[PATCH v5 net-next 13/15] net: dsa: netc: initialize buffer pool table and implement flow-control

Wei Fang
2026-04-30T02:49:30Z

The buffer pool is a quantity of memory available for buffering a group
of flows (e.g. frames having the same priority, frames received from the
same port), while waiting to be transmitted on a port. The buffer pool
tracks internal memory consumption with upper bound limits and optionally
a non-shared portion when associated with a shared buffer pool. Currently
the shared buffer pool is not supported, it will be added in the future.

For i.MX94, the switch has 4 ports and 8 buffer pools, so each port is
allocated two buffer pools. For frames with priorities of 0 to 3, they
will be mapped to the first buffer pool; For frames with priorities of
4 to 7, they will be mapped to the second buffer pool. Each buffer pool
has a flow control on threshold and a flow control off threshold. By
setting these threshold, add the flow control support to each port.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
---
drivers/net/dsa/netc/netc_main.c | 128 ++++++++++++++++++++++++++
drivers/net/dsa/netc/netc_platform.c | 2 +-
drivers/net/dsa/netc/netc_switch.h | 19 ++++
drivers/net/dsa/netc/netc_switch_hw.h | 10 ++
4 files changed, 158 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/netc/netc_main.c b/drivers/net/dsa/netc/netc_main.c
index 7f1ab1fbb6fb..fd02a943824d 100644
--- a/drivers/net/dsa/netc/netc_main.c
+++ b/drivers/net/dsa/netc/netc_main.c
@@ -208,6 +208,9 @@ static void netc_get_switch_capabilities(struct netc_switch *priv)

val = netc_base_rd(regs, NETC_FDBHTCAPR);
priv->num_fdb_gmac = FIELD_GET(FDBHTCAPR_NUM_GMAC, val);
+
+ val = netc_base_rd(regs, NETC_BPCAPR);
+ priv->num_bp = FIELD_GET(BPCAPR_NUM_BP, val);
}

static int netc_init_all_ports(struct netc_switch *priv)
@@ -398,6 +401,15 @@ static void netc_port_fixed_config(struct netc_port *np)
/* Enable L2 and L3 DOS */
netc_port_rmw(np, NETC_PCR, PCR_L2DOSE | PCR_L3DOSE,
PCR_L2DOSE | PCR_L3DOSE);
+
+ /* Set the quanta value of TX PAUSE frame */
+ netc_mac_port_wr(np, NETC_PM_PAUSE_QUANTA(0), NETC_PAUSE_QUANTA);
+
+ /* When a quanta timer counts down and reaches this value,
+ * the MAC sends a refresh PAUSE frame with the programmed
+ * full quanta value if a pause condition still exists.
+ */
+ netc_mac_port_wr(np, NETC_PM_PAUSE_THRESH(0), NETC_PAUSE_THRESH);
}

static void netc_port_default_config(struct netc_port *np)
@@ -617,6 +629,77 @@ static int netc_add_standalone_fdb_bcast_entry(struct netc_switch *priv)
bcast, NETC_STANDALONE_PVID);
}

+static void netc_port_set_pbpmcr(struct netc_port *np, u64 mapping)
+{
+ u32 pbpmcr0 = lower_32_bits(mapping);
+ u32 pbpmcr1 = upper_32_bits(mapping);
+
+ netc_port_wr(np, NETC_PBPMCR0, pbpmcr0);
+ netc_port_wr(np, NETC_PBPMCR1, pbpmcr1);
+}
+
+static void netc_ipv_to_buffer_pool_mapping(struct netc_switch *priv)
+{
+ int bp_per_port = priv->num_bp / priv->info->num_ports;
+ int q = NETC_IPV_NUM / bp_per_port;
+ int r = NETC_IPV_NUM % bp_per_port;
+ int num = q + r;
+
+ /* IPV-to–buffer-pool mapping per port:
+ * Each port is allocated 'bp_per_port' buffer pools and supports 8
+ * IPVs, where a higher IPV indicates a higher frame priority. Each
+ * IPV can be mapped to only one buffer pool.
+ *
+ * The mapping rule is as follows:
+ * - The first 'num' IPVs share the port's first buffer pool (index
+ * 'base_id').
+ * - After that, every 'q' IPVs share one buffer pool, with pool
+ * indices increasing sequentially.
+ */
+ for (int i = 0; i < priv->info->num_ports; i++) {
+ u32 base_id = i * bp_per_port;
+ u32 bp_id = base_id;
+ u64 mapping = 0;
+
+ for (int ipv = 0; ipv < NETC_IPV_NUM; ipv++) {
+ /* Update the buffer pool index */
+ if (ipv >= num)
+ bp_id = base_id + ((ipv - num) / q) + 1;
+
+ mapping |= (u64)bp_id << (ipv * 8);
+ }
+
+ netc_port_set_pbpmcr(priv->ports[i], mapping);
+ }
+}
+
+static int netc_switch_bpt_default_config(struct netc_switch *priv)
+{
+ if (priv->num_bp < priv->info->num_ports)
+ return -EINVAL;
+
+ priv->bpt_list = devm_kcalloc(priv->dev, priv->num_bp,
+ sizeof(struct bpt_cfge_data),
+ GFP_KERNEL);
+ if (!priv->bpt_list)
+ return -ENOMEM;
+
+ /* Initialize the maximum threshold of each buffer pool entry */
+ for (int i = 0; i < priv->num_bp; i++) {
+ struct bpt_cfge_data *cfge = &priv->bpt_list[i];
+ int err;
+
+ cfge->max_thresh = cpu_to_le16(NETC_BP_THRESH);
+ err = ntmp_bpt_update_entry(&priv->ntmp, i, cfge);
+ if (err)
+ return err;
+ }
+
+ netc_ipv_to_buffer_pool_mapping(priv);
+
+ return 0;
+}
+
static int netc_setup(struct dsa_switch *ds)
{
struct netc_switch *priv = ds->priv;
@@ -646,6 +729,10 @@ static int netc_setup(struct dsa_switch *ds)
dsa_switch_for_each_available_port(dp, ds)
netc_port_default_config(priv->ports[dp->index]);

