net: ethtool: Add attributes for cable test reports

Add the attributes needed to report cable test results to userspace.
The reports are expected to be per twisted pair. A nested property per
pair can report the result of the cable test. A nested property can
also report the length of the cable to any fault.

v2:
Grammar fixes
Change length from u16 to u32
s/DEV/HEADER/g
Add status attributes
Rename pairs from numbers to letters.

v3:
Fixed example in document
Add ETHTOOL_A_CABLE_NEST_* enum
Add ETHTOOL_MSG_CABLE_TEST_NTF to documentation
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/networking/ethtool-netlink.rst

@@ -236,6 +236,7 @@ Kernel to userspace:
   ``ETHTOOL_MSG_EEE_GET_REPLY``         EEE settings
   ``ETHTOOL_MSG_EEE_NTF``               EEE settings
   ``ETHTOOL_MSG_TSINFO_GET_REPLY``	timestamping info
+  ``ETHTOOL_MSG_CABLE_TEST_NTF``        Cable test results
   ===================================== =================================
 
 ``GET`` requests are sent by userspace applications to retrieve device
@@ -970,6 +971,46 @@ Request contents:
   ``ETHTOOL_A_CABLE_TEST_HEADER``       nested  request header
   ====================================  ======  ==========================
 
+Notification contents:
+
+An Ethernet cable typically contains 1, 2 or 4 pairs. The length of
+the pair can only be measured when there is a fault in the pair and
+hence a reflection. Information about the fault may not be available,
+depending on the specific hardware. Hence the contents of the notify
+message are mostly optional. The attributes can be repeated an
+arbitrary number of times, in an arbitrary order, for an arbitrary
+number of pairs.
+
+The example shows the notification sent when the test is completed for
+a T2 cable, i.e. two pairs. One pair is OK and hence has no length
+information. The second pair has a fault and does have length
+information.
+
+ +---------------------------------------------+--------+---------------------+
+ | ``ETHTOOL_A_CABLE_TEST_HEADER``             | nested | reply header        |
+ +---------------------------------------------+--------+---------------------+
+ | ``ETHTOOL_A_CABLE_TEST_STATUS``             | u8     | completed           |
+ +---------------------------------------------+--------+---------------------+
+ | ``ETHTOOL_A_CABLE_TEST_NTF_NEST``           | nested | all the results     |
+ +-+-------------------------------------------+--------+---------------------+
+ | | ``ETHTOOL_A_CABLE_NEST_RESULT``           | nested | cable test result   |
+ +-+-+-----------------------------------------+--------+---------------------+
+ | | | ``ETHTOOL_A_CABLE_RESULTS_PAIR``        | u8     | pair number         |
+ +-+-+-----------------------------------------+--------+---------------------+
+ | | | ``ETHTOOL_A_CABLE_RESULTS_CODE``        | u8     | result code         |
+ +-+-+-----------------------------------------+--------+---------------------+
+ | | ``ETHTOOL_A_CABLE_NEST_RESULT``           | nested | cable test results  |
+ +-+-+-----------------------------------------+--------+---------------------+
+ | | | ``ETHTOOL_A_CABLE_RESULTS_PAIR``        | u8     | pair number         |
+ +-+-+-----------------------------------------+--------+---------------------+
+ | | | ``ETHTOOL_A_CABLE_RESULTS_CODE``        | u8     | result code         |
+ +-+-+-----------------------------------------+--------+---------------------+
+ | | ``ETHTOOL_A_CABLE_NEST_FAULT_LENGTH``     | nested | cable length        |
+ +-+-+-----------------------------------------+--------+---------------------+
+ | | | ``ETHTOOL_A_CABLE_FAULT_LENGTH_PAIR``   | u8     | pair number         |
+ +-+-+-----------------------------------------+--------+---------------------+
+ | | | ``ETHTOOL_A_CABLE_FAULT_LENGTH_CM``     | u32    | length in cm        |
+ +-+-+-----------------------------------------+--------+---------------------+
 
 Request translation
 ===================

include/uapi/linux/ethtool_netlink.h

@@ -75,6 +75,7 @@ enum {
 	ETHTOOL_MSG_EEE_GET_REPLY,
 	ETHTOOL_MSG_EEE_NTF,
 	ETHTOOL_MSG_TSINFO_GET_REPLY,
+	ETHTOOL_MSG_CABLE_TEST_NTF,
 
