[PATCH 04/13] cxl: Introduce endpoint decoders

From: Ben Widawsky <ben.widawsky@intel.com>
To: linux-cxl@vger.kernel.org
Cc: Ben Widawsky <ben.widawsky@intel.com>,
	Alison Schofield <alison.schofield@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Ira Weiny <ira.weiny@intel.com>,
	Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
	Vishal Verma <vishal.l.verma@intel.com>
Subject: [PATCH 04/13] cxl: Introduce endpoint decoders
Date: Thu,  2 Sep 2021 12:50:08 -0700	[thread overview]
Message-ID: <20210902195017.2516472-5-ben.widawsky@intel.com> (raw)
In-Reply-To: <20210902195017.2516472-1-ben.widawsky@intel.com>

Endpoints have decoders too. It is useful to share the same
infrastructure from cxl_core. Endpoints do not have dports (downstream
targets), only the underlying physical medium. As a result, some special
casing is needed.

There is no functional change introduced yet as endpoints don't actually
enumerate decoders yet.

Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
---
 drivers/cxl/core/bus.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/cxl/core/bus.c b/drivers/cxl/core/bus.c
index 8d5061b0794d..6202ce5a5ac2 100644
--- a/drivers/cxl/core/bus.c
+++ b/drivers/cxl/core/bus.c
@@ -175,6 +175,12 @@ static const struct attribute_group *cxl_decoder_switch_attribute_groups[] = {
 	NULL,
 };
 
+static const struct attribute_group *cxl_decoder_endpoint_attribute_groups[] = {
+	&cxl_decoder_base_attribute_group,
+	&cxl_base_attribute_group,
+	NULL,
+};
+
 static void cxl_decoder_release(struct device *dev)
 {
 	struct cxl_decoder *cxld = to_cxl_decoder(dev);
@@ -184,6 +190,12 @@ 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,
@@ -196,6 +208,11 @@ 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;
@@ -472,7 +489,7 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets)
 	struct device *dev;
 	int rc = 0;
 
-	if (nr_targets > CXL_DECODER_MAX_INTERLEAVE || nr_targets < 1)
+	if (nr_targets > CXL_DECODER_MAX_INTERLEAVE)
 		return ERR_PTR(-EINVAL);
 
 	cxld = kzalloc(struct_size(cxld, target, nr_targets), GFP_KERNEL);
@@ -491,8 +508,11 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets)
 	dev->parent = &port->dev;
 	dev->bus = &cxl_bus_type;
 
+	/* Endpoints don't have a target list */
+	if (nr_targets == 0)
+		dev->type = &cxl_decoder_endpoint_type;
 	/* root ports do not have a cxl_port_type parent */
-	if (port->dev.parent->type == &cxl_port_type)
+	else if (port->dev.parent->type == &cxl_port_type)
 		dev->type = &cxl_decoder_switch_type;
 	else
 		dev->type = &cxl_decoder_root_type;
@@ -532,9 +552,11 @@ int cxl_decoder_add(struct device *host, struct cxl_decoder *cxld,
 	if (IS_ERR(cxld))
 		return PTR_ERR(cxld);
 
+	dev = &cxld->dev;
+
 	port = to_cxl_port(cxld->dev.parent);
 	device_lock(&port->dev);
-	if (list_empty(&port->dports)) {
+	if (is_endpoint_decoder(dev) && list_empty(&port->dports)) {
 		rc = -EINVAL;
 		goto out_unlock;
 	}
@@ -551,7 +573,6 @@ int cxl_decoder_add(struct device *host, struct cxl_decoder *cxld,
 	}
 	device_unlock(&port->dev);
 
-	dev = &cxld->dev;
 	rc = dev_set_name(dev, "decoder%d.%d", port->id, cxld->id);
 	if (rc)
 		return rc;
-- 
2.33.0

