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Date:      Mon, 22 Oct 2018 13:40:50 +0000 (UTC)
From:      Leandro Lupori <luporl@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r339589 - head/sys/powerpc/powernv
Message-ID:  <201810221340.w9MDeoIN084624@repo.freebsd.org>
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Author: luporl
Date: Mon Oct 22 13:40:50 2018
New Revision: 339589
URL: https://svnweb.freebsd.org/changeset/base/339589

Log:
  ppc64: limited 32-bit DMA address range
  
  Further investigation of issues with 32-bit DMA on PowerNV revealed that
  its window is hardcoded by OPAL (at least in skiboot version 5.4.9) and
  cannot be changed by the OS.
  Thus, now jhb suggestion of limiting the range in PCI DMA tag seems
  the best way to deal with it.
  
  Reviewed by:	jhibbits, nwhitehorn, sbruno
  Approved by:	jhibbits(mentor)
  Differential Revision:	https://reviews.freebsd.org/D17601

Modified:
  head/sys/powerpc/powernv/opal_pci.c

Modified: head/sys/powerpc/powernv/opal_pci.c
==============================================================================
--- head/sys/powerpc/powernv/opal_pci.c	Mon Oct 22 13:25:26 2018	(r339588)
+++ head/sys/powerpc/powernv/opal_pci.c	Mon Oct 22 13:40:50 2018	(r339589)
@@ -96,6 +96,9 @@ static int opalpci_route_interrupt(device_t bus, devic
 static void opalpic_pic_enable(device_t dev, u_int irq, u_int vector);
 static void opalpic_pic_eoi(device_t dev, u_int irq);
 
+/* Bus interface */
+static bus_dma_tag_t opalpci_get_dma_tag(device_t dev, device_t child);
+
 /*
  * Commands
  */
@@ -119,6 +122,8 @@ static void opalpic_pic_eoi(device_t dev, u_int irq);
  */
 #define OPAL_PCI_DEFAULT_PE			1
 
+#define OPAL_PCI_BUS_SPACE_LOWADDR_32BIT	0x7FFFFFFFUL
+
 /*
  * Driver methods.
  */
@@ -142,6 +147,9 @@ static device_method_t	opalpci_methods[] = {
 	DEVMETHOD(pic_enable,		opalpic_pic_enable),
 	DEVMETHOD(pic_eoi,		opalpic_pic_eoi),
 
+	/* Bus interface */
+	DEVMETHOD(bus_get_dma_tag,	opalpci_get_dma_tag),
+
 	DEVMETHOD_END
 };
 
@@ -424,6 +432,23 @@ opalpci_attach(device_t dev)
 			    msi_ranges[1], msi_ranges[0]);
 	}
 
+	/* Create the parent DMA tag */
+	err = bus_dma_tag_create(bus_get_dma_tag(dev), /* parent */
+	    1, 0,				/* alignment, bounds */
+	    OPAL_PCI_BUS_SPACE_LOWADDR_32BIT,	/* lowaddr */
+	    BUS_SPACE_MAXADDR_32BIT,		/* highaddr */
+	    NULL, NULL,				/* filter, filterarg */
+	    BUS_SPACE_MAXSIZE,			/* maxsize */
+	    BUS_SPACE_UNRESTRICTED,		/* nsegments */
+	    BUS_SPACE_MAXSIZE,			/* maxsegsize */
+	    0,					/* flags */
+	    NULL, NULL,				/* lockfunc, lockarg */
+	    &sc->ofw_sc.sc_dmat);
+	if (err != 0) {
+		device_printf(dev, "Failed to create DMA tag\n");
+		return (err);
+	}
+
 	/*
 	 * General OFW PCI attach
 	 */
@@ -660,4 +685,13 @@ static void opalpic_pic_eoi(device_t dev, u_int irq)
 	opal_call(OPAL_PCI_MSI_EOI, sc->phb_id, irq);
 
 	PIC_EOI(root_pic, irq);
+}
+
+static bus_dma_tag_t
+opalpci_get_dma_tag(device_t dev, device_t child)
+{
+	struct opalpci_softc *sc;
+
+	sc = device_get_softc(dev);
+	return (sc->ofw_sc.sc_dmat);
 }

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