[RFC PATCH net-next v3 1/5] net: dsa: pass PHY flags when connecting shared ports

[Yongzhao Chen <yongzhao.derek@gmail.com>]

DSA calls get_phy_flags() for user ports, but passes zero when connecting
CPU or DSA port PHYs. Pass the callback result before PHY initialization
for shared ports too. Drivers without the callback still pass zero.

Keep bcm_sf2 and ksz88xx shared-port flags at zero, preserving their
existing behavior. Document the extended callback scope.

This lets qca8k pass revision information and a SmartSpeed quirk to an
internal PHY used as a CPU link. The remaining patches supply that user.

Assisted-by: LLM
Signed-off-by: Yongzhao Chen <yongzhao.derek@gmail.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 Documentation/networking/dsa/dsa.rst | 2 ++
 drivers/net/dsa/bcm_sf2.c            | 4 ++++
 drivers/net/dsa/microchip/ksz8.c     | 4 ++++
 net/dsa/port.c                       | 6 +++++-
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/Documentation/networking/dsa/dsa.rst b/Documentation/networking/dsa/dsa.rst
index 7edfdd555..647f952e3 100644
--- a/Documentation/networking/dsa/dsa.rst
+++ b/Documentation/networking/dsa/dsa.rst
@@ -668,6 +668,8 @@ PHY devices and link management
   on its own (e.g.: coming from switch memory mapped registers), this function
   should return a 32-bit bitmask of "flags" that is private between the switch
   driver and the Ethernet PHY driver in ``drivers/net/phy/\*``.
+  It is called when connecting PHYs for user, CPU and DSA ports. Drivers
+  should return zero for ports that do not need switch-specific PHY flags.
 
 - ``phy_read``: Function invoked by the DSA user MDIO bus when attempting to read
   the switch port MDIO registers. If unavailable, return 0xffff for each read.
diff --git a/drivers/net/dsa/bcm_sf2.c b/drivers/net/dsa/bcm_sf2.c
index 9e5713015..f516fc396 100644
--- a/drivers/net/dsa/bcm_sf2.c
+++ b/drivers/net/dsa/bcm_sf2.c
@@ -709,6 +709,10 @@ static u32 bcm_sf2_sw_get_phy_flags(struct dsa_switch *ds, int port)
 {
 	struct bcm_sf2_priv *priv = bcm_sf2_to_priv(ds);
 
+	/* Shared ports previously received no PHY flags. */
+	if (!dsa_is_user_port(ds, port))
+		return 0;
+
 	/* The BCM7xxx PHY driver expects to find the integrated PHY revision
 	 * in bits 15:8 and the patch level in bits 7:0 which is exactly what
 	 * the REG_PHY_REVISION register layout is.
diff --git a/drivers/net/dsa/microchip/ksz8.c b/drivers/net/dsa/microchip/ksz8.c
index d74981320..be8861a7a 100644
--- a/drivers/net/dsa/microchip/ksz8.c
+++ b/drivers/net/dsa/microchip/ksz8.c
@@ -3076,6 +3076,10 @@ static u32 ksz88xx_get_phy_flags(struct dsa_switch *ds, int port)
 {
 	struct ksz_device *dev = ds->priv;
 
+	/* Shared ports previously received no PHY flags. */
+	if (!dsa_is_user_port(ds, port))
+		return 0;
+
 	switch (dev->chip_id) {
 	case KSZ88X3_CHIP_ID:
 		/* Silicon Errata Sheet (DS80000830A):
diff --git a/net/dsa/port.c b/net/dsa/port.c
index 1f5536c0d..4db7e6f9c 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -1666,6 +1666,7 @@ static int dsa_shared_port_phylink_register(struct dsa_port *dp)
 {
 	struct dsa_switch *ds = dp->ds;
 	struct device_node *port_dn = dp->dn;
+	u32 phy_flags = 0;
 	int err;
 
 	dp->pl_config.dev = ds->dev;
@@ -1675,7 +1676,10 @@ static int dsa_shared_port_phylink_register(struct dsa_port *dp)
 	if (err)
 		return err;
 
-	err = phylink_of_phy_connect(dp->pl, port_dn, 0);
+	if (ds->ops->get_phy_flags)
+		phy_flags = ds->ops->get_phy_flags(ds, dp->index);
+
+	err = phylink_of_phy_connect(dp->pl, port_dn, phy_flags);
 	if (err && err != -ENODEV) {
 		pr_err("could not attach to PHY: %d\n", err);
 		goto err_phy_connect;
-- 
2.43.0