"Standard" Practice for config of SanDisk compact pci memory for 405gp ppc

"Standard" Practice for config of SanDisk compact pci memory for 405gp ppc

[Jerry Walden]

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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Need Help w/ PPC Boot

[Jerry Walden]

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 */


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Re: Need Help w/ PPC Boot

[Gary Thomas]

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


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Re: Need Help w/ PPC Boot

[Wolfgang Denk]

In message <EGEGIJHKDKJGAJMGIDPNEEEICDAA.jwalden@digitalatlantic.com> you wrote:
>
> 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

The obvious answer is:

Do not post the same message to several mailing lists.

This has been answered before (on U-Boot-Users).


Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
A failure will not appear until a unit has passed final inspection.

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