From: Stefan Agner Date: Wed, 16 Aug 2017 18:00:55 +0000 (-0700) Subject: doc: add Serial Download Protocol documentation X-Git-Tag: v2017.09-rc4~39^2~17 X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=f9c39d95f16e62a39d751d9b886f673c6d1e90b8;p=u-boot doc: add Serial Download Protocol documentation Document the U-Boot Serial Download Protocol implementation and some typical use cases. Signed-off-by: Stefan Agner Reviewed-by: Łukasz Majewski --- diff --git a/doc/README.sdp b/doc/README.sdp new file mode 100644 index 0000000000..9b438c0746 --- /dev/null +++ b/doc/README.sdp @@ -0,0 +1,100 @@ +------------- +SDP in U-Boot +------------- + +SDP stands for serial download protocol. It is the protocol used in NXP's +i.MX SoCs ROM Serial Downloader and provides means to download a program +image to the chip over USB and UART serial connection. + +The implementation in U-Boot uses the USB Downloader Gadget (g_dnl) to +provide a SDP implementation over USB. This allows to download program +images to the target in SPL/U-Boot using the same protocol/tooling the +SoC's recovery mechanism is using. + +The SDP protocol over USB is a USB HID class protocol. USB HID class +protocols allow to access a USB device without OS specific drivers. The +U-Boot implementation has primarly been tested using the open source +imx_loader utility (https://github.com/toradex/imx_loader). + +The host side utilities are typically capable to interpret the i.MX +specific image header (see doc/README.imximage). There are extensions +for imx_loader's imx_usb utility which allow to interpret the U-Boot +specific legacy image format (see mkimage(1)). Also the U-Boot side +support beside the i.MX specific header the U-Boot legacy header. + +Usage +----- + +This implementation can be started in U-Boot using the sdp command +(CONFIG_CMD_USB_SDP) or in SPL if Serial Downloader boot mode has been +detected (CONFIG_SPL_USB_SDP_SUPPORT). + +A typical use case is downloading full U-Boot after SPL has been +downloaded through the boot ROM's Serial Downloader. Using boot mode +detection the SPL will run the SDP implementation automatically in +this case: + + # imx_usb SPL + +Targets Serial Console: + + Trying to boot from USB SDP + SDP: initialize... + SDP: handle requests... + +At this point the SPL reenumerated as a new HID device and emulating +the boot ROM's SDP protocol. The USB VID/PID will depend on standard +U-Boot configurations CONFIG_G_DNL_(VENDOR|PRODUCT)_NUM. Make sure +imx_usb is aware of the USB VID/PID for your device by adding a +configuration entry in imx_usb.conf: + + 0x1b67:0x4fff, mx6_usb_sdp_spl.conf + +And the device specific configuration file mx6_usb_sdp_spl.conf: + + mx6_spl_sdp + hid,uboot_header,1024,0x910000,0x10000000,1G,0x00900000,0x40000 + +This allows to download the regular U-Boot with legacy image headers +(u-boot.img) using a second invocation of imx_usb: + + # imx_usb u-boot.img + +Furthermore, when U-Boot is running the sdp command can be used to +download and run scripts: + + # imx_usb script.scr + +imx_usb configuration files can be also used to download multiple +files and of arbitrary types, e.g. + + mx6_usb_sdp_uboot + hid,1024,0x10000000,1G,0x00907000,0x31000 + full.itb:load 0x12100000 + boot.scr:load 0x12000000,jump 0x12000000 + +There is also a batch mode which allows imx_usb to handle multiple +consecutive reenumerations by adding multiple VID/PID specifications +in imx_usb.conf: + + 0x15a2:0x0061, mx6_usb_rom.conf, 0x1b67:0x4fff, mx6_usb_sdp_spl.conf + +In this mode the file to download (imx_usb job) needs to be specified +in the configuration files. + +mx6_usb_rom.conf: + + mx6_qsb + hid,1024,0x910000,0x10000000,1G,0x00900000,0x40000 + SPL:jump header2 + +mx6_usb_sdp_spl.conf: + + mx6_spl_sdp + hid,uboot_header,1024,0x10000000,1G,0x00907000,0x31000 + u-boot.img:jump header2 + +With that SPL and U-Boot can be downloaded with a single invocation +of imx_usb without arguments: + + # imx_usb