mlxsw: core: Add support for using EMAD string TLV

In case the firmware had an error while processing EMADs, it can send back
an ASCII string with the reason using EMAD string TLV.

This patch adds the support for using EMAD string TLV. In case of an error,
reports the reason using devlink hwerr tracepoint.
Signed-off-by: Shalom Toledo <shalomt@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -71,6 +71,7 @@ struct mlxsw_core {
 		struct list_head trans_list;
 		spinlock_t trans_list_lock; /* protects trans_list writes */
 		bool use_emad;
+		bool enable_string_tlv;
 	} emad;
 	struct {
 		u8 *mapping; /* lag_id+port_index to local_port mapping */
@@ -323,6 +324,12 @@ static void mlxsw_emad_pack_reg_tlv(char *reg_tlv,
 	memcpy(reg_tlv + sizeof(u32), payload, reg->len);
 }
 
+static void mlxsw_emad_pack_string_tlv(char *string_tlv)
+{
+	mlxsw_emad_string_tlv_type_set(string_tlv, MLXSW_EMAD_TLV_TYPE_STRING);
+	mlxsw_emad_string_tlv_len_set(string_tlv, MLXSW_EMAD_STRING_TLV_LEN);
+}
+
 static void mlxsw_emad_pack_op_tlv(char *op_tlv,
 				   const struct mlxsw_reg_info *reg,
 				   enum mlxsw_core_reg_access_type type,
@@ -364,7 +371,7 @@ static void mlxsw_emad_construct(struct sk_buff *skb,
 				 const struct mlxsw_reg_info *reg,
 				 char *payload,
 				 enum mlxsw_core_reg_access_type type,
-				 u64 tid)
+				 u64 tid, bool enable_string_tlv)
 {
 	char *buf;
 
@@ -374,6 +381,11 @@ static void mlxsw_emad_construct(struct sk_buff *skb,
 	buf = skb_push(skb, reg->len + sizeof(u32));
 	mlxsw_emad_pack_reg_tlv(buf, reg, payload);
 
+	if (enable_string_tlv) {
+		buf = skb_push(skb, MLXSW_EMAD_STRING_TLV_LEN * sizeof(u32));
+		mlxsw_emad_pack_string_tlv(buf);
+	}
+
 	buf = skb_push(skb, MLXSW_EMAD_OP_TLV_LEN * sizeof(u32));
 	mlxsw_emad_pack_op_tlv(buf, reg, type, tid);
 
@@ -418,6 +430,17 @@ static char *mlxsw_emad_op_tlv(const struct sk_buff *skb)
 	return ((char *) (skb->data + offsets->op_tlv));
 }
 
+static char *mlxsw_emad_string_tlv(const struct sk_buff *skb)
+{
+	struct mlxsw_emad_tlv_offsets *offsets =
+		(struct mlxsw_emad_tlv_offsets *) skb->cb;
+
+	if (!offsets->string_tlv)
+		return NULL;
+
+	return ((char *) (skb->data + offsets->string_tlv));
+}
+
 static char *mlxsw_emad_reg_tlv(const struct sk_buff *skb)
 {
 	struct mlxsw_emad_tlv_offsets *offsets =
@@ -499,10 +522,31 @@ struct mlxsw_reg_trans {
 	const struct mlxsw_reg_info *reg;
 	enum mlxsw_core_reg_access_type type;
 	int err;
+	char *emad_err_string;
 	enum mlxsw_emad_op_tlv_status emad_status;
 	struct rcu_head rcu;
 };
 
+static void mlxsw_emad_process_string_tlv(const struct sk_buff *skb,
+					  struct mlxsw_reg_trans *trans)
+{
+	char *string_tlv;
+	char *string;
+
+	string_tlv = mlxsw_emad_string_tlv(skb);
+	if (!string_tlv)
+		return;
+
+	trans->emad_err_string = kzalloc(MLXSW_EMAD_STRING_TLV_STRING_LEN,
+					 GFP_ATOMIC);
+	if (!trans->emad_err_string)
+		return;
+
+	string = mlxsw_emad_string_tlv_string_data(string_tlv);
+	strlcpy(trans->emad_err_string, string,
+		MLXSW_EMAD_STRING_TLV_STRING_LEN);
+}
+
 #define MLXSW_EMAD_TIMEOUT_DURING_FW_FLASH_MS	3000
 #define MLXSW_EMAD_TIMEOUT_MS			200
 
