[PATCH 12/16] PCI: PCIe portdrv: Add cxl_isolation sysfs attributes

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

Add sysfs attributes to enable/disable CXL isolation and transaction
timeout. The intended use for these attributes is to disable isolation
and/or timeout as part of device maintenance or hotplug.

The attributes are added under a new "cxl_isolation" group on the PCIe
Root Port device.

Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
---
 drivers/cxl/core/port.c          |  29 ++++++
 drivers/pci/pci-sysfs.c          |   3 +
 drivers/pci/pci.h                |   4 +
 drivers/pci/pcie/cxl_isolation.c | 158 +++++++++++++++++++++++++++++++
 include/cxl/isolation.h          |   8 ++
 5 files changed, 202 insertions(+)

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 6591e83e719c..b5a306341bb2 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1346,6 +1346,7 @@ static int cxl_dport_enable_timeout_isolation(struct device *host,
 	if (!(cap & CXL_ISOLATION_CAP_MEM_TIME_SUPP))
 		cxl_enable_timeout(dport);
 
+	pcie_update_cxl_isolation_group(dport->dport_dev);
 	return 0;
 }
 
@@ -1598,6 +1599,34 @@ struct cxl_port *find_cxl_port(struct device *dport_dev,
 	return port;
 }
 
+/**
+ * cxl_find_pcie_rp - Find CXL port that contains a CXL-capable PCIe Root Port
+ * @dport_dev: CXL-capable PCIe Root Port device
+ * @rp: Pointer to store found dport in
+ *
+ * Returns CXL port with elevated reference count if @dport_dev is found
+ */
+struct cxl_port *cxl_find_pcie_rp(struct pci_dev *dport_dev,
+				  struct cxl_dport **rp)
+{
+	struct cxl_dport *dport;
+	struct cxl_port *parent;
+
+	struct cxl_port *hb __free(put_cxl_port) =
+		find_cxl_port(&dport_dev->dev, &dport);
+	if (!hb || !dport)
+		return NULL;
+
+	parent = parent_port_of(hb);
+	if (!parent || !is_cxl_root(parent))
+		return NULL;
+
+	if (rp)
+		*rp = dport;
+
+	return_ptr(hb);
+}
+
 static struct cxl_port *find_cxl_port_at(struct cxl_port *parent_port,
 					 struct device *dport_dev,
 					 struct cxl_dport **dport)
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 268c69daa4d5..86e8d8d918cf 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1815,6 +1815,9 @@ const struct attribute_group *pci_dev_attr_groups[] = {
 #endif
 #ifdef CONFIG_PCI_DOE
 	&pci_doe_sysfs_group,
+#endif
+#ifdef CONFIG_CXL_ISOLATION
+	&cxl_isolation_attr_group,
 #endif
 	NULL,
 };
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index c7fc86d93bea..3510a75c880b 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -677,6 +677,10 @@ static inline void pci_rcec_exit(struct pci_dev *dev) { }
 static inline void pcie_link_rcec(struct pci_dev *rcec) { }
 #endif
 
+#ifdef CONFIG_CXL_ISOLATION
+extern struct attribute_group cxl_isolation_attr_group;
+#endif
+
 #ifdef CONFIG_PCI_ATS
 /* Address Translation Service */
 void pci_ats_init(struct pci_dev *dev);
diff --git a/drivers/pci/pcie/cxl_isolation.c b/drivers/pci/pcie/cxl_isolation.c
index 5a56a327b599..9d2ad14810e8 100644
--- a/drivers/pci/pcie/cxl_isolation.c
+++ b/drivers/pci/pcie/cxl_isolation.c
@@ -77,6 +77,164 @@ pcie_cxl_dport_get_isolation_info(struct pci_dev *dport_dev)
 	return get_service_data(to_pcie_device(dev));
 }
 
