[RFC PATCH 3/9] PCI/portdrv: Add pcie_walk_rcec() to walk RCiEPs associated with RCEC

Sean V Kelley
2020-07-24T17:23:08Z

From: Qiuxu Zhuo <qiuxu.zhuo@intel.com>

When an RCEC device signals error(s) to a CPU core, the CPU core
needs to walk all the RCiEPs associated with that RCEC to check
errors. So add the function pcie_walk_rcec() to walk all RCiEPs
associated with the RCEC device.

Co-developed-by: Sean V Kelley <sean.v.kelley@intel.com>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Sean V Kelley <sean.v.kelley@intel.com>
---
drivers/pci/pcie/portdrv.h | 2 +
drivers/pci/pcie/portdrv_core.c | 82 +++++++++++++++++++++++++++++++++
2 files changed, 84 insertions(+)

diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
index af7cf237432a..c11d5ecbad76 100644
--- a/drivers/pci/pcie/portdrv.h
+++ b/drivers/pci/pcie/portdrv.h
@@ -116,6 +116,8 @@ void pcie_port_service_unregister(struct pcie_port_service_driver *new);

extern struct bus_type pcie_port_bus_type;
int pcie_port_device_register(struct pci_dev *dev);
+void pcie_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
+ void *userdata);
#ifdef CONFIG_PM
int pcie_port_device_suspend(struct device *dev);
int pcie_port_device_resume_noirq(struct device *dev);
diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
index 50a9522ab07d..bdcbb34764c2 100644
--- a/drivers/pci/pcie/portdrv_core.c
+++ b/drivers/pci/pcie/portdrv_core.c
@@ -14,6 +14,7 @@
#include <linux/pm_runtime.h>
#include <linux/string.h>
#include <linux/slab.h>
+#include <linux/bitops.h>
#include <linux/aer.h>

#include "../pci.h"
@@ -365,6 +366,87 @@ int pcie_port_device_register(struct pci_dev *dev)
return status;
}

+static int pcie_walk_rciep_devfn(struct pci_bus *pbus, int (*cb)(struct pci_dev *, void *),
+ void *userdata, unsigned long bitmap)
+{
+ unsigned int dev, fn;
+ struct pci_dev *pdev;
+ int retval;
+
+ for_each_set_bit(dev, &bitmap, 32) {
+ for (fn = 0; fn < 8; fn++) {
+ pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn));
+
+ if (!pdev || pci_pcie_type(pdev) != PCI_EXP_TYPE_RC_END)
+ continue;
+
+ retval = cb(pdev, userdata);
+ if (retval)
+ return retval;
+ }
+ }
+
+ return 0;
+}
+
+/** pcie_walk_rcec - Walk RCiEP devices associating with RCEC and call callback.
+ * @rcec RCEC whose RCiEP devices should be walked.
+ * @cb Callback to be called for each RCiEP device found.
+ * @userdata Arbitrary pointer to be passed to callback.
+ *
+ * Walk the given RCEC. Call the provided callback on each RCiEP device found.
+ *
+ * We check the return of @cb each time. If it returns anything
+ * other than 0, we break out.
+ *
+ */
+void pcie_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
+ void *userdata)
+{
+ u32 pos, bitmap, hdr, busn;
+ u8 ver, nextbusn, lastbusn;
+ struct pci_bus *pbus;
+ unsigned int bnr;
+
+ pos = pci_find_ext_capability(rcec, PCI_EXT_CAP_ID_RCEC);
+ if (!pos)
+ return;
+
+ pbus = pci_find_bus(pci_domain_nr(rcec->bus), rcec->bus->number);
+ if (!pbus)
+ return;
+
+ pci_read_config_dword(rcec, pos + PCI_RCEC_RCIEP_BITMAP, &bitmap);
+
+ /* Find RCiEP devices on the same bus as the RCEC */
+ if (pcie_walk_rciep_devfn(pbus, cb, userdata, (unsigned long)bitmap))
+ return;
+
+ /* Check whether RCEC BUSN register is present */
+ pci_read_config_dword(rcec, pos, &hdr);
+ ver = PCI_EXT_CAP_VER(hdr);
+ if (ver < PCI_RCEC_BUSN_REG_VER)
+ return;
+
+ pci_read_config_dword(rcec, pos + PCI_RCEC_BUSN, &busn);
+ nextbusn = PCI_RCEC_BUSN_NEXT(busn);
+ lastbusn = PCI_RCEC_BUSN_LAST(busn);
+
+ /* All RCiEP devices are on the same bus as the RCEC */
+ if (nextbusn == 0xff && lastbusn == 0x00)
+ return;
+
+ for (bnr = nextbusn; bnr < (lastbusn + 1); bnr++) {
+ pbus = pci_find_bus(pci_domain_nr(rcec->bus), bnr);
+ if (!pbus)
+ continue;
+
+ /* Find RCiEP devices on the given bus */
+ if (pcie_walk_rciep_devfn(pbus, cb, userdata, 0xffffffff))
+ return;
+ }
+}
+
#ifdef CONFIG_PM
typedef int (*pcie_pm_callback_t)(struct pcie_device *);

--
2.27.0