# #
#################################################################################################
-# Define basic characteristics for the CPU. The AT91SAM9G20 processor is a subtle variant of
-# the AT91SAM9260 and shares the same tap ID as it.
+# FIXME use some standard target config, maybe create one from this
+#
+# source [find target/...cfg]
-set _CHIPNAME at91sam9g20
-set _ENDIAN little
-set _CPUTAPID 0x0792603f
+source [find target/at91sam9g20.cfg]
-# Set reset type. Note that the AT91SAM9G20-EK board has the trst signal disconnected. In theory this script
-# therefore should require "srst_only". With some J-Link debuggers at least, "srst_only" causes a temporary USB
-# communication fault. This appears to be more likely attributed to an internal proprietary firmware quirk inside the
-# dongle itself. Using "trst_and_srst" works fine, however. So if you can't beat them -- join them. If you are using
-# something other the a J-Link dongle you may be able to change this back to "srst_only".
+set _FLASHTYPE nandflash_cs3
-reset_config trst_and_srst
+# Set reset type. Note that the AT91SAM9G20-EK board has the trst signal disconnected. Therefore
+# the reset needs to be configured for "srst_only". If for some reason, a zero-ohm jumper is
+# added to the board to connect the trst signal, then this parameter may need to be changed.
-# Set up the CPU and generate a new jtag tap for AT91SAM9G20.
+reset_config srst_only
-jtag newtap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_CPUTAPID
-
-# Use caution changing the delays listed below. These seem to be affected by the board and type of
-# debugger dongle. A value of 200 ms seems to work reliably for the configuration listed in the file header above.
-
-jtag_nsrst_delay 200
+adapter_nsrst_delay 200
jtag_ntrst_delay 200
-# Set fallback clock to 1/6 of worst-case clock speed (which would be the 32.768 kHz slow clock).
-
-jtag_rclk 5
-
-set _TARGETNAME [format "%s.cpu" $_CHIPNAME]
-target create $_TARGETNAME arm926ejs -endian $_ENDIAN -chain-position $_TARGETNAME -variant arm926ejs
-
-# Establish internal SRAM memory work areas that are important to pre-bootstrap loaders, etc. The
-# AT91SAM9G20 has two SRAM areas, one starting at 0x00200000 and the other starting at 0x00300000.
-# Both areas are 16 kB long.
-
-$_TARGETNAME configure -work-area-virt 0 -work-area-phys 0x00200000 -work-area-size 0x4000 -work-area-backup 1
-$_TARGETNAME configure -work-area-virt 0 -work-area-phys 0x00300000 -work-area-size 0x4000 -work-area-backup 1
-
# If you don't want to execute built-in boot rom code (and there are good reasons at times not to do that) in the
# AT91SAM9 family, the microcontroller is a lump on a log without initialization. Because this family has
# some powerful features, we want to have a special function that handles "reset init". To do this we declare
# an event handler where these special activities can take place.
scan_chain
-$_TARGETNAME configure -event reset-init {at91sam9g20_init}
+$_TARGETNAME configure -event reset-init {at91sam9g20_reset_init}
+$_TARGETNAME configure -event reset-start {at91sam9g20_reset_start}
# NandFlash configuration and definition
-# Future TBD
+
+nand device nandflash_cs3 at91sam9 $_TARGETNAME 0x40000000 0xfffffe800
+at91sam9 cle 0 22
+at91sam9 ale 0 21
+at91sam9 rdy_busy 0 0xfffff800 13
+at91sam9 ce 0 0xfffff800 14
proc read_register {register} {
set result ""
- ocd_mem2array result 32 $register 1
+ mem2array result 32 $register 1
return $result(0)
}
-proc at91sam9g20_init { } {
-
+proc at91sam9g20_reset_start { } {
+
+ # Make sure that the the jtag is running slow, since there are a number of different ways the board
+ # can be configured coming into this state that can cause communication problems with the jtag
+ # adapter. Also since this call can be made following a "reset init" where fast memory accesses
+ # are enabled, need to temporarily shut this down so that the RSTC_MR register can be written at slower
+ # jtag speed without causing GDB keep alive problem.
+
+ arm7_9 fast_memory_access disable
+ adapter_khz 2 ;# Slow-speed oscillator enabled at reset, so run jtag speed slow.
+ halt ;# Make sure processor is halted, or error will result in following steps.
+ wait_halt 10000
+ mww 0xfffffd08 0xa5000501 ;# RSTC_MR : enable user reset.
