[net-next PATCH v2 13/14] net: macb: Support external PCSs

Sean Anderson
2025-04-07T23:22:10Z

This adds support for external PCSs. For example, the Xilinx UltraScale+
processor exposes its GMII interface to the FPGA fabric. This fabric may
implement PCS to convert GMII to a serial interface such as SGMII or
1000BASE-X. When present, the external PCS takes precedence over the
internal PCSs.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
---

Changes in v2:
- Move update to macb_pcs_get_state to previous patch

drivers/net/ethernet/cadence/macb.h | 1 +
drivers/net/ethernet/cadence/macb_main.c | 26 ++++++++++++++++++++++--
2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index c9a5c8beb2fa..9d310814f052 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -1291,6 +1291,7 @@ struct macb {
struct phylink_config phylink_config;
struct phylink_pcs phylink_usx_pcs;
struct phylink_pcs phylink_sgmii_pcs;
+ struct phylink_pcs *phylink_ext_pcs;

u32 caps;
unsigned int dma_burst_length;
diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index ed37b1d85212..61810c914270 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -21,6 +21,7 @@
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/dma-mapping.h>
+#include <linux/pcs.h>
#include <linux/platform_device.h>
#include <linux/phylink.h>
#include <linux/of.h>
@@ -707,7 +708,10 @@ static struct phylink_pcs *macb_mac_select_pcs(struct phylink_config *config,
struct net_device *ndev = to_net_dev(config->dev);
struct macb *bp = netdev_priv(ndev);

- if (interface == PHY_INTERFACE_MODE_10GBASER)
+ if (bp->phylink_ext_pcs &&
+ test_bit(interface, bp->phylink_ext_pcs->supported_interfaces))
+ return bp->phylink_ext_pcs;
+ else if (interface == PHY_INTERFACE_MODE_10GBASER)
return &bp->phylink_usx_pcs;
else if (interface == PHY_INTERFACE_MODE_SGMII)
return &bp->phylink_sgmii_pcs;
@@ -733,7 +737,10 @@ static void macb_mac_config(struct phylink_config *config, unsigned int mode,
if (state->interface == PHY_INTERFACE_MODE_RMII)
ctrl |= MACB_BIT(RM9200_RMII);
} else if (macb_is_gem(bp)) {
- if (macb_mac_select_pcs(config, state->interface))
+ struct phylink_pcs *pcs = macb_mac_select_pcs(config,
+ state->interface);
+
+ if (pcs && pcs != bp->phylink_ext_pcs)
ctrl |= GEM_BIT(PCSSEL);
else
ctrl &= ~GEM_BIT(PCSSEL);
@@ -907,6 +914,14 @@ static int macb_mii_probe(struct net_device *dev)
bp->phylink_sgmii_pcs.ops = &macb_phylink_pcs_ops;
bp->phylink_usx_pcs.ops = &macb_phylink_usx_pcs_ops;

+ bp->phylink_ext_pcs = pcs_get_by_fwnode_optional(&bp->pdev->dev,
+ bp->pdev->dev.fwnode,
+ NULL);
+ if (IS_ERR(bp->phylink_ext_pcs))
+ return dev_err_probe(&bp->pdev->dev,
+ PTR_ERR(bp->phylink_ext_pcs),
+ "Could not get external PCS\n");
+
bp->phylink_config.dev = &dev->dev;
bp->phylink_config.type = PHYLINK_NETDEV;
bp->phylink_config.mac_managed_pm = true;
@@ -924,6 +939,11 @@ static int macb_mii_probe(struct net_device *dev)
__set_bit(PHY_INTERFACE_MODE_RMII,
bp->phylink_config.supported_interfaces);

+ if (bp->phylink_ext_pcs)
+ phy_interface_or(bp->phylink_config.supported_interfaces,
+ bp->phylink_config.supported_interfaces,
+ bp->phylink_ext_pcs->supported_interfaces);
+
/* Determine what modes are supported */
if (macb_is_gem(bp) && (bp->caps & MACB_CAPS_GIGABIT_MODE_AVAILABLE)) {
bp->phylink_config.mac_capabilities |= MAC_1000FD;
@@ -950,6 +970,7 @@ static int macb_mii_probe(struct net_device *dev)
if (IS_ERR(bp->phylink)) {
netdev_err(dev, "Could not create a phylink instance (%ld)\n",
PTR_ERR(bp->phylink));
+ pcs_put(&bp->pdev->dev, bp->phylink_ext_pcs);
return PTR_ERR(bp->phylink);
}

@@ -5462,6 +5483,7 @@ static void macb_remove(struct platform_device *pdev)
bp->rx_clk, bp->tsu_clk);
pm_runtime_set_suspended(&pdev->dev);
}
+ pcs_put(&pdev->dev, bp->phylink_ext_pcs);
phylink_destroy(bp->phylink);
free_netdev(dev);
}
--
2.35.1.1320.gc452695387.dirty