xref: /openbmc/u-boot/doc/README.mpc85xx (revision 7b0789e8)
1External Debug Support
2----------------------
3
4Freescale's e500v1 and e500v2 cores (used in mpc85xx chips) have some
5restrictions on external debugging (JTAG).  In particular, for the debugger to
6be able to receive control after a single step or breakpoint:
7	- MSR[DE] must be set
8	- A valid opcode must be fetchable, through the MMU, from the debug
9	  exception vector (IVPR + IVOR15).
10
11To maximize the time during which this requirement is met, U-Boot sets MSR[DE]
12immediately on entry and keeps it set. It also uses a temporary TLB to keep a
13mapping to a valid opcode at the debug exception vector, even if we normally
14don't support exception vectors being used that early, and that's not the area
15where U-Boot currently executes from.
16
17Note that there may still be some small windows where debugging will not work,
18such as in between updating IVPR and IVOR15.
19
20Config Switches:
21----------------
22
23Please refer README section "MPC85xx External Debug Support"
24
25Major Config Switches during various boot Modes
26----------------------------------------------
27
28NOR boot
29		!defined(CONFIG_SYS_RAMBOOT) && !defined(CONFIG_SPL)
30NOR boot Secure
31		!defined(CONFIG_SYS_RAMBOOT) && defined(CONFIG_SECURE_BOOT)
32RAMBOOT(SD, SPI & NAND boot)
33		 defined(CONFIG_SYS_RAMBOOT)
34RAMBOOT Secure (SD, SPI & NAND)
35		 defined(CONFIG_SYS_RAMBOOT) && defined(CONFIG_SECURE_BOOT)
36NAND SPL BOOT
37		 defined(CONFIG_SYS_RAMBOOT) && defined(CONFIG_NAND_SPL)
