[PATCH ethtool v2] ethtool: Support for FEC encoding control

From: Dustin Byford <redacted>

As FEC settings and different FEC modes are mandatory
and configurable across various interfaces of 25G/50G/100G/40G,
the lack of FEC encoding control and reporting today is a source
for interoperability issues for many vendors

set-fec/show-fec option(s) are designed to provide control and report
the FEC encoding on the link.

$ethtool --set-fec swp1 encoding [off | RS | BaseR | auto]

Encoding: Types of encoding
Off    :  Turning off FEC
RS     :  Force RS-FEC encoding
BaseR  :  Force BaseR encoding
Auto   :  Default FEC settings for drivers, and would represent
          asking the hardware to essentially go into a best effort mode.

Here are a few examples of what we would expect if encoding=auto:
- if autoneg is on, we are  expecting FEC to be negotiated as on or off
  as long as protocol supports it
- if the hardware is capable of detecting the FEC encoding on it's
  receiver it will reconfigure its encoder to match
- in absence of the above, the configuration would be set to IEEE
  defaults.

From our understanding, this is essentially what most hardware/driver
combinations are doing today in the absence of a way for users to
control the behavior.

$ethtool --show-fec  swp1
FEC parameters for swp1:
FEC encodings:  RS

ethtool devname output:
$ethtool swp1
Settings for swp1:
root@hpe-7712-03:~# ethtool swp18
Settings for swp18:
    Supported ports: [ FIBRE ]
    Supported link modes:   40000baseCR4/Full
                            40000baseSR4/Full
                            40000baseLR4/Full
                            100000baseSR4/Full
                            100000baseCR4/Full
                            100000baseLR4_ER4/Full
    Supported pause frame use: No
    Supports auto-negotiation: Yes
    Supported FEC modes: [RS | BaseR | None | Not reported]
    Advertised link modes:  Not reported
    Advertised pause frame use: No
    Advertised auto-negotiation: No
    Advertised FEC modes: [RS | BaseR | None | Not reported]
    Speed: 100000Mb/s
    Duplex: Full
    Port: FIBRE
    PHYAD: 106
    Transceiver: internal
    Auto-negotiation: off
    Link detected: yes

Signed-off-by: Vidya Sagar Ravipati <redacted>
Signed-off-by: Dustin Byford <redacted>
[code style + man page edits + commit message update]
Signed-off-by: Dirk van der Merwe <redacted>
---
v2:
 - don't break lines after opening parnes.

 ethtool.8.in |  31 ++++++++++++++++
 ethtool.c    | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 150 insertions(+)

diff --git a/ethtool.8.in b/ethtool.8.in
index 7ca8bfe43607..9573ffdc985d 100644
--- a/ethtool.8.in
+++ b/ethtool.8.in

@@ -378,6 +378,13 @@ ethtool \- query or control network driver and hardware settings
 .RB [ ap-shared ]
 .RB [ dedicated ]
 .RB [ all ]
+.HP
+.B ethtool \-\-show\-fec
+.I devname
+.HP
+.B ethtool \-\-set\-fec
+.I devname
+.B4 encoding auto off rs baser
 .
 .\" Adjust lines (i.e. full justification) and hyphenate.
 .ad

@@ -1070,6 +1077,30 @@ All components dedicated to this interface
 .B all
 All components used by this interface, even if shared
 .RE
+.TP
+.B \-\-show\-fec
+Queries the specified network device for its support of Forward Error Correction.
+.TP
+.B \-\-set\-fec
+Configures Forward Error Correction for the specified network device.
+
+Forward Error Correction modes selected by a user are expected to be persisted
+after any hotplug events. If a module is swapped that does not support the
+current FEC mode, the driver or firmware must take the link down
+administratively and report the problem in the system logs for users to correct.
+.RS 4
+.TP
+.A4 encoding auto off rs baser
+Sets the FEC encoding for the device.
+.TS
+nokeep;
+lB	l.
+auto	Use the driver's default encoding
+off	Turn off FEC
+RS	Force RS-FEC encoding
+BaseR	Force BaseR encoding
+.TE
+.RE
 .SH BUGS
 Not supported (in part or whole) on all network drivers.
 .SH AUTHOR

diff --git a/ethtool.c b/ethtool.c
index 488f6bfb8378..79c076e42c6e 100644
--- a/ethtool.c
+++ b/ethtool.c

@@ -542,6 +542,9 @@ static void init_global_link_mode_masks(void)
 		ETHTOOL_LINK_MODE_Pause_BIT,
 		ETHTOOL_LINK_MODE_Asym_Pause_BIT,
 		ETHTOOL_LINK_MODE_Backplane_BIT,
+		ETHTOOL_LINK_MODE_FEC_NONE_BIT,
+		ETHTOOL_LINK_MODE_FEC_RS_BIT,
+		ETHTOOL_LINK_MODE_FEC_BASER_BIT,
 	};
 	unsigned int i;
 

@@ -689,6 +692,7 @@ static void dump_link_caps(const char *prefix, const char *an_prefix,
 	};
 	int indent;
 	int did1, new_line_pend, i;
+	int fecreported = 0;
 
 	/* Indent just like the separate functions used to */
 	indent = strlen(prefix) + 14;

