytes plus \0 */
+#define RESPONSE_LEN   (64 + 1)
+
+#define EP_BUFFER_SIZE                 4096
+
+struct f_fastboot {
+       struct usb_function usb_function;
+
+       /* IN/OUT EP's and correspoinding requests */
+       struct usb_ep *in_ep, *out_ep;
+       struct usb_request *in_req, *out_req;
+};
+
+static inline struct f_fastboot *func_to_fastboot(struct usb_function *f)
+{
+       return container_of(f, struct f_fastboot, usb_function);
+}
+
+static struct f_fastboot *fastboot_func;
+static unsigned int download_size;
+static unsigned int download_bytes;
+
+static struct usb_endpoint_descriptor fs_ep_in = {
+       .bLength            = USB_DT_ENDPOINT_SIZE,
+       .bDescriptorType    = USB_DT_ENDPOINT,
+       .bEndpointAddress   = USB_DIR_IN,
+       .bmAttributes       = USB_ENDPOINT_XFER_BULK,
+       .wMaxPacketSize     = TX_ENDPOINT_MAXIMUM_PACKET_SIZE,
+       .bInterval          = 0x00,
+};
+
+static struct usb_endpoint_descriptor fs_ep_out = {
+       .bLength                = USB_DT_ENDPOINT_SIZE,
+       .bDescriptorType        = USB_DT_ENDPOINT,
+       .bEndpointAddress       = USB_DIR_OUT,
+       .bmAttributes           = USB_ENDPOINT_XFER_BULK,
+       .wMaxPacketSize         = RX_ENDPOINT_MAXIMUM_PACKET_SIZE_1_1,
+       .bInterval              = 0x00,
+};
+
+static struct usb_endpoint_descriptor hs_ep_out = {
+       .bLength                = USB_DT_ENDPOINT_SIZE,
+       .bDescriptorType        = USB_DT_ENDPOINT,
+       .bEndpointAddress       = USB_DIR_OUT,
+       .bmAttributes           = USB_ENDPOINT_XFER_BULK,
+       .wMaxPacketSize         = RX_ENDPOINT_MAXIMUM_PACKET_SIZE_2_0,
+       .bInterval              = 0x00,
+};
+
+static struct usb_interface_descriptor interface_desc = {
+       .bLength                = USB_DT_INTERFACE_SIZE,
+       .bDescriptorType        = USB_DT_INTERFACE,
+       .bInterfaceNumber       = 0x00,
+       .bAlternateSetting      = 0x00,
+       .bNumEndpoints          = 0x02,
+       .bInterfaceClass        = FASTBOOT_INTERFACE_CLASS,
+       .bInterfaceSubClass     = FASTBOOT_INTERFACE_SUB_CLASS,
+       .bInterfaceProtocol     = FASTBOOT_INTERFACE_PROTOCOL,
+};
+
+static struct usb_descriptor_header *fb_runtime_descs[] = {
+       (struct usb_descriptor_header *)&interface_desc,
+       (struct usb_descriptor_header *)&fs_ep_in,
+       (struct usb_descriptor_header *)&hs_ep_out,
+       NULL,
+};
+
+/*
+ * static strings, in UTF-8
+ */
+static const char fastboot_name[] = "Android Fastboot";
+
+static struct usb_string fastboot_string_defs[] = {
+       [0].s = fastboot_name,
+       {  }                    /* end of list */
+};
+
+static struct usb_gadget_strings stringtab_fastboot = {
+       .language       = 0x0409,       /* en-us */
+       .strings        = fastboot_string_defs,
+};
+
+static struct usb_gadget_strings *fastboot_strings[] = {
+       &stringtab_fastboot,
+       NULL,
+};
+
+static void rx_handler_command(struct usb_ep *ep, struct usb_request *req);
+
+static void fastboot_complete(struct usb_ep *ep, struct usb_request *req)
+{
+       int status = req->status;
+       if (!status)
+               return;
+       printf("status: %d ep '%s' trans: %d\n", status, ep->name, req->actual);
+}
+
+static int fastboot_bind(struct usb_configuration *c, struct usb_function *f)
+{
+       int id;
+       struct usb_gadget *gadget = c->cdev->gadget;
+       struct f_fastboot *f_fb = func_to_fastboot(f);
+
+       /* DYNAMIC interface numbers assignments */
+       id = usb_interface_id(c, f);
+       if (id < 0)
+               return id;
+       interface_desc.bInterfaceNumber = id;
+
+       id = usb_string_id(c->cdev);
+       if (id < 0)
+               return id;
+       fastboot_string_defs[0].id = id;
