mlxsw: spectrum_buffers: Allow pools of infinite size

The MC pool should have an infinite size (i.e. no quota).

To that end, add infi_size to the SBPR register and extend
mlxsw_reg_sbpr_pack(). Also add MLXSW_SP_SB_INFI to denote
buffers that should have an infinite size.

Change mlxsw_sp_sb_pr_write() to take as parameter byte size,
instead of cell size, and add the special handling of infinite
buffers. Report pools with infinite size as if they actually
take the full 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

@@ -8336,8 +8336,15 @@ MLXSW_ITEM32(reg, sbpr, dir, 0x00, 24, 2);
  */
 MLXSW_ITEM32(reg, sbpr, pool, 0x00, 0, 4);
 
+/* reg_sbpr_infi_size
+ * Size is infinite.
+ * Access: RW
+ */
+MLXSW_ITEM32(reg, sbpr, infi_size, 0x04, 31, 1);
+
 /* reg_sbpr_size
  * Pool size in buffer cells.
+ * Reserved when infi_size = 1.
  * Access: RW
  */
 MLXSW_ITEM32(reg, sbpr, size, 0x04, 0, 24);
@@ -8355,13 +8362,15 @@ MLXSW_ITEM32(reg, sbpr, mode, 0x08, 0, 4);
 
 static inline void mlxsw_reg_sbpr_pack(char *payload, u8 pool,
 				       enum mlxsw_reg_sbxx_dir dir,
-				       enum mlxsw_reg_sbpr_mode mode, u32 size)
+				       enum mlxsw_reg_sbpr_mode mode, u32 size,
+				       bool infi_size)
 {
 	MLXSW_REG_ZERO(sbpr, payload);
 	mlxsw_reg_sbpr_pool_set(payload, pool);
 	mlxsw_reg_sbpr_dir_set(payload, dir);
 	mlxsw_reg_sbpr_mode_set(payload, mode);
 	mlxsw_reg_sbpr_size_set(payload, size);
+	mlxsw_reg_sbpr_infi_size_set(payload, infi_size);
 }
 
 /* SBCM - Shared Buffer Class Management Register

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

@@ -29,6 +29,8 @@ struct mlxsw_sp_sb_cm {
 	struct mlxsw_cp_sb_occ occ;
 };
 
+#define MLXSW_SP_SB_INFI -1U
+
 struct mlxsw_sp_sb_pm {
 	u32 min_buff;
 	u32 max_buff;
@@ -115,19 +117,23 @@ static struct mlxsw_sp_sb_pm *mlxsw_sp_sb_pm_get(struct mlxsw_sp *mlxsw_sp,
 }
 
 static int mlxsw_sp_sb_pr_write(struct mlxsw_sp *mlxsw_sp, u16 pool_index,
-				enum mlxsw_reg_sbpr_mode mode, u32 size)
+				enum mlxsw_reg_sbpr_mode mode,
+				u32 size, bool infi_size)
 {
 	const struct mlxsw_sp_sb_pool_des *des =
 		&mlxsw_sp_sb_pool_dess[pool_index];
 	char sbpr_pl[MLXSW_REG_SBPR_LEN];
 	struct mlxsw_sp_sb_pr *pr;
 	int err;
 
-	mlxsw_reg_sbpr_pack(sbpr_pl, des->pool, des->dir, mode, size);
+	mlxsw_reg_sbpr_pack(sbpr_pl, des->pool, des->dir, mode,
+			    size, infi_size);
 	err = mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(sbpr), sbpr_pl);
 	if (err)
 		return err;
 
+	if (infi_size)
+		size = mlxsw_sp_bytes_cells(mlxsw_sp, mlxsw_sp->sb->sb_size);
 	pr = mlxsw_sp_sb_pr_get(mlxsw_sp, pool_index);
 	pr->mode = mode;
 	pr->size = size;
@@ -322,9 +328,17 @@ static int mlxsw_sp_sb_prs_init(struct mlxsw_sp *mlxsw_sp,
 	int err;
 
 	for (i = 0; i < prs_len; i++) {
-		u32 size = mlxsw_sp_bytes_cells(mlxsw_sp, prs[i].size);
-
-		err = mlxsw_sp_sb_pr_write(mlxsw_sp, i, prs[i].mode, size);
+		u32 size = prs[i].size;
+		u32 size_cells;
+
+		if (size == MLXSW_SP_SB_INFI) {
+			err = mlxsw_sp_sb_pr_write(mlxsw_sp, i, prs[i].mode,
+						   0, true);
+		} else {
+			size_cells = mlxsw_sp_bytes_cells(mlxsw_sp, size);
+			err = mlxsw_sp_sb_pr_write(mlxsw_sp, i, prs[i].mode,
+						   size_cells, false);
+		}
 		if (err)
 			return err;
 	}
@@ -685,7 +699,8 @@ int mlxsw_sp_sb_pool_set(struct mlxsw_core *mlxsw_core,
 		return -EINVAL;
 
 	mode = (enum mlxsw_reg_sbpr_mode) threshold_type;
-	return mlxsw_sp_sb_pr_write(mlxsw_sp, pool_index, mode, pool_size);
+	return mlxsw_sp_sb_pr_write(mlxsw_sp, pool_index, mode,
+				    pool_size, false);
 }
 
 #define MLXSW_SP_SB_THRESHOLD_TO_ALPHA_OFFSET (-2) /* 3->1, 16->14 */