From: kettenis <kettenis@openbsd.org>
Date: Sun, 7 Apr 2024 21:08:59 +0000 (+0000)
Subject: The RISC-V architecture has cache-coherent DMA... until it doesn't.  This
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=16c51e1a089c5661c8fd59ecd70bdd987735791f;p=openbsd

The RISC-V architecture has cache-coherent DMA... until it doesn't.  This
is indicated by a "dma-noncoherent" property on the bus or device nodes
in the device tree.  Set the BUS_DMA_COHERENT flag on the DMA tag for
mainbus(4) and modify the flags based on the presence of "dma-coherent"
and "dma-noncoherent" properties where appropriate.

ok patrick@
---

diff --git a/sys/arch/riscv64/dev/mainbus.c b/sys/arch/riscv64/dev/mainbus.c
index d68acbd68c4..c51f6b025e8 100644
--- a/sys/arch/riscv64/dev/mainbus.c
+++ b/sys/arch/riscv64/dev/mainbus.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: mainbus.c,v 1.8 2021/06/20 16:51:37 deraadt Exp $ */
+/*	$OpenBSD: mainbus.c,v 1.9 2024/04/07 21:08:59 kettenis Exp $ */
 
 /*
  * Copyright (c) 2016 Patrick Wildt <patrick@blueri.se>
@@ -64,7 +64,7 @@ struct cfdriver mainbus_cd = {
 
 struct machine_bus_dma_tag mainbus_dma_tag = {
 	NULL,
-	0,
+	BUS_DMA_COHERENT,
 	_dmamap_create,
 	_dmamap_destroy,
 	_dmamap_load,
@@ -246,6 +246,18 @@ mainbus_attach_node(struct device *self, int node, cfmatch_t submatch)
 		OF_getpropintarray(node, "interrupts", fa.fa_intr, len);
 	}
 
+	if (OF_getproplen(node, "dma-noncoherent") >= 0) {
+		fa.fa_dmat = malloc(sizeof(*sc->sc_dmat),
+		    M_DEVBUF, M_WAITOK | M_ZERO);
+		memcpy(fa.fa_dmat, sc->sc_dmat, sizeof(*sc->sc_dmat));
+		fa.fa_dmat->_flags &= ~BUS_DMA_COHERENT;
+	} else if (OF_getproplen(node, "dma-coherent") >= 0) {
+		fa.fa_dmat = malloc(sizeof(*sc->sc_dmat),
+		    M_DEVBUF, M_WAITOK | M_ZERO);
+		memcpy(fa.fa_dmat, sc->sc_dmat, sizeof(*sc->sc_dmat));
+		fa.fa_dmat->_flags |= BUS_DMA_COHERENT;
+	}
+
 	if (submatch == NULL && sc->sc_early == 0)
 		print = mainbus_print;
 	if (submatch == NULL)
diff --git a/sys/arch/riscv64/dev/simplebus.c b/sys/arch/riscv64/dev/simplebus.c
index 3f74e2367e0..082395c1322 100644
--- a/sys/arch/riscv64/dev/simplebus.c
+++ b/sys/arch/riscv64/dev/simplebus.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: simplebus.c,v 1.6 2023/09/22 01:10:44 jsg Exp $	*/
+/*	$OpenBSD: simplebus.c,v 1.7 2024/04/07 21:08:59 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2016 Patrick Wildt <patrick@blueri.se>
@@ -226,7 +226,12 @@ simplebus_attach_node(struct device *self, int node)
 		OF_getpropintarray(node, "interrupts", fa.fa_intr, len);
 	}
 
-	if (OF_getproplen(node, "dma-coherent") >= 0) {
+	if (OF_getproplen(node, "dma-noncoherent") >= 0) {
+		fa.fa_dmat = malloc(sizeof(sc->sc_dma),
+		    M_DEVBUF, M_WAITOK | M_ZERO);
+		memcpy(fa.fa_dmat, &sc->sc_dma, sizeof(sc->sc_dma));
+		fa.fa_dmat->_flags &= ~BUS_DMA_COHERENT;
+	} else if (OF_getproplen(node, "dma-coherent") >= 0) {
 		fa.fa_dmat = malloc(sizeof(sc->sc_dma),
 		    M_DEVBUF, M_WAITOK | M_ZERO);
 		memcpy(fa.fa_dmat, &sc->sc_dma, sizeof(sc->sc_dma));