+ err = netc_switch_bpt_default_config(priv);
+ if (err)
+ goto free_lock_and_ntmp_user;
+
err = netc_add_standalone_vlan_entry(priv);
if (err)
goto free_lock_and_ntmp_user;
@@ -1201,6 +1288,45 @@ static void netc_port_set_rmii_mii_mac(struct netc_port *np,
netc_mac_port_rmw(np, NETC_PM_IF_MODE(0), mask, val);
}

+static void netc_port_set_tx_pause(struct netc_port *np, bool tx_pause)
+{
+ struct netc_switch *priv = np->switch_priv;
+ int port = np->dp->index;
+ int i, j, num_bp;
+
+ num_bp = priv->num_bp / priv->info->num_ports;
+ for (i = 0, j = port * num_bp; i < num_bp; i++, j++) {
+ struct bpt_cfge_data *cfge = &priv->bpt_list[j];
+ struct bpt_cfge_data old_cfge = *cfge;
+
+ if (tx_pause) {
+ cfge->fc_on_thresh = cpu_to_le16(NETC_FC_THRESH_ON);
+ cfge->fc_off_thresh = cpu_to_le16(NETC_FC_THRESH_OFF);
+ cfge->fccfg_sbpen = FIELD_PREP(BPT_FC_CFG,
+ BPT_FC_CFG_EN_BPFC);
+ cfge->fc_ports = cpu_to_le32(BIT(port));
+ } else {
+ cfge->fc_on_thresh = cpu_to_le16(0);
+ cfge->fc_off_thresh = cpu_to_le16(0);
+ cfge->fccfg_sbpen = 0;
+ cfge->fc_ports = cpu_to_le32(0);
+ }
+
+ if (ntmp_bpt_update_entry(&priv->ntmp, j, cfge)) {
+ *cfge = old_cfge;
+ dev_warn(priv->dev,
+ "Failed to %s TX pause of buffer pool %d (swp%d)\n",
+ tx_pause ? "enable" : "disable", j, port);
+ }
+ }
+}
+
+static void netc_port_set_rx_pause(struct netc_port *np, bool rx_pause)
+{
+ netc_mac_port_rmw(np, NETC_PM_CMD_CFG(0), PM_CMD_CFG_PAUSE_IGN,
+ rx_pause ? 0 : PM_CMD_CFG_PAUSE_IGN);
+}
+
static void netc_port_mac_rx_enable(struct netc_port *np)
{
netc_port_rmw(np, NETC_POR, POR_RXDIS, 0);
@@ -1302,6 +1428,8 @@ static void netc_mac_link_up(struct phylink_config *config,
interface == PHY_INTERFACE_MODE_MII)
netc_port_set_rmii_mii_mac(np, speed, duplex);

