Our hardware guy is tells me that the SanDisk can be placed
in one of three modes:
1) PC Card Memory Mode
2) PC Card I/O Mode
3) True IDE Mode
The device is going on a custom ppc 405GPr board.
He is also asking me how the device will be accessed
1) on bytes
2) on words
3) or both
I am not much of a hardware person, so I am not even certain if the
question I am asking makes sense.
The main goal is to use u-boot to bootstrap and initialize the board,
and to load the linux kernel/file system from the compact flash.
Does anyone have a reference design for a ppc based SBC with a
san-disc like part on it that runs Linux?
If not, is there a "standard" configuration the the compact flash
is placed on the bus?
Kindest Regards,
Jerry
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On Thu, 2002-12-26 at 12:51, Jerry Walden wrote:
Greetings:
I apologize in advance if this is a stupid question, or a question
with an obvious answer. The fact is that I have place linux on
and ARM, and an X86 board, however never on a PPC platform. In
fact I have very little experience with the PPC, and RISC processors
in general. I am trying to trace my way through the u-boot code -
since I do not have access to an in circuit emulator, I am somewhat
hindered. However I do have the capability to turn on a LED via a
GPIO register. So I am tracing through the code in a "burn an learn"
fashion.
I have a routine called "led" that turns on an led. The code below is
from start.S from the u-boot distro from the cpu/ppc4xx, my processor is
a ppc 405GPr.
The below code turns the LEN on. Note the branch instruction that branches
to some code to turn the led on. If I put the branch instruction AFTER
the "mtmsr r4" instruction the LED does not turn on. I cannot figure out
what is going on. If anyone has any recommendations on documentation to
read (I have the 600 page "green book") or if there is something I am
obviously missing (i.e. not being familiar enough with how a risc
processor works) any advice is welcome.
. = EXC_OFF_SYS_RESET
.globl _start
_start:
/* Clear and set up some registers. */
addi r4,r0,0x0000
mtspr sgr,r4
mtspr dcwr,r4
mtesr r4 /* clear Exception Syndrome Reg */
mttcr r4 /* clear Timer Control Reg */
mtxer r4 /* clear Fixed-Point Exception Reg */
mtevpr r4 /* clear Exception Vector Prefix Reg */
addi r4,r0,0x1000 /* set ME bit (Machine Exceptions) */
oris r4,r4,0x0002 /* set CE bit (Critical Exceptions) */
This is going to turn on these bits in the MSR: 0x00021000, probably
not what you want. A better sequence would be:
mfmsr r4
ori r4,r4,0x1002 /* Set ME, CE */
mtmsr r4
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
Greetings:
I apologize in advance if this is a stupid question, or a question
with an obvious answer. The fact is that I have place linux on
and ARM, and an X86 board, however never on a PPC platform. In
fact I have very little experience with the PPC, and RISC processors
in general. I am trying to trace my way through the u-boot code -
since I do not have access to an in circuit emulator, I am somewhat
hindered. However I do have the capability to turn on a LED via a
GPIO register. So I am tracing through the code in a "burn an learn"
fashion.
I have a routine called "led" that turns on an led. The code below is
from start.S from the u-boot distro from the cpu/ppc4xx, my processor is
a ppc 405GPr.
The below code turns the LEN on. Note the branch instruction that branches
to some code to turn the led on. If I put the branch instruction AFTER
the "mtmsr r4" instruction the LED does not turn on. I cannot figure out
what is going on. If anyone has any recommendations on documentation to
read (I have the 600 page "green book") or if there is something I am
obviously missing (i.e. not being familiar enough with how a risc
processor works) any advice is welcome.
. = EXC_OFF_SYS_RESET
.globl _start
_start:
/* Clear and set up some registers. */
addi r4,r0,0x0000
mtspr sgr,r4
mtspr dcwr,r4
mtesr r4 /* clear Exception Syndrome Reg */
mttcr r4 /* clear Timer Control Reg */
mtxer r4 /* clear Fixed-Point Exception Reg */
mtevpr r4 /* clear Exception Vector Prefix Reg */
addi r4,r0,0x1000 /* set ME bit (Machine Exceptions) */
oris r4,r4,0x0002 /* set CE bit (Critical Exceptions) */
/* the LED will turn on if I branch here */
b LED
mtmsr r4 /* change MSR */
/* the LED will NOT turn on if I branch here */
/*b LED */
addi r4,r0,(0xFFFF-0x10000) /* set r4 to 0xFFFFFFFF */
/* dbsr is cleared by setting bits to 1) */
mtdbsr r4 /* clear/reset the dbsr */
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/