[PATCH net-next v2] net: dsa: yt921x: Add limited ACL flow statistics support

[PATCH net-next v2] net: dsa: yt921x: Add limited ACL flow statistics support

[David Yang]

The yt921x supports flow statistics, which might be used to implement
.cls_flower_stats(). However, the number of flow counter are limited,
and you must choose between byte mode or packet mode. As there is no
interface for statistics preference for now, we pick one on our own
initiative.

Signed-off-by: David Yang <mmyangfl@gmail.com>
---
v1: https://lore.kernel.org/r/20260610202508.845328-1-mmyangfl@gmail.com
  - use a safe counter reader
  - use flow_stats_update()
  - do not use hardware counter if assisted by software
  - set extack on exhausted counter
 drivers/net/dsa/yt921x.c | 135 ++++++++++++++++++++++++++++++++++++++-
 drivers/net/dsa/yt921x.h |  17 +++++
 2 files changed, 151 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/yt921x.c b/drivers/net/dsa/yt921x.c
index 9929676a15e1..3dddedd0776a 100644
--- a/drivers/net/dsa/yt921x.c
+++ b/drivers/net/dsa/yt921x.c
@@ -266,6 +266,36 @@ yt921x_reg_toggle_bits(struct yt921x_priv *priv, u32 reg, u32 mask, bool set)
 	return yt921x_reg_update_bits(priv, reg, mask, !set ? 0 : mask);
 }
 
+/* Reliably read a 64bit counter */
+static int yt921x_counter_read(struct yt921x_priv *priv, u32 reg, u64 *valp)
+{
+	u32 old_lo;
+	int res;
+	u32 hi;
+	u32 lo;
+
+	res = yt921x_reg_read(priv, reg, &old_lo);
+	if (res)
+		return res;
+
+	for (int i = 0; i < 16; i++) {
+		res = yt921x_reg_read(priv, reg + 4, &hi);
+		if (res)
+			return res;
+		res = yt921x_reg_read(priv, reg, &lo);
+		if (res)
+			return res;
+
+		if (lo >= old_lo) {
+			*valp = ((u64)hi << 32) | lo;
+			return 0;
+		}
+		old_lo = lo;
+	}
+
+	return -ETIMEDOUT;
+}
+
 /* Some multi-word registers, like VLANn_CTRL, should be treated as a single
  * long register. More specifically, writes to parts of its words won't become
  * visible, until the last word is written.
@@ -2167,6 +2197,8 @@ yt921x_acl_rule_ext_parse_flow(struct yt921x_acl_rule_ext *ruleext, int port,
 	yt921x_acl_rule_set_ports(&ruleext->r, 0, BIT(port));
 	ruleext->r.tag = cls->cookie;
 	ruleext->r.type = TC_SETUP_CLSFLOWER;
+	/* Align with sja1105 */
+	ruleext->r.stat_pkt_mode = true;
 	return 0;
 }
 
@@ -2224,6 +2256,47 @@ yt921x_acl_reserve(struct yt921x_priv *priv, unsigned int entscnt,
 	return UINT_MAX;
 }
 
+static int
+yt921x_acl_stat(struct yt921x_priv *priv, enum tc_setup_type type,
+		unsigned long tag, struct flow_stats *stats)
+{
+	struct yt921x_acl_rule *aclrule;
+	const struct yt921x_acl_blk *aclblk;
+	unsigned int statid;
+	unsigned int binid;
+	unsigned int blkid;
+	unsigned int entid;
+	u64 diff;
+	u64 stat;
+	int res;
+
+	entid = yt921x_acl_find(priv, type, tag);
+	if (entid == UINT_MAX)
+		return -ENOENT;
+
+	blkid = entid / YT921X_ACL_ENT_PER_BLK;
+	binid = entid % YT921X_ACL_ENT_PER_BLK;
+	aclblk = priv->acl_blks[blkid];
+	aclrule = aclblk->rules[binid];
+
+	if (!(aclrule->action[0] & YT921X_ACL_ACTa_FLOWSTAT_EN))
+		return -EOPNOTSUPP;
+
+	statid = FIELD_GET(YT921X_ACL_ACTa_FLOWSTAT_ID_M, aclrule->action[0]);
+	res = yt921x_counter_read(priv, YT921X_FLOWSTATn_STAT(statid), &stat);
+	if (res)
+		return res;
+
+	diff = stat - aclrule->laststat;
+	if (diff)
+		aclrule->lastused = jiffies;
+	aclrule->laststat = stat;
+	flow_stats_update(stats, aclrule->stat_pkt_mode ? 0 : diff,
+			  !aclrule->stat_pkt_mode ? 0 : diff, 0,
+			  aclrule->lastused, FLOW_ACTION_HW_STATS_IMMEDIATE);
+	return 0;
+}
+
 static int
 yt921x_acl_commit(struct yt921x_priv *priv, unsigned int entid, u8 entsmask)
 {
@@ -2336,6 +2409,10 @@ yt921x_acl_del(struct yt921x_priv *priv, enum tc_setup_type type,
 		clear_bit(FIELD_GET(YT921X_ACL_ACTa_METER_ID_M,
 				    aclrule->action[0]),
 			  priv->meters_map);
+	if (aclrule->action[0] & YT921X_ACL_ACTa_FLOWSTAT_EN)
+		clear_bit(FIELD_GET(YT921X_ACL_ACTa_FLOWSTAT_ID_M,
+				    aclrule->action[0]),
+			  priv->flowstats_map);
 	priv->acl_masks[blkid] &= ~aclrule->mask;
 	kvfree(aclrule);
 	if (!priv->acl_masks[blkid]) {
@@ -2353,13 +2430,15 @@ yt921x_acl_add(struct yt921x_priv *priv,
 	unsigned int entscnt = hweight8(ruleext->r.mask);
 	struct yt921x_acl_rule *aclrule;
 	struct yt921x_acl_blk *aclblk;
-	bool use_trap = false;
 	unsigned int meterid;
+	unsigned int statid;
 	unsigned long mask;
 	unsigned int binid;
 	unsigned int blkid;
 	unsigned int entid;
 	unsigned int o;
+	bool use_trap;
+	u32 ctrl;
 	int res;
 
