[PATCH v4 0/2] fpga: dfl: optional VSEC for start of dfl

[PATCH v4 0/2] fpga: dfl: optional VSEC for start of dfl

[matthew.gerlach]

From: Matthew Gerlach <matthew.gerlach@linux.intel.com>

The start of a Device Feature List (DFL) is currently assumed to be at
Bar0/Offset 0 on the PCIe bus by drivers/fpga/dfl-pci.c.  This patchset
adds support for the start one or more DFLs to be specified in a
Vendor-Specific Capability (VSEC) structure in PCIe config space.  If no
such VSEC structure exists, then the start is assumed to be
Bar0/Offset 0 for backward compatibility.

Matthew Gerlach (2):
  fpga: dfl: refactor cci_enumerate_feature_devs()
  fpga: dfl-pci: locate DFLs by PCIe vendor specific capability

 Documentation/fpga/dfl.rst |  27 ++++++
 drivers/fpga/dfl-pci.c     | 165 +++++++++++++++++++++++++++++--------
 2 files changed, 157 insertions(+), 35 deletions(-)

-- 
2.25.2

[PATCH v4 1/2] fpga: dfl: refactor cci_enumerate_feature_devs()

[matthew.gerlach]

From: Matthew Gerlach <matthew.gerlach@linux.intel.com>

In preparation of looking for dfls based on a vendor specific pci
capability, move the code for the default method of finding the first
dfl at offset 0 of Bar 0 to its own function.

Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Acked-by: Wu Hao <hao.wu@intel.com>
---
v4: add comment
    squash local variable definition

v3: no change

v2: remove spurious blank lines
    rename find_dfl_in_bar0 to find_dfls_by_default
---
 drivers/fpga/dfl-pci.c | 84 +++++++++++++++++++++++-------------------
 1 file changed, 47 insertions(+), 37 deletions(-)

diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c
index a2203d03c9e2..5100695e27cd 100644
--- a/drivers/fpga/dfl-pci.c
+++ b/drivers/fpga/dfl-pci.c
@@ -119,49 +119,20 @@ static int *cci_pci_create_irq_table(struct pci_dev *pcidev, unsigned int nvec)
 	return table;
 }
 
-/* enumerate feature devices under pci device */
-static int cci_enumerate_feature_devs(struct pci_dev *pcidev)
+/* default method of finding dfls starting at offset 0 of bar 0 */
+static int find_dfls_by_default(struct pci_dev *pcidev,
+				struct dfl_fpga_enum_info *info)
 {
-	struct cci_drvdata *drvdata = pci_get_drvdata(pcidev);
-	int port_num, bar, i, nvec, ret = 0;
-	struct dfl_fpga_enum_info *info;
-	struct dfl_fpga_cdev *cdev;
+	int port_num, bar, i, ret = 0;
 	resource_size_t start, len;
 	void __iomem *base;
-	int *irq_table;
 	u32 offset;
 	u64 v;
 
-	/* allocate enumeration info via pci_dev */
-	info = dfl_fpga_enum_info_alloc(&pcidev->dev);
-	if (!info)
-		return -ENOMEM;
-
-	/* add irq info for enumeration if the device support irq */
-	nvec = cci_pci_alloc_irq(pcidev);
-	if (nvec < 0) {
-		dev_err(&pcidev->dev, "Fail to alloc irq %d.\n", nvec);
-		ret = nvec;
-		goto enum_info_free_exit;
-	} else if (nvec) {
-		irq_table = cci_pci_create_irq_table(pcidev, nvec);
-		if (!irq_table) {
-			ret = -ENOMEM;
-			goto irq_free_exit;
-		}
-
-		ret = dfl_fpga_enum_info_add_irq(info, nvec, irq_table);
-		kfree(irq_table);
-		if (ret)
-			goto irq_free_exit;
-	}
-
-	/* start to find Device Feature List in Bar 0 */
+	/* start to find Device Feature List from Bar 0 */
 	base = cci_pci_ioremap_bar0(pcidev);
-	if (!base) {
-		ret = -ENOMEM;
-		goto irq_free_exit;
-	}
+	if (!base)
+		return -ENOMEM;
 
 	/*
 	 * PF device has FME and Ports/AFUs, and VF device only has one
@@ -208,12 +179,51 @@ static int cci_enumerate_feature_devs(struct pci_dev *pcidev)
 		dfl_fpga_enum_info_add_dfl(info, start, len);
 	} else {
 		ret = -ENODEV;
-		goto irq_free_exit;
 	}
 
 	/* release I/O mappings for next step enumeration */
 	pcim_iounmap_regions(pcidev, BIT(0));
 