38
39
40TLB Entries during u-boot execution
41-----------------------------------
42
43Note: Sequence number is in order of execution
44
45A) defined(CONFIG_SYS_RAMBOOT) i.e. SD, SPI, NAND RAMBOOT & NAND_SPL boot
46
47   1) TLB entry to overcome e500 v1/v2 debug restriction
48       Location	  : Label "_start_e500"
49       TLB Entry  : CONFIG_SYS_PPC_E500_DEBUG_TLB
50       EPN -->RPN : CONFIG_SYS_MONITOR_BASE --> CONFIG_SYS_MONITOR_BASE
51       Properties : 256K, AS0, I, IPROT
52
53   2) TLB entry for working in AS1
54       Location	  : Label "create_init_ram_area"
55       TLB Entry  : 15
56       EPN -->RPN : CONFIG_SYS_MONITOR_BASE --> CONFIG_SYS_MONITOR_BASE
57       Properties : 1M, AS1, I, G, IPROT
58
59   3) TLB entry for the stack during AS1
60       Location	  : Lable "create_init_ram_area"
61       TLB Entry  : 14
62       EPN -->RPN : CONFIG_SYS_INIT_RAM_ADDR --> CONFIG_SYS_INIT_RAM_ADDR
63       Properties : 16K, AS1, IPROT
64
65   4) TLB entry for CCSRBAR during AS1 execution
66       Location	  : cpu_init_early_f
67       TLB Entry  : 13
68       EPN -->RPN : CONFIG_SYS_CCSRBAR --> CONFIG_SYS_CCSRBAR
69       Properties : 1M, AS1, I, G
70
71   5) Invalidate unproctected TLB Entries
72       Location	  : cpu_init_early_f
73       Invalidated: 13
74
75   6) Create TLB entries as per boards/freescale/<board>/tlb.c
76       Location	  : cpu_init_early_f --> init_tlbs()
77       Properties : ..., AS0, ...
78      Please note It can overwrites previous TLB Entries.
79
80   7) Disable TLB Entries of AS1
81       Location	  : cpu_init_f --> disable_tlb()
82       Disable	  : 15, 14
83
84   8) Update Flash's TLB entry
85       Location	  : Board_init_r
86       TLB entry  : Search from TLB entries
87       EPN -->RPN : CONFIG_SYS_FLASH_BASE --> CONFIG_SYS_FLASH_BASE_PHYS
88       Properties : Board specific size, AS0, I, G, IPROT
89
90
91B) !defined(CONFIG_SYS_RAMBOOT) i.e. NOR boot
92
93   1) TLB entry to overcome e500 v1/v2 debug restriction
94       Location	  : Label "_start_e500"
95       TLB Entry  : CONFIG_SYS_PPC_E500_DEBUG_TLB
96#if defined(CONFIG_SECURE_BOOT)
97       EPN -->RPN : CONFIG_SYS_MONITOR_BASE --> CONFIG_SYS_PBI_FLASH_WINDOW
98       Properties : 1M, AS1, I, G, IPROT
99#else
100       EPN -->RPN : CONFIG_SYS_MONITOR_BASE & 0xffc00000 --> 0xffc00000
101       Properties : 4M, AS0, I, G, IPROT
102#endif
103
104   2) TLB entry for working in AS1
105       Location	  : Label "create_init_ram_area"
106       TLB Entry  : 15
107#if defined(CONFIG_SECURE_BOOT)
108       EPN -->RPN : CONFIG_SYS_MONITOR_BASE --> CONFIG_SYS_PBI_FLASH_WINDOW
109       Properties : 1M, AS1, I, G, IPROT
110#else
111       EPN -->RPN : CONFIG_SYS_MONITOR_BASE & 0xffc00000 --> 0xffc00000
112       Properties : 4M, AS1, I, G, IPROT
113#endif
114
115   3) TLB entry for the stack during AS1
116       Location	  : Lable "create_init_ram_area"
117       TLB Entry  : 14
118       EPN -->RPN : CONFIG_SYS_INIT_RAM_ADDR --> CONFIG_SYS_INIT_RAM_ADDR
119       Properties : 16K, AS1, IPROT
120
121   4) TLB entry for CCSRBAR during AS1 execution
122       Location	  : cpu_init_early_f
123       TLB Entry  : 13
124       EPN -->RPN : CONFIG_SYS_CCSRBAR --> CONFIG_SYS_CCSRBAR
125       Properties : 1M, AS1, I, G
126
127   5) TLB entry for Errata workaround CONFIG_SYS_FSL_ERRATUM_IFC_A003399
128       Location	  : cpu_init_early_f
129       TLB Entry  : 9
130       EPN -->RPN : SRAM_BASE_ADDR --> SRAM_BASE_ADDR
131       Properties : 1M, AS1, I
132
133   6) CONFIG_SYS_FSL_ERRATUM_IFC_A003399 Adjust flash's phys addr
134       Location	  : cpu_init_early_f --> setup_ifc
135       TLB Entry  : Get Flash TLB
136       EPN -->RPN : Adjusted flash_phys --> Adjusted flash_phys
137       Properties : 4M, AS1, I, G, IPROT
138
139   7) CONFIG_SYS_FSL_ERRATUM_IFC_A003399: E500 v1,v2 debug restriction
140       Location	  : cpu_init_early_f --> setup_ifc
141       TLB Entry  : CONFIG_SYS_PPC_E500_DEBUG_TLB
142       EPN -->RPN : Adjusted flash_phys --> Adjusted flash_phys
143       Properties : 4M, AS0, I, G, IPROT
144
145   8) Invalidate unproctected TLB Entries
146       Location	  : cpu_init_early_f
147       Invalidated: 13, 9
148
149   9) Create TLB entries as per boards/freescale/<board>/tlb.c
150       Location	  : cpu_init_early_f --> init_tlbs()
151       Properties : ..., AS0, ...
152      Note: It can overwrites previous TLB Entries
153
154   10) Disable TLB Entries of AS1
155       Location	  : cpu_init_f --> disable_tlb()
156       Disable	  : 15, 14
157
158   11) Create DDR's TLB entriy
159       Location	  : Board_init_f -> init_func_ram -> initdram
160       TLB entry  : Search free TLB entry
161
162   12) Update Flash's TLB entry
163       Location	  : Board_init_r
164       TLB entry  : Search from TLB entries
165       EPN -->RPN : CONFIG_SYS_FLASH_BASE --> CONFIG_SYS_FLASH_BASE_PHYS
166       Properties : Board specific size, AS0, I, G, IPROT
167