[PATCH ethtool-next v2 2/3] cmis: Print CDB messaging support advertisement

[Danielle Ratson <danieller@nvidia.com>]

From: Ido Schimmel <idosch@nvidia.com>

Parse and print CDB messaging support advertisement information to aid
in debugging CDB related problems. Example output:

 # ethtool -m swp23
 Identifier                                : 0x18 (QSFP-DD Double Density 8X Pluggable Transceiver (INF-8628))
 [...]
 CDB instances                             : 1
 CDB background mode                       : Supported
 CDB EPL pages                             : 0
 CDB Maximum EPL RW length                 : 128
 CDB Maximum LPL RW length                 : 128
 CDB trigger method                        : Single write

Fields that are not used by the CDB code in the kernel are not printed,
but can be added in the future, when needed.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Danielle Ratson <danieller@nvidia.com>
---
 cmis.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 cmis.h | 11 ++++++++
 2 files changed, 91 insertions(+)

diff --git a/cmis.c b/cmis.c
index bbbbb47..6fe5dfb 100644
--- a/cmis.c
+++ b/cmis.c
@@ -928,6 +928,85 @@ static void cmis_show_fw_version(const struct cmis_memory_map *map)
 	cmis_show_fw_inactive_version(map);
 }
 
+static u8 cmis_cdb_instances_get(const struct cmis_memory_map *map)
+{
+	return (map->page_01h[CMIS_CDB_ADVER_OFFSET] &
+		CMIS_CDB_ADVER_INSTANCES_MASK) >> 6;
+}
+
+static bool cmis_cdb_is_supported(const struct cmis_memory_map *map)
+{
+	__u8 cdb_instances = cmis_cdb_instances_get(map);
+
+	/* Up to two CDB instances are supported. */
+	return cdb_instances == 1 || cdb_instances == 2;
+}
+
+static void cmis_show_cdb_instances(const struct cmis_memory_map *map)
+{
+	__u8 cdb_instances = cmis_cdb_instances_get(map);
+
+	printf("\t%-41s : %u\n", "CDB instances", cdb_instances);
+}
+
+static void cmis_show_cdb_mode(const struct cmis_memory_map *map)
+{
+	__u8 mode = map->page_01h[CMIS_CDB_ADVER_OFFSET] &
+		    CMIS_CDB_ADVER_MODE_MASK;
+
+	printf("\t%-41s : %s\n", "CDB background mode",
+	       mode ? "Supported" : "Not supported");
+}
+
+static void cmis_show_cdb_epl_pages(const struct cmis_memory_map *map)
+{
+	__u8 epl_pages = map->page_01h[CMIS_CDB_ADVER_OFFSET] &
+			 CMIS_CDB_ADVER_EPL_MASK;
+
+	printf("\t%-41s : %u\n", "CDB EPL pages", epl_pages);
+}
+
+static void cmis_show_cdb_rw_len(const struct cmis_memory_map *map)
+{
+	__u16 rw_len = map->page_01h[CMIS_CDB_ADVER_RW_LEN_OFFSET];
+
+	/* Maximum read / write length for CDB EPL pages and the LPL page in
+	 * units of 8 bytes, in addition to the minimum 8 bytes.
+	 */
+	rw_len = (rw_len + 1) * 8;
+	printf("\t%-41s : %u\n", "CDB Maximum EPL RW length", rw_len);
+	printf("\t%-41s : %u\n", "CDB Maximum LPL RW length",
+	       rw_len > CMIS_PAGE_SIZE ? CMIS_PAGE_SIZE : rw_len);
+}
+
+static void cmis_show_cdb_trigger(const struct cmis_memory_map *map)
+{
+	__u8 trigger = map->page_01h[CMIS_CDB_ADVER_TRIGGER_OFFSET] &
+		       CMIS_CDB_ADVER_TRIGGER_MASK;
+
+	/* Whether a CDB command can be triggered in a single write to the LPL
+	 * page, or by multiple writes ending with the writing of the CDB
+	 * Command Code (CMDID).
+	 */
+	printf("\t%-41s : %s\n", "CDB trigger method",
+	       trigger ? "Single write" : "Multiple writes");
+}
+
+/* Print CDB messaging support advertisement. Relevant documents:
+ * [1] CMIS Rev. 5, page 133, section 8.4.11
+ */
+static void cmis_show_cdb_adver(const struct cmis_memory_map *map)
+{
+	if (!map->page_01h || !cmis_cdb_is_supported(map))
+		return;
+
+	cmis_show_cdb_instances(map);
+	cmis_show_cdb_mode(map);
+	cmis_show_cdb_epl_pages(map);
+	cmis_show_cdb_rw_len(map);
+	cmis_show_cdb_trigger(map);
+}
+
 static void cmis_show_all_common(const struct cmis_memory_map *map)
 {
 	cmis_show_identifier(map);
@@ -945,6 +1024,7 @@ static void cmis_show_all_common(const struct cmis_memory_map *map)
 	cmis_show_mod_lvl_controls(map);
 	cmis_show_dom(map);
 	cmis_show_fw_version(map);
+	cmis_show_cdb_adver(map);
 }
 
 static void cmis_memory_map_init_buf(struct cmis_memory_map *map,
diff --git a/cmis.h b/cmis.h
index 3015c54..cee2a38 100644
--- a/cmis.h
+++ b/cmis.h
@@ -191,6 +191,17 @@
 #define CMIS_SIG_INTEG_TX_OFFSET		0xA1
 #define CMIS_SIG_INTEG_RX_OFFSET		0xA2
 
+/* CDB Messaging Support Advertisement */
+#define CMIS_CDB_ADVER_OFFSET			0xA3
+#define CMIS_CDB_ADVER_INSTANCES_MASK		0xC0
+#define CMIS_CDB_ADVER_MODE_MASK		0x20
+#define CMIS_CDB_ADVER_EPL_MASK			0x0F
+
+#define CMIS_CDB_ADVER_RW_LEN_OFFSET		0xA4
+
+#define CMIS_CDB_ADVER_TRIGGER_OFFSET		0xA5
+#define CMIS_CDB_ADVER_TRIGGER_MASK		0x80
+
 /*-----------------------------------------------------------------------
  * Upper Memory Page 0x02: Optional Page that informs about module-defined
  * thresholds for module-level and lane-specific threshold crossing monitors.
-- 
2.45.0