+	return ret;
+}
+
+/* enumerate feature devices under pci device */
+static int cci_enumerate_feature_devs(struct pci_dev *pcidev)
+{
+	struct cci_drvdata *drvdata = pci_get_drvdata(pcidev);
+	struct dfl_fpga_enum_info *info;
+	struct dfl_fpga_cdev *cdev;
+	int nvec, ret = 0;
+	int *irq_table;
+
+	/* allocate enumeration info via pci_dev */
+	info = dfl_fpga_enum_info_alloc(&pcidev->dev);
+	if (!info)
+		return -ENOMEM;
+
+	/* add irq info for enumeration if the device support irq */
+	nvec = cci_pci_alloc_irq(pcidev);
+	if (nvec < 0) {
+		dev_err(&pcidev->dev, "Fail to alloc irq %d.\n", nvec);
+		ret = nvec;
+		goto enum_info_free_exit;
+	} else if (nvec) {
+		irq_table = cci_pci_create_irq_table(pcidev, nvec);
+		if (!irq_table) {
+			ret = -ENOMEM;
+			goto irq_free_exit;
+		}
+
+		ret = dfl_fpga_enum_info_add_irq(info, nvec, irq_table);
+		kfree(irq_table);
+		if (ret)
+			goto irq_free_exit;
+	}
+
+	ret = find_dfls_by_default(pcidev, info);
+	if (ret)
+		goto irq_free_exit;
+
 	/* start enumeration with prepared enumeration information */
 	cdev = dfl_fpga_feature_devs_enumerate(info);
 	if (IS_ERR(cdev)) {
-- 
2.25.2

[PATCH v4 2/2] fpga: dfl-pci: locate DFLs by PCIe vendor specific capability

[matthew.gerlach]

From: Matthew Gerlach <matthew.gerlach@linux.intel.com>

A PCIe vendor specific extended capability is introduced by Intel to
specify the start of a number of DFLs.

Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
---
v4: Clarify PCI vs. PCIe in documentation
    Various cleanup suggested by hao.wu@intel.com
    Document and enforce specifying a single DFL per BAR

v3: Add text and ascii art to documentation.
    Ensure not to exceed PCIe config space in loop.

v2: Update documentation for clarity.
    Clean up  macro names.
    Use GENMASK.
    Removed spurious blank lines.
    Changed some calls from dev_info to dev_dbg.
    Specifically check for VSEC not found, -ENODEV.
    Ensure correct pci vendor id.
    Remove check for page alignment.
    Rename find_dfl_in_cfg to find_dfls_by_vsec.
    Initialize target memory of pci_read_config_dword to invalid values before use.
---
 Documentation/fpga/dfl.rst | 27 ++++++++++++
 drivers/fpga/dfl-pci.c     | 87 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
index 0404fe6ffc74..ea8cefc18bdb 100644
--- a/Documentation/fpga/dfl.rst
+++ b/Documentation/fpga/dfl.rst
@@ -501,6 +501,33 @@ Developer only needs to provide a sub feature driver with matched feature id.
 FME Partial Reconfiguration Sub Feature driver (see drivers/fpga/dfl-fme-pr.c)
 could be a reference.
 
+Location of DFLs on a PCI Device
+===========================
+The original method for finding a DFL on a PCI device assumed the start of the
+first DFL to offset 0 of bar 0.  If the first node of the DFL is an FME,
+then further DFLs in the port(s) are specified in FME header registers.
+Alternatively, a PCIe vendor specific capability structure can be used to
+specify the location of all the DFLs on the device, providing flexibility
+for the type of starting node in the DFL.  Intel has reserved the
+VSEC ID of 0x43 for this purpose.  The vendor specific
+data begins with a 4 byte vendor specific register for the number of DFLs followed 4 byte
+Offset/BIR vendor specific registers for each DFL. Bits 2:0 of Offset/BIR register
+indicates the BAR, and bits 31:3 form the 8 byte aligned offset where bits 2:0 are
+zero.
+
+        +----------------------------+
+        |31     Number of DFLS      0|
+        +----------------------------+
+        |31     Offset     3|2 BIR  0|
+        +----------------------------+
+                      . . .
+        +----------------------------+
+        |31     Offset     3|2 BIR  0|
+        +----------------------------+
+
+Being able to specify more than one DFL per BAR has been considered, but it
+was determined the use case did not provide value.  Specifying a single DFL
+per BAR simplifies the implementation and allows for extra error checking.
 
