cxl/core/port: Add endpoint decoders

Recall that a CXL Port is any object that publishes a CXL HDM Decoder
Capability structure. That is Host Bridge and Switches that have been
enabled so far. Now, add decoder support to the 'endpoint' CXL Ports
registered by the cxl_mem driver. They mostly share the same enumeration
as Bridges and Switches, but witout a target list. The target of
endpoint decode is device-internal DPA space, not another downstream
port.

Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[djbw: clarify changelog, hookup enumeration in the port driver]
Link: https://lore.kernel.org/r/164386092069.765089.14895687988217608642.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 80280db316c096d8af4e16ac612a8076af69e7cf..05b0b292e72d873aa94f67892c46d896a0eee3a2 100644 (file)
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -186,6 +186,9 @@ static void init_hdm_decoder(struct cxl_decoder *cxld, int *target_map,
        else
                cxld->target_type = CXL_DECODER_ACCELERATOR;
 
+       if (is_cxl_endpoint(to_cxl_port(cxld->dev.parent)))
+               return;
+
        target_list.value =
                ioread64_hi_lo(hdm + CXL_HDM_DECODER0_TL_LOW(which));
        for (i = 0; i < cxld->interleave_ways; i++)
@@ -225,7 +228,10 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm)
                int rc, target_count = cxlhdm->target_count;
                struct cxl_decoder *cxld;
 
-               cxld = cxl_switch_decoder_alloc(port, target_count);
+               if (is_cxl_endpoint(port))
+                       cxld = cxl_endpoint_decoder_alloc(port);
+               else
+                       cxld = cxl_switch_decoder_alloc(port, target_count);
                if (IS_ERR(cxld)) {
                        dev_warn(&port->dev,
                                 "Failed to allocate the decoder\n");

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 359d4303de9ab4fd296ae82e0042ed9062cf89ef..bc18d339738b7bead02641b2a0a7b1ecd5b31fac 100644 (file)
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -228,6 +228,22 @@ static const struct attribute_group *cxl_decoder_switch_attribute_groups[] = {
        NULL,
 };
 
+static struct attribute *cxl_decoder_endpoint_attrs[] = {
+       &dev_attr_target_type.attr,
+       NULL,
+};
+
+static struct attribute_group cxl_decoder_endpoint_attribute_group = {
+       .attrs = cxl_decoder_endpoint_attrs,
+};
+
+static const struct attribute_group *cxl_decoder_endpoint_attribute_groups[] = {
+       &cxl_decoder_base_attribute_group,
+       &cxl_decoder_endpoint_attribute_group,
+       &cxl_base_attribute_group,
+       NULL,
+};
+
 static void cxl_decoder_release(struct device *dev)
 {
        struct cxl_decoder *cxld = to_cxl_decoder(dev);
@@ -237,6 +253,12 @@ static void cxl_decoder_release(struct device *dev)
        kfree(cxld);
 }
 
+static const struct device_type cxl_decoder_endpoint_type = {
+       .name = "cxl_decoder_endpoint",
+       .release = cxl_decoder_release,
+       .groups = cxl_decoder_endpoint_attribute_groups,
+};
+
 static const struct device_type cxl_decoder_switch_type = {
        .name = "cxl_decoder_switch",
        .release = cxl_decoder_release,
@@ -249,6 +271,11 @@ static const struct device_type cxl_decoder_root_type = {
        .groups = cxl_decoder_root_attribute_groups,
 };
 
+static bool is_endpoint_decoder(struct device *dev)
+{
+       return dev->type == &cxl_decoder_endpoint_type;
+}
+
 bool is_root_decoder(struct device *dev)
 {
        return dev->type == &cxl_decoder_root_type;
@@ -1129,7 +1156,9 @@ static int decoder_populate_targets(struct cxl_decoder *cxld,
  * cxl_decoder_alloc - Allocate a new CXL decoder
  * @port: owning port of this decoder
  * @nr_targets: downstream targets accessible by this decoder. All upstream
- *             ports and root ports must have at least 1 target.
+ *             ports and root ports must have at least 1 target. Endpoint
+ *             devices will have 0 targets. Callers wishing to register an
+ *             endpoint device should specify 0.
  *
  * A port should contain one or more decoders. Each of those decoders enable
  * some address space for CXL.mem utilization. A decoder is expected to be
@@ -1145,7 +1174,7 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
        struct device *dev;
        int rc = 0;
 
