[U-Boot] [patch] rm9200 lowevel_init: don't touch reserved/readonly registers

[David Brownell]

For some reason the AT91rm9200 lowlevel init writes to a bunch of
reserved or read-only addresses.  All the boards seem to define the
value-to-be-written values as zero ... but they shouldn't actually
be writing *anything* there.

No documented erratum justifies these accesses.  It looks like maybe
some pre-release BDI-2000 setup code has been carried along by cargo
cult programming since at least late 2004 (per GIT history).

Here's a patch disabling what seems to be bogosity.  Tested on a
csb337; there were no behavioral changes.
---
 cpu/arm920t/at91rm9200/lowlevel_init.S |   14 ++------------
 include/configs/at91rm9200dk.h         |    5 -----
 include/configs/at91rm9200ek.h         |    5 -----
 include/configs/cmc_pu2.h              |    5 -----
 include/configs/csb637.h               |    5 -----
 include/configs/m501sk.h               |    5 -----
 include/configs/mp2usb.h               |    5 -----
 7 files changed, 2 insertions(+), 42 deletions(-)

--- a/cpu/arm920t/at91rm9200/lowlevel_init.S
+++ b/cpu/arm920t/at91rm9200/lowlevel_init.S
@@ -81,6 +81,7 @@ LoopOsc:
 	bne	0b
 	/* delay - this is all done by guess */
 	ldr	r0, =0x00010000
+	/* (vs reading PMC_SR for LOCKA, LOCKB ... or MOSCS earlier) */
 1:
 	subs	r0, r0, #1
 	bhi	1b
@@ -108,16 +109,6 @@ LoopOsc:
 	.ltorg
 
 SMRDATA:
-	.word AT91C_MC_PUIA
-	.word CONFIG_SYS_MC_PUIA_VAL
-	.word AT91C_MC_PUP
-	.word CONFIG_SYS_MC_PUP_VAL
-	.word AT91C_MC_PUER
-	.word CONFIG_SYS_MC_PUER_VAL
-	.word AT91C_MC_ASR
-	.word CONFIG_SYS_MC_ASR_VAL
-	.word AT91C_MC_AASR
-	.word CONFIG_SYS_MC_AASR_VAL
 	.word AT91C_EBI_CFGR
 	.word CONFIG_SYS_EBI_CFGR_VAL
 	.word AT91C_SMC_CSR0
@@ -128,8 +119,7 @@ SMRDATA:
 	.word CONFIG_SYS_PLLBR_VAL
 	.word AT91C_MCKR
 	.word CONFIG_SYS_MCKR_VAL
-	/* SMRDATA is 80 bytes long */
-	/* here there's a delay of 100 */
+	/* here there's a delay */
 SMRDATA1:
 	.word AT91C_PIOC_ASR
 	.word CONFIG_SYS_PIOC_ASR_VAL
--- a/include/configs/at91rm9200dk.h
+++ b/include/configs/at91rm9200dk.h
@@ -45,11 +45,6 @@
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 #define CONFIG_SYS_USE_MAIN_OSCILLATOR		1
 /* flash */
-#define CONFIG_SYS_MC_PUIA_VAL	0x00000000
-#define CONFIG_SYS_MC_PUP_VAL	0x00000000
-#define CONFIG_SYS_MC_PUER_VAL	0x00000000
-#define CONFIG_SYS_MC_ASR_VAL	0x00000000
-#define CONFIG_SYS_MC_AASR_VAL	0x00000000
 #define CONFIG_SYS_EBI_CFGR_VAL	0x00000000
 #define CONFIG_SYS_SMC_CSR0_VAL	0x00003284 /* 16bit, 2 TDF, 4 WS */
 