+}
+
+proc at91sam9g20_reset_init { } {
+
# At reset AT91SAM9G20 chip runs on slow clock (32.768 kHz). To shift over to a normal clock requires
# a number of steps that must be carefully performed. The process outline below follows the
# recommended procedure outlined in the AT91SAM9G20 technical manual.
# means the master clock (MCLK) must be at or below 133 MHz or timing errors will occur. The processor
# core can operate up to 400 MHz and therefore PCLK must be at or below this to function properly.
- jtag_khz 2 # Slow-speed oscillator enabled at reset, so run jtag speed slow.
- halt # Make sure processor is halted, or error will result in following steps.
- mww 0xfffffd08 0xa5000501 # RSTC_MR : enable user reset.
- mww 0xfffffd44 0x00008000 # WDT_MR : disable watchdog.
+ mww 0xfffffd44 0x00008000 ;# WDT_MR : disable watchdog.
# Enable the main 18.432 MHz oscillator in CKGR_MOR register.
# Wait for MOSCS in PMC_SR to assert indicating oscillator is again stable after change to CKGR_MOR.
mww 0xfffffc30 0x00000101
while { [expr [read_register 0xfffffc68] & 0x08] != 8 } { sleep 1 }
-
+
# Now change PMC_MCKR register to select PLLA.
# Wait for MCKRDY signal from PMC_SR to assert.
# Switch over to adaptive clocking.
- jtag_khz 0
+ adapter_khz 0
- # Enable faster DCC downloads.
+ # Enable faster DCC downloads and memory accesses.
arm7_9 dcc_downloads enable
+ arm7_9 fast_memory_access enable
# To be able to use external SDRAM, several peripheral configuration registers must
# be modified. The first change is made to PIO_ASR to select peripheral functions
# The AT91SAM9G20-EK evaluation board has built-in NandFlash. The exact physical timing characteristics
# for the memory type used on the current board (MT29F2G08AACWP) can be established by setting
- # four registers in order: SMC_SETUP3, SMC_PULSE3, SMC_CYCLE3, and SMC_MODE3.
-
- mww 0xffffec30 0x00020002
- mww 0xffffec34 0x04040404
- mww 0xffffec38 0x00070007
- mww 0xffffec3c 0x00030003
-
- # Identify NandFlash bank 0. Disabled at the moment because a memory driver is not yet complete.
-
-# nand probe 0
+ # a number of registers. The first step involves setting up the general I/O pins on the processor
+ # to be able to interface and support the external memory.
+
+ mww 0xfffffc10 0x00000010 ;# PMC_PCER : enable PIOC clock
+ mww 0xfffff800 0x00006000 ;# PIOC_PER : enable PIO function for 13(RDY/~BSY) and 14(~CS)
+ mww 0xfffff810 0x00004000 ;# PIOC_OER : enable output on 14
+ mww 0xfffff814 0x00002000 ;# PIOC_ODR : disable output on 13
+ mww 0xfffff830 0x00004000 ;# PIOC_SODR : set 14 to disable NAND
+
+ # The exact physical timing characteristics for the memory type used on the current board
+ # (MT29F2G08AACWP) can be established by setting four registers in order: SMC_SETUP3,
+ # SMC_PULSE3, SMC_CYCLE3, and SMC_MODE3. Computing the exact values of these registers
+ # is a little tedious to do here. If you have questions about how to do this, Atmel has
+ # a decent application note #6255B that covers this process.
+
+ mww 0xffffec30 0x00020002 ;# SMC_SETUP3 : 2 clock cycle setup for NRD and NWE
+ mww 0xffffec34 0x04040404 ;# SMC_PULSE3 : 4 clock cycle pulse for all signals
+ mww 0xffffec38 0x00070006 ;# SMC_CYCLE3 : 7 clock cycle NRD and 6 NWE cycle
+ mww 0xffffec3C 0x00020003 ;# SMC_MODE3 : NRD and NWE control, no NWAIT, 8-bit DBW,
+
+ mww 0xffffe800 0x00000001 ;# ECC_CR : reset the ECC parity registers
+ mww 0xffffe804 0x00000002 ;# ECC_MR : page size is 2112 words (word is 8 bits)
+
+ # Identify NandFlash bank 0.
+
+ nand probe nandflash_cs3
+
+ # The AT91SAM9G20-EK evaluation board has build-in serial data flash also.
# Now setup SDRAM. This is tricky and configuration is very important for reliability! The current calculations
# 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
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