net: dsa: microchip: ksz8: Make flow control, speed, and duplex on CPU port configurable

Allow flow control, speed, and duplex settings on the CPU port to be
configurable. Previously, the speed and duplex relied on default switch
values, which limited flexibility. Additionally, flow control was
hardcoded and only functional in duplex mode. This update enhances the
configurability of these parameters.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/20231127145101.3039399-2-o.rempel@pengutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

3 files changed, 56 insertions, 2 deletions

diff --git a/drivers/net/dsa/microchip/ksz8.h b/drivers/net/dsa/microchip/ksz8.h
index 4cea811e73ac..1a5225264e6a 100644
--- a/drivers/net/dsa/microchip/ksz8.h
+++ b/drivers/net/dsa/microchip/ksz8.h
@@ -56,5 +56,9 @@ int ksz8_reset_switch(struct ksz_device *dev);
 int ksz8_switch_init(struct ksz_device *dev);
 void ksz8_switch_exit(struct ksz_device *dev);
 int ksz8_change_mtu(struct ksz_device *dev, int port, int mtu);
+void ksz8_phylink_mac_link_up(struct ksz_device *dev, int port,
+			      unsigned int mode, phy_interface_t interface,
+			      struct phy_device *phydev, int speed, int duplex,
+			      bool tx_pause, bool rx_pause);
 
 #endif
diff --git a/drivers/net/dsa/microchip/ksz8795.c b/drivers/net/dsa/microchip/ksz8795.c
index 4bf4d67557dc..88b10aa527d6 100644
--- a/drivers/net/dsa/microchip/ksz8795.c
+++ b/drivers/net/dsa/microchip/ksz8795.c
@@ -1439,6 +1439,57 @@ void ksz8_config_cpu_port(struct dsa_switch *ds)
 	}
 }
 
+/**
+ * ksz8_cpu_port_link_up - Configures the CPU port of the switch.
+ * @dev: The KSZ device instance.
+ * @speed: The desired link speed.
+ * @duplex: The desired duplex mode.
+ * @tx_pause: If true, enables transmit pause.
+ * @rx_pause: If true, enables receive pause.
+ *
+ * Description:
+ * The function configures flow control and speed settings for the CPU
+ * port of the switch based on the desired settings, current duplex mode, and
+ * speed.
+ */
+static void ksz8_cpu_port_link_up(struct ksz_device *dev, int speed, int duplex,
+				  bool tx_pause, bool rx_pause)
+{
+	const u16 *regs = dev->info->regs;
+	u8 ctrl = 0;
+
+	/* SW_FLOW_CTRL, SW_HALF_DUPLEX, and SW_10_MBIT bits are bootstrappable
+	 * at least on KSZ8873. They can have different values depending on your
+	 * board setup.
+	 */
+	if (tx_pause || rx_pause)
+		ctrl |= SW_FLOW_CTRL;
+
+	if (duplex == DUPLEX_HALF)
+		ctrl |= SW_HALF_DUPLEX;
+
+	/* This hardware only supports SPEED_10 and SPEED_100. For SPEED_10
+	 * we need to set the SW_10_MBIT bit. Otherwise, we can leave it 0.
+	 */
+	if (speed == SPEED_10)
+		ctrl |= SW_10_MBIT;
+
+	ksz_rmw8(dev, regs[S_BROADCAST_CTRL], SW_HALF_DUPLEX | SW_FLOW_CTRL |
+		 SW_10_MBIT, ctrl);
+}
+
+void ksz8_phylink_mac_link_up(struct ksz_device *dev, int port,
+			      unsigned int mode, phy_interface_t interface,
+			      struct phy_device *phydev, int speed, int duplex,
+			      bool tx_pause, bool rx_pause)
+{
+	/* If the port is the CPU port, apply special handling. Only the CPU
+	 * port is configured via global registers.
+	 */
+	if (dev->cpu_port == port)
+		ksz8_cpu_port_link_up(dev, speed, duplex, tx_pause, rx_pause);
+}
+
 static int ksz8_handle_global_errata(struct dsa_switch *ds)
 {
 	struct ksz_device *dev = ds->priv;
@@ -1487,8 +1538,6 @@ int ksz8_setup(struct dsa_switch *ds)
 	 */
 	ds->vlan_filtering_is_global = true;
 
-	ksz_cfg(dev, S_REPLACE_VID_CTRL, SW_FLOW_CTRL, true);
-
 	/* Enable automatic fast aging when link changed detected. */
 	ksz_cfg(dev, S_LINK_AGING_CTRL, SW_LINK_AUTO_AGING, true);
 
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c
index 3fed406fb46a..0ee7cfb8d4bd 100644
--- a/drivers/net/dsa/microchip/ksz_common.c
+++ b/drivers/net/dsa/microchip/ksz_common.c
@@ -277,6 +277,7 @@ static const struct ksz_dev_ops ksz8_dev_ops = {
 	.mirror_add = ksz8_port_mirror_add,
 	.mirror_del = ksz8_port_mirror_del,
 	.get_caps = ksz8_get_caps,
+	.phylink_mac_link_up = ksz8_phylink_mac_link_up,
 	.config_cpu_port = ksz8_config_cpu_port,
 	.enable_stp_addr = ksz8_enable_stp_addr,
 	.reset = ksz8_reset_switch,