+static ssize_t isolation_ctrl_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t n)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct cxl_port *port;
+	bool enable;
+	int rc;
+
+	rc = kstrtobool(buf, &enable);
+	if (rc)
+		return rc;
+
+	struct cxl_dport **dport __free(kfree) =
+		kzalloc(sizeof(*dport), GFP_KERNEL);
+	if (!dport)
+		return -ENOMEM;
+
+	port = cxl_find_pcie_rp(pdev, dport);
+	if (!port || !(*dport))
+		return -ENODEV;
+
+	if (enable)
+		cxl_enable_isolation(*dport);
+	else
+		rc = cxl_disable_isolation(*dport);
+
+	put_device(&port->dev);
+	return rc ? rc : n;
+}
+
+static ssize_t isolation_ctrl_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct cxl_port *port;
+	u32 ctrl;
+
+	struct cxl_dport **dport __free(kfree) =
+		kzalloc(sizeof(*dport), GFP_KERNEL);
+	if (!dport)
+		return -ENOMEM;
+
+	port = cxl_find_pcie_rp(pdev, dport);
+	if (!port || !(*dport))
+		return -ENODEV;
+
+	if (!(*dport)->regs.isolation)
+		return -ENXIO;
+
+	ctrl = readl((*dport)->regs.isolation + CXL_ISOLATION_CTRL_OFFSET);
+	put_device(&port->dev);
+
+	return sysfs_emit(buf, "%lu\n",
+			  FIELD_GET(CXL_ISOLATION_CTRL_MEM_ISO_ENABLE, ctrl));
+}
+DEVICE_ATTR_RW(isolation_ctrl);
+
+static ssize_t timeout_ctrl_store(struct device *dev,
+				  struct device_attribute *attr,
+				  const char *buf, size_t n)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct cxl_port *port;
+	bool enable;
+	int rc;
+
+	rc = kstrtobool(buf, &enable);
+	if (rc)
+		return rc;
+
+	struct cxl_dport **dport __free(kfree) =
+		kzalloc(sizeof(*dport), GFP_KERNEL);
+	if (!dport)
+		return -ENOMEM;
+
+	port = cxl_find_pcie_rp(pdev, dport);
+	if (!port || !(*dport))
+		return -ENODEV;
+
+	if (enable)
+		cxl_enable_timeout(*dport);
+	else
+		cxl_disable_timeout(*dport);
+
+	put_device(&port->dev);
+	return n;
+}
+
+static ssize_t timeout_ctrl_show(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct cxl_port *port;
+	u32 ctrl;
+
+	struct cxl_dport **dport __free(kfree) =
+		kzalloc(sizeof(*dport), GFP_KERNEL);
+	if (!dport)
+		return -ENOMEM;
+
+	port = cxl_find_pcie_rp(pdev, dport);
+	if (!port || !(*dport))
+		return -ENODEV;
+
+	if (!(*dport)->regs.isolation)
+		return -ENXIO;
+
+	ctrl = readl((*dport)->regs.isolation + CXL_ISOLATION_CTRL_OFFSET);
+	put_device(&port->dev);
+
+	return sysfs_emit(buf, "%lu\n",
+			  FIELD_GET(CXL_ISOLATION_CTRL_MEM_TIME_ENABLE, ctrl));
+}
+DEVICE_ATTR_RW(timeout_ctrl);
+
+static struct attribute *isolation_attrs[] = {
+	&dev_attr_timeout_ctrl.attr,
+	&dev_attr_isolation_ctrl.attr,
+	NULL,
+};
+
+static umode_t cxl_isolation_attrs_visible(struct kobject *kobj,
+					   struct attribute *a, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct pci_dev *pdev = to_pci_dev(dev);
+
+	if (!pcie_is_cxl(pdev) || pci_pcie_type(pdev) != PCI_EXP_TYPE_ROOT_PORT)
+		return 0;
+
+	if (pcie_port_find_device(pdev, PCIE_PORT_SERVICE_CXLISO))
+		return a->mode;
+	return 0;
+}
+
+const struct attribute_group cxl_isolation_attr_group = {
+	.name = "cxl_isolation",
+	.attrs = isolation_attrs,
+	.is_visible = cxl_isolation_attrs_visible,
+};
+
+void
+pcie_update_cxl_isolation_group(struct device *dport_dev)
+{
+	struct device *dev;
+
+	if (!dev_is_pci(dport_dev))
+		return;
+
+	dev = pcie_port_find_device(to_pci_dev(dport_dev),
+				    PCIE_PORT_SERVICE_CXLISO);
+	if (!dev)
+		return;
+
+	sysfs_update_group(&dport_dev->kobj, &cxl_isolation_attr_group);
+}
+
 static int cxl_isolation_probe(struct pcie_device *dev)
 {
 	struct cxl_isolation_info *info;
diff --git a/include/cxl/isolation.h b/include/cxl/isolation.h
index 73282ac262a6..0b6e4f0160a8 100644
--- a/include/cxl/isolation.h
+++ b/include/cxl/isolation.h
@@ -31,21 +31,29 @@ int cxl_disable_isolation(struct cxl_dport *dport);
 void cxl_enable_timeout(struct cxl_dport *dport);
 void cxl_disable_timeout(struct cxl_dport *dport);
 
+struct cxl_port *cxl_find_pcie_rp(struct pci_dev *pdev,
+				  struct cxl_dport **dport);
 #else /* !CONFIG_CXL_BUS */
 static inline void cxl_enable_isolation(struct cxl_dport *dport) {}
 static inline int cxl_disable_isolation(struct cxl_dport *dport)
 { return -ENXIO; }
 static inline void cxl_enable_timeout(struct cxl_dport *dport) {}
 static inline void cxl_disable_timeout(struct cxl_dport *dport) {}
+
+static inline struct cxl_port *cxl_find_pcie_rp(struct pci_dev *pdev,
+						struct cxl_dport **dport);
+{ return NULL; }
 #endif /* !CONFIG_CXL_BUS */
 
 #ifdef CONFIG_CXL_ISOLATION
 struct cxl_isolation_info *
 pcie_cxl_dport_get_isolation_info(struct pci_dev *dport_dev);
+void pcie_update_cxl_isolation_group(struct device *dport_dev);
 #else /* !CONFIG_CXL_ISOLATION */
 static inline struct cxl_isolation_info *
 pcie_cxl_dport_get_isolation_info(struct pci_dev *dport_dev)
 { return NULL; }
+static inline void pcie_update_cxl_isolation_group(struct device *dport_dev) {}
 #endif /* !CONFIG_CXL_ISOLATION */
 
 #endif
-- 
2.34.1