nfp: abm: allow to opt-out of RED offload

FW team asks to be able to not support RED even if NIC is capable
of buffering for testing and experimentation.  Add an opt-out flag.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/abm/ctrl.c

@@ -17,6 +17,8 @@
 #define NFP_NUM_BANDS_SYM_NAME	"_abi_pci_dscp_num_band_%u"
 #define NFP_ACT_MASK_SYM_NAME	"_abi_nfd_out_q_actions_%u"
 
+#define NFP_RED_SUPPORT_SYM_NAME	"_abi_nfd_out_red_offload_%u"
+
 #define NFP_QLVL_SYM_NAME	"_abi_nfd_out_q_lvls_%u%s"
 #define NFP_QLVL_STRIDE		16
 #define NFP_QLVL_BLOG_BYTES	0
@@ -358,6 +360,12 @@ int nfp_abm_ctrl_find_addrs(struct nfp_abm *abm)
 
 	abm->pf_id = nfp_cppcore_pcie_unit(pf->cpp);
 
+	/* Check if Qdisc offloads are supported */
+	res = nfp_pf_rtsym_read_optional(pf, NFP_RED_SUPPORT_SYM_NAME, 1);
+	if (res < 0)
+		return res;
+	abm->red_support = res;
+
 	/* Read count of prios and prio bands */
 	res = nfp_pf_rtsym_read_optional(pf, NFP_NUM_BANDS_SYM_NAME, 1);
 	if (res < 0)
@@ -390,6 +398,9 @@ int nfp_abm_ctrl_find_addrs(struct nfp_abm *abm)
 	}
 
 	/* Find level and stat symbols */
+	if (!abm->red_support)
+		return 0;
+
 	sym = nfp_abm_ctrl_find_q_rtsym(abm, NFP_QLVL_SYM_NAME,
 					NFP_QLVL_STRIDE);
 	if (IS_ERR(sym))

drivers/net/ethernet/netronome/nfp/abm/main.c

@@ -207,6 +207,9 @@ static int nfp_abm_eswitch_set_switchdev(struct nfp_abm *abm)
 	struct nfp_net *nn;
 	int err;
 
+	if (!abm->red_support)
+		return -EOPNOTSUPP;
+
 	err = nfp_abm_ctrl_qm_enable(abm);
 	if (err)
 		return err;
@@ -418,12 +421,26 @@ nfp_abm_port_get_stats_strings(struct nfp_app *app, struct nfp_port *port,
 	return data;
 }
 
+static int nfp_abm_fw_init_reset(struct nfp_abm *abm)
+{
+	unsigned int i;
+
+	if (!abm->red_support)
+		return 0;
+
+	for (i = 0; i < abm->num_bands * NFP_NET_MAX_RX_RINGS; i++) {
+		__nfp_abm_ctrl_set_q_lvl(abm, i, NFP_ABM_LVL_INFINITY);
+		__nfp_abm_ctrl_set_q_act(abm, i, NFP_ABM_ACT_DROP);
+	}
+
+	return nfp_abm_ctrl_qm_disable(abm);
+}
+
 static int nfp_abm_init(struct nfp_app *app)
 {
 	struct nfp_pf *pf = app->pf;
 	struct nfp_reprs *reprs;
 	struct nfp_abm *abm;
-	unsigned int i;
 	int err;
 
 	if (!pf->eth_tbl) {
@@ -460,18 +477,14 @@ static int nfp_abm_init(struct nfp_app *app)
 				   sizeof(*abm->thresholds), GFP_KERNEL);
 	if (!abm->thresholds)
 		goto err_free_thresh_umap;
-	for (i = 0; i < abm->num_bands * NFP_NET_MAX_RX_RINGS; i++)
-		__nfp_abm_ctrl_set_q_lvl(abm, i, NFP_ABM_LVL_INFINITY);
 
 	abm->actions = kvcalloc(abm->num_thresholds, sizeof(*abm->actions),
 				GFP_KERNEL);
 	if (!abm->actions)
 		goto err_free_thresh;
-	for (i = 0; i < abm->num_bands * NFP_NET_MAX_RX_RINGS; i++)
-		__nfp_abm_ctrl_set_q_act(abm, i, NFP_ABM_ACT_DROP);
 
 	/* We start in legacy mode, make sure advanced queuing is disabled */
-	err = nfp_abm_ctrl_qm_disable(abm);
+	err = nfp_abm_fw_init_reset(abm);
 	if (err)
 		goto err_free_act;
 

drivers/net/ethernet/netronome/nfp/abm/main.h

@@ -40,6 +40,7 @@ enum nfp_abm_q_action {
  * @app:	back pointer to nfp_app
  * @pf_id:	ID of our PF link
  *
+ * @red_support:	is RED offload supported
  * @num_prios:	number of supported DSCP priorities
  * @num_bands:	number of supported DSCP priority bands
  * @action_mask:	bitmask of supported actions
@@ -63,6 +64,7 @@ struct nfp_abm {
 	struct nfp_app *app;
 	unsigned int pf_id;
 
+	unsigned int red_support;
 	unsigned int num_prios;
 	unsigned int num_bands;
 	unsigned int action_mask;