Date:   Wed, 27 Nov 2019 09:58:52 +0000
From:   Po Liu <po.liu@....com>
To:     "rmk+kernel@...linux.org.uk" <rmk+kernel@...linux.org.uk>,
        "linville@...driver.com" <linville@...driver.com>,
        "netdev-owner@...r.kernel.org" <netdev-owner@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     "vinicius.gomes@...el.com" <vinicius.gomes@...el.com>,
        "simon.horman@...ronome.com" <simon.horman@...ronome.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Vladimir Oltean <vladimir.oltean@....com>,
        Xiaoliang Yang <xiaoliang.yang_1@....com>,
        Roy Zang <roy.zang@....com>, Mingkai Hu <mingkai.hu@....com>,
        Jerry Huang <jerry.huang@....com>, Leo Li <leoyang.li@....com>,
        Po Liu <po.liu@....com>
Subject: [v1,ethtool] ethtool: add setting frame preemption of traffic classes

IEEE Std 802.1Qbu standard defined the frame preemption of port
trffic classes. User can set a value to hardware. The value will
be translated to a binary, each bit represent a traffic class.
Bit "1" means preemptable traffic class. Bit "0" means express
traffic class.  MSB represent high number traffic class.

ethtool -k devname

This command would show if the tx-preemption feature is available.
If hareware set preemption feature. The property would be a fixed
value 'on' if hardware support the frame preemption. Feature would
show a fixed value 'off' if hardware don't support the frame preemption.

ethtool devname

This command would show include an item 'preemption'. A following
value '0' means all traffic classes are 'express'. A value none zero
means traffic classes preemption capabilities. The value will be
translated to a binary, each bit represent a traffic class. Bit '1'
means preemptable traffic class. Bit '0' means express traffic class.
MSB represent high number traffic class.

ethtool -s devname preemption N

This command would set which traffic classes are frame preemptable.
The value will be translated to a binary, each bit represent a
traffic class. Bit '1' means preemptable traffic class. Bit '0'
means express traffic class. MSB represent high number traffic class.

Signed-off-by: Po Liu <Po.Liu@....com>
---
 ethtool-copy.h |  6 +++++-
 ethtool.8.in   |  8 ++++++++
 ethtool.c      | 18 ++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/ethtool-copy.h b/ethtool-copy.h
index 9afd2e6..e04bdf3 100644
--- a/ethtool-copy.h
+++ b/ethtool-copy.h
@@ -1662,6 +1662,9 @@ static __inline__ int ethtool_validate_duplex(__u8 duplex)
 #define AUTONEG_DISABLE		0x00
 #define AUTONEG_ENABLE		0x01
 
+/* Disable preemtion. */
+#define PREEMPTION_DISABLE	0x0
+
 /* MDI or MDI-X status/control - if MDI/MDI_X/AUTO is set then
  * the driver is required to renegotiate link
  */
@@ -1878,7 +1881,8 @@ struct ethtool_link_settings {
 	__s8	link_mode_masks_nwords;
 	__u8	transceiver;
 	__u8	reserved1[3];
-	__u32	reserved[7];
+	__u32	preemption;
+	__u32	reserved[6];
 	__u32	link_mode_masks[0];
 	/* layout of link_mode_masks fields:
 	 * __u32 map_supported[link_mode_masks_nwords];
diff --git a/ethtool.8.in b/ethtool.8.in
index 062695a..7d612b2 100644
--- a/ethtool.8.in
+++ b/ethtool.8.in
@@ -236,6 +236,7 @@ ethtool \- query or control network driver and hardware settings
 .B2 autoneg on off
 .BN advertise
 .BN phyad
+.BN preemption
 .B2 xcvr internal external
 .RB [ wol \ \*(WO]
 .RB [ sopass \ \*(MA]
@@ -703,6 +704,13 @@ lB	l	lB.
 .BI phyad \ N
 PHY address.
 .TP
+.BI preemption \ N
+Set preemptable traffic classes by bits.
+.B A
+value will be translated to a binary, each bit represent a traffic class.
+Bit "1" means preemptable traffic class. Bit "0" means express traffic class.
+MSB represent high number traffic class.
+.TP
 .A2 xcvr internal external
 Selects transceiver type. Currently only internal and external can be
 specified, in the future further types might be added.
diff --git a/ethtool.c b/ethtool.c
index acf183d..d5240f8 100644
--- a/ethtool.c
+++ b/ethtool.c
@@ -928,6 +928,12 @@ dump_link_usettings(const struct ethtool_link_usettings *link_usettings)
 		}
 	}
 
+	if (link_usettings->base.preemption == PREEMPTION_DISABLE)
+		fprintf(stdout, "	Preemption: 0x0 (off)\n");
+	else
+		fprintf(stdout, "	Preemption: 0x%x\n",
+			link_usettings->base.preemption);
+
 	return 0;
 }
 
@@ -2869,6 +2875,7 @@ static int do_sset(struct cmd_context *ctx)
 	int port_wanted = -1;
 	int mdix_wanted = -1;
 	int autoneg_wanted = -1;
+	int preemption_wanted = -1;
 	int phyad_wanted = -1;
 	int xcvr_wanted = -1;
 	u32 *full_advertising_wanted = NULL;
@@ -2957,6 +2964,12 @@ static int do_sset(struct cmd_context *ctx)
 			} else {
 				exit_bad_args();
 			}
+		} else if (!strcmp(argp[i], "preemption")) {
+			gset_changed = 1;
+			i += 1;
+			if (i >= argc)
+				exit_bad_args();
+			preemption_wanted = get_u32(argp[i], 16);
 		} else if (!strcmp(argp[i], "advertise")) {
 			gset_changed = 1;
 			i += 1;
@@ -3094,6 +3107,9 @@ static int do_sset(struct cmd_context *ctx)
 			}
 			if (autoneg_wanted != -1)
 				link_usettings->base.autoneg = autoneg_wanted;
+			if (preemption_wanted != -1)
+				link_usettings->base.preemption
+					= preemption_wanted;
 			if (phyad_wanted != -1)
 				link_usettings->base.phy_address = phyad_wanted;
 			if (xcvr_wanted != -1)
@@ -3186,6 +3202,8 @@ static int do_sset(struct cmd_context *ctx)
 				fprintf(stderr, "  not setting transceiver\n");
 			if (mdix_wanted != -1)
 				fprintf(stderr, "  not setting mdix\n");
+			if (preemption_wanted != -1)
+				fprintf(stderr, "  not setting preemption\n");
 		}
 	}
 
-- 
2.17.1

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