nfp: abm: enable advanced queuing on demand

ABM NIC FW has a cut-through mode where the PCIe queuing
is bypassed, thus working like our standard NIC FWs.  Use this
mode by default and only enable queuing in switchdev mode where
users can configure it.
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

@@ -36,10 +36,23 @@
 
 #include "../nfpcore/nfp_cpp.h"
 #include "../nfp_app.h"
+#include "../nfp_abi.h"
 #include "../nfp_main.h"
 #include "../nfp_net.h"
 #include "main.h"
 
+int nfp_abm_ctrl_qm_enable(struct nfp_abm *abm)
+{
+	return nfp_mbox_cmd(abm->app->pf, NFP_MBOX_PCIE_ABM_ENABLE,
+			    NULL, 0, NULL, 0);
+}
+
+int nfp_abm_ctrl_qm_disable(struct nfp_abm *abm)
+{
+	return nfp_mbox_cmd(abm->app->pf, NFP_MBOX_PCIE_ABM_DISABLE,
+			    NULL, 0, NULL, 0);
+}
+
 void nfp_abm_ctrl_read_params(struct nfp_abm_link *alink)
 {
 	alink->queue_base = nn_readl(alink->vnic, NFP_NET_CFG_START_RXQ);

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

@@ -182,6 +182,7 @@ static enum devlink_eswitch_mode nfp_abm_eswitch_mode_get(struct nfp_app *app)
 static int nfp_abm_eswitch_set_legacy(struct nfp_abm *abm)
 {
 	nfp_abm_kill_reprs_all(abm);
+	nfp_abm_ctrl_qm_disable(abm);
 
 	abm->eswitch_mode = DEVLINK_ESWITCH_MODE_LEGACY;
 	return 0;
@@ -200,6 +201,10 @@ static int nfp_abm_eswitch_set_switchdev(struct nfp_abm *abm)
 	struct nfp_net *nn;
 	int err;
 
+	err = nfp_abm_ctrl_qm_enable(abm);
+	if (err)
+		return err;
+
 	list_for_each_entry(nn, &pf->vnics, vnic_list) {
 		struct nfp_abm_link *alink = nn->app_priv;
 
@@ -217,6 +222,7 @@ static int nfp_abm_eswitch_set_switchdev(struct nfp_abm *abm)
 
 err_kill_all_reprs:
 	nfp_abm_kill_reprs_all(abm);
+	nfp_abm_ctrl_qm_disable(abm);
 	return err;
 }
 
@@ -350,6 +356,11 @@ static int nfp_abm_init(struct nfp_app *app)
 	if (err)
 		goto err_free_abm;
 
+	/* We start in legacy mode, make sure advanced queuing is disabled */
+	err = nfp_abm_ctrl_qm_disable(abm);
+	if (err)
+		goto err_free_abm;
+
 	err = -ENOMEM;
 	reprs = nfp_reprs_alloc(pf->max_data_vnics);
 	if (!reprs)

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

@@ -72,4 +72,6 @@ struct nfp_abm_link {
 
 void nfp_abm_ctrl_read_params(struct nfp_abm_link *alink);
 int nfp_abm_ctrl_find_addrs(struct nfp_abm *abm);
+int nfp_abm_ctrl_qm_enable(struct nfp_abm *abm);
+int nfp_abm_ctrl_qm_disable(struct nfp_abm *abm);
 #endif

drivers/net/ethernet/netronome/nfp/nfp_abi.h

@@ -59,12 +59,26 @@
  * @NFP_MBOX_POOL_SET:	set shared buffer pool info/config
  * Input  - struct nfp_shared_buf_pool_info_set
  * Output - None
+ *
+ * @NFP_MBOX_PCIE_ABM_ENABLE:	enable PCIe-side advanced buffer management
+ * Enable advanced buffer management of the PCIe block.  If ABM is disabled
+ * PCIe block maintains a very short queue of buffers and does tail drop.
+ * ABM allows more advanced buffering and priority control.
+ * Input  - None
+ * Output - None
+ *
+ * @NFP_MBOX_PCIE_ABM_DISABLE:	disable PCIe-side advanced buffer management
+ * Input  - None
+ * Output - None
  */
 enum nfp_mbox_cmd {
 	NFP_MBOX_NO_CMD			= 0x00,
 
 	NFP_MBOX_POOL_GET		= 0x01,
 	NFP_MBOX_POOL_SET		= 0x02,
+
+	NFP_MBOX_PCIE_ABM_ENABLE	= 0x03,
+	NFP_MBOX_PCIE_ABM_DISABLE	= 0x04,
 };
 
 #define NFP_SHARED_BUF_COUNT_SYM_NAME	"_abi_nfd_pf%u_sb_cnt"