CXL root ports (the downstream port to a host bridge) are to be
enumerated by a platform specific driver. In the case of ACPI compliant
systems, this is like the cxl_acpi driver. Root ports are the first
CXL spec defined component that can be "found" by that platform specific
driver.
By storing a list of these root ports components in lower levels of the
topology (switches and endpoints), have a mechanism to walk up their
device hierarchy to find an enumerated root port. This will be necessary
for region programming.
Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
---
Dan points out in review this is possible to do without a new global
list. While I agree, I was unable to get it working in a reasonable
mount of time. Will punt on that for now.
---
drivers/cxl/acpi.c | 4 ++--
drivers/cxl/core/bus.c | 34 +++++++++++++++++++++++++++++++++-
drivers/cxl/cxl.h | 5 ++++-
tools/testing/cxl/mock_acpi.c | 4 ++--
4 files changed, 41 insertions(+), 6 deletions(-)
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 82cc42ab38c6..c12e4fed7941 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -159,7 +159,7 @@ __mock int match_add_root_ports(struct pci_dev *pdev, void *data)
creg = cxl_reg_block(pdev, &map);
port_num = FIELD_GET(PCI_EXP_LNKCAP_PN, lnkcap);
- rc = cxl_add_dport(port, &pdev->dev, port_num, creg);
+ rc = cxl_add_dport(port, &pdev->dev, port_num, creg, true);
if (rc) {
ctx->error = rc;
return rc;
@@ -341,7 +341,7 @@ static int add_host_bridge_dport(struct device *match, void *arg)
return 0;
}
- rc = cxl_add_dport(root_port, match, uid, ctx.chbcr);
+ rc = cxl_add_dport(root_port, match, uid, ctx.chbcr, false);
if (rc) {
dev_err(host, "failed to add downstream port: %s\n",
dev_name(match));
diff --git a/drivers/cxl/core/bus.c b/drivers/cxl/core/bus.c
index 2ad38167796d..9e0d7d5d9298 100644
--- a/drivers/cxl/core/bus.c
+++ b/drivers/cxl/core/bus.c
@@ -26,6 +26,8 @@
static DEFINE_IDA(cxl_port_ida);
static DECLARE_RWSEM(topology_host_sem);
+static LIST_HEAD(cxl_root_ports);
+static DECLARE_RWSEM(root_port_sem);
static struct device *cxl_topology_host;
@@ -326,12 +328,31 @@ struct cxl_port *to_cxl_port(struct device *dev)
return container_of(dev, struct cxl_port, dev);
}
+struct cxl_dport *cxl_get_root_dport(struct device *dev)
+{
+ struct cxl_dport *ret = NULL;
+ struct cxl_dport *dport;
+
+ down_read(&root_port_sem);
+ list_for_each_entry(dport, &cxl_root_ports, root_port_link) {
+ if (dport->dport == dev) {
+ ret = dport;
+ break;
+ }
+ }
+
+ up_read(&root_port_sem);
+ return ret;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_get_root_dport, CXL);
+
static void unregister_port(void *_port)
{
struct cxl_port *port = _port;
struct cxl_dport *dport;
device_lock(&port->dev);
+ down_read(&root_port_sem);
list_for_each_entry(dport, &port->dports, list) {
char link_name[CXL_TARGET_STRLEN];
@@ -339,7 +360,10 @@ static void unregister_port(void *_port)
dport->port_id) >= CXL_TARGET_STRLEN)
continue;
sysfs_remove_link(&port->dev.kobj, link_name);
+
+ list_del_init(&dport->root_port_link);
}
+ up_read(&root_port_sem);
device_unlock(&port->dev);
device_unregister(&port->dev);
}
@@ -493,12 +517,13 @@ static int add_dport(struct cxl_port *port, struct cxl_dport *new)
* @dport_dev: firmware or PCI device representing the dport
* @port_id: identifier for this dport in a decoder's target list
* @component_reg_phys: optional location of CXL component registers
+ * @root_port: is this a root port (hostbridge downstream)
*
* Note that all allocations and links are undone by cxl_port deletion
* and release.
*/
int cxl_add_dport(struct cxl_port *port, struct device *dport_dev, int port_id,
- resource_size_t component_reg_phys)
+ resource_size_t component_reg_phys, bool root_port)
{
char link_name[CXL_TARGET_STRLEN];
struct cxl_dport *dport;
@@ -513,6 +538,7 @@ int cxl_add_dport(struct cxl_port *port, struct device *dport_dev, int port_id,
return -ENOMEM;
INIT_LIST_HEAD(&dport->list);
+ INIT_LIST_HEAD(&dport->root_port_link);
dport->dport = get_device(dport_dev);
dport->port_id = port_id;
dport->component_reg_phys = component_reg_phys;
@@ -526,6 +552,12 @@ int cxl_add_dport(struct cxl_port *port, struct device *dport_dev, int port_id,
if (rc)
goto err;
+ if (root_port) {
+ down_write(&root_port_sem);
+ list_add_tail(&dport->root_port_link, &cxl_root_ports);
+ up_write(&root_port_sem);
+ }
+
return 0;
err:
cxl_dport_release(dport);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 6fac4826d22b..3962a5e6a950 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -272,6 +272,7 @@ struct cxl_port {
* @component_reg_phys: downstream port component registers
* @port: reference to cxl_port that contains this downstream port
* @list: node for a cxl_port's list of cxl_dport instances
+ * @root_port_link: node for global list of root ports
*/
struct cxl_dport {
struct device *dport;
@@ -279,6 +280,7 @@ struct cxl_dport {
resource_size_t component_reg_phys;
struct cxl_port *port;
struct list_head list;
+ struct list_head root_port_link;
};
struct cxl_port *to_cxl_port(struct device *dev);
@@ -287,7 +289,8 @@ struct cxl_port *devm_cxl_add_port(struct device *uport,
struct cxl_port *parent_port);
int cxl_add_dport(struct cxl_port *port, struct device *dport, int port_id,
- resource_size_t component_reg_phys);
+ resource_size_t component_reg_phys, bool root_port);
+struct cxl_dport *cxl_get_root_dport(struct device *dev);
struct cxl_decoder *to_cxl_decoder(struct device *dev);
bool is_root_decoder(struct device *dev);
diff --git a/tools/testing/cxl/mock_acpi.c b/tools/testing/cxl/mock_acpi.c
index 4c8a493ace56..ddefc4345f36 100644
--- a/tools/testing/cxl/mock_acpi.c
+++ b/tools/testing/cxl/mock_acpi.c
@@ -57,7 +57,7 @@ static int match_add_root_port(struct pci_dev *pdev, void *data)
/* TODO walk DVSEC to find component register base */
port_num = FIELD_GET(PCI_EXP_LNKCAP_PN, lnkcap);
- rc = cxl_add_dport(port, &pdev->dev, port_num, CXL_RESOURCE_NONE);
+ rc = cxl_add_dport(port, &pdev->dev, port_num, CXL_RESOURCE_NONE, true);
if (rc) {
dev_err(dev, "failed to add dport: %s (%d)\n",
dev_name(&pdev->dev), rc);
@@ -78,7 +78,7 @@ static int mock_add_root_port(struct platform_device *pdev, void *data)
struct device *dev = ctx->dev;
int rc;
- rc = cxl_add_dport(port, &pdev->dev, pdev->id, CXL_RESOURCE_NONE);
+ rc = cxl_add_dport(port, &pdev->dev, pdev->id, CXL_RESOURCE_NONE, true);
if (rc) {
dev_err(dev, "failed to add dport: %s (%d)\n",
dev_name(&pdev->dev), rc);
--
2.34.0
