From bcf988aff1316d675b4353549197662e6f5d7b17 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Fri, 23 Aug 2019 21:39:20 +0200
Subject: bcm64: deal with discontinuous memory regions, avoid virtual memory
 aliasing, implement vmap() proper

on the 2GB and 4GB raspberry pi 4 variants, there are two
memory regions for ram:

[0x00000000..0x3e600000)
[0x40000000..0xfc000000)

the framebuffer is somewhere at the end of the first
GB of memory.

to handle these, we append the region base and limit
of the second region to *maxmem= like:

*maxmem=0x3e600000 0x40000000 0xfc000000

the mmu code has been changed to have non-existing
ram unmapped and mmukmap() now uses small 64K pages
instead of 512GB pages to avoid aliasing (framebuffer).

the VIRTPCI mapping has been removed as we now have
a proper vmap() implementation which assigns vritual
addresses automatically.
---
 sys/src/9/bcm/bootargs.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

(limited to 'sys/src/9/bcm')

diff --git a/sys/src/9/bcm/bootargs.c b/sys/src/9/bcm/bootargs.c
index d2304af0f..efb0183b5 100644
--- a/sys/src/9/bcm/bootargs.c
+++ b/sys/src/9/bcm/bootargs.c
@@ -11,7 +11,7 @@
 static char *confname[MAXCONF];
 static char *confval[MAXCONF];
 static int nconf;
-static char maxmem[11];
+static char maxmem[256];
 
 static int
 findconf(char *k)
@@ -89,13 +89,25 @@ beget4(uchar *p)
 static void
 devtreeprop(char *path, char *key, void *val, int len)
 {
-	if(strcmp(path, "/memory") == 0 && strcmp(key, "reg") == 0 && len == 3*4){
-		if(findconf("*maxmem") < 0){
+	if(strcmp(path, "/memory") == 0 && strcmp(key, "reg") == 0){
+		if(findconf("*maxmem") < 0 && len > 0 && (len % (3*4)) == 0){
 			uvlong top;
+			uchar *p = val;
+			char *s;
 
-			top = (uvlong)beget4((uchar*)val)<<32 | beget4((uchar*)val+4);
-			top += beget4((uchar*)val+8);
-			snprint(maxmem, sizeof(maxmem), "%#llux", top);
+			top = (uvlong)beget4(p)<<32 | beget4(p+4);
+			top += beget4(p+8);
+			s = seprint(maxmem, &maxmem[sizeof(maxmem)], "%#llux", top);
+			p += 3*4;
+			len -= 3*4;
+			while(len > 0){
+				top = (uvlong)beget4(p)<<32 | beget4(p+4);
+				s = seprint(s, &maxmem[sizeof(maxmem)], " %#llux", top);
+				top += beget4(p+8);
+				s = seprint(s, &maxmem[sizeof(maxmem)], " %#llux", top);
+				p += 3*4;
+				len -= 3*4;
+			}
 			addconf("*maxmem", maxmem);
 		}
 		return;
-- 
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