mlxsw: spectrum_buffers: Allow an infinite maximum for per-TC pool limit

The SBCM register configures the shared buffer configuration according
to port and TC. So far all pools have had a dynamic size, where the
infinite size is easy to express by using max_buff of 0xff. However the
MC pool should be configured with static size, and the infinite size
thus needs to be set using the field SBCM.infi_max.

Therefore add the field infi_max to the SBCM register and to
mlxsw_reg_sbcm_pack(). Extend mlxsw_sp_sb_cm_write() to handle infinite
sizes as well. Report infinite pool limits as if the limit actually were
the total shared buffer size.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Reviewed-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/reg.h

@@ -8418,6 +8418,12 @@ MLXSW_ITEM32(reg, sbcm, min_buff, 0x18, 0, 24);
 #define MLXSW_REG_SBXX_DYN_MAX_BUFF_MIN 1
 #define MLXSW_REG_SBXX_DYN_MAX_BUFF_MAX 14
 
+/* reg_sbcm_infi_max
+ * Max buffer is infinite.
+ * Access: RW
+ */
+MLXSW_ITEM32(reg, sbcm, infi_max, 0x1C, 31, 1);
+
 /* reg_sbcm_max_buff
  * When the pool associated to the port-pg/tclass is configured to
  * static, Maximum buffer size for the limiter configured in cells.
@@ -8427,6 +8433,7 @@ MLXSW_ITEM32(reg, sbcm, min_buff, 0x18, 0, 24);
  * 0: 0
  * i: (1/128)*2^(i-1), for i=1..14
  * 0xFF: Infinity
+ * Reserved when infi_max = 1.
  * Access: RW
  */
 MLXSW_ITEM32(reg, sbcm, max_buff, 0x1C, 0, 24);
@@ -8439,14 +8446,16 @@ MLXSW_ITEM32(reg, sbcm, pool, 0x24, 0, 4);
 
 static inline void mlxsw_reg_sbcm_pack(char *payload, u8 local_port, u8 pg_buff,
 				       enum mlxsw_reg_sbxx_dir dir,
-				       u32 min_buff, u32 max_buff, u8 pool)
+				       u32 min_buff, u32 max_buff,
+				       bool infi_max, u8 pool)
 {
 	MLXSW_REG_ZERO(sbcm, payload);
 	mlxsw_reg_sbcm_local_port_set(payload, local_port);
 	mlxsw_reg_sbcm_pg_buff_set(payload, pg_buff);
 	mlxsw_reg_sbcm_dir_set(payload, dir);
 	mlxsw_reg_sbcm_min_buff_set(payload, min_buff);
 	mlxsw_reg_sbcm_max_buff_set(payload, max_buff);
+	mlxsw_reg_sbcm_infi_max_set(payload, infi_max);
 	mlxsw_reg_sbcm_pool_set(payload, pool);
 }
 

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

@@ -142,20 +142,24 @@ static int mlxsw_sp_sb_pr_write(struct mlxsw_sp *mlxsw_sp, u16 pool_index,
 
 static int mlxsw_sp_sb_cm_write(struct mlxsw_sp *mlxsw_sp, u8 local_port,
 				u8 pg_buff, u32 min_buff, u32 max_buff,
-				u16 pool_index)
+				bool infi_max, u16 pool_index)
 {
 	const struct mlxsw_sp_sb_pool_des *des =
 		&mlxsw_sp_sb_pool_dess[pool_index];
 	char sbcm_pl[MLXSW_REG_SBCM_LEN];
+	struct mlxsw_sp_sb_cm *cm;
 	int err;
 
 	mlxsw_reg_sbcm_pack(sbcm_pl, local_port, pg_buff, des->dir,
-			    min_buff, max_buff, des->pool);
+			    min_buff, max_buff, infi_max, des->pool);
 	err = mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(sbcm), sbcm_pl);
 	if (err)
 		return err;
+
 	if (mlxsw_sp_sb_cm_exists(pg_buff, des->dir)) {
-		struct mlxsw_sp_sb_cm *cm;
+		if (infi_max)
+			max_buff = mlxsw_sp_bytes_cells(mlxsw_sp,
+							mlxsw_sp->sb->sb_size);
 
 		cm = mlxsw_sp_sb_cm_get(mlxsw_sp, local_port, pg_buff,
 					des->dir);
@@ -451,9 +455,14 @@ static int __mlxsw_sp_sb_cms_init(struct mlxsw_sp *mlxsw_sp, u8 local_port,
 		 * therefore 'max_buff' isn't specified in cells.
 		 */
 		min_buff = mlxsw_sp_bytes_cells(mlxsw_sp, cm->min_buff);
-		err = mlxsw_sp_sb_cm_write(mlxsw_sp, local_port, i,
-					   min_buff, cm->max_buff,
-					   cm->pool_index);
+		if (cm->max_buff == MLXSW_SP_SB_INFI)
+			err = mlxsw_sp_sb_cm_write(mlxsw_sp, local_port, i,
+						   min_buff, 0,
+						   true, cm->pool_index);
+		else
+			err = mlxsw_sp_sb_cm_write(mlxsw_sp, local_port, i,
+						   min_buff, cm->max_buff,
+						   false, cm->pool_index);
 		if (err)
 			return err;
 	}
@@ -813,7 +822,7 @@ int mlxsw_sp_sb_tc_pool_bind_set(struct mlxsw_core_port *mlxsw_core_port,
 		return err;
 
 	return mlxsw_sp_sb_cm_write(mlxsw_sp, local_port, pg_buff,
-				    0, max_buff, pool_index);
+				    0, max_buff, false, pool_index);
 }
 
 #define MASKED_COUNT_MAX \