RE: [PATCH 1/9 v2] pci:msi: add weak function for returning msi region info

-----Original Message-----
From: linux-pci-owner@vger.kernel.org [mailto:linux-pci-owner@vger.kernel=

.org]

On Behalf Of Bjorn Helgaas
Sent: Tuesday, November 26, 2013 5:06 AM
To: Bhushan Bharat-R65777
Cc: alex.williamson@redhat.com; joro@8bytes.org; agraf@suse.de; Wood Scot=

t-

B07421; Yoder Stuart-B08248; iommu@lists.linux-foundation.org; linux-
pci@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; linux-
kernel@vger.kernel.org; Bhushan Bharat-R65777
Subject: Re: [PATCH 1/9 v2] pci:msi: add weak function for returning msi =

region

info
=20
On Tue, Nov 19, 2013 at 10:47:05AM +0530, Bharat Bhushan wrote:

quoted

In Aperture type of IOMMU (like FSL PAMU), VFIO-iommu system need to
know the MSI region to map its window in h/w. This patch just defines
the required weak functions only and will be used by followup patches.

Signed-off-by: Bharat Bhushan <redacted>
---
v1->v2
 - Added description on "struct msi_region"

 drivers/pci/msi.c   |   22 ++++++++++++++++++++++
 include/linux/msi.h |   14 ++++++++++++++
 2 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index

d5f90d6..2643a29 100644

--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c

@@ -67,6 +67,28 @@ int __weak arch_msi_check_device(struct pci_dev *dev=

, int

nvec, int type)

quoted

 	return chip->check_device(chip, dev, nvec, type);  }

+int __weak arch_msi_get_region_count(void) {
+	return 0;
+}
+
+int __weak arch_msi_get_region(int region_num, struct msi_region
+*region) {
+	return 0;
+}
+
+int msi_get_region_count(void)
+{
+	return arch_msi_get_region_count();
+}
+EXPORT_SYMBOL(msi_get_region_count);
+
+int msi_get_region(int region_num, struct msi_region *region) {
+	return arch_msi_get_region(region_num, region); }
+EXPORT_SYMBOL(msi_get_region);
+
 int __weak arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int
type)  {
 	struct msi_desc *entry;

diff --git a/include/linux/msi.h b/include/linux/msi.h index

b17ead8..ade1480 100644

--- a/include/linux/msi.h
+++ b/include/linux/msi.h

@@ -51,6 +51,18 @@ struct msi_desc {
 };

 /*
+ * This structure is used to get
+ * - physical address
+ * - size
+ * of a msi region
+ */
+struct msi_region {
+	int region_num; /* MSI region number */
+	dma_addr_t addr; /* Address of MSI region */
+	size_t size; /* Size of MSI region */ };
+
+/*
  * The arch hooks to setup up msi irqs. Those functions are
  * implemented as weak symbols so that they /can/ be overriden by
  * architecture specific code if needed.

@@ -64,6 +76,8 @@ void arch_restore_msi_irqs(struct pci_dev *dev, int

irq);

 void default_teardown_msi_irqs(struct pci_dev *dev);  void
default_restore_msi_irqs(struct pci_dev *dev, int irq);
+int arch_msi_get_region_count(void);
+int arch_msi_get_region(int region_num, struct msi_region *region);

=20
It doesn't look like any of this (struct msi_region, msi_get_region(),
msi_get_region_count()) is actually used by drivers/pci/msi.c, so I don't=

 think

it needs to be declared in generic code.  It looks like it's only used in
drivers/vfio/vfio_iommu_fsl_pamu.c, where you already know you have an FS=

L

IOMMU, and you can just call FSL-specific interfaces directly.

Thanks Bjorn,

Want to be sure of what you are suggesting.

What I understood is that we define these (struct msi_region, msi_get_regio=
n(), msi_get_region_count()) in arch/powerpc/include/fsl_msi.h (a new file)=
. Include this header file directly in driver/vfio/vfio_iommu_fsl_pamu.c

Same also applies for msi_set_iova() in patch-5 ?

-Bharat

=20
Bjorn
=20

quoted

 struct msi_chip {
 	struct module *owner;
--
1.7.0.4

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