@@ -740,6 +744,26 @@ static void dump_link_caps(const char *prefix, const char *an_prefix,
 			fprintf(stdout, "Yes\n");
 		else
 			fprintf(stdout, "No\n");
+
+		fprintf(stdout, "	%s FEC modes:", prefix);
+		if (ethtool_link_mode_test_bit(ETHTOOL_LINK_MODE_FEC_NONE_BIT,
+					       mask)) {
+			fprintf(stdout, " None");
+			fecreported = 1;
+		}
+		if (ethtool_link_mode_test_bit(ETHTOOL_LINK_MODE_FEC_BASER_BIT,
+					       mask)) {
+			fprintf(stdout, " BaseR");
+			fecreported = 1;
+		}
+		if (ethtool_link_mode_test_bit(ETHTOOL_LINK_MODE_FEC_RS_BIT,
+					       mask)) {
+			fprintf(stdout, " RS");
+			fecreported = 1;
+		}
+		if (!fecreported)
+			fprintf(stdout, " Not reported");
+		fprintf(stdout, "\n");
 	}
 }
 

@@ -1562,6 +1586,20 @@ static void dump_eeecmd(struct ethtool_eee *ep)
 	dump_link_caps("Link partner advertised EEE", "", link_mode, 1);
 }
 
+static void dump_fec(u32 fec)
+{
+	if (fec & ETHTOOL_FEC_NONE)
+		fprintf(stdout, " None");
+	if (fec & ETHTOOL_FEC_AUTO)
+		fprintf(stdout, " Auto");
+	if (fec & ETHTOOL_FEC_OFF)
+		fprintf(stdout, " Off");
+	if (fec & ETHTOOL_FEC_BASER)
+		fprintf(stdout, " BaseR");
+	if (fec & ETHTOOL_FEC_RS)
+		fprintf(stdout, " RS");
+}
+
 #define N_SOTS 7
 
 static char *so_timestamping_labels[N_SOTS] = {

@@ -4812,6 +4850,84 @@ static int do_set_phy_tunable(struct cmd_context *ctx)
 	return err;
 }
 
+static int fecmode_str_to_type(const char *str)
+{
+	int fecmode = 0;
+
+	if (!str)
+		return fecmode;
+
+	if (!strcasecmp(str, "auto"))
+		fecmode |= ETHTOOL_FEC_AUTO;
+	else if (!strcasecmp(str, "off"))
+		fecmode |= ETHTOOL_FEC_OFF;
+	else if (!strcasecmp(str, "rs"))
+		fecmode |= ETHTOOL_FEC_RS;
+	else if (!strcasecmp(str, "baser"))
+		fecmode |= ETHTOOL_FEC_BASER;
+
+	return fecmode;
+}
+
+static int do_gfec(struct cmd_context *ctx)
+{
+	struct ethtool_fecparam feccmd = { 0 };
+	int rv;
+
+	if (ctx->argc != 0)
+		exit_bad_args();
+
+	feccmd.cmd = ETHTOOL_GFECPARAM;
+	rv = send_ioctl(ctx, &feccmd);
+	if (rv != 0) {
+		perror("Cannot get FEC settings");
+		return rv;
+	}
+
+	fprintf(stdout, "FEC parameters for %s:\n", ctx->devname);
+	fprintf(stdout, "Configured FEC encodings:");
+	dump_fec(feccmd.fec);
+	fprintf(stdout, "\n");
+
+	fprintf(stdout, "Active FEC encoding:");
+	dump_fec(feccmd.active_fec);
+	fprintf(stdout, "\n");
+
+	return 0;
+}
+
+static int do_sfec(struct cmd_context *ctx)
+{
+	char *fecmode_str = NULL;
+	struct ethtool_fecparam feccmd;
+	struct cmdline_info cmdline_fec[] = {
+		{ "encoding", CMDL_STR,  &fecmode_str,  &feccmd.fec},
+	};
+	int changed;
+	int fecmode;
+	int rv;
+
+	parse_generic_cmdline(ctx, &changed, cmdline_fec,
+			      ARRAY_SIZE(cmdline_fec));
+
+	if (!fecmode_str)
+		exit_bad_args();
+
+	fecmode = fecmode_str_to_type(fecmode_str);
+	if (!fecmode)
+		exit_bad_args();
+
+	feccmd.cmd = ETHTOOL_SFECPARAM;
+	feccmd.fec = fecmode;
+	rv = send_ioctl(ctx, &feccmd);
+	if (rv != 0) {
+		perror("Cannot set FEC settings");
+		return rv;
+	}
+
+	return 0;
+}
+
 #ifndef TEST_ETHTOOL
 int send_ioctl(struct cmd_context *ctx, void *cmd)
 {

@@ -5000,6 +5116,9 @@ static const struct option {
 	  "		[ ap-shared ]\n"
 	  "		[ dedicated ]\n"
 	  "		[ all ]\n"},
+	{ "--show-fec", 1, do_gfec, "Show FEC settings"},
+	{ "--set-fec", 1, do_sfec, "Set FEC settings",
+	  "		[ encoding auto|off|rs|baser ]\n"},
 	{ "-h|--help", 0, show_usage, "Show this help" },
 	{ "--version", 0, do_version, "Show version number" },
 	{}

-- 
2.15.1