kernel: backport MT7530 ageing time support

Allow setting ageing time from 1 to 1,048,576 seconds.

Signed-off-by: DENG Qingfang <[email protected]>
Tested-by: Arınç ÜNAL <[email protected]>
Tested-by: Stijn Tintel <[email protected]>

target/linux/generic/backport-5.10/764-v5.11-net-dsa-mt7530-support-setting-ageing-time.patch

@@ -0,0 +1,99 @@
+From ea6d5c924e391872d402acac38461a5f8261e57f Mon Sep 17 00:00:00 2001
+From: DENG Qingfang <[email protected]>
+Date: Tue, 8 Dec 2020 15:00:28 +0800
+Subject: [PATCH] net: dsa: mt7530: support setting ageing time
+
+MT7530 has a global address age control register, so use it to set
+ageing time.
+
+The applied timer is (AGE_CNT + 1) * (AGE_UNIT + 1) seconds
+
+Signed-off-by: DENG Qingfang <[email protected]>
+Reviewed-by: Andrew Lunn <[email protected]>
+Reviewed-by: Vladimir Oltean <[email protected]>
+Reviewed-by: Florian Fainelli <[email protected]>
+Signed-off-by: David S. Miller <[email protected]>
+---
+ drivers/net/dsa/mt7530.c | 41 ++++++++++++++++++++++++++++++++++++++++
+ drivers/net/dsa/mt7530.h | 13 +++++++++++++
+ 2 files changed, 54 insertions(+)
+
+--- a/drivers/net/dsa/mt7530.c
++++ b/drivers/net/dsa/mt7530.c
+@@ -870,6 +870,46 @@ mt7530_get_sset_count(struct dsa_switch
+ 	return ARRAY_SIZE(mt7530_mib);
+ }
+ 
++static int
++mt7530_set_ageing_time(struct dsa_switch *ds, unsigned int msecs)
++{
++	struct mt7530_priv *priv = ds->priv;
++	unsigned int secs = msecs / 1000;
++	unsigned int tmp_age_count;
++	unsigned int error = -1;
++	unsigned int age_count;
++	unsigned int age_unit;
++
++	/* Applied timer is (AGE_CNT + 1) * (AGE_UNIT + 1) seconds */
++	if (secs < 1 || secs > (AGE_CNT_MAX + 1) * (AGE_UNIT_MAX + 1))
++		return -ERANGE;
++
++	/* iterate through all possible age_count to find the closest pair */
++	for (tmp_age_count = 0; tmp_age_count <= AGE_CNT_MAX; ++tmp_age_count) {
++		unsigned int tmp_age_unit = secs / (tmp_age_count + 1) - 1;
++
++		if (tmp_age_unit <= AGE_UNIT_MAX) {
++			unsigned int tmp_error = secs -
++				(tmp_age_count + 1) * (tmp_age_unit + 1);
++
++			/* found a closer pair */
++			if (error > tmp_error) {
++				error = tmp_error;
++				age_count = tmp_age_count;
++				age_unit = tmp_age_unit;
++			}
++
++			/* found the exact match, so break the loop */
++			if (!error)
++				break;
++		}
++	}
++
++	mt7530_write(priv, MT7530_AAC, AGE_CNT(age_count) | AGE_UNIT(age_unit));
++
++	return 0;
++}
++
+ static void mt7530_setup_port5(struct dsa_switch *ds, phy_interface_t interface)
+ {
+ 	struct mt7530_priv *priv = ds->priv;
+@@ -2699,6 +2739,7 @@ static const struct dsa_switch_ops mt753
+ 	.phy_write		= mt753x_phy_write,
+ 	.get_ethtool_stats	= mt7530_get_ethtool_stats,
+ 	.get_sset_count		= mt7530_get_sset_count,
++	.set_ageing_time	= mt7530_set_ageing_time,
+ 	.port_enable		= mt7530_port_enable,
+ 	.port_disable		= mt7530_port_disable,
+ 	.port_change_mtu	= mt7530_port_change_mtu,
+--- a/drivers/net/dsa/mt7530.h
++++ b/drivers/net/dsa/mt7530.h
+@@ -161,6 +161,19 @@ enum mt7530_vlan_egress_attr {
+ 	MT7530_VLAN_EGRESS_STACK = 3,
+ };
+ 
++/* Register for address age control */
++#define MT7530_AAC			0xa0
++/* Disable ageing */
++#define  AGE_DIS			BIT(20)
++/* Age count */
++#define  AGE_CNT_MASK			GENMASK(19, 12)
++#define  AGE_CNT_MAX			0xff
++#define  AGE_CNT(x)			(AGE_CNT_MASK & ((x) << 12))
++/* Age unit */
++#define  AGE_UNIT_MASK			GENMASK(11, 0)
++#define  AGE_UNIT_MAX			0xfff
++#define  AGE_UNIT(x)			(AGE_UNIT_MASK & (x))
++
+ /* Register for port STP state control */
+ #define MT7530_SSP_P(x)			(0x2000 + ((x) * 0x100))
+ #define  FID_PST(x)			((x) & 0x3)