[PATCH net-next v4] net: dsa: mxl-gsw1xx: force internal PHYs into a known reset state

[A. Sverdlin]

From: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxxxx>

When bootstrapped with PS_NOWAIT = 0 the internal PHYs stay held in
reset, so the driver only worked with PS_NOWAIT = 1 where they are
released automatically.

Add a ->setup() hook, run before the MDIO bus is registered so PHY IDs
are readable during the bus scan, that programs the RST_REQ PHY reset
lines: release the PHYs of used (DSA user) ports and hold all other
internal PHYs in reset. Driving both directions yields the same state
regardless of the PS_NOWAIT bootstrap and keeps unused PHYs from staying
powered.

A single 300ms settle delay is applied only when at least one PHY is
released.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxxxx>
---
Changelog:
v4:
- dropped PHY_INTERFACE_MODE_INTERNAL and "phy-handle" dance
- now correctly asserting the reset bits of the unused PHYs
v3:
- put unused PHYs into reset state (changed patch subject accordingly)
- https://lore.kernel.org/all/20260915091856.1375914-1-alexander.sverdlin@xxxxxxxxxxx/
v2:
- Reverse Christmas tree.
- https://lore.kernel.org/all/20260908103030.4032992-1-alexander.sverdlin@xxxxxxxxxxx/
v1:
- https://lore.kernel.org/all/20260901165049.672446-1-alexander.sverdlin@xxxxxxxxxxx/

 drivers/net/dsa/lantiq/lantiq_gswip.h        |  2 ++
 drivers/net/dsa/lantiq/lantiq_gswip_common.c | 10 ++++++
 drivers/net/dsa/lantiq/mxl-gsw1xx.c          | 35 ++++++++++++++++++++
 drivers/net/dsa/lantiq/mxl-gsw1xx.h          |  1 +
 4 files changed, 48 insertions(+)

diff --git a/drivers/net/dsa/lantiq/lantiq_gswip.h b/drivers/net/dsa/lantiq/lantiq_gswip.h
index 0b75be14dc109..4f95877c59d1d 100644
--- a/drivers/net/dsa/lantiq/lantiq_gswip.h
+++ b/drivers/net/dsa/lantiq/lantiq_gswip.h
@@ -261,6 +261,8 @@ struct gswip_hw_info {
 	const struct gswip_pce_microcode (*pce_microcode)[];
 	size_t pce_microcode_size;
 	enum dsa_tag_protocol tag_protocol;
+
+	int (*setup)(struct dsa_switch *ds);
 	void (*phylink_get_caps)(struct dsa_switch *ds, int port,
 				 struct phylink_config *config);
 	struct phylink_pcs *(*mac_select_pcs)(struct phylink_config *config,
diff --git a/drivers/net/dsa/lantiq/lantiq_gswip_common.c b/drivers/net/dsa/lantiq/lantiq_gswip_common.c
index 6150dc3ffb641..7c53ded178367 100644
--- a/drivers/net/dsa/lantiq/lantiq_gswip_common.c
+++ b/drivers/net/dsa/lantiq/lantiq_gswip_common.c
@@ -689,6 +689,16 @@ static int gswip_setup(struct dsa_switch *ds)
 	 */
 	regmap_write(priv->mdio, GSWIP_MDIO_MDC_CFG0, 0x0);
 
+	/* GSW1xx will wake up the PHYs here, so it makes sense that it happens
+	 * after the auto-polling deactivation above, but before the MDIO bus
+	 * registration below
+	 */
+	if (priv->hw_info->setup) {
+		err = priv->hw_info->setup(ds);
+		if (err)
+			return err;
+	}
+
 	/* Configure the MDIO Clock 2.5 MHz */
 	regmap_write_bits(priv->mdio, GSWIP_MDIO_MDC_CFG1, 0xff, 0x09);
 
diff --git a/drivers/net/dsa/lantiq/mxl-gsw1xx.c b/drivers/net/dsa/lantiq/mxl-gsw1xx.c
index 66bf7e3319057..5722a9fadc0a7 100644
--- a/drivers/net/dsa/lantiq/mxl-gsw1xx.c
+++ b/drivers/net/dsa/lantiq/mxl-gsw1xx.c
@@ -589,6 +589,37 @@ static void gsw150_phylink_get_caps(struct dsa_switch *ds, int port,
 	gsw1xx_phylink_get_lpi_caps(config);
 }
 
