3 * Dave Ellis, SIXNET, dge@sixnetio.com
5 * SPDX-License-Identifier: GPL-2.0+
8 Using the Motorola MPC8XXFADS development board
9 ===============================================
14 There are ready-to-use default configurations available for the
15 FADS823, FADS850SAR and FADS860T. The FADS860T configuration also
16 works for the 855T processor.
18 LOADING U-Boot INTO FADS FLASH MEMORY
19 --------------------------------------
21 MPC8BUG can load U-Boot into the FLASH memory using LOADF.
23 loadf u-boot.srec 100000
26 STARTING U-Boot FROM MPC8BUG
27 -----------------------------
29 To start U-Boot from MPC8BUG:
34 2. Change BR0 and OR0 back to their values at reset:
38 3. Modify DER so MPC8BUG gets control only when it should:
41 4. Start as if from reset:
44 This is NOT exactly the same as starting U-Boot without
45 MPC8BUG. MPC8BUG turns off the watchdog as part of the hard reset.
46 After it does the reset it writes SYPCR (to disable the watchdog)
47 and sets BR0 and OR0 to map the FLASH at 0x02800000 (and does lots
48 of other initialization). That is why it is necessary to set BR0
49 and OR0 to map the FLASH everywhere. U-Boot can't turn on the
50 watchdog after that, since MPC8BUG has used the only chance to write
53 Here is a bizarre sequence of MPC8BUG and U-Boot commands that lets
54 U-Boot write to SYPCR. It works with MPC8BUG 1.5 and an 855T
55 processor (your mileage may vary). It is probably better (and a lot
56 easier) just to accept having the watchdog disabled when the debug
66 Now U-Boot is running with the MPC8BUG value for SYPCR. Use the
67 U-Boot 'reset' command to reset the board.
73 Now U-Boot is running with the U-Boot value for SYPCR.