1 # SPDX-License-Identifier: GPL-2.0-or-later
3 #################################################################################################
5 # Author: Gary Carlson (gcarlson@carlson-minot.com) #
6 # Generated for Atmel AT91SAM9G20-EK evaluation board using Atmel SAM-ICE (J-Link) version 8. #
8 #################################################################################################
10 source [find target/at91sam9g20.cfg]
12 set _FLASHTYPE nandflash_cs3
14 # Set reset type. Note that the AT91SAM9G20-EK board has the trst signal disconnected. Therefore
15 # the reset needs to be configured for "srst_only". If for some reason, a zero-ohm jumper is
16 # added to the board to connect the trst signal, then this parameter may need to be changed.
18 reset_config srst_only
20 adapter srst delay 200
23 # If you don't want to execute built-in boot rom code (and there are good reasons at times not to do that) in the
24 # AT91SAM9 family, the microcontroller is a lump on a log without initialization. Because this family has
25 # some powerful features, we want to have a special function that handles "reset init". To do this we declare
26 # an event handler where these special activities can take place.
29 $_TARGETNAME configure -event reset-init {at91sam9g20_reset_init}
30 $_TARGETNAME configure -event reset-start {at91sam9g20_reset_start}
32 # NandFlash configuration and definition
34 nand device nandflash_cs3 at91sam9 $_TARGETNAME 0x40000000 0xfffffe800
37 at91sam9 rdy_busy 0 0xfffff800 13
38 at91sam9 ce 0 0xfffff800 14
40 proc read_register {register} {
41 return [read_memory $register 32 1]
44 proc at91sam9g20_reset_start { } {
46 # Make sure that the the jtag is running slow, since there are a number of different ways the board
47 # can be configured coming into this state that can cause communication problems with the jtag
48 # adapter. Also since this call can be made following a "reset init" where fast memory accesses
49 # are enabled, need to temporarily shut this down so that the RSTC_MR register can be written at slower
50 # jtag speed without causing GDB keep alive problem.
52 arm7_9 fast_memory_access disable
53 adapter speed 2 ;# Slow-speed oscillator enabled at reset, so run jtag speed slow.
54 halt ;# Make sure processor is halted, or error will result in following steps.
56 mww 0xfffffd08 0xa5000501 ;# RSTC_MR : enable user reset.
59 proc at91sam9g20_reset_init { } {
61 # At reset AT91SAM9G20 chip runs on slow clock (32.768 kHz). To shift over to a normal clock requires
62 # a number of steps that must be carefully performed. The process outline below follows the
63 # recommended procedure outlined in the AT91SAM9G20 technical manual.
65 # Several key and very important things to keep in mind:
66 # The SDRAM parts used currently on the Atmel evaluation board are -75 grade parts. This
67 # means the master clock (MCLK) must be at or below 133 MHz or timing errors will occur. The processor
68 # core can operate up to 400 MHz and therefore PCLK must be at or below this to function properly.
70 mww 0xfffffd44 0x00008000 ;# WDT_MR : disable watchdog.
72 # Enable the main 18.432 MHz oscillator in CKGR_MOR register.
73 # Wait for MOSCS in PMC_SR to assert indicating oscillator is again stable after change to CKGR_MOR.
75 mww 0xfffffc20 0x00004001
76 while { [expr {[read_register 0xfffffc68] & 0x01}] != 1 } { sleep 1 }
78 # Set PLLA Register for 792.576 MHz (divider: bypass, multiplier: 43).
79 # Wait for LOCKA signal in PMC_SR to assert indicating PLLA is stable.
81 mww 0xfffffc28 0x202a3f01
82 while { [expr {[read_register 0xfffffc68] & 0x02}] != 2 } { sleep 1 }
84 # Set master system clock prescaler divide by 6 and processor clock divide by 2 in PMC_MCKR.
85 # Wait for MCKRDY signal from PMC_SR to assert.
87 mww 0xfffffc30 0x00000101
88 while { [expr {[read_register 0xfffffc68] & 0x08}] != 8 } { sleep 1 }
90 # Now change PMC_MCKR register to select PLLA.
91 # Wait for MCKRDY signal from PMC_SR to assert.
93 mww 0xfffffc30 0x00001302
94 while { [expr {[read_register 0xfffffc68] & 0x08}] != 8 } { sleep 1 }
96 # Processor and master clocks are now operating and stable at maximum frequency possible:
97 # -> MCLK = 132.096 MHz
98 # -> PCLK = 396.288 MHz
100 # Switch over to adaptive clocking.
104 # Enable faster DCC downloads and memory accesses.