 	/* Allocate resources */
@@ -2367,6 +2446,10 @@ yt921x_acl_add(struct yt921x_priv *priv,
 	if (entid == UINT_MAX)
 		return -EOPNOTSUPP;
 
+	use_trap = (ruleext->r.action[2] & YT921X_ACL_ACTc_FWD_EN) &&
+		   (FIELD_GET(YT921X_ACL_ACTc_FWD_M,
+			      ruleext->r.action[2]) == YT921X_ACL_ACTc_FWD_TRAP);
+
 	if (!(ruleext->r.action[0] & YT921X_ACL_ACTa_METER_EN)) {
 		meterid = YT921X_METER_NUM;
 	} else {
@@ -2386,6 +2469,35 @@ yt921x_acl_add(struct yt921x_priv *priv,
 		}
 	}
 
+	if (ruleext->r.sw_assisted && use_trap) {
+		statid = YT921X_FLOWSTAT_NUM;
+	} else {
+		statid = find_first_zero_bit(priv->flowstats_map,
+					     YT921X_FLOWSTAT_NUM);
+		if (statid >= YT921X_FLOWSTAT_NUM) {
+			NL_SET_ERR_MSG_MOD(extack,
+					   "No more flowstats available");
+		} else {
+			u32 zeros[2] = {};
+
+			ctrl = YT921X_FLOWSTAT_CTRL_TYPE_FLOW |
+			       YT921X_FLOWSTAT_CTRL_EN;
+			if (ruleext->r.stat_pkt_mode)
+				ctrl |= YT921X_FLOWSTAT_CTRL_PKT_MODE;
+			res = yt921x_reg_write(priv,
+					       YT921X_FLOWSTATn_CTRL(statid),
+					       ctrl);
+			if (res)
+				return res;
+
+			res = yt921x_reg64_write(priv,
+						 YT921X_FLOWSTATn_STAT(statid),
+						 zeros);
+			if (res)
+				return res;
+		}
+	}
+
 	/* Prepare acl block ctrlblk */
 	blkid = entid / YT921X_ACL_ENT_PER_BLK;
 	binid = entid % YT921X_ACL_ENT_PER_BLK;
@@ -2426,6 +2538,9 @@ yt921x_acl_add(struct yt921x_priv *priv,
 		aclrule->action[0] |= YT921X_ACL_ACTa_METER_ID(meterid);
 	else
 		aclrule->action[0] &= ~YT921X_ACL_ACTa_METER_EN;
+	if (statid < YT921X_FLOWSTAT_NUM)
+		aclrule->action[0] |= YT921X_ACL_ACTa_FLOWSTAT_EN |
+				      YT921X_ACL_ACTa_FLOWSTAT_ID(statid);
 
 	/* Write rules */
 	aclblk->rules[binid] = aclrule;
@@ -2438,6 +2553,8 @@ yt921x_acl_add(struct yt921x_priv *priv,
 
 	if (meterid < YT921X_METER_NUM)
 		set_bit(meterid, priv->meters_map);
+	if (statid < YT921X_FLOWSTAT_NUM)
+		set_bit(statid, priv->flowstats_map);
 	priv->acl_masks[blkid] |= aclrule->mask;
 	return 0;
 
