[RFC PATCH 2/6] pcie/cxl_timeout: Add CXL Timeout & Isolation service driver

[Ben Cheatham <Benjamin.Cheatham@amd.com>]

Add a CXL Timeout & Isolation (CXL 3.0 12.3) service driver to the
PCIe port bus driver for CXL root ports. The service will support
enabling/programming CXL.mem transaction timeout, error isolation,
and interrupt handling.

Add code to find and map CXL Timeout & Isolation capability register
(CXL 3.0 8.2.4.23.1) from service driver. Then use capability register
mapping to enable CXL.mem transaction timeout with the default value.

Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
---
 drivers/cxl/cxl.h              |   4 +
 drivers/pci/pcie/Kconfig       |  10 ++
 drivers/pci/pcie/Makefile      |   1 +
 drivers/pci/pcie/cxl_timeout.c | 197 +++++++++++++++++++++++++++++++++
 drivers/pci/pcie/portdrv.c     |   1 +
 drivers/pci/pcie/portdrv.h     |  10 +-
 6 files changed, 222 insertions(+), 1 deletion(-)
 create mode 100644 drivers/pci/pcie/cxl_timeout.c

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 87f3178d6642..0c65f4ec7aae 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -129,7 +129,11 @@ static inline int ways_to_eiw(unsigned int ways, u8 *eiw)
 
 /* CXL 3.0 8.2.4.23 CXL Timeout and Isolation Capability Structure */
 #define CXL_TIMEOUT_CAPABILITY_OFFSET 0x0
+#define   CXL_TIMEOUT_CAP_MEM_TIMEOUT_SUPP BIT(4)
+#define CXL_TIMEOUT_CONTROL_OFFSET 0x8
+#define   CXL_TIMEOUT_CONTROL_MEM_TIMEOUT_ENABLE BIT(4)
 #define CXL_TIMEOUT_CAPABILITY_LENGTH 0x10
+
 /* RAS Registers CXL 2.0 8.2.5.9 CXL RAS Capability Structure */
 #define CXL_RAS_UNCORRECTABLE_STATUS_OFFSET 0x0
 #define   CXL_RAS_UNCORRECTABLE_STATUS_MASK (GENMASK(16, 14) | GENMASK(11, 0))
diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
index 8999fcebde6a..27820af4502e 100644
--- a/drivers/pci/pcie/Kconfig
+++ b/drivers/pci/pcie/Kconfig
@@ -58,6 +58,16 @@ config PCIEAER_CXL
 
 	  If unsure, say Y.
 