106 arm7_9 dcc_downloads enable
107 arm7_9 fast_memory_access enable
109 # To be able to use external SDRAM, several peripheral configuration registers must
110 # be modified. The first change is made to PIO_ASR to select peripheral functions
111 # for D15 through D31. The second change is made to the PIO_PDR register to disable
112 # this for D15 through D31.
114 mww 0xfffff870 0xffff0000
115 mww 0xfffff804 0xffff0000
117 # The EBI chip select register EBI_CS must be specifically configured to enable the internal SDRAM controller
118 # using CS1. Additionally we want CS3 assigned to NandFlash. Also VDDIO is connected physically on
119 # the board to the 3.3 VDC power supply so set the appropriate register bit to notify the micrcontroller.
121 mww 0xffffef1c 0x000100a
123 # The AT91SAM9G20-EK evaluation board has built-in NandFlash. The exact physical timing characteristics
124 # for the memory type used on the current board (MT29F2G08AACWP) can be established by setting
125 # a number of registers. The first step involves setting up the general I/O pins on the processor
126 # to be able to interface and support the external memory.
128 mww 0xfffffc10 0x00000010 ;# PMC_PCER : enable PIOC clock
129 mww 0xfffff800 0x00006000 ;# PIOC_PER : enable PIO function for 13(RDY/~BSY) and 14(~CS)
130 mww 0xfffff810 0x00004000 ;# PIOC_OER : enable output on 14
131 mww 0xfffff814 0x00002000 ;# PIOC_ODR : disable output on 13
132 mww 0xfffff830 0x00004000 ;# PIOC_SODR : set 14 to disable NAND
134 # The exact physical timing characteristics for the memory type used on the current board
135 # (MT29F2G08AACWP) can be established by setting four registers in order: SMC_SETUP3,
136 # SMC_PULSE3, SMC_CYCLE3, and SMC_MODE3. Computing the exact values of these registers
137 # is a little tedious to do here. If you have questions about how to do this, Atmel has
138 # a decent application note #6255B that covers this process.
140 mww 0xffffec30 0x00020002 ;# SMC_SETUP3 : 2 clock cycle setup for NRD and NWE
141 mww 0xffffec34 0x04040404 ;# SMC_PULSE3 : 4 clock cycle pulse for all signals
142 mww 0xffffec38 0x00070006 ;# SMC_CYCLE3 : 7 clock cycle NRD and 6 NWE cycle
143 mww 0xffffec3C 0x00020003 ;# SMC_MODE3 : NRD and NWE control, no NWAIT, 8-bit DBW,
145 mww 0xffffe800 0x00000001 ;# ECC_CR : reset the ECC parity registers
146 mww 0xffffe804 0x00000002 ;# ECC_MR : page size is 2112 words (word is 8 bits)
148 # Identify NandFlash bank 0.
150 nand probe nandflash_cs3
152 # The AT91SAM9G20-EK evaluation board has built-in serial data flash also.
154 # Now setup SDRAM. This is tricky and configuration is very important for reliability! The current calculations
155 # are based on 2 x Micron MT48LC16M16A2-75 memory (4 M x 16 bit x 4 banks). If you use this file as a reference
156 # for a new board that uses different SDRAM devices or clock rates, you need to recalculate the value inserted
157 # into the SDRAM_CR register. Using the memory datasheet for the -75 grade part and assuming a master clock
158 # of 132.096 MHz then the SDCLK period is equal to 7.6 ns. This means the device requires:
160 # CAS latency = 3 cycles
167 # 9 column, 13 row, 4 banks
168 # refresh equal to or less then 7.8 us for commercial/industrial rated devices
170 # Thus SDRAM_CR = 0xa6339279
172 mww 0xffffea08 0xa6339279
174 # Next issue a 'NOP' command through the SDRAMC_MR register followed by writing a zero value into
175 # the starting memory location for the SDRAM.
177 mww 0xffffea00 0x00000001
180 # Issue an 'All Banks Precharge' command through the SDRAMC_MR register followed by writing a zero
181 # value into the starting memory location for the SDRAM.
183 mww 0xffffea00 0x00000002
186 # Now issue an 'Auto-Refresh' command through the SDRAMC_MR register. Follow this operation by writing
187 # zero values eight times into the starting memory location for the SDRAM.
199 # Almost done, so next issue a 'Load Mode Register' command followed by a zero value write to the
200 # the starting memory location for the SDRAM.
205 # Signal normal mode using the SDRAMC_MR register and follow with a zero value write the the starting
206 # memory location for the SDRAM.
211 # Finally set the refresh rate to about every 7 us (7.5 ns x 924 cycles).
213 mww 0xffffea04 0x0000039c