[PATCH v3 03/10] PCI/RCEC: Cache RCEC capabilities in pci_init_capabilities()

[Sean V Kelley]

Extend support for Root Complex Event Collectors by decoding and
caching the RCEC Endpoint Association Extended Capabilities when
enumerating. Use that cached information for later error source
reporting. See PCI Express Base Specification, version 5.0-1,
section 7.9.10.

Suggested-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Co-developed-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
Signed-off-by: Sean V Kelley <sean.v.kelley@xxxxxxxxx>
---
 drivers/pci/pci.h         | 18 ++++++++++++++
 drivers/pci/pcie/Makefile |  2 +-
 drivers/pci/pcie/rcec.c   | 52 +++++++++++++++++++++++++++++++++++++++
 drivers/pci/probe.c       |  2 ++
 include/linux/pci.h       |  4 +++
 5 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 drivers/pci/pcie/rcec.c

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 6d3f75867106..bd25e6047b54 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -448,6 +448,16 @@ int aer_get_device_error_info(struct pci_dev *dev, struct aer_err_info *info);
 void aer_print_error(struct pci_dev *dev, struct aer_err_info *info);
 #endif	/* CONFIG_PCIEAER */
 
+#ifdef CONFIG_PCIEPORTBUS
+/* Cached RCEC Associated Endpoint Extended Capabilities */
+struct rcec_ext {
+	u8		ver;
+	u8		nextbusn;
+	u8		lastbusn;
+	u32		bitmap;
+};
+#endif
+
 #ifdef CONFIG_PCIE_DPC
 void pci_save_dpc_state(struct pci_dev *dev);
 void pci_restore_dpc_state(struct pci_dev *dev);
@@ -460,6 +470,14 @@ static inline void pci_restore_dpc_state(struct pci_dev *dev) {}
 static inline void pci_dpc_init(struct pci_dev *pdev) {}
 #endif
 
+#ifdef CONFIG_PCIEPORTBUS
+void pci_rcec_init(struct pci_dev *dev);
+void pci_rcec_exit(struct pci_dev *dev);
+#else
+static inline void pci_rcec_init(struct pci_dev *dev) {}
+static inline void pci_rcec_exit(struct pci_dev *dev) {}
+#endif
+
 #ifdef CONFIG_PCI_ATS
 /* Address Translation Service */
 void pci_ats_init(struct pci_dev *dev);
diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
index 68da9280ff11..d9697892fa3e 100644
--- a/drivers/pci/pcie/Makefile
+++ b/drivers/pci/pcie/Makefile
@@ -2,7 +2,7 @@
 #
 # Makefile for PCI Express features and port driver
 
-pcieportdrv-y			:= portdrv_core.o portdrv_pci.o err.o
+pcieportdrv-y			:= portdrv_core.o portdrv_pci.o err.o rcec.o
 
 obj-$(CONFIG_PCIEPORTBUS)	+= pcieportdrv.o
 
diff --git a/drivers/pci/pcie/rcec.c b/drivers/pci/pcie/rcec.c
new file mode 100644
index 000000000000..519ae086ff41
--- /dev/null
+++ b/drivers/pci/pcie/rcec.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Root Complex Event Collector Support
+ *
+ * Authors:
+ *  Sean V Kelley <sean.v.kelley@xxxxxxxxx>
+ *  Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
+ *
+ * Copyright (C) 2020 Intel Corp.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/bitops.h>
+#include <linux/pci.h>
+#include <linux/pci_regs.h>
+
+#include "../pci.h"
+
+void pci_rcec_init(struct pci_dev *dev)
+{
+	u32 rcec, hdr, busn;
+
+	/* Only for Root Complex Event Collectors */
+	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_EC)
+		return;
+
+	dev->rcec_cap = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_RCEC);
+	if (!dev->rcec_cap)
+		return;
+
+	dev->rcec_ext = kzalloc(sizeof(*dev->rcec_ext), GFP_KERNEL);
+
+	rcec = dev->rcec_cap;
+	pci_read_config_dword(dev, rcec + PCI_RCEC_RCIEP_BITMAP, &dev->rcec_ext->bitmap);
+
+	/* Check whether RCEC BUSN register is present */
+	pci_read_config_dword(dev, rcec, &hdr);
+	dev->rcec_ext->ver = PCI_EXT_CAP_VER(hdr);
+	if (dev->rcec_ext->ver < PCI_RCEC_BUSN_REG_VER)
+		return;
+
+	pci_read_config_dword(dev, rcec + PCI_RCEC_BUSN, &busn);
+	dev->rcec_ext->nextbusn = PCI_RCEC_BUSN_NEXT(busn);
+	dev->rcec_ext->lastbusn = PCI_RCEC_BUSN_LAST(busn);
+}
+
+void pci_rcec_exit(struct pci_dev *dev)
+{
+	kfree(dev->rcec_ext);
+	dev->rcec_ext = NULL;
+}
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 2f66988cea25..2ad1e3e4ee6a 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -2195,6 +2195,7 @@ static void pci_configure_device(struct pci_dev *dev)
 static void pci_release_capabilities(struct pci_dev *dev)
 {
 	pci_aer_exit(dev);
+	pci_rcec_exit(dev);
 	pci_vpd_release(dev);
 	pci_iov_release(dev);
 	pci_free_cap_save_buffers(dev);
@@ -2394,6 +2395,7 @@ static void pci_init_capabilities(struct pci_dev *dev)
 	pci_ptm_init(dev);		/* Precision Time Measurement */
 	pci_aer_init(dev);		/* Advanced Error Reporting */
 	pci_dpc_init(dev);		/* Downstream Port Containment */
+	pci_rcec_init(dev);		/* Root Complex Event Collector */
 
 	pcie_report_downtraining(dev);
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c79d83304e52..c7fc5726872c 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -326,6 +326,10 @@ struct pci_dev {
 #ifdef CONFIG_PCIEAER
 	u16		aer_cap;	/* AER capability offset */
 	struct aer_stats *aer_stats;	/* AER stats for this device */
+#endif
+#ifdef CONFIG_PCIEPORTBUS
+	u16		rcec_cap;	/* RCEC capability offset */
+	struct rcec_ext *rcec_ext;	/* RCEC cached assoc. endpoint extended capabilities */
 #endif
 	u8		pcie_cap;	/* PCIe capability offset */
 	u8		msi_cap;	/* MSI capability offset */
-- 
2.28.0