Add an openbsd,dma-constraint property to the /chosen node and set it

to an appropriate value for the Raspberry Pi 4.

ok patrick@

Author: kettenis

sys/arch/arm64/stand/efiboot/conf.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: conf.c,v 1.26 2020/03/22 14:59:11 kettenis Exp $	*/
+/*	$OpenBSD: conf.c,v 1.27 2020/04/21 07:54:01 kettenis Exp $	*/
 
 /*
  * Copyright (c) 1996 Michael Shalayeff
@@ -46,7 +46,7 @@
 #include "efipxe.h"
 #include "softraid_arm64.h"
 
-const char version[] = "0.21";
+const char version[] = "0.22";
 int	debug = 0;
 
 struct fs_ops file_system[] = {

sys/arch/arm64/stand/efiboot/efiacpi.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: efiacpi.c,v 1.6 2019/12/26 13:13:18 kettenis Exp $	*/
+/*	$OpenBSD: efiacpi.c,v 1.7 2020/04/21 07:54:01 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2018 Mark Kettenis <kettenis@openbsd.org>
@@ -659,6 +659,7 @@ efi_acpi_spcr(struct acpi_table_header *hdr)
 void *
 efi_acpi(void)
 {
+	extern uint64_t dma_constraint[2];
 	extern u_char dt_blob_start[];
 	void *fdt = dt_blob_start;
 	struct acpi_table_header *hdr;
@@ -714,6 +715,11 @@ efi_acpi(void)
 	node = fdt_find_node("/acpi");
 	fdt_node_set_property(node, "reg", reg, sizeof(reg));
 
+	/* Raspberry Pi 4 is "special". */
+	if (memcmp(xsdt->hdr_oemid, "RPIFDN", 6) == 0 &&
+	    memcmp(xsdt->hdr_oemtableid, "RPI4", 4) == 0)
+		dma_constraint[1] = htobe64(0x3bffffff);
+
 	fdt_finalize();
 
 	return fdt;

sys/arch/arm64/stand/efiboot/efiboot.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: efiboot.c,v 1.27 2020/03/22 14:59:11 kettenis Exp $	*/
+/*	$OpenBSD: efiboot.c,v 1.28 2020/04/21 07:54:01 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2015 YASUOKA Masahiko <yasuoka@yasuoka.net>
@@ -457,6 +457,24 @@ efi_console(void)
 	fdt_node_add_property(node, "stdout-path", path, strlen(path) + 1);
 }
 
+uint64_t dma_constraint[2] = { 0, -1 };
+
+void
+efi_dma_constraint(void)
+{
+	void *node;
+
+	/* Raspberry Pi 4 is "special". */
+	node = fdt_find_node("/");
+	if (fdt_node_is_compatible(node, "brcm,bcm2711"))
+		dma_constraint[1] = htobe64(0x3bffffff);
+
+	/* Pass DMA constraint. */
+	node = fdt_find_node("/chosen");
+	fdt_node_add_property(node, "openbsd,dma-constraint",
+	    dma_constraint, sizeof(dma_constraint));
+}
+
 int acpi = 0;
 void *fdt = NULL;
 char *bootmac = NULL;
@@ -534,6 +552,7 @@ efi_makebootargs(char *bootargs)
 
 	efi_framebuffer();
 	efi_console();
+	efi_dma_constraint();
 
 	fdt_finalize();