From 9eb192f586316361a78cf399b410716ee20ed132 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@felloff.net>
Date: Sun, 7 Nov 2021 17:51:12 +0000
Subject: [PATCH] bcm64: parse the emmc2bus/dma-ranges device-tree property and
 provide *emmc2bus kernel parameter

 /*
  * emmc2 has different DMA constraints based on SoC revisions. It was
  * moved into its own bus, so as for RPi4's firmware to update them.
  * The firmware will find whether the emmc2bus alias is defined, and if
  * so, it'll edit the dma-ranges property below accordingly.
  */
 emmc2bus: emmc2bus {
 compatible = "simple-bus";
 ranges = <0x0 0x7e000000  0x0 0xfe000000  0x01800000>;
 dma-ranges = <0x0 0xc0000000  0x0 0x00000000  0x40000000>;
 emmc2: mmc@7e340000 {
 compatible = "brcm,bcm2711-emmc2";
 reg = <0x0 0x7e340000 0x100>;
 interrupts = <GIC_SPI 126 IRQ_TYPE_LEVEL_HIGH>;
 clocks = <&clocks BCM2711_CLOCK_EMMC2>;
 status = "disabled";
 };
 };
---
 sys/src/9/bcm/bootargs.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sys/src/9/bcm/bootargs.c b/sys/src/9/bcm/bootargs.c
index 445e0baef..9b6c13a83 100644
--- a/sys/src/9/bcm/bootargs.c
+++ b/sys/src/9/bcm/bootargs.c
@@ -12,6 +12,7 @@ static char *confname[MAXCONF];
 static char *confval[MAXCONF];
 static int nconf;
 static char maxmem[256];
+static char emmc2bus[38];
 static char pciwin[38], pcidmawin[38];
 
 static int
@@ -114,6 +115,16 @@ devtreeprop(char *path, char *key, void *val, int len)
 		}
 		return;
 	}
+	if(strcmp(path, "/emmc2bus") == 0 && strcmp(key, "dma-ranges") == 0 && len == (2*4 + 2*4 + 1*4)){
+		if(findconf("*emmc2bus") < 0){
+			addr = (uvlong)beget4(p+0*4)<<32 | beget4(p+1*4);
+			addr -= (uvlong)beget4(p+2*4)<<32 | beget4(p+3*4);
+			size = beget4(p+4*4);
+			snprint(emmc2bus, sizeof(emmc2bus), "%#llux %#llux", addr, addr+size);
+			addconf("*emmc2bus", emmc2bus);
+		}
+		return;
+	}
 	if(strncmp(path, "/scb/pcie@", 10) == 0 && len == (3*4 + 4*4)){
 		if((beget4(p) & 0x3000000) == 0x2000000){
 			size = (uvlong)beget4(p+5*4)<<32 | beget4(p+5*4+4);