[RFC PATCH v8 03/10] cxl/mbox: Add GET_FEATURE mailbox command

[shiju.jose]

From: Shiju Jose <shiju.jose@xxxxxxxxxx>

Add support for GET_FEATURE mailbox command.

CXL spec 3.1 section 8.2.9.6 describes optional device specific features.
The settings of a feature can be retrieved using Get Feature command.

Signed-off-by: Shiju Jose <shiju.jose@xxxxxxxxxx>
---
 drivers/cxl/core/mbox.c | 53 +++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/cxlmem.h    | 28 ++++++++++++++++++++++
 2 files changed, 81 insertions(+)

diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
index 82e279b821e2..999965871048 100644
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
@@ -1318,6 +1318,59 @@ int cxl_get_supported_features(struct cxl_memdev_state *mds,
 }
 EXPORT_SYMBOL_NS_GPL(cxl_get_supported_features, CXL);
 
+size_t cxl_get_feature(struct cxl_memdev_state *mds,
+		       const uuid_t feat_uuid, void *feat_out,
+		       size_t feat_out_size,
+		       size_t feat_out_min_size,
+		       enum cxl_get_feat_selection selection)
+{
+	struct cxl_dev_state *cxlds = &mds->cxlds;
+	struct cxl_mbox_get_feat_in pi;
+	struct cxl_mbox_cmd mbox_cmd;
+	size_t data_rcvd_size = 0;
+	size_t data_to_rd_size, size_out;
+	int rc;
+
+	if (feat_out_size < feat_out_min_size) {
+		dev_err(cxlds->dev,
+			"%s: feature out buffer size(%lu) is not big enough\n",
+			__func__, feat_out_size);
+		return 0;
+	}
+
+	if (feat_out_size <= mds->payload_size)
+		size_out = feat_out_size;
+	else
+		size_out = mds->payload_size;
+	pi.uuid = feat_uuid;
+	pi.selection = selection;
+	do {
+		if ((feat_out_min_size - data_rcvd_size) <= mds->payload_size)
+			data_to_rd_size = feat_out_min_size - data_rcvd_size;
+		else
+			data_to_rd_size = mds->payload_size;
+
+		pi.offset = cpu_to_le16(data_rcvd_size);
+		pi.count = cpu_to_le16(data_to_rd_size);
+
+		mbox_cmd = (struct cxl_mbox_cmd) {
+			.opcode = CXL_MBOX_OP_GET_FEATURE,
+			.size_in = sizeof(pi),
+			.payload_in = &pi,
+			.size_out = size_out,
+			.payload_out = feat_out + data_rcvd_size,
+			.min_out = data_to_rd_size,
+		};
+		rc = cxl_internal_send_cmd(mds, &mbox_cmd);
+		if (rc < 0 || mbox_cmd.size_out == 0)
+			return 0;
+		data_rcvd_size += mbox_cmd.size_out;
+	} while (data_rcvd_size < feat_out_min_size);
+
+	return data_rcvd_size;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_get_feature, CXL);
+
 int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
 		       struct cxl_region *cxlr)
 {
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 06231e63373e..c822eb30e6d1 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -528,6 +528,7 @@ enum cxl_opcode {
 	CXL_MBOX_OP_GET_SUPPORTED_LOGS	= 0x0400,
 	CXL_MBOX_OP_GET_LOG		= 0x0401,
 	CXL_MBOX_OP_GET_SUPPORTED_FEATURES	= 0x0500,
+	CXL_MBOX_OP_GET_FEATURE		= 0x0501,
 	CXL_MBOX_OP_IDENTIFY		= 0x4000,
 	CXL_MBOX_OP_GET_PARTITION_INFO	= 0x4100,
 	CXL_MBOX_OP_SET_PARTITION_INFO	= 0x4101,
@@ -754,6 +755,28 @@ struct cxl_mbox_get_supp_feats_out {
 	struct cxl_mbox_supp_feat_entry feat_entries[];
 } __packed;
 
+/*
+ * Get Feature CXL 3.1 Spec 8.2.9.6.2
+ */
+
+/*
+ * Get Feature input payload
+ * CXL rev 3.1 section 8.2.9.6.2 Table 8-99
+ */
+enum cxl_get_feat_selection {
+	CXL_GET_FEAT_SEL_CURRENT_VALUE,
+	CXL_GET_FEAT_SEL_DEFAULT_VALUE,
+	CXL_GET_FEAT_SEL_SAVED_VALUE,
+	CXL_GET_FEAT_SEL_MAX
+};
+
+struct cxl_mbox_get_feat_in {
+	uuid_t uuid;
+	__le16 offset;
+	__le16 count;
+	u8 selection;
+}  __packed;
+
 /* Get Poison List  CXL 3.0 Spec 8.2.9.8.4.1 */
 struct cxl_mbox_poison_in {
 	__le64 offset;
@@ -888,6 +911,11 @@ int cxl_set_timestamp(struct cxl_memdev_state *mds);
 int cxl_get_supported_features(struct cxl_memdev_state *mds,
 			       u32 count, u16 start_index,
 			       struct cxl_mbox_get_supp_feats_out *feats_out);
+size_t cxl_get_feature(struct cxl_memdev_state *mds,
+		       const uuid_t feat_uuid, void *feat_out,
+		       size_t feat_out_size,
+		       size_t feat_out_min_size,
+		       enum cxl_get_feat_selection selection);
 int cxl_poison_state_init(struct cxl_memdev_state *mds);
 int cxl_mem_get_poison(struct cxl_memdev *cxlmd, u64 offset, u64 len,
 		       struct cxl_region *cxlr);
-- 
2.34.1