1 ------------- 2 SDP in U-Boot 3 ------------- 4 5 SDP stands for serial download protocol. It is the protocol used in NXP's 6 i.MX SoCs ROM Serial Downloader and provides means to download a program 7 image to the chip over USB and UART serial connection. 8 9 The implementation in U-Boot uses the USB Downloader Gadget (g_dnl) to 10 provide a SDP implementation over USB. This allows to download program 11 images to the target in SPL/U-Boot using the same protocol/tooling the 12 SoC's recovery mechanism is using. 13 14 The SDP protocol over USB is a USB HID class protocol. USB HID class 15 protocols allow to access a USB device without OS specific drivers. The 16 U-Boot implementation has primarly been tested using the open source 17 imx_loader utility (https://github.com/boundarydevices/imx_usb_loader). 18 19 The host side utilities are typically capable to interpret the i.MX 20 specific image header (see doc/README.imximage). There are extensions 21 for imx_loader's imx_usb utility which allow to interpret the U-Boot 22 specific legacy image format (see mkimage(1)). Also the U-Boot side 23 support beside the i.MX specific header the U-Boot legacy header. 24 25 Usage 26 ----- 27 28 This implementation can be started in U-Boot using the sdp command 29 (CONFIG_CMD_USB_SDP) or in SPL if Serial Downloader boot mode has been 30 detected (CONFIG_SPL_USB_SDP_SUPPORT). 31 32 A typical use case is downloading full U-Boot after SPL has been 33 downloaded through the boot ROM's Serial Downloader. Using boot mode 34 detection the SPL will run the SDP implementation automatically in 35 this case: 36 37 # imx_usb SPL 38 39 Targets Serial Console: 40 41 Trying to boot from USB SDP 42 SDP: initialize... 43 SDP: handle requests... 44 45 At this point the SPL reenumerated as a new HID device and emulating 46 the boot ROM's SDP protocol. The USB VID/PID will depend on standard 47 U-Boot configurations CONFIG_G_DNL_(VENDOR|PRODUCT)_NUM. Make sure 48 imx_usb is aware of the USB VID/PID for your device by adding a 49 configuration entry in imx_usb.conf: 50 51 0x1b67:0x4fff, mx6_usb_sdp_spl.conf 52 53 And the device specific configuration file mx6_usb_sdp_spl.conf: 54 55 mx6_spl_sdp 56 hid,uboot_header,1024,0x910000,0x10000000,1G,0x00900000,0x40000 57 58 This allows to download the regular U-Boot with legacy image headers 59 (u-boot.img) using a second invocation of imx_usb: 60 61 # imx_usb u-boot.img 62 63 Furthermore, when U-Boot is running the sdp command can be used to 64 download and run scripts: 65 66 # imx_usb script.scr 67 68 imx_usb configuration files can be also used to download multiple 69 files and of arbitrary types, e.g. 70 71 mx6_usb_sdp_uboot 72 hid,1024,0x10000000,1G,0x00907000,0x31000 73 full.itb:load 0x12100000 74 boot.scr:load 0x12000000,jump 0x12000000 75 76 There is also a batch mode which allows imx_usb to handle multiple 77 consecutive reenumerations by adding multiple VID/PID specifications 78 in imx_usb.conf: 79 80 0x15a2:0x0061, mx6_usb_rom.conf, 0x1b67:0x4fff, mx6_usb_sdp_spl.conf 81 82 In this mode the file to download (imx_usb job) needs to be specified 83 in the configuration files. 84 85 mx6_usb_rom.conf: 86 87 mx6_qsb 88 hid,1024,0x910000,0x10000000,1G,0x00900000,0x40000 89 SPL:jump header2 90 91 mx6_usb_sdp_spl.conf: 92 93 mx6_spl_sdp 94 hid,uboot_header,1024,0x10000000,1G,0x00907000,0x31000 95 u-boot.img:jump header2 96 97 With that SPL and U-Boot can be downloaded with a single invocation 98 of imx_usb without arguments: 99 100 # imx_usb 101