 Open discussion
 ===============
diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c
index 5100695e27cd..04e47e266f26 100644
--- a/drivers/fpga/dfl-pci.c
+++ b/drivers/fpga/dfl-pci.c
@@ -27,6 +27,14 @@
 #define DRV_VERSION	"0.8"
 #define DRV_NAME	"dfl-pci"
 
+#define PCI_VSEC_ID_INTEL_DFLS 0x43
+
+#define PCI_VNDR_DFLS_CNT 0x8
+#define PCI_VNDR_DFLS_RES 0xc
+
+#define PCI_VNDR_DFLS_RES_BAR_MASK GENMASK(2, 0)
+#define PCI_VNDR_DFLS_RES_OFF_MASK GENMASK(31, 3)
+
 struct cci_drvdata {
 	struct dfl_fpga_cdev *cdev;	/* container device */
 };
@@ -119,6 +127,80 @@ static int *cci_pci_create_irq_table(struct pci_dev *pcidev, unsigned int nvec)
 	return table;
 }
 
+static int find_dfls_by_vsec(struct pci_dev *pcidev, struct dfl_fpga_enum_info *info)
+{
+	u32 bir, offset, vndr_hdr, dfl_cnt, dfl_res;
+	int dfl_res_off, i, bars, voff = 0;
+	resource_size_t start, len;
+
+	while ((voff = pci_find_next_ext_capability(pcidev, voff, PCI_EXT_CAP_ID_VNDR))) {
+		vndr_hdr = 0;
+		pci_read_config_dword(pcidev, voff + PCI_VNDR_HEADER, &vndr_hdr);
+
+		if (PCI_VNDR_HEADER_ID(vndr_hdr) == PCI_VSEC_ID_INTEL_DFLS &&
+		    pcidev->vendor == PCI_VENDOR_ID_INTEL)
+			break;
+	}
+
+	if (!voff) {
+		dev_dbg(&pcidev->dev, "%s no DFL VSEC found\n", __func__);
+		return -ENODEV;
+	}
+
+	dfl_cnt = 0;
+	pci_read_config_dword(pcidev, voff + PCI_VNDR_DFLS_CNT, &dfl_cnt);
+	if (dfl_cnt > PCI_STD_NUM_BARS) {
+		dev_err(&pcidev->dev, "%s too many DFLs %d > %d\n",
+			__func__, dfl_cnt, PCI_STD_NUM_BARS);
+		return -EINVAL;
+	}
+
+	dfl_res_off = voff + PCI_VNDR_DFLS_RES;
+	if (dfl_res_off + (dfl_cnt * sizeof(u32)) > PCI_CFG_SPACE_EXP_SIZE) {
+		dev_err(&pcidev->dev, "%s DFL VSEC too big for PCIe config space\n",
+			__func__);
+		return -EINVAL;
+	}
+
+	for (i = 0, bars = 0; i < dfl_cnt; i++, dfl_res_off += sizeof(u32)) {
+		dfl_res = GENMASK(31, 0);
+		pci_read_config_dword(pcidev, dfl_res_off, &dfl_res);
+
+		bir = dfl_res & PCI_VNDR_DFLS_RES_BAR_MASK;
+		if (bir >= PCI_STD_NUM_BARS) {
+			dev_err(&pcidev->dev, "%s bad bir number %d\n",
+				__func__, bir);
+			return -EINVAL;
+		}
+
+		if (bars & BIT(bir)) {
+			dev_err(&pcidev->dev, "%s DFL for BAR %d already specified\n",
+				__func__, bir);
+			return -EINVAL;
+		}
+
+		bars |= BIT(bir);
+
+		len = pci_resource_len(pcidev, bir);
+		offset = dfl_res & PCI_VNDR_DFLS_RES_OFF_MASK;
+		if (offset >= len) {
+			dev_err(&pcidev->dev, "%s bad offset %u >= %pa\n",
+				__func__, offset, &len);
+			return -EINVAL;
+		}
+
+		dev_dbg(&pcidev->dev, "%s BAR %d offset 0x%x\n", __func__, bir, offset);
+
+		len -= offset;
+
+		start = pci_resource_start(pcidev, bir) + offset;
+
+		dfl_fpga_enum_info_add_dfl(info, start, len);
+	}
+
+	return 0;
+}
+
 /* default method of finding dfls starting at offset 0 of bar 0 */
 static int find_dfls_by_default(struct pci_dev *pcidev,
 				struct dfl_fpga_enum_info *info)
@@ -220,7 +302,10 @@ static int cci_enumerate_feature_devs(struct pci_dev *pcidev)
 			goto irq_free_exit;
 	}
 
-	ret = find_dfls_by_default(pcidev, info);
+	ret = find_dfls_by_vsec(pcidev, info);
+	if (ret == -ENODEV)
+		ret = find_dfls_by_default(pcidev, info);
+
 	if (ret)
 		goto irq_free_exit;
 
-- 
2.25.2