+       interface_desc.iInterface = id;
+
+       f_fb->in_ep = usb_ep_autoconfig(gadget, &fs_ep_in);
+       if (!f_fb->in_ep)
+               return -ENODEV;
+       f_fb->in_ep->driver_data = c->cdev;
+
+       f_fb->out_ep = usb_ep_autoconfig(gadget, &fs_ep_out);
+       if (!f_fb->out_ep)
+               return -ENODEV;
+       f_fb->out_ep->driver_data = c->cdev;
+
+       hs_ep_out.bEndpointAddress = fs_ep_out.bEndpointAddress;
+
+       return 0;
+}
+
+static void fastboot_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+       memset(fastboot_func, 0, sizeof(*fastboot_func));
+}
+
+static void fastboot_disable(struct usb_function *f)
+{
+       struct f_fastboot *f_fb = func_to_fastboot(f);
+
+       usb_ep_disable(f_fb->out_ep);
+       usb_ep_disable(f_fb->in_ep);
+
+       if (f_fb->out_req) {
+               free(f_fb->out_req->buf);
+               usb_ep_free_request(f_fb->out_ep, f_fb->out_req);
+               f_fb->out_req = NULL;
+       }
+       if (f_fb->in_req) {
+               free(f_fb->in_req->buf);
+               usb_ep_free_request(f_fb->in_ep, f_fb->in_req);
+               f_fb->in_req = NULL;
+       }
+}
+
+static struct usb_request *fastboot_start_ep(struct usb_ep *ep)
+{
+       struct usb_request *req;
+
+       req = usb_ep_alloc_request(ep, 0);
+       if (!req)
+               return NULL;
+
+       req->length = EP_BUFFER_SIZE;
+       req->buf = memalign(CONFIG_SYS_CACHELINE_SIZE, EP_BUFFER_SIZE);
+       if (!req->buf) {
+               usb_ep_free_request(ep, req);
+               return NULL;
+       }
+
+       memset(req->buf, 0, req->length);
+       return req;
+}
+
+static int fastboot_set_alt(struct usb_function *f,
+                           unsigned interface, unsigned alt)
+{
+       int ret;
+       struct usb_composite_dev *cdev = f->config->cdev;
+       struct usb_gadget *gadget = cdev->gadget;
+       struct f_fastboot *f_fb = func_to_fastboot(f);
+
+       debug("%s: func: %s intf: %d alt: %d\n",
+             __func__, f->name, interface, alt);
+
+       /* make sure we don't enable the ep twice */
+       if (gadget->speed == USB_SPEED_HIGH)
+               ret = usb_ep_enable(f_fb->out_ep, &hs_ep_out);
+       else
+               ret = usb_ep_enable(f_fb->out_ep, &fs_ep_out);
+       if (ret) {
+               puts("failed to enable out ep\n");
+               return ret;
+       }
+
+       f_fb->out_req = fastboot_start_ep(f_fb->out_ep);
+       if (!f_fb->out_req) {
+               puts("failed to alloc out req\n");
+               ret = -EINVAL;
+               goto err;
+       }
+       f_fb->out_req->complete = rx_handler_command;
+
+       ret = usb_ep_enable(f_fb->in_ep, &fs_ep_in);
+       if (ret) {
+               puts("failed to enable in ep\n");
+               goto err;
+       }
+
+       f_fb->in_req = fastboot_start_ep(f_fb->in_ep);
+       if (!f_fb->in_req) {
+               puts("failed alloc req in\n");
+               ret = -EINVAL;
+               goto err;
+       }
+       f_fb->in_req->complete = fastboot_complete;
+
+       ret = usb_ep_queue(f_fb->out_ep, f_fb->out_req, 0);
+       if (ret)
+               goto err;
+
+       return 0;
+err:
+       fastboot_disable(f);
+       return ret;
+}
+
+static int fastboot_add(struct usb_configuration *c)
+{
+       struct f_fastboot *f_fb = fastboot_func;
+       int status;
+
+       debug("%s: cdev: 0x%p\n", __func__, c->cdev);
+
+       if (!f_fb) {
+               f_fb = memalign(CONFIG_SYS_CACHELINE_SIZE, sizeof(*f_fb));
+               if (!f_fb)
+                       return -ENOMEM;
+
+               fastboot_func = f_fb;
+               memset(f_fb, 0, sizeof(*f_fb));
+       }
+
+       f_fb->usb_function.name = "f_fastboot";
