patch: linux-2.4.20 alpha broken cia(rev1) fix

[Bjoern Brauel <bjb@gentoo.org>]

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Hi,

The attached patch fixes the initialization for CIA revision 1 chips 
that can be found on most Alcor machines. As it is impossible to boot 
such a box together with the Qlogic ISP SCSI controller without this 
patch I believe it is important to include it in the official kernel.

  cheers .. Bjoern

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--- linux-2.4.20/arch/alpha/kernel/core_cia.c	2002-11-29 17:09:02.000000000 +0000
+++ linux-2.4.20-bjb/arch/alpha/kernel/core_cia.c	2002-11-29 17:09:10.000000000 +0000
@@ -370,7 +370,7 @@
 }
 
 static inline void
-cia_prepare_tbia_workaround(void)
+cia_prepare_tbia_workaround(int cia_rev, int is_pyxis)
 {
 	unsigned long *ppte, pte;
 	long i;
@@ -382,10 +382,21 @@
 	for (i = 0; i < CIA_BROKEN_TBIA_SIZE / sizeof(unsigned long); ++i)
 		ppte[i] = pte;
 
-	*(vip)CIA_IOC_PCI_W1_BASE = CIA_BROKEN_TBIA_BASE | 3;
-	*(vip)CIA_IOC_PCI_W1_MASK = (CIA_BROKEN_TBIA_SIZE*1024 - 1)
-				    & 0xfff00000;
-	*(vip)CIA_IOC_PCI_T1_BASE = virt_to_phys(ppte) >> 2;
+	if (is_pyxis || cia_rev != 1) {
+	/* We can use W1 for SG on PYXIS/CIA rev 2. */
+		*(vip)CIA_IOC_PCI_W1_BASE = CIA_BROKEN_TBIA_BASE | 3;
+		*(vip)CIA_IOC_PCI_W1_MASK = (CIA_BROKEN_TBIA_SIZE*1024 - 1)
+			& 0xfff00000;
+		*(vip)CIA_IOC_PCI_T1_BASE = virt_to_phys(ppte) >> 2;
+	} else {
+	/* CIA rev 1 can't use W1 or W2 for SG, apparently,
+	     so use W3, which we made sure is not used for DAC. */
+		*(vip)CIA_IOC_PCI_W3_BASE = CIA_BROKEN_TBIA_BASE | 3;
+		*(vip)CIA_IOC_PCI_W3_MASK = (CIA_BROKEN_TBIA_SIZE*1024 - 1)
+			& 0xfff00000;
+		*(vip)CIA_IOC_PCI_T3_BASE = virt_to_phys(ppte) >> 2;
+	}
+
 }
 
 static void __init
@@ -715,8 +726,14 @@
 	   are compared against W_DAC.  We can, however, directly map 4GB,
 	   which is better than before.  However, due to assumptions made
 	   elsewhere, we should not claim that we support DAC unless that
-	   4GB covers all of physical memory.  */
-	if (is_pyxis || max_low_pfn > (0x100000000 >> PAGE_SHIFT)) {
+	   4GB covers all of physical memory.
+
+	   Also, don't do DAC on CIA rev 1, it has other problems and is
+	   unlikely to have more than 2GB of memory anyway, so direct is
+	   fine.
+	*/
+	if (cia_rev == 1 || is_pyxis ||
+	    max_low_pfn > (0x100000000 >> PAGE_SHIFT)) {
 		*(vip)CIA_IOC_PCI_W3_BASE = 0;
 	} else {
 		*(vip)CIA_IOC_PCI_W3_BASE = 0x00000000 | 1 | 8;
@@ -728,7 +745,7 @@
 	}
 
 	/* Prepare workaround for apparently broken tbia. */
-	cia_prepare_tbia_workaround();
+	cia_prepare_tbia_workaround(cia_rev, is_pyxis);
 }
 
 void __init