+ netc_port_set_tx_pause(np, tx_pause);
+ netc_port_set_rx_pause(np, rx_pause);
netc_port_mac_tx_enable(np);
netc_port_mac_rx_enable(np);
}
diff --git a/drivers/net/dsa/netc/netc_platform.c b/drivers/net/dsa/netc/netc_platform.c
index bb4f92d238cb..34aeb6fceb3c 100644
--- a/drivers/net/dsa/netc/netc_platform.c
+++ b/drivers/net/dsa/netc/netc_platform.c
@@ -14,7 +14,7 @@ struct netc_switch_platform {
static void imx94_switch_phylink_get_caps(int port,
struct phylink_config *config)
{
- config->mac_capabilities = MAC_1000FD;
+ config->mac_capabilities = MAC_ASYM_PAUSE | MAC_SYM_PAUSE | MAC_1000FD;

switch (port) {
case 0 ... 1:
diff --git a/drivers/net/dsa/netc/netc_switch.h b/drivers/net/dsa/netc/netc_switch.h
index 3efe37fca390..9fea3d4287a3 100644
--- a/drivers/net/dsa/netc/netc_switch.h
+++ b/drivers/net/dsa/netc/netc_switch.h
@@ -27,11 +27,27 @@

#define NETC_TC_NUM 8
#define NETC_CBDR_NUM 2
+#define NETC_IPV_NUM 8

#define NETC_MAX_FRAME_LEN 9600

#define NETC_STANDALONE_PVID 0

+/* Threshold format: MANT (bits 11:4) * 2^EXP (bits 3:0)
+ * Unit: Memory words (average of 20 bytes each)
+ * NETC_BP_THRESH = 0x334, MANT = 0x33, EXP = 4. Threshold: 816 words
+ * NETC_FC_THRESH_ON = 0x533, MANT = 0x53, EXP = 3. Threshold: 664 words
+ * NETC_FC_THRESH_OFF = 0x3c3, MANT = 0x3c, EXP = 3. Threshold: 480 words
+ */
+#define NETC_BP_THRESH 0x334
+#define NETC_FC_THRESH_ON 0x533
+#define NETC_FC_THRESH_OFF 0x3c3
+
+/* PAUSE quanta: 0xFFFF = 65535 quanta (each quanta = 512 bit times) */
+#define NETC_PAUSE_QUANTA 0xFFFF
+/* PAUSE refresh threshold: send refresh when timer reaches this value */
+#define NETC_PAUSE_THRESH 0xFF00
+
struct netc_switch;

struct netc_switch_info {
@@ -93,6 +109,9 @@ struct netc_switch {

/* Switch hardware capabilities */
u32 num_fdb_gmac;
+ u32 num_bp;
+
+ struct bpt_cfge_data *bpt_list;
};

#define NETC_PRIV(ds) ((struct netc_switch *)((ds)->priv))
diff --git a/drivers/net/dsa/netc/netc_switch_hw.h b/drivers/net/dsa/netc/netc_switch_hw.h
index b04e9866d72a..caf5977c5100 100644
--- a/drivers/net/dsa/netc/netc_switch_hw.h
+++ b/drivers/net/dsa/netc/netc_switch_hw.h
@@ -12,6 +12,12 @@
#define NETC_SWITCH_DEVICE_ID 0xeef2

/* Definition of Switch base registers */
+#define NETC_BPCAPR 0x0008
+#define BPCAPR_NUM_BP GENMASK(7, 0)
+
+#define NETC_PBPMCR0 0x0400
+#define NETC_PBPMCR1 0x0404
+
#define NETC_CBDRMR(a) (0x0800 + (a) * 0x30)
#define NETC_CBDRBAR0(a) (0x0810 + (a) * 0x30)
#define NETC_CBDRBAR1(a) (0x0814 + (a) * 0x30)
@@ -141,6 +147,7 @@ enum netc_stg_stage {
#define NETC_PM_CMD_CFG(a) (0x1008 + (a) * 0x400)
#define PM_CMD_CFG_TX_EN BIT(0)
#define PM_CMD_CFG_RX_EN BIT(1)
+#define PM_CMD_CFG_PAUSE_IGN BIT(8)

#define NETC_PM_MAXFRM(a) (0x1014 + (a) * 0x400)
#define PM_MAXFRAM GENMASK(15, 0)
@@ -149,6 +156,9 @@ enum netc_stg_stage {
#define PM_IEVENT_TX_EMPTY BIT(5)
#define PM_IEVENT_RX_EMPTY BIT(6)

+#define NETC_PM_PAUSE_QUANTA(a) (0x1054 + (a) * 0x400)
+#define NETC_PM_PAUSE_THRESH(a) (0x1064 + (a) * 0x400)
+
#define NETC_PM_IF_MODE(a) (0x1300 + (a) * 0x400)
#define PM_IF_MODE_IFMODE GENMASK(2, 0)
#define IFMODE_MII 1
--
2.34.1