+       f_fb->usb_function.hs_descriptors = fb_runtime_descs;
+       f_fb->usb_function.bind = fastboot_bind;
+       f_fb->usb_function.unbind = fastboot_unbind;
+       f_fb->usb_function.set_alt = fastboot_set_alt;
+       f_fb->usb_function.disable = fastboot_disable;
+       f_fb->usb_function.strings = fastboot_strings;
+
+       status = usb_add_function(c, &f_fb->usb_function);
+       if (status) {
+               free(f_fb);
+               fastboot_func = f_fb;
+       }
+
+       return status;
+}
+DECLARE_GADGET_BIND_CALLBACK(usb_dnl_fastboot, fastboot_add);
+
+int fastboot_tx_write(const char *buffer, unsigned int buffer_size)
+{
+       struct usb_request *in_req = fastboot_func->in_req;
+       int ret;
+
+       memcpy(in_req->buf, buffer, buffer_size);
+       in_req->length = buffer_size;
+       ret = usb_ep_queue(fastboot_func->in_ep, in_req, 0);
+       if (ret)
+               printf("Error %d on queue\n", ret);
+       return 0;
+}
+
+static int fastboot_tx_write_str(const char *buffer)
+{
+       return fastboot_tx_write(buffer, strlen(buffer));
+}
+
+static void compl_do_reset(struct usb_ep *ep, struct usb_request *req)
+{
+       do_reset(NULL, 0, 0, NULL);
+}
+
+static void cb_reboot(struct usb_ep *ep, struct usb_request *req)
+{
+       fastboot_func->in_req->complete = compl_do_reset;
+       fastboot_tx_write_str("OKAY");
+}
+
+static int strcmp_l1(const char *s1, const char *s2)
+{
+       if (!s1 || !s2)
+               return -1;
+       return strncmp(s1, s2, strlen(s1));
+}
+
+static void cb_getvar(struct usb_ep *ep, struct usb_request *req)
+{
+       char *cmd = req->buf;
+       char response[RESPONSE_LEN];
+       const char *s;
+
+       strcpy(response, "OKAY");
+       strsep(&cmd, ":");
+       if (!cmd) {
+               fastboot_tx_write_str("FAILmissing var");
+               return;
+       }
+
+       if (!strcmp_l1("version", cmd)) {
+               strncat(response, FASTBOOT_VERSION, sizeof(response));
+       } else if (!strcmp_l1("bootloader-version", cmd)) {
+               strncat(response, U_BOOT_VERSION, sizeof(response));
+       } else if (!strcmp_l1("downloadsize", cmd)) {
+               char str_num[12];
+
+               sprintf(str_num, "%08x", CONFIG_USB_FASTBOOT_BUF_SIZE);
+               strncat(response, str_num, sizeof(response));
+       } else if (!strcmp_l1("serialno", cmd)) {
+               s = getenv("serial#");
+               if (s)
+                       strncat(response, s, sizeof(response));
+               else
+                       strcpy(response, "FAILValue not set");
+       } else {
+               strcpy(response, "FAILVariable not implemented");
+       }
+       fastboot_tx_write_str(response);
+}
+
+static unsigned int rx_bytes_expected(void)
+{
+       int rx_remain = download_size - download_bytes;
+       if (rx_remain < 0)
+               return 0;
+       if (rx_remain > EP_BUFFER_SIZE)
+               return EP_BUFFER_SIZE;
+       return rx_remain;
+}
+
+#define BYTES_PER_DOT  0x20000
+static void rx_handler_dl_image(struct usb_ep *ep, struct usb_request *req)
+{
+       char response[RESPONSE_LEN];
+       unsigned int transfer_size = download_size - download_bytes;
+       const unsigned char *buffer = req->buf;
+       unsigned int buffer_size = req->actual;
+
+       if (req->status != 0) {
+               printf("Bad status: %d\n", req->status);
+               return;
+       }
+
+       if (buffer_size < transfer_size)
+               transfer_size = buffer_size;
+
+       memcpy((void *)CONFIG_USB_FASTBOOT_BUF_ADDR + download_bytes,
+              buffer, transfer_size);
+
+       download_bytes += transfer_size;
+
+       /* Check if transfer is done */
