linux-kernel - [PATCH v3] PCI: endpoint: Add prefetch BAR support

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Date:   Thu, 20 Jan 2022 02:30:39 +0000
From:   Li Chen <lchen@...arella.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
CC:     Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH v3] PCI: endpoint: Add prefetch BAR support

Before this commit, epf cannot set BAR to be prefetchable.
Prefetchable BAR can also help epf device to use bridge's
prefetch memory window.

Signed-off-by: Li Chen <lchen@...arella.com>
---
Changes in v2:
Remove Gerrit Change-id
Changes in v3:
capitalize "BAR" in the subject and commit log as suggested by Bjorn.

 drivers/pci/endpoint/functions/pci-epf-test.c | 4 ++++
 include/linux/pci-epc.h                       | 2 ++
 2 files changed, 6 insertions(+)

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index 90d84d3bc868..96489cfdf58d 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -817,15 +817,19 @@ static void pci_epf_configure_bar(struct pci_epf *epf,
 {
 	struct pci_epf_bar *epf_bar;
 	bool bar_fixed_64bit;
+	bool bar_prefetch;
 	int i;
 
 	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
 		epf_bar = &epf->bar[i];
 		bar_fixed_64bit = !!(epc_features->bar_fixed_64bit & (1 << i));
+		bar_prefetch = !!(epc_features->bar_prefetch & (1 << i));
 		if (bar_fixed_64bit)
 			epf_bar->flags |= PCI_BASE_ADDRESS_MEM_TYPE_64;
 		if (epc_features->bar_fixed_size[i])
 			bar_size[i] = epc_features->bar_fixed_size[i];
+		if (bar_prefetch)
+			epf_bar->flags |= PCI_BASE_ADDRESS_MEM_PREFETCH;
 	}
 }
 
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index a48778e1a4ee..825632d581d0 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -161,6 +161,7 @@ struct pci_epc {
  * @msix_capable: indicate if the endpoint function has MSI-X capability
  * @reserved_bar: bitmap to indicate reserved BAR unavailable to function driver
  * @bar_fixed_64bit: bitmap to indicate fixed 64bit BARs
+ * @bar_prefetch: bitmap to indicate prefetchable BARs
  * @bar_fixed_size: Array specifying the size supported by each BAR
  * @align: alignment size required for BAR buffer allocation
  */
@@ -171,6 +172,7 @@ struct pci_epc_features {
 	unsigned int	msix_capable : 1;
 	u8	reserved_bar;
 	u8	bar_fixed_64bit;
+	u8	bar_prefetch;
 	u64	bar_fixed_size[PCI_STD_NUM_BARS];
 	size_t	align;
 };
-- 
2.34.1

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