net-spl: add README file and sample debrick scripts for NAND and SPI

Added README file with the description of required netboot /
restore_flash setup as well as sample debrick scripts for NAND and SPI
flash.

Signed-off-by: Ilya Yanok <ilya.yanok@cogentembedded.com>
Signed-off-by: Tom Rini <trini@ti.com>

3 files changed, 123 insertions, 0 deletions

diff --git a/doc/am335x.net-spl/README b/doc/am335x.net-spl/README
new file mode 100644
index 000000000..df3fb63ec
--- /dev/null
+++ b/doc/am335x.net-spl/README
@@ -0,0 +1,96 @@
+USING AM335x NETBOOT FEATURE
+
+ Some boards (like TI AM335x based ones) have quite big on-chip RAM and
+have support for booting via network in ROM. The following describes
+how to setup network booting and flash NAND and bricked (empty) board
+with only a network cable.
+
+ I. Building the required images
+  1. You have to enable generic SPL configuration options (see
+docs/README.SPL) as well as CONFIG_SPL_NET_SUPPORT,
+CONFIG_ETH_SUPPORT, CONFIG_SPL_LIBGENERIC_SUPPORT and
+CONFIG_SPL_LIBCOMMON_SUPPORT in your board configuration file to build
+SPL with support for booting over the network. Also you have to enable
+the driver for the NIC used and CONFIG_SPL_BOARD_INIT option if your
+board needs some board-specific initialization (TI AM335x EVM does).
+If you want SPL to use some Vendor Class Identifier (VCI) you can set
+one with CONFIG_SPL_NET_VCI_STRING option. am335x_evm configuration
+comes with support for network booting preconfigured.
+ 2. Define CONFIG_BOOTCOMMAND for your board to load and run debrick
+script after boot:
+#define CONFIG_BOOTCOMMAND					\
+	"setenv autoload no; "					\
+	"bootp; "						\
+	"if tftp 80000000 debrick.scr; then "			\
+		"source 80000000; "				\
+	"fi"
+(Or create additional board configuration with such option).
+For AM335x EVM just use am335x_evm_restore_flash config instead of
+plain am335x_evm.
+ 3. Build U-Boot as usual
+  $ make <your_board_name>
+    You will need u-boot.img and spl/u-boot.bin images to perform
+network boot. Copy them to u-boot-restore.img and
+u-boot-spl-restore.bin respectively to distinguish this version
+(with automatic restore running) from the main one.
+
+ II. Host configuration.
+  1. Setup DHCP server (recommended server is ISC DHCPd).
+   - Install DHCP server and setup it to listen on the interface you
+chose to connect to the board (usually configured in
+/etc/default/dhcpd or /etc/default/isc-dhcp-server). Make sure there
+are no other active DHCP servers in the same network segment.
+   - Edit your dhcpd.conf and subnet declaration matching the address
+on the interface. Specify the range of assigned addresses and bootfile
+to use. IMPORTANT! Both RBL and SPL use the image filename provided
+in the BOOTP reply but obviously they need different images (RBL needs
+raw SPL image -- u-boot-spl-restore.bin while SPL needs main U-Boot
+image -- u-boot-restore.img). So you have to configure DHCP server to
+provide different image filenames to RBL and SPL (and possibly another
+one to main U-Boot). This can be done by checking Vendor Class
+Identifier (VCI) set by BOOTP client (RBL sets VCI to "DM814x ROM v1.0"
+and you can set VCI used by SPL with CONFIG_SPL_NET_VCI_STRING option,
+see above).
+   - If you plan to use TFTP server on another machine you have to set
+server-name option to point to it.
+   - Here is sample configuration for ISC DHCPd, assuming the interface
+used to connect to the board is eth0, and it has address 192.168.8.1:
+
+subnet 192.168.8.0 netmask 255.255.255.0 {
+  range dynamic-bootp 192.168.8.100 192.168.8.199;
+
+  if substring (option vendor-class-identifier, 0, 10) = "DM814x ROM" {
+    filename "u-boot-spl-restore.bin";
+  } elsif substring (option vendor-class-identifier, 0, 17) = "AM335x U-Boot SPL" {
+    filename "u-boot-restore.img";
+  } else {
+    filename "uImage";
+  }
+}
+
+  2. Setup TFTP server.
+     Install TFTP server and put image files to it's root directory
+(likely /tftpboot or /var/lib/tftpboot or /srv/tftp). You will need
+u-boot.img and spl/u-boot-spl-bin files from U-Boot build directory.
+
+ III. Reflashing (debricking) the board.
+  1. Write debrick script. You will need to writea script that will
+be executed after network boot to perform actual rescue actions. You
+can use usual U-Boot commands from this script: tftp to load additional
+files, nand erase/nand write to erase/write the NAND flash. Please see
+doc/am335x.net-spl/debrick-nand.scr as a reference.
+
+  2. Create script image from your script. From U-Boot build directory:
+
+$ ./tools/mkimage -A arm -O U-Boot -C none -T script -d <your script> debrick.scr
+
+This will create debrick.scr file with your script inside.
+
+  3. Copy debrick.scr to TFTP root directory. You also need to copy
+there all the files your script tries to load via TFTP. Example script
+loads u-boot.img and MLO. You have to create these files doing regular
+(not restore_flash) build and copy them to tftpboot directory.
+
+  4. Boot the board from the network, U-Boot will load debrick script
+and run it after boot.
+
diff --git a/doc/am335x.net-spl/debrick-nand.txt b/doc/am335x.net-spl/debrick-nand.txt
new file mode 100644
index 000000000..90204ecf2
--- /dev/null
+++ b/doc/am335x.net-spl/debrick-nand.txt
@@ -0,0 +1,14 @@
+# set NAND ECC mode to HW
+nandecc hw 2
+# erase NAND
+nand erase.chip
+# get MLO
+tftp 0x81000000 MLO
+# make 4 copies in the RAM
+cp.b 0x81000000 0x81020000 20000
+cp.b 0x81000000 0x81040000 20000
+cp.b 0x81000000 0x81060000 20000
+# get u-boot.img
+tftp 0x81080000 u-boot.img
+# write the whole block (4*MLO + u-boot.img) to NAND
+nand write 0x81000000 0x0 0x260000
diff --git a/doc/am335x.net-spl/debrick-spi.txt b/doc/am335x.net-spl/debrick-spi.txt
new file mode 100644
index 000000000..87e5e8ab2
--- /dev/null
+++ b/doc/am335x.net-spl/debrick-spi.txt
@@ -0,0 +1,13 @@
+# NOTE: 'loadaddr' is part of the default environment
+# Probe the chip
+sf probe 0
+# Erase SPL, U-Boot and U-Boot Environment
+sf erase 0 +80000
+# get MLO.spi
+tftp ${loadaddr} MLO.spi
+# Write to SPI
+sf write ${loadaddr} 0x0 0x20000
+# get u-boot.img
+tftp ${loadaddr} u-boot.bin
+# Write to SPI
+sf write ${loadaddr} 0x20000 0x40000