+config PCIE_CXL_TIMEOUT
+	bool "PCI Express CXL.mem Timeout & Isolation Interrupt support"
+	depends on PCIEPORTBUS
+	depends on CXL_BUS=PCIEPORTBUS && CXL_PORT
+	help
+	  Enables the CXL.mem Timeout & Isolation PCIE port service driver. This
+	  driver, in combination with the CXL driver core, is responsible for
+	  handling CXL capable PCIE root ports that undergo CXL.mem error isolation
+	  due to either a CXL.mem transaction timeout or uncorrectable device error.
+
 #
 # PCI Express ECRC
 #
diff --git a/drivers/pci/pcie/Makefile b/drivers/pci/pcie/Makefile
index 8de4ed5f98f1..433ef08efc6f 100644
--- a/drivers/pci/pcie/Makefile
+++ b/drivers/pci/pcie/Makefile
@@ -13,3 +13,4 @@ obj-$(CONFIG_PCIE_PME)		+= pme.o
 obj-$(CONFIG_PCIE_DPC)		+= dpc.o
 obj-$(CONFIG_PCIE_PTM)		+= ptm.o
 obj-$(CONFIG_PCIE_EDR)		+= edr.o
+obj-$(CONFIG_PCIE_CXL_TIMEOUT)	+= cxl_timeout.o
diff --git a/drivers/pci/pcie/cxl_timeout.c b/drivers/pci/pcie/cxl_timeout.c
new file mode 100644
index 000000000000..84f2df0e0397
--- /dev/null
+++ b/drivers/pci/pcie/cxl_timeout.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Implements CXL Timeout & Isolation (CXL 3.0 12.3.2) interrupt support as a
+ * PCIE port service driver. The driver is set up such that near all of the
+ * work for setting up and handling interrupts are in this file, while the
+ * CXL core enables the interrupts during port enumeration.
+ *
+ * Copyright (C) 2024, Advanced Micro Devices, Inc.
+ * All Rights Reserved.
+ *
+ * Author: Ben Cheatham <Benjamin.Cheatham@amd.com>
+ */
+
+#define pr_fmt(fmt) "cxl_timeout: " fmt
+#define dev_fmt pr_fmt
+
+#include <linux/pci.h>
+#include <linux/acpi.h>
+
+#include "../../cxl/cxlpci.h"
+#include "portdrv.h"
+
+struct cxl_timeout {
+	struct pcie_device *dev;
+	void __iomem *regs;
+	u32 cap;
+};
+
+struct pcie_cxlt_data {
+	struct cxl_timeout *cxlt;
+	struct cxl_dport *dport;
+};
+
+static int cxl_map_timeout_regs(struct pci_dev *port,
+				struct cxl_register_map *map,
+				struct cxl_component_regs *regs)
+{
+	int rc = 0;
+
+	rc = cxl_find_regblock(port, CXL_REGLOC_RBI_COMPONENT, map);
+	if (rc)
+		return rc;
+
+	rc = cxl_setup_regs(map);
+	if (rc)
+		return rc;
+
+	rc = cxl_map_component_regs(map, regs,
+				    BIT(CXL_CM_CAP_CAP_ID_TIMEOUT));
+	return rc;
+}
+
+static void cxl_unmap_timeout_regs(struct pci_dev *port,
+				   struct cxl_register_map *map,
+				   struct cxl_component_regs *regs)
+{
+	struct cxl_reg_map *timeout_map = &map->component_map.timeout;
+
+	devm_iounmap(map->host, regs->timeout);
+	devm_release_mem_region(map->host, map->resource + timeout_map->offset,
+				timeout_map->size);
+}
+
+static struct cxl_timeout *cxl_create_cxlt(struct pcie_device *dev)
+{
+	struct cxl_component_regs *regs;
+	struct cxl_register_map *map;
+	struct cxl_timeout *cxlt;
+	int rc;
+
+	regs = devm_kmalloc(&dev->device, sizeof(*regs), GFP_KERNEL);
+	if (!regs)
+		return ERR_PTR(-ENOMEM);
+
+	map = devm_kmalloc(&dev->device, sizeof(*map), GFP_KERNEL);
+	if (!map) {
+		devm_kfree(&dev->device, regs);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	rc = cxl_map_timeout_regs(dev->port, map, regs);
+	if (rc)
+		goto err;
+
+	cxlt = devm_kmalloc(&dev->device, sizeof(*cxlt), GFP_KERNEL);
+	if (!cxlt)
+		goto err;
+
+	cxlt->regs = regs->timeout;
+	cxlt->dev = dev;
+	cxlt->cap = readl(cxlt->regs + CXL_TIMEOUT_CAPABILITY_OFFSET);
+
+	return cxlt;
+
+err:
+	cxl_unmap_timeout_regs(dev->port, map, regs);
+	return ERR_PTR(rc);
+}
+
+int cxl_find_timeout_cap(struct pci_dev *dev, u32 *cap)
+{
+	struct cxl_component_regs regs;
+	struct cxl_register_map map;
+	int rc = 0;
+
+	rc = cxl_map_timeout_regs(dev, &map, &regs);
+	if (rc)
+		return rc;
+
+	*cap = readl(regs.timeout + CXL_TIMEOUT_CAPABILITY_OFFSET);
+	cxl_unmap_timeout_regs(dev, &map, &regs);
+
+	return rc;
+}
+
+static struct pcie_cxlt_data *cxlt_create_pdata(struct pcie_device *dev)
+{
+	struct pcie_cxlt_data *data;
+
+	data = devm_kzalloc(&dev->device, sizeof(*data), GFP_KERNEL);
+	if (IS_ERR_OR_NULL(data))
+		return ERR_PTR(-ENOMEM);
+
+	data->cxlt = cxl_create_cxlt(dev);
+	if (IS_ERR_OR_NULL(data->cxlt))
+		return ERR_PTR(PTR_ERR(data->cxlt));
+
+	data->dport = NULL;
+
+	return data;
+}
+
+static void cxl_disable_timeout(void *data)
+{
+	struct cxl_timeout *cxlt = data;
+	u32 cntrl = readl(cxlt->regs + CXL_TIMEOUT_CONTROL_OFFSET);
+
+	cntrl &= ~CXL_TIMEOUT_CONTROL_MEM_TIMEOUT_ENABLE;
+	writel(cntrl, cxlt->regs + CXL_TIMEOUT_CONTROL_OFFSET);
+}
+
+static int cxl_enable_timeout(struct pcie_device *dev, struct cxl_timeout *cxlt)
+{
+	u32 cntrl;
+
+	if (!cxlt || !FIELD_GET(CXL_TIMEOUT_CAP_MEM_TIMEOUT_SUPP, cxlt->cap))
+		return -ENXIO;
+
+	cntrl = readl(cxlt->regs + CXL_TIMEOUT_CONTROL_OFFSET);
+	cntrl |= CXL_TIMEOUT_CONTROL_MEM_TIMEOUT_ENABLE;
+	writel(cntrl, cxlt->regs + CXL_TIMEOUT_CONTROL_OFFSET);
+
+	return devm_add_action_or_reset(&dev->device, cxl_disable_timeout,
+					cxlt);
+}
+
+static int cxl_timeout_probe(struct pcie_device *dev)
+{
+	struct pci_dev *port = dev->port;
+	struct pcie_cxlt_data *pdata;
+	struct cxl_timeout *cxlt;
+	int rc = 0;
+
+	/* Limit to CXL root ports */
+	if (!pci_find_dvsec_capability(port, PCI_DVSEC_VENDOR_ID_CXL,
+				       CXL_DVSEC_PORT_EXTENSIONS))
+		return -ENODEV;
+
+	pdata = cxlt_create_pdata(dev);
+	if (IS_ERR_OR_NULL(pdata))
+		return PTR_ERR(pdata);
+
+	set_service_data(dev, pdata);
+	cxlt = pdata->cxlt;
+
+	rc = cxl_enable_timeout(dev, cxlt);
+	if (rc)
+		pci_dbg(dev->port, "Failed to enable CXL.mem timeout: %d\n",
+			rc);
+
+	return rc;
+}
+
+static struct pcie_port_service_driver cxltdriver = {
+	.name		= "cxl_timeout",
+	.port_type	= PCI_EXP_TYPE_ROOT_PORT,
+	.service	= PCIE_PORT_SERVICE_CXLT,
+
+	.probe		= cxl_timeout_probe,
+};
+
+int __init pcie_cxlt_init(void)
+{
+	return pcie_port_service_register(&cxltdriver);
+}
+
+MODULE_IMPORT_NS(CXL);
diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
index 14a4b89a3b83..7aa0a6f2da4e 100644
--- a/drivers/pci/pcie/portdrv.c
+++ b/drivers/pci/pcie/portdrv.c
@@ -829,6 +829,7 @@ static void __init pcie_init_services(void)
 	pcie_pme_init();
 	pcie_dpc_init();
 	pcie_hp_init();
+	pcie_cxlt_init();
 }
 
