[coreboot] Flashrom problems on SB600

Carl-Daniel Hailfinger c-d.hailfinger.devel.2006 at gmx.net
Tue Mar 17 00:45:17 CET 2009

On 17.03.2009 00:24, Peter Stuge wrote:
> Carl-Daniel Hailfinger wrote:
>> Can't we just rely on the SPI/LPC selection register to be
>> unchanged after boot?
> That would be perfect.

This hunk does it, it even explains what is being done.

--- chipset_enable.c	(revision 312)
+++ chipset_enable.c	(working copy)
@@ -680,8 +680,16 @@
 	flashbus = BUS_TYPE_SB600_SPI;
 	/* Enable SPI ROM in SB600 PM register. */
+	/* If we enable SPI ROM here, we have to disable it after we leave.
+	 * But how can we know which ROM we are going to handle? So we have
+	 * to trade off. We only access LPC ROM if we boot via LPC ROM. And
+	 * only SPI ROM if we boot via SPI ROM. If you want to do it crossly,
+	 * you have to use the code below.
+	 */
+	/*
 	OUTB(0x8f, 0xcd6);
 	OUTB(0x0e, 0xcd7);
+	*/
 	return 0;

>> If someone deliberately changes that register,
> Which register? I couldn't find one. :\

See the patch hunk above. Look for CD6 in the SB600 RRG. Notice CD6 is
PM_INDEX. CD7 is PM_DATA. Look at section Power Management (PM)
Registers. 8F is FakeAsrEn.
FakeAsrEn has two interesting fields: UseBypassRom and BypassRomSel.

Basically, the patch hunk above does simply remove the forcing of SPI
access and relies on the default boot-up method. Back when you NAKed
that change, I wondered why but I assumed you wanted some more design to
go into it.

Other parts of the patch introduce timeout handling to the SB600 SPI
functions and change the programming interface a bit.

I think the patch is committable, but it should be split into multiple
pieces with one conceptual change each.

Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>



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