--- a/include/configs/at91rm9200ek.h
+++ b/include/configs/at91rm9200ek.h
@@ -56,11 +56,6 @@
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 #define CONFIG_SYS_USE_MAIN_OSCILLATOR		1
 /* flash */
-#define CONFIG_SYS_MC_PUIA_VAL	0x00000000
-#define CONFIG_SYS_MC_PUP_VAL	0x00000000
-#define CONFIG_SYS_MC_PUER_VAL	0x00000000
-#define CONFIG_SYS_MC_ASR_VAL	0x00000000
-#define CONFIG_SYS_MC_AASR_VAL	0x00000000
 #define CONFIG_SYS_EBI_CFGR_VAL	0x00000000
 #define CONFIG_SYS_SMC_CSR0_VAL	0x00003284 /* 16bit, 2 TDF, 4 WS */
 
--- a/include/configs/cmc_pu2.h
+++ b/include/configs/cmc_pu2.h
@@ -44,11 +44,6 @@
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 #define CONFIG_SYS_USE_MAIN_OSCILLATOR		1
 /* flash */
-#define CONFIG_SYS_MC_PUIA_VAL	0x00000000
-#define CONFIG_SYS_MC_PUP_VAL	0x00000000
-#define CONFIG_SYS_MC_PUER_VAL	0x00000000
-#define CONFIG_SYS_MC_ASR_VAL	0x00000000
-#define CONFIG_SYS_MC_AASR_VAL	0x00000000
 #define CONFIG_SYS_EBI_CFGR_VAL	0x00000000
 #define CONFIG_SYS_SMC_CSR0_VAL	0x100032ad /* 16bit, 2 TDF, 4 WS */
 
--- a/include/configs/csb637.h
+++ b/include/configs/csb637.h
@@ -45,11 +45,6 @@
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 #define CONFIG_SYS_USE_MAIN_OSCILLATOR		1
 /* flash */
-#define CONFIG_SYS_MC_PUIA_VAL	0x00000000
-#define CONFIG_SYS_MC_PUP_VAL	0x00000000
-#define CONFIG_SYS_MC_PUER_VAL	0x00000000
-#define CONFIG_SYS_MC_ASR_VAL	0x00000000
-#define CONFIG_SYS_MC_AASR_VAL	0x00000000
 #define CONFIG_SYS_EBI_CFGR_VAL	0x00000000
 #define CONFIG_SYS_SMC_CSR0_VAL	0x00003284 /* 16bit, 2 TDF, 4 WS */
 
--- a/include/configs/m501sk.h
+++ b/include/configs/m501sk.h
@@ -46,11 +46,6 @@
  */
 #define CONFIG_SYS_USE_MAIN_OSCILLATOR		1
 /* flash */
-#define CONFIG_SYS_MC_PUIA_VAL	0x00000000
-#define CONFIG_SYS_MC_PUP_VAL	0x00000000
-#define CONFIG_SYS_MC_PUER_VAL	0x00000000
-#define CONFIG_SYS_MC_ASR_VAL	0x00000000
-#define CONFIG_SYS_MC_AASR_VAL	0x00000000
 #define CONFIG_SYS_EBI_CFGR_VAL	0x00000000
 #define CONFIG_SYS_SMC_CSR0_VAL	0x00003284 /* 16bit, 2 TDF, 4 WS */
 
--- a/include/configs/mp2usb.h
+++ b/include/configs/mp2usb.h
@@ -49,11 +49,6 @@
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 #define CONFIG_SYS_USE_MAIN_OSCILLATOR	1
 /* flash */
-#define CONFIG_SYS_MC_PUIA_VAL	0x00000000
-#define CONFIG_SYS_MC_PUP_VAL	0x00000000
-#define CONFIG_SYS_MC_PUER_VAL	0x00000000
-#define CONFIG_SYS_MC_ASR_VAL	0x00000000
-#define CONFIG_SYS_MC_AASR_VAL	0x00000000
 #define CONFIG_SYS_EBI_CFGR_VAL	0x00000000
 #define CONFIG_SYS_SMC_CSR0_VAL	0x00003084 /* 16bit, 2 TDF, 4 WS */