[PATCH v24 06/11] cxl/hdm: Add support for getting region from committed decoder

[<alejandro.lucero-palau@amd.com>]

From: Alejandro Lucero <alucerop@amd.com>

A Type2 device configured by the BIOS can already have its HDM
committed. Add a cxl_get_committed_decoder() function for cheking
so after memdev creation. A CXL region should have been created
during memdev initialization, therefore a Type2 driver can ask for
such a region for working with the HPA. If the HDM is not committed,
a Type2 driver will create the region after obtaining proper HPA
and DPA space.

Signed-off-by: Alejandro Lucero <alucerop@amd.com>
---
 drivers/cxl/core/hdm.c | 39 +++++++++++++++++++++++++++++++++++++++
 include/cxl/cxl.h      |  3 +++
 2 files changed, 42 insertions(+)

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index c222e98ae736..006be88efaa5 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -686,6 +686,45 @@ int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, u64 size)
 	return devm_add_action_or_reset(&port->dev, cxl_dpa_release, cxled);
 }
 
+static int find_committed_endpoint_decoder(struct device *dev, const void *data)
+{
+	struct cxl_endpoint_decoder *cxled;
+	struct cxl_port *port;
+
+	if (!is_endpoint_decoder(dev))
+		return 0;
+
+	cxled = to_cxl_endpoint_decoder(dev);
+	port = cxled_to_port(cxled);
+
+	return cxled->cxld.id == port->hdm_end;
+}
+
+struct cxl_endpoint_decoder *cxl_get_committed_decoder(struct cxl_memdev *cxlmd,
+						       struct cxl_region **cxlr)
+{
+	struct cxl_port *endpoint = cxlmd->endpoint;
+	struct cxl_endpoint_decoder *cxled;
+	struct device *cxled_dev;
+
+	if (!endpoint)
+		return NULL;
+
+	guard(rwsem_read)(&cxl_rwsem.dpa);
+	cxled_dev = device_find_child(&endpoint->dev, NULL,
+				      find_committed_endpoint_decoder);
+
+	if (!cxled_dev)
+		return NULL;
+
+	cxled = to_cxl_endpoint_decoder(cxled_dev);
+	*cxlr = cxled->cxld.region;
+
+	put_device(cxled_dev);
+	return cxled;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_get_committed_decoder, "CXL");
+
 static void cxld_set_interleave(struct cxl_decoder *cxld, u32 *ctrl)
 {
 	u16 eig;
diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
index 10a9b8fa2f6b..2a61138e2a73 100644
--- a/include/cxl/cxl.h
+++ b/include/cxl/cxl.h
@@ -231,4 +231,7 @@ struct cxl_dev_state *_devm_cxl_dev_state_create(struct device *dev,
 int cxl_set_capacity(struct cxl_dev_state *cxlds, u64 capacity);
 struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds,
 				       const struct cxl_memdev_attach *attach);
+struct cxl_region;
+struct cxl_endpoint_decoder *cxl_get_committed_decoder(struct cxl_memdev *cxlmd,
+						       struct cxl_region **cxlr);
 #endif /* __CXL_CXL_H__ */
-- 
2.34.1