net: dsa: lantiq_gswip: serialize access to the PCE registers

The GSWIP switch accesses various bridging layer tables (VLANs, FDBs,
forwarding rules) indirectly through PCE registers. These hardware
accesses are non-atomic, being comprised of several register reads and
writes.

These accesses are currently serialized by the rtnl_lock, but DSA is
changing its driver API and that lock will no longer be held when
calling ->port_fdb_add() and ->port_fdb_del().

So this driver needs to serialize the access to the PCE registers using
its own locking scheme. This patch adds that.

Note that the driver also uses the gswip_pce_load_microcode() function
to load a static configuration for the packet classification engine into
a table using the same registers. It is currently not protected, but
since that configuration is only done from the dsa_switch_ops :: setup
method, there is no risk of it being concurrent with other operations.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/lantiq_gswip.c b/drivers/net/dsa/lantiq_gswip.c
index a3e937a371ef1ca3ae4b69f74cbeb19800782377..7056d98d8177b3de1a94854e5d5bdccac7db3972 100644 (file)
--- a/drivers/net/dsa/lantiq_gswip.c
+++ b/drivers/net/dsa/lantiq_gswip.c
@@ -276,6 +276,7 @@ struct gswip_priv {
        int num_gphy_fw;
        struct gswip_gphy_fw *gphy_fw;
        u32 port_vlan_filter;
+       struct mutex pce_table_lock;
 };
 
 struct gswip_pce_table_entry {
@@ -523,10 +524,14 @@ static int gswip_pce_table_entry_read(struct gswip_priv *priv,
        u16 addr_mode = tbl->key_mode ? GSWIP_PCE_TBL_CTRL_OPMOD_KSRD :
                                        GSWIP_PCE_TBL_CTRL_OPMOD_ADRD;
 
+       mutex_lock(&priv->pce_table_lock);
+
        err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
                                     GSWIP_PCE_TBL_CTRL_BAS);
-       if (err)
+       if (err) {
+               mutex_unlock(&priv->pce_table_lock);
                return err;
+       }
 
        gswip_switch_w(priv, tbl->index, GSWIP_PCE_TBL_ADDR);
        gswip_switch_mask(priv, GSWIP_PCE_TBL_CTRL_ADDR_MASK |
@@ -536,8 +541,10 @@ static int gswip_pce_table_entry_read(struct gswip_priv *priv,
 
        err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
                                     GSWIP_PCE_TBL_CTRL_BAS);
-       if (err)
+       if (err) {
+               mutex_unlock(&priv->pce_table_lock);
                return err;
+       }
 
        for (i = 0; i < ARRAY_SIZE(tbl->key); i++)
                tbl->key[i] = gswip_switch_r(priv, GSWIP_PCE_TBL_KEY(i));
@@ -553,6 +560,8 @@ static int gswip_pce_table_entry_read(struct gswip_priv *priv,
        tbl->valid = !!(crtl & GSWIP_PCE_TBL_CTRL_VLD);
        tbl->gmap = (crtl & GSWIP_PCE_TBL_CTRL_GMAP_MASK) >> 7;
 
+       mutex_unlock(&priv->pce_table_lock);
+
        return 0;
 }
 
@@ -565,10 +574,14 @@ static int gswip_pce_table_entry_write(struct gswip_priv *priv,
        u16 addr_mode = tbl->key_mode ? GSWIP_PCE_TBL_CTRL_OPMOD_KSWR :
                                        GSWIP_PCE_TBL_CTRL_OPMOD_ADWR;
 
+       mutex_lock(&priv->pce_table_lock);
+
        err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
                                     GSWIP_PCE_TBL_CTRL_BAS);
-       if (err)
+       if (err) {
+               mutex_unlock(&priv->pce_table_lock);
                return err;
+       }
 
        gswip_switch_w(priv, tbl->index, GSWIP_PCE_TBL_ADDR);
        gswip_switch_mask(priv, GSWIP_PCE_TBL_CTRL_ADDR_MASK |
@@ -600,8 +613,12 @@ static int gswip_pce_table_entry_write(struct gswip_priv *priv,
        crtl |= GSWIP_PCE_TBL_CTRL_BAS;
        gswip_switch_w(priv, crtl, GSWIP_PCE_TBL_CTRL);
 
-       return gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
-                                     GSWIP_PCE_TBL_CTRL_BAS);
+       err = gswip_switch_r_timeout(priv, GSWIP_PCE_TBL_CTRL,
+                                    GSWIP_PCE_TBL_CTRL_BAS);
+
+       mutex_unlock(&priv->pce_table_lock);
+
+       return err;
 }
 
 /* Add the LAN port into a bridge with the CPU port by
@@ -2104,6 +2121,7 @@ static int gswip_probe(struct platform_device *pdev)
        priv->ds->priv = priv;
        priv->ds->ops = priv->hw_info->ops;
        priv->dev = dev;
+       mutex_init(&priv->pce_table_lock);
        version = gswip_switch_r(priv, GSWIP_VERSION);
 
        np = dev->of_node;