+static int gsw1xx_setup(struct dsa_switch *ds)
+{
+	struct gsw1xx_priv *priv = container_of(ds->priv, struct gsw1xx_priv, gswip);
+	struct gswip_priv *gswip_priv = ds->priv;
+	u32 phy_mask = 0, active_mask = 0;
+	int port, ret;
+
+	/* Reset bits exist only for the internal-PHY ports preceding the first
+	 * MII port.
+	 */
+	for (port = 0; port < gswip_priv->hw_info->max_ports; port++) {
+		if (gswip_priv->hw_info->mii_cfg[port] != -1)
+			break;
+
+		phy_mask |= GSW1XX_RST_REQ_PHY(port);
+
+		if (dsa_port_is_user(dsa_to_port(ds, port)))
+			active_mask |= GSW1XX_RST_REQ_PHY(port);
+	}
+
+	ret = regmap_update_bits(priv->shell, GSW1XX_SHELL_RST_REQ, phy_mask,
+				 phy_mask & ~active_mask);
+	if (ret)
+		return ret;
+
+	if (active_mask)
+		msleep(300);
+
+	return 0;
+}
+
 static struct phylink_pcs *gsw1xx_phylink_mac_select_pcs(struct phylink_config *config,
 							 phy_interface_t interface)
 {
@@ -830,6 +861,7 @@ static const struct gswip_hw_info gsw12x_data = {
 		[GSW1XX_MII_PORT] = GSWIP_MII_PCDU0,
 		[GSW1XX_MII_PORT + 1 ... GSWIP_MAX_PORTS - 1] = -1,
 	},
+	.setup			= gsw1xx_setup,
 	.mac_select_pcs		= gsw1xx_phylink_mac_select_pcs,
 	.phylink_get_caps	= &gsw1xx_phylink_get_caps,
 	.supports_2500m		= true,
@@ -852,6 +884,7 @@ static const struct gswip_hw_info gsw140_data = {
 		[GSW1XX_MII_PORT] = GSWIP_MII_PCDU0,
 		[GSW1XX_MII_PORT + 1 ... GSWIP_MAX_PORTS - 1] = -1,
 	},
+	.setup			= gsw1xx_setup,
 	.mac_select_pcs		= gsw1xx_phylink_mac_select_pcs,
 	.phylink_get_caps	= &gsw1xx_phylink_get_caps,
 	.supports_2500m		= true,
@@ -874,6 +907,7 @@ static const struct gswip_hw_info gsw141_data = {
 		[GSW1XX_MII_PORT] = GSWIP_MII_PCDU0,
 		[GSW1XX_MII_PORT + 1 ... GSWIP_MAX_PORTS - 1] = -1,
 	},
+	.setup			= gsw1xx_setup,
 	.mac_select_pcs		= gsw1xx_phylink_mac_select_pcs,
 	.phylink_get_caps	= gsw1xx_phylink_get_caps,
 	.port_setup		= gsw1xx_port_setup,
@@ -895,6 +929,7 @@ static const struct gswip_hw_info gsw150_data = {
 		[5] = 1,
 		[6] = 11,
 	},
+	.setup			= gsw1xx_setup,
 	.phylink_get_caps	= gsw150_phylink_get_caps,
 	/* There is only a single RGMII_SLEW_CFG register in GSW150 and it is
 	 * unknown if RGMII slew configuration affects both RGMII ports
diff --git a/drivers/net/dsa/lantiq/mxl-gsw1xx.h b/drivers/net/dsa/lantiq/mxl-gsw1xx.h
index caa8f1008587a..a7976a5988bd8 100644
--- a/drivers/net/dsa/lantiq/mxl-gsw1xx.h
+++ b/drivers/net/dsa/lantiq/mxl-gsw1xx.h
@@ -110,6 +110,7 @@
 #define GSW1XX_SHELL_BASE			0xfa00
 #define  GSW1XX_SHELL_RST_REQ			0x01
 #define   GSW1XX_RST_REQ_SGMII_SHELL		BIT(5)
+#define   GSW1XX_RST_REQ_PHY(p)			BIT(p)
 #define  GSW1XX_SHELL_MANU_ID			0x10
 #define   GSW1XX_SHELL_MANU_ID_PNUML		GENMASK(15, 12)
 #define   GSW1XX_SHELL_MANU_ID_MANID		GENMASK(11, 1)
-- 
2.55.0