mlxsw: spectrum: Support RED qdisc offload

Add support for ndo_setup_tc with enum tc_setup_type value of TC_SETUP_RED.
This call sets RED qdisc on a traffic class.
This patch supports RED qdisc only as a root qdisc and set in on the
default tclass. It can be set with or without ECN.

Signed-off-by: Yuval Mintz <yuvalm@mellanox.com>
Signed-off-by: Nogah Frankel <nogahf@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/Makefile

@@ -19,7 +19,8 @@ mlxsw_spectrum-objs		:= spectrum.o spectrum_buffers.o \
 				   spectrum_acl.o spectrum_flower.o \
 				   spectrum_cnt.o spectrum_fid.o \
 				   spectrum_ipip.o spectrum_acl_flex_actions.o \
-				   spectrum_mr.o spectrum_mr_tcam.o
+				   spectrum_mr.o spectrum_mr_tcam.o \
+				   spectrum_qdisc.o
 mlxsw_spectrum-$(CONFIG_MLXSW_SPECTRUM_DCB)	+= spectrum_dcb.o
 mlxsw_spectrum-$(CONFIG_NET_DEVLINK) += spectrum_dpipe.o
 obj-$(CONFIG_MLXSW_MINIMAL)	+= mlxsw_minimal.o

drivers/net/ethernet/mellanox/mlxsw/spectrum.c

@@ -1797,6 +1797,8 @@ static int mlxsw_sp_setup_tc(struct net_device *dev, enum tc_setup_type type,
 	switch (type) {
 	case TC_SETUP_BLOCK:
 		return mlxsw_sp_setup_tc_block(mlxsw_sp_port, type_data);
+	case TC_SETUP_QDISC_RED:
+		return mlxsw_sp_setup_tc_red(mlxsw_sp_port, type_data);
 	default:
 		return -EOPNOTSUPP;
 	}

drivers/net/ethernet/mellanox/mlxsw/spectrum.h

@@ -203,6 +203,16 @@ struct mlxsw_sp_port_vlan {
 	struct list_head bridge_vlan_node;
 };
 
+enum mlxsw_sp_qdisc_type {
+	MLXSW_SP_QDISC_NO_QDISC,
+	MLXSW_SP_QDISC_RED,
+};
+
+struct mlxsw_sp_qdisc {
+	u32 handle;
+	enum mlxsw_sp_qdisc_type type;
+};
+
 struct mlxsw_sp_port {
 	struct net_device *dev;
 	struct mlxsw_sp_port_pcpu_stats __percpu *pcpu_stats;
@@ -236,6 +246,7 @@ struct mlxsw_sp_port {
 	} periodic_hw_stats;
 	struct mlxsw_sp_port_sample *sample;
 	struct list_head vlans_list;
+	struct mlxsw_sp_qdisc root_qdisc;
 };
 
 static inline bool
@@ -546,6 +557,10 @@ void mlxsw_sp_flower_destroy(struct mlxsw_sp_port *mlxsw_sp_port, bool ingress,
 int mlxsw_sp_flower_stats(struct mlxsw_sp_port *mlxsw_sp_port, bool ingress,
 			  struct tc_cls_flower_offload *f);
 
+/* spectrum_qdisc.c */
+int mlxsw_sp_setup_tc_red(struct mlxsw_sp_port *mlxsw_sp_port,
+			  struct tc_red_qopt_offload *p);
+
 /* spectrum_fid.c */
 int mlxsw_sp_fid_flood_set(struct mlxsw_sp_fid *fid,
 			   enum mlxsw_sp_flood_type packet_type, u8 local_port,

drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c

@@ -0,0 +1,174 @@
+/*
+ * drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c
+ * Copyright (c) 2017 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2017 Nogah Frankel <nogahf@mellanox.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/netdevice.h>
+#include <net/pkt_cls.h>
+
+#include "spectrum.h"
+#include "reg.h"
+
+static int
+mlxsw_sp_tclass_congestion_enable(struct mlxsw_sp_port *mlxsw_sp_port,
+				  int tclass_num, u32 min, u32 max,
+				  u32 probability, bool is_ecn)
+{
+	char cwtp_cmd[max_t(u8, MLXSW_REG_CWTP_LEN, MLXSW_REG_CWTPM_LEN)];
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	int err;
+
+	mlxsw_reg_cwtp_pack(cwtp_cmd, mlxsw_sp_port->local_port, tclass_num);
+	mlxsw_reg_cwtp_profile_pack(cwtp_cmd, MLXSW_REG_CWTP_DEFAULT_PROFILE,
+				    roundup(min, MLXSW_REG_CWTP_MIN_VALUE),
+				    roundup(max, MLXSW_REG_CWTP_MIN_VALUE),
+				    probability);
+
+	err = mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(cwtp), cwtp_cmd);
+	if (err)
+		return err;
+
+	mlxsw_reg_cwtpm_pack(cwtp_cmd, mlxsw_sp_port->local_port, tclass_num,
+			     MLXSW_REG_CWTP_DEFAULT_PROFILE, true, is_ecn);
+
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(cwtpm), cwtp_cmd);
+}
+
+static int
+mlxsw_sp_tclass_congestion_disable(struct mlxsw_sp_port *mlxsw_sp_port,
+				   int tclass_num)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	char cwtpm_cmd[MLXSW_REG_CWTPM_LEN];
+
+	mlxsw_reg_cwtpm_pack(cwtpm_cmd, mlxsw_sp_port->local_port, tclass_num,
+			     MLXSW_REG_CWTPM_RESET_PROFILE, false, false);
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(cwtpm), cwtpm_cmd);
+}
+
+static int
+mlxsw_sp_qdisc_red_destroy(struct mlxsw_sp_port *mlxsw_sp_port, u32 handle,
+			   struct mlxsw_sp_qdisc *mlxsw_sp_qdisc,
+			   int tclass_num)
+{
+	int err;
+
+	if (mlxsw_sp_qdisc->handle != handle)
+		return 0;
+
+	err = mlxsw_sp_tclass_congestion_disable(mlxsw_sp_port, tclass_num);
+	mlxsw_sp_qdisc->handle = TC_H_UNSPEC;
+	mlxsw_sp_qdisc->type = MLXSW_SP_QDISC_NO_QDISC;
+
+	return err;
+}
+
+static int
+mlxsw_sp_qdisc_red_replace(struct mlxsw_sp_port *mlxsw_sp_port, u32 handle,
+			   struct mlxsw_sp_qdisc *mlxsw_sp_qdisc,
+			   int tclass_num,
+			   struct tc_red_qopt_offload_params *p)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	u32 min, max;
+	u64 prob;
+	int err = 0;
+
+	if (p->min > p->max) {
+		dev_err(mlxsw_sp->bus_info->dev,
+			"spectrum: RED: min %u is bigger then max %u\n", p->min,
+			p->max);
+		goto err_bad_param;
+	}
+	if (p->max > MLXSW_CORE_RES_GET(mlxsw_sp->core, MAX_BUFFER_SIZE)) {
+		dev_err(mlxsw_sp->bus_info->dev,
+			"spectrum: RED: max value %u is too big\n", p->max);
+		goto err_bad_param;
+	}
+	if (p->min == 0 || p->max == 0) {
+		dev_err(mlxsw_sp->bus_info->dev,
+			"spectrum: RED: 0 value is illegal for min and max\n");
+		goto err_bad_param;
+	}
+
+	/* calculate probability in percentage */
+	prob = p->probability;
+	prob *= 100;
+	prob = DIV_ROUND_UP(prob, 1 << 16);
+	prob = DIV_ROUND_UP(prob, 1 << 16);
+	min = mlxsw_sp_bytes_cells(mlxsw_sp, p->min);
+	max = mlxsw_sp_bytes_cells(mlxsw_sp, p->max);
+	err = mlxsw_sp_tclass_congestion_enable(mlxsw_sp_port, tclass_num, min,
+						max, prob, p->is_ecn);
+	if (err)
+		goto err_config;
+
+	mlxsw_sp_qdisc->type = MLXSW_SP_QDISC_RED;
+	mlxsw_sp_qdisc->handle = handle;
+	return 0;
+
+err_bad_param:
+	err = -EINVAL;
+err_config:
+	mlxsw_sp_qdisc_red_destroy(mlxsw_sp_port, mlxsw_sp_qdisc->handle,
+				   mlxsw_sp_qdisc, tclass_num);
+	return err;
+}
+
+#define MLXSW_SP_PORT_DEFAULT_TCLASS 0
+
+int mlxsw_sp_setup_tc_red(struct mlxsw_sp_port *mlxsw_sp_port,
+			  struct tc_red_qopt_offload *p)
+{
+	struct mlxsw_sp_qdisc *mlxsw_sp_qdisc;
+	int tclass_num;
+
+	if (p->parent != TC_H_ROOT)
+		return -EOPNOTSUPP;
+
+	mlxsw_sp_qdisc = &mlxsw_sp_port->root_qdisc;
+	tclass_num = MLXSW_SP_PORT_DEFAULT_TCLASS;
+
+	switch (p->command) {
+	case TC_RED_REPLACE:
+		return mlxsw_sp_qdisc_red_replace(mlxsw_sp_port, p->handle,
+						  mlxsw_sp_qdisc, tclass_num,
+						  &p->set);
+	case TC_RED_DESTROY:
+		return mlxsw_sp_qdisc_red_destroy(mlxsw_sp_port, p->handle,
+						  mlxsw_sp_qdisc, tclass_num);
+	default:
+		return -EOPNOTSUPP;
+	}
+}