 	/* add new constants above here */
 	__ETHTOOL_MSG_KERNEL_CNT,
@@ -417,6 +418,64 @@ enum {
 	ETHTOOL_A_CABLE_TEST_MAX = __ETHTOOL_A_CABLE_TEST_CNT - 1
 };
 
+/* CABLE TEST NOTIFY */
+enum {
+	ETHTOOL_A_CABLE_RESULT_CODE_UNSPEC,
+	ETHTOOL_A_CABLE_RESULT_CODE_OK,
+	ETHTOOL_A_CABLE_RESULT_CODE_OPEN,
+	ETHTOOL_A_CABLE_RESULT_CODE_SAME_SHORT,
+	ETHTOOL_A_CABLE_RESULT_CODE_CROSS_SHORT,
+};
+
+enum {
+	ETHTOOL_A_CABLE_PAIR_A,
+	ETHTOOL_A_CABLE_PAIR_B,
+	ETHTOOL_A_CABLE_PAIR_C,
+	ETHTOOL_A_CABLE_PAIR_D,
+};
+
+enum {
+	ETHTOOL_A_CABLE_RESULT_UNSPEC,
+	ETHTOOL_A_CABLE_RESULT_PAIR,		/* u8 ETHTOOL_A_CABLE_PAIR_ */
+	ETHTOOL_A_CABLE_RESULT_CODE,		/* u8 ETHTOOL_A_CABLE_RESULT_CODE_ */
+
+	__ETHTOOL_A_CABLE_RESULT_CNT,
+	ETHTOOL_A_CABLE_RESULT_MAX = (__ETHTOOL_A_CABLE_RESULT_CNT - 1)
+};
+
+enum {
+	ETHTOOL_A_CABLE_FAULT_LENGTH_UNSPEC,
+	ETHTOOL_A_CABLE_FAULT_LENGTH_PAIR,	/* u8 ETHTOOL_A_CABLE_PAIR_ */
+	ETHTOOL_A_CABLE_FAULT_LENGTH_CM,	/* u32 */
+
+	__ETHTOOL_A_CABLE_FAULT_LENGTH_CNT,
+	ETHTOOL_A_CABLE_FAULT_LENGTH_MAX = (__ETHTOOL_A_CABLE_FAULT_LENGTH_CNT - 1)
+};
+
+enum {
+	ETHTOOL_A_CABLE_TEST_NTF_STATUS_UNSPEC,
+	ETHTOOL_A_CABLE_TEST_NTF_STATUS_STARTED,
+	ETHTOOL_A_CABLE_TEST_NTF_STATUS_COMPLETED
+};
+
+enum {
+	ETHTOOL_A_CABLE_NEST_UNSPEC,
+	ETHTOOL_A_CABLE_NEST_RESULT,		/* nest - ETHTOOL_A_CABLE_RESULT_ */
+	ETHTOOL_A_CABLE_NEST_FAULT_LENGTH,	/* nest - ETHTOOL_A_CABLE_FAULT_LENGTH_ */
+	__ETHTOOL_A_CABLE_NEST_CNT,
+	ETHTOOL_A_CABLE_NEST_MAX = (__ETHTOOL_A_CABLE_NEST_CNT - 1)
+};
+
+enum {
+	ETHTOOL_A_CABLE_TEST_NTF_UNSPEC,
+	ETHTOOL_A_CABLE_TEST_NTF_HEADER,	/* nest - ETHTOOL_A_HEADER_* */
+	ETHTOOL_A_CABLE_TEST_NTF_STATUS,	/* u8 - _STARTED/_COMPLETE */
+	ETHTOOL_A_CABLE_TEST_NTF_NEST,		/* nest - of results: */
+
+	__ETHTOOL_A_CABLE_TEST_NTF_CNT,
+	ETHTOOL_A_CABLE_TEST_NTF_MAX = (__ETHTOOL_A_CABLE_TEST_NTF_CNT - 1)
+};
+
 /* generic netlink info */
 #define ETHTOOL_GENL_NAME "ethtool"
 #define ETHTOOL_GENL_VERSION 1