-       if (nr_targets > CXL_DECODER_MAX_INTERLEAVE || nr_targets == 0)
+       if (nr_targets > CXL_DECODER_MAX_INTERLEAVE)
                return ERR_PTR(-EINVAL);
 
        cxld = kzalloc(struct_size(cxld, target, nr_targets), GFP_KERNEL);
@@ -1166,6 +1195,8 @@ static struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port,
        dev->bus = &cxl_bus_type;
        if (is_cxl_root(port))
                cxld->dev.type = &cxl_decoder_root_type;
+       else if (is_cxl_endpoint(port))
+               cxld->dev.type = &cxl_decoder_endpoint_type;
        else
                cxld->dev.type = &cxl_decoder_switch_type;
 
@@ -1215,13 +1246,28 @@ EXPORT_SYMBOL_NS_GPL(cxl_root_decoder_alloc, CXL);
 struct cxl_decoder *cxl_switch_decoder_alloc(struct cxl_port *port,
                                             unsigned int nr_targets)
 {
-       if (is_cxl_root(port))
+       if (is_cxl_root(port) || is_cxl_endpoint(port))
                return ERR_PTR(-EINVAL);
 
        return cxl_decoder_alloc(port, nr_targets);
 }
 EXPORT_SYMBOL_NS_GPL(cxl_switch_decoder_alloc, CXL);
 
+/**
+ * cxl_endpoint_decoder_alloc - Allocate an endpoint decoder
+ * @port: owning port of this decoder
+ *
+ * Return: A new cxl decoder to be registered by cxl_decoder_add()
+ */
+struct cxl_decoder *cxl_endpoint_decoder_alloc(struct cxl_port *port)
+{
+       if (!is_cxl_endpoint(port))
+               return ERR_PTR(-EINVAL);
+
+       return cxl_decoder_alloc(port, 0);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_endpoint_decoder_alloc, CXL);
+
 /**
  * cxl_decoder_add_locked - Add a decoder with targets
  * @cxld: The cxl decoder allocated by cxl_decoder_alloc()
@@ -1256,12 +1302,15 @@ int cxl_decoder_add_locked(struct cxl_decoder *cxld, int *target_map)
        if (cxld->interleave_ways < 1)
                return -EINVAL;
 
+       dev = &cxld->dev;
+
        port = to_cxl_port(cxld->dev.parent);
-       rc = decoder_populate_targets(cxld, port, target_map);
-       if (rc)
-               return rc;
+       if (!is_endpoint_decoder(dev)) {
+               rc = decoder_populate_targets(cxld, port, target_map);
+               if (rc)
+                       return rc;
+       }
 
-       dev = &cxld->dev;
        rc = dev_set_name(dev, "decoder%d.%d", port->id, cxld->id);
        if (rc)
                return rc;

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index f5e5b4ac8228b4c1e908bfb34444d5b959a794b1..990b6670222ed5f22b527eb1a79ec24fae9ea113 100644 (file)
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -346,6 +346,7 @@ struct cxl_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
 struct cxl_decoder *cxl_switch_decoder_alloc(struct cxl_port *port,
                                             unsigned int nr_targets);
 int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map);
+struct cxl_decoder *cxl_endpoint_decoder_alloc(struct cxl_port *port);
 int cxl_decoder_add_locked(struct cxl_decoder *cxld, int *target_map);
 int cxl_decoder_autoremove(struct device *host, struct cxl_decoder *cxld);
 int cxl_endpoint_autoremove(struct cxl_memdev *cxlmd, struct cxl_port *endpoint);

diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
index 4d4e23b9adfff89899214acb9a1b918e0e0d384f..d420da5fc39c913017077db9f2c28fdeb58877dc 100644 (file)
--- a/drivers/cxl/port.c
+++ b/drivers/cxl/port.c
@@ -40,16 +40,17 @@ static int cxl_port_probe(struct device *dev)
                struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport);
 
                get_device(&cxlmd->dev);
-               return devm_add_action_or_reset(dev, schedule_detach, cxlmd);
+               rc = devm_add_action_or_reset(dev, schedule_detach, cxlmd);
+               if (rc)
+                       return rc;
+       } else {
+               rc = devm_cxl_port_enumerate_dports(port);
+               if (rc < 0)
+                       return rc;
+               if (rc == 1)
+                       return devm_cxl_add_passthrough_decoder(port);
        }
 
-       rc = devm_cxl_port_enumerate_dports(port);
-       if (rc < 0)
-               return rc;
-
-       if (rc == 1)
-               return devm_cxl_add_passthrough_decoder(port);
-
        cxlhdm = devm_cxl_setup_hdm(port);
        if (IS_ERR(cxlhdm))
                return PTR_ERR(cxlhdm);