[PATCH v2 2/2] fpga: dfl: look for vendor specific capability

matthew.gerlach
2020-11-18T19:01:01Z

A DFL may not begin at offset 0 of BAR 0. A PCIe vendor
specific capability can be used to specify the start of a
number of DFLs.

Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
---
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 | 13 ++++++
drivers/fpga/dfl-pci.c | 87 +++++++++++++++++++++++++++++++++++++-
2 files changed, 98 insertions(+), 2 deletions(-)

diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
index 0404fe6ffc74..37016ff35a90 100644
--- a/Documentation/fpga/dfl.rst
+++ b/Documentation/fpga/dfl.rst
@@ -501,6 +501,19 @@ 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 PCI Device
+===========================
+The start of the first DFL is assumed to be 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 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.

Open discussion
===============
diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c
index b27fae045536..3a6807e3e10c 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 8
+#define PCI_VNDR_DFLS_RES 0x0c
+
+#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 */
};
@@ -119,8 +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 bar, offset, vndr_hdr, dfl_cnt, dfl_res;
+ int dfl_res_off, i, voff = 0;
+ resource_size_t start, len;
+
+ if (pcidev->vendor != PCI_VENDOR_ID_INTEL)
+ return -ENODEV;
+
+ 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);
+
+ dev_dbg(&pcidev->dev,
+ "vendor-specific capability id 0x%x, rev 0x%x len 0x%x\n",
+ PCI_VNDR_HEADER_ID(vndr_hdr),
+ PCI_VNDR_HEADER_REV(vndr_hdr),
+ PCI_VNDR_HEADER_LEN(vndr_hdr));
+
+ if (PCI_VNDR_HEADER_ID(vndr_hdr) == PCI_VSEC_ID_INTEL_DFLS)
+ break;
+ }
+
+ if (!voff) {
+ dev_dbg(&pcidev->dev, "%s no VSEC found\n", __func__);
+ return -ENODEV;
+ }
+
+ dfl_cnt = 0;
+ pci_read_config_dword(pcidev, voff + PCI_VNDR_DFLS_CNT, &dfl_cnt);
+ dev_dbg(&pcidev->dev, "dfl_cnt %d\n", dfl_cnt);
+ for (i = 0; i < dfl_cnt; i++) {
+ dfl_res_off = voff + PCI_VNDR_DFLS_RES +
+ (i * sizeof(dfl_res));
+ dfl_res = GENMASK(31, 0);
+ pci_read_config_dword(pcidev, dfl_res_off, &dfl_res);
+
+ dev_dbg(&pcidev->dev, "dfl_res 0x%x\n", dfl_res);
+
+ bar = dfl_res & PCI_VNDR_DFLS_RES_BAR_MASK;
+ if (bar >= PCI_STD_NUM_BARS) {
+ dev_err(&pcidev->dev, "%s bad bar number %d\n",
+ __func__, bar);
+ return -EINVAL;
+ }
+
+ len = pci_resource_len(pcidev, bar);
+ if (len == 0) {
+ dev_err(&pcidev->dev, "%s unmapped bar number %d\n",
+ __func__, bar);
+ return -EINVAL;
+ }
+
+ 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__, bar, offset);
+
+ len -= offset;
+
+ start = pci_resource_start(pcidev, bar) + offset;
+
+ dfl_fpga_enum_info_add_dfl(info, start, len);
+ }
+
+ return 0;
+}
+
static int find_dfls_by_default(struct pci_dev *pcidev,
- struct dfl_fpga_enum_info *info)
+ struct dfl_fpga_enum_info *info)
{
resource_size_t start, len;
int port_num, bar, i;
@@ -220,7 +300,10 @@ 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