+       if (download_bytes >= download_size) {
+               /*
+                * Reset global transfer variable, keep download_bytes because
+                * it will be used in the next possible flashing command
+                */
+               download_size = 0;
+               req->complete = rx_handler_command;
+               req->length = EP_BUFFER_SIZE;
+
+               sprintf(response, "OKAY");
+               fastboot_tx_write_str(response);
+
+               printf("\ndownloading of %d bytes finished\n", download_bytes);
+       } else {
+               req->length = rx_bytes_expected();
+               if (req->length < ep->maxpacket)
+                       req->length = ep->maxpacket;
+       }
+
+       if (download_bytes && !(download_bytes % BYTES_PER_DOT)) {
+               putc('.');
+               if (!(download_bytes % (74 * BYTES_PER_DOT)))
+                       putc('\n');
+       }
+       req->actual = 0;
+       usb_ep_queue(ep, req, 0);
+}
+
+static void cb_download(struct usb_ep *ep, struct usb_request *req)
+{
+       char *cmd = req->buf;
+       char response[RESPONSE_LEN];
+
+       strsep(&cmd, ":");
+       download_size = simple_strtoul(cmd, NULL, 16);
+       download_bytes = 0;
+
+       printf("Starting download of %d bytes\n", download_size);
+
+       if (0 == download_size) {
+               sprintf(response, "FAILdata invalid size");
+       } else if (download_size > CONFIG_USB_FASTBOOT_BUF_SIZE) {
+               download_size = 0;
+               sprintf(response, "FAILdata too large");
+       } else {
+               sprintf(response, "DATA%08x", download_size);
+               req->complete = rx_handler_dl_image;
+               req->length = rx_bytes_expected();
+               if (req->length < ep->maxpacket)
+                       req->length = ep->maxpacket;
+       }
+       fastboot_tx_write_str(response);
+}
+
+static void do_bootm_on_complete(struct usb_ep *ep, struct usb_request *req)
+{
+       char boot_addr_start[12];
+       char *bootm_args[] = { "bootm", boot_addr_start, NULL };
+
+       puts("Booting kernel..\n");
+
+       sprintf(boot_addr_start, "0x%lx", load_addr);
+       do_bootm(NULL, 0, 2, bootm_args);
+
+       /* This only happens if image is somehow faulty so we start over */
+       do_reset(NULL, 0, 0, NULL);
+}
+
+static void cb_boot(struct usb_ep *ep, struct usb_request *req)
+{
+       fastboot_func->in_req->complete = do_bootm_on_complete;
+       fastboot_tx_write_str("OKAY");
+}
+
+struct cmd_dispatch_info {
+       char *cmd;
+       void (*cb)(struct usb_ep *ep, struct usb_request *req);
+};
+
+static const struct cmd_dispatch_info cmd_dispatch_info[] = {
+       {
+               .cmd = "reboot",
+               .cb = cb_reboot,
+       }, {
+               .cmd = "getvar:",
+               .cb = cb_getvar,
+       }, {
+               .cmd = "download:",
+               .cb = cb_download,
+       }, {
+               .cmd = "boot",
+               .cb = cb_boot,
+       },
+};
+
+static void rx_handler_command(struct usb_ep *ep, struct usb_request *req)
+{
+       char *cmdbuf = req->buf;
+       void (*func_cb)(struct usb_ep *ep, struct usb_request *req) = NULL;
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(cmd_dispatch_info); i++) {
+               if (!strcmp_l1(cmd_dispatch_info[i].cmd, cmdbuf)) {
+                       func_cb = cmd_dispatch_info[i].cb;
+                       break;
+               }
+       }
+
+       if (!func_cb)
+               fastboot_tx_write_str("FAILunknown command");
+       else
+               func_cb(ep, req);
+
+       if (req->status == 0) {
+               *cmdbuf = '\0';
+               req->actual = 0;
+               usb_ep_queue(ep, req, 0);
+       }
+}