@@ -2449,6 +2566,21 @@ yt921x_acl_add(struct yt921x_priv *priv,
 	return res;
 }
 
+static int
+yt921x_dsa_cls_flower_stats(struct dsa_switch *ds, int port,
+			    struct flow_cls_offload *cls, bool ingress)
+{
+	struct yt921x_priv *priv = to_yt921x_priv(ds);
+	int res;
+
+	mutex_lock(&priv->reg_lock);
+	res = yt921x_acl_stat(priv, TC_SETUP_CLSFLOWER, cls->cookie,
+			      &cls->stats);
+	mutex_unlock(&priv->reg_lock);
+
+	return res;
+}
+
 static int
 yt921x_dsa_cls_flower_del(struct dsa_switch *ds, int port,
 			  struct flow_cls_offload *cls, bool ingress)
@@ -4817,6 +4949,7 @@ static const struct dsa_switch_ops yt921x_dsa_switch_ops = {
 	.port_policer_add	= yt921x_dsa_port_policer_add,
 	.port_setup_tc		= yt921x_dsa_port_setup_tc,
 	/* acl */
+	.cls_flower_stats	= yt921x_dsa_cls_flower_stats,
 	.cls_flower_del		= yt921x_dsa_cls_flower_del,
 	.cls_flower_add		= yt921x_dsa_cls_flower_add,
 	/* hsr */
diff --git a/drivers/net/dsa/yt921x.h b/drivers/net/dsa/yt921x.h
index 555046526669..0851102d8b35 100644
--- a/drivers/net/dsa/yt921x.h
+++ b/drivers/net/dsa/yt921x.h
@@ -759,6 +759,16 @@ enum yt921x_l4_type {
 #define  YT921X_METER_CTRLa_EIR_M		GENMASK(17, 0)
 #define   YT921X_METER_CTRLa_EIR(x)			FIELD_PREP(YT921X_METER_CTRLa_EIR_M, (x))
 #define YT921X_METERn_STAT(x)		(0x221000 + 8 * (x))
+#define YT921X_FLOWSTATn_STAT(x)	(0x221400 + 8 * (x))
+#define YT921X_FLOWSTATn_CTRL(x)	(0x221c00 + 4 * (x))
+#define  YT921X_FLOWSTAT_CTRL_EN		BIT(3)
+#define  YT921X_FLOWSTAT_CTRL_PKT_MODE		BIT(2)	/* 0: byte mode */
+#define  YT921X_FLOWSTAT_CTRL_TYPE_M		GENMASK(1, 0)
+#define   YT921X_FLOWSTAT_CTRL_TYPE(x)			FIELD_PREP(YT921X_FLOWSTAT_CTRL_TYPE_M, (x))
+#define   YT921X_FLOWSTAT_CTRL_TYPE_FLOW		YT921X_FLOWSTAT_CTRL_TYPE(0)
+#define   YT921X_FLOWSTAT_CTRL_TYPE_CPU_CODE		YT921X_FLOWSTAT_CTRL_TYPE(1)
+#define   YT921X_FLOWSTAT_CTRL_TYPE_DROP_CODE		YT921X_FLOWSTAT_CTRL_TYPE(2)
+#define   YT921X_FLOWSTAT_CTRL_TYPE_PORT		YT921X_FLOWSTAT_CTRL_TYPE(3)
 
 #define YT921X_PORTn_VLAN_CTRL(port)	(0x230010 + 4 * (port))
 #define  YT921X_PORT_VLAN_CTRL_SVLAN_PRIO_EN	BIT(31)
@@ -830,6 +840,8 @@ enum yt921x_fdb_entry_status {
 #define YT921X_SHAPE_CIR_MAX	((1 << 18) - 1)
 #define YT921X_SHAPE_CBS_MAX	((1 << 14) - 1)
 
+#define YT921X_FLOWSTAT_NUM	64
+
 #define YT921X_LAG_NUM		2
 #define YT921X_LAG_PORT_NUM	4
 
@@ -920,6 +932,10 @@ struct yt921x_acl_rule {
 	u32 action[3];
 	bool sw_assisted;
 
+	bool stat_pkt_mode;
+	u64 laststat;
+	u64 lastused;
+
 	u8 mask;
 	struct yt921x_acl_entry entries[YT921X_ACL_ENT_PER_BLK];
 };
@@ -969,6 +985,7 @@ struct yt921x_priv {
 	u16 eee_ports_mask;
 
 	DECLARE_BITMAP(meters_map, YT921X_METER_NUM);
+	DECLARE_BITMAP(flowstats_map, YT921X_FLOWSTAT_NUM);
 
 	u8 acl_masks[YT921X_ACL_BLK_NUM];
 	struct yt921x_acl_blk *acl_blks[YT921X_ACL_BLK_NUM];
-- 
2.53.0

Re: [PATCH net-next v2] net: dsa: yt921x: Add limited ACL flow statistics support

[Jakub Kicinski]

On Mon, 15 Jun 2026 21:03:53 +0800 David Yang wrote:
> The yt921x supports flow statistics, which might be used to implement
> .cls_flower_stats(). However, the number of flow counter are limited,
> and you must choose between byte mode or packet mode. As there is no
> interface for statistics preference for now, we pick one on our own
> initiative.

net-next is closed, please repost after the merge window
-- 
pw-bot: defer