@@ -600,6 +644,8 @@ static void mlxsw_emad_process_response(struct mlxsw_core *mlxsw_core,
 				trans->cb(mlxsw_core,
 					  mlxsw_emad_reg_payload(reg_tlv),
 					  trans->reg->len, trans->cb_priv);
+		} else {
+			mlxsw_emad_process_string_tlv(skb, trans);
 		}
 		mlxsw_emad_trans_finish(trans, err);
 	}
@@ -692,7 +738,7 @@ static void mlxsw_emad_fini(struct mlxsw_core *mlxsw_core)
 }
 
 static struct sk_buff *mlxsw_emad_alloc(const struct mlxsw_core *mlxsw_core,
-					u16 reg_len)
+					u16 reg_len, bool enable_string_tlv)
 {
 	struct sk_buff *skb;
 	u16 emad_len;
@@ -700,6 +746,8 @@ static struct sk_buff *mlxsw_emad_alloc(const struct mlxsw_core *mlxsw_core,
 	emad_len = (reg_len + sizeof(u32) + MLXSW_EMAD_ETH_HDR_LEN +
 		    (MLXSW_EMAD_OP_TLV_LEN + MLXSW_EMAD_END_TLV_LEN) *
 		    sizeof(u32) + mlxsw_core->driver->txhdr_len);
+	if (enable_string_tlv)
+		emad_len += MLXSW_EMAD_STRING_TLV_LEN * sizeof(u32);
 	if (emad_len > MLXSW_EMAD_MAX_FRAME_LEN)
 		return NULL;
 
@@ -721,6 +769,7 @@ static int mlxsw_emad_reg_access(struct mlxsw_core *mlxsw_core,
 				 mlxsw_reg_trans_cb_t *cb,
 				 unsigned long cb_priv, u64 tid)
 {
+	bool enable_string_tlv;
 	struct sk_buff *skb;
 	int err;
 
@@ -728,7 +777,12 @@ static int mlxsw_emad_reg_access(struct mlxsw_core *mlxsw_core,
 		tid, reg->id, mlxsw_reg_id_str(reg->id),
 		mlxsw_core_reg_access_type_str(type));
 
-	skb = mlxsw_emad_alloc(mlxsw_core, reg->len);
+	/* Since this can be changed during emad_reg_access, read it once and
+	 * use the value all the way.
+	 */
+	enable_string_tlv = mlxsw_core->emad.enable_string_tlv;
+
+	skb = mlxsw_emad_alloc(mlxsw_core, reg->len, enable_string_tlv);
 	if (!skb)
 		return -ENOMEM;
 
@@ -745,7 +799,8 @@ static int mlxsw_emad_reg_access(struct mlxsw_core *mlxsw_core,
 	trans->reg = reg;
 	trans->type = type;
 
-	mlxsw_emad_construct(skb, reg, payload, type, trans->tid);
+	mlxsw_emad_construct(skb, reg, payload, type, trans->tid,
+			     enable_string_tlv);
 	mlxsw_core->driver->txhdr_construct(skb, &trans->tx_info);
 
 	spin_lock_bh(&mlxsw_core->emad.trans_list_lock);
@@ -1707,12 +1762,15 @@ static int mlxsw_reg_trans_wait(struct mlxsw_reg_trans *trans)
 			mlxsw_emad_op_tlv_status_str(trans->emad_status));
 
 		snprintf(err_string, MLXSW_REG_TRANS_ERR_STRING_SIZE,
-			 "(tid=%llx,reg_id=%x(%s)) %s\n", trans->tid,
+			 "(tid=%llx,reg_id=%x(%s)) %s (%s)\n", trans->tid,
 			 trans->reg->id, mlxsw_reg_id_str(trans->reg->id),
-			 mlxsw_emad_op_tlv_status_str(trans->emad_status));
+			 mlxsw_emad_op_tlv_status_str(trans->emad_status),
+			 trans->emad_err_string ? trans->emad_err_string : "");
 
 		trace_devlink_hwerr(priv_to_devlink(mlxsw_core),
 				    trans->emad_status, err_string);
+
+		kfree(trans->emad_err_string);
 	}
 
 	list_del(&trans->bulk_list);
@@ -2283,6 +2341,12 @@ u32 mlxsw_core_read_frc_l(struct mlxsw_core *mlxsw_core)
 }
 EXPORT_SYMBOL(mlxsw_core_read_frc_l);
 
+void mlxsw_core_emad_string_tlv_enable(struct mlxsw_core *mlxsw_core)
+{
+	mlxsw_core->emad.enable_string_tlv = true;
+}
+EXPORT_SYMBOL(mlxsw_core_emad_string_tlv_enable);
+
 static int __init mlxsw_core_module_init(void)
 {
 	int err;

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

@@ -347,6 +347,8 @@ void mlxsw_core_fw_flash_end(struct mlxsw_core *mlxsw_core);
 u32 mlxsw_core_read_frc_h(struct mlxsw_core *mlxsw_core);
 u32 mlxsw_core_read_frc_l(struct mlxsw_core *mlxsw_core);
 
+void mlxsw_core_emad_string_tlv_enable(struct mlxsw_core *mlxsw_core);
+
 bool mlxsw_core_res_valid(struct mlxsw_core *mlxsw_core,
 			  enum mlxsw_res_id res_id);