 static int __init pcie_portdrv_init(void)
diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
index 1f3803bde7ee..5395a0e36956 100644
--- a/drivers/pci/pcie/portdrv.h
+++ b/drivers/pci/pcie/portdrv.h
@@ -22,8 +22,10 @@
 #define PCIE_PORT_SERVICE_DPC		(1 << PCIE_PORT_SERVICE_DPC_SHIFT)
 #define PCIE_PORT_SERVICE_BWNOTIF_SHIFT	4	/* Bandwidth notification */
 #define PCIE_PORT_SERVICE_BWNOTIF	(1 << PCIE_PORT_SERVICE_BWNOTIF_SHIFT)
+#define PCIE_PORT_SERVICE_CXLT_SHIFT	5	/* CXL Timeout & Isolation */
+#define PCIE_PORT_SERVICE_CXLT		(1 << PCIE_PORT_SERVICE_CXLT_SHIFT)
 
-#define PCIE_PORT_DEVICE_MAXSERVICES   5
+#define PCIE_PORT_DEVICE_MAXSERVICES   6
 
 extern bool pcie_ports_dpc_native;
 
@@ -51,6 +53,12 @@ int pcie_dpc_init(void);
 static inline int pcie_dpc_init(void) { return 0; }
 #endif
 
+#ifdef CONFIG_PCIE_CXL_TIMEOUT
+int pcie_cxlt_init(void);
+#else
+static inline int pcie_cxlt_init(void) { return 0; }
+#endif
+
 /* Port Type */
 #define PCIE_ANY_PORT			(~0)
 
-- 
2.34.1