net: dsa: b53: fix ageing time for BCM53101

[ Upstream commit 674b34c4c770551e916ae707829c7faea4782d3a ]

For some reason Broadcom decided that BCM53101 uses 0.5s increments for
the ageing time register, but kept the field width the same [1]. Due to
this, the actual ageing time was always half of what was configured.

Fix this by adapting the limits and value calculation for BCM53101.

So far it looks like this is the only chip with the increased tick
speed:

$ grep -l -r "Specifies the aging time in 0.5 seconds" cdk/PKG/chip | sort
cdk/PKG/chip/bcm53101/bcm53101_a0_defs.h

$ grep -l -r "Specifies the aging time in seconds" cdk/PKG/chip | sort
cdk/PKG/chip/bcm53010/bcm53010_a0_defs.h
cdk/PKG/chip/bcm53020/bcm53020_a0_defs.h
cdk/PKG/chip/bcm53084/bcm53084_a0_defs.h
cdk/PKG/chip/bcm53115/bcm53115_a0_defs.h
cdk/PKG/chip/bcm53118/bcm53118_a0_defs.h
cdk/PKG/chip/bcm53125/bcm53125_a0_defs.h
cdk/PKG/chip/bcm53128/bcm53128_a0_defs.h
cdk/PKG/chip/bcm53134/bcm53134_a0_defs.h
cdk/PKG/chip/bcm53242/bcm53242_a0_defs.h
cdk/PKG/chip/bcm53262/bcm53262_a0_defs.h
cdk/PKG/chip/bcm53280/bcm53280_a0_defs.h
cdk/PKG/chip/bcm53280/bcm53280_b0_defs.h
cdk/PKG/chip/bcm53600/bcm53600_a0_defs.h
cdk/PKG/chip/bcm89500/bcm89500_a0_defs.h

[1] https://github.com/Broadcom/OpenMDK/blob/a5d3fc9b12af3eeb68f2ca0ce7ec4056cd14d6c2/cdk/PKG/chip/bcm53101/bcm53101_a0_defs.h#L28966

Fixes: e39d14a760c0 ("net: dsa: b53: implement setting ageing time")
Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://patch.msgid.link/20250905124507.59186-1-jonas.gorski@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/dsa/b53/b53_common.c b/drivers/net/dsa/b53/b53_common.c
index d15d912690c40e77660d06bd1f1765ca347cc0cc..073d20241a4c9cf847b664b2ca6eab3f6b4218ec 100644 (file)
--- a/drivers/net/dsa/b53/b53_common.c
+++ b/drivers/net/dsa/b53/b53_common.c
@@ -1229,9 +1229,15 @@ static int b53_setup(struct dsa_switch *ds)
         */
        ds->untag_vlan_aware_bridge_pvid = true;
 
-       /* Ageing time is set in seconds */
-       ds->ageing_time_min = 1 * 1000;
-       ds->ageing_time_max = AGE_TIME_MAX * 1000;
+       if (dev->chip_id == BCM53101_DEVICE_ID) {
+               /* BCM53101 uses 0.5 second increments */
+               ds->ageing_time_min = 1 * 500;
+               ds->ageing_time_max = AGE_TIME_MAX * 500;
+       } else {
+               /* Everything else uses 1 second increments */
+               ds->ageing_time_min = 1 * 1000;
+               ds->ageing_time_max = AGE_TIME_MAX * 1000;
+       }
 
        ret = b53_reset_switch(dev);
        if (ret) {
@@ -2448,7 +2454,10 @@ int b53_set_ageing_time(struct dsa_switch *ds, unsigned int msecs)
        else
                reg = B53_AGING_TIME_CONTROL;
 
-       atc = DIV_ROUND_CLOSEST(msecs, 1000);
+       if (dev->chip_id == BCM53101_DEVICE_ID)
+               atc = DIV_ROUND_CLOSEST(msecs, 500);
+       else
+               atc = DIV_ROUND_CLOSEST(msecs, 1000);
 
        if (!is5325(dev) && !is5365(dev))
                atc |= AGE_CHANGE;