[PATCH] lan743x: Added fixed link support

From: Roelof Berg
Date: Wed May 13 2020 - 15:07:41 EST


Microchip lan7431 is frequently connected to a phy. However, it
can also be directly connected to a MII remote peer without
any phy in between. For supporting such a phyless hardware setup
in Linux we added the capability to the driver to understand
the fixed-link and the phy-connection-type entries in the device
tree.

If a fixed-link node is configured in the device tree the lan7431
device will deactivate auto negotiation and uses the speed and
duplex settings configured in the fixed-link node.

Also the phy-connection-type can be configured in the device tree
and in case of a fixed-link connection the RGMII mode can be
configured, all other modes fall back to the default: GMII.

Example:

&pcie {
status = "okay";

host@0 {
reg = <0 0 0 0 0>;

#address-cells = <3>;
#size-cells = <2>;

ethernet@0 {
compatible = "weyland-yutani,noscom1", "microchip,lan743x";
status = "okay";
reg = <0 0 0 0 0>;
phy-connection-type = "rgmii";

fixed-link {
speed = <100>;
full-duplex;
};
};
};
};

Signed-off-by: Roelof Berg <rberg@xxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/microchip/lan743x_main.c | 94 +++++++++++++++++--
drivers/net/ethernet/microchip/lan743x_main.h | 4 +
2 files changed, 89 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index a43140f7b5eb..85f12881340b 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.c
+++ b/drivers/net/ethernet/microchip/lan743x_main.c
@@ -9,9 +9,12 @@
#include <linux/microchipphy.h>
#include <linux/net_tstamp.h>
#include <linux/phy.h>
+#include <linux/phy_fixed.h>
#include <linux/rtnetlink.h>
#include <linux/iopoll.h>
#include <linux/crc16.h>
+#include <linux/of_mdio.h>
+#include <linux/of_net.h>
#include "lan743x_main.h"
#include "lan743x_ethtool.h"

@@ -974,6 +977,8 @@ static void lan743x_phy_close(struct lan743x_adapter *adapter)

phy_stop(netdev->phydev);
phy_disconnect(netdev->phydev);
+ if (of_phy_is_fixed_link(adapter->pdev->dev.of_node))
+ of_phy_deregister_fixed_link(adapter->pdev->dev.of_node);
netdev->phydev = NULL;
}

@@ -982,18 +987,86 @@ static int lan743x_phy_open(struct lan743x_adapter *adapter)
struct lan743x_phy *phy = &adapter->phy;
struct phy_device *phydev;
struct net_device *netdev;
+ struct device_node *phynode;
+ u32 data;
+ phy_interface_t phyifc = PHY_INTERFACE_MODE_GMII;
+ bool fixed_link = false;
int ret = -EIO;

netdev = adapter->netdev;
- phydev = phy_find_first(adapter->mdiobus);
- if (!phydev)
- goto return_error;
+ phynode = of_node_get(adapter->pdev->dev.of_node);
+ if (phynode)
+ of_get_phy_mode(phynode, &phyifc);
+
+ /* check if a fixed-link is defined in device-tree */
+ if (phynode && of_phy_is_fixed_link(phynode)) {
+ fixed_link = true;
+ netdev_dbg(netdev, "fixed-link detected\n");
+
+ ret = of_phy_register_fixed_link(phynode);
+ if (ret) {
+ netdev_err(netdev, "cannot register fixed PHY\n");
+ goto return_error;
+ }

- ret = phy_connect_direct(netdev, phydev,
- lan743x_phy_link_status_change,
- PHY_INTERFACE_MODE_GMII);
- if (ret)
- goto return_error;
+ phydev = of_phy_connect(netdev, phynode,
+ lan743x_phy_link_status_change,
+ 0, phyifc);
+ if (!phydev)
+ goto return_error;
+
+ /* Configure MAC to fixed link parameters */
+ data = lan743x_csr_read(adapter, MAC_CR);
+ /* Disable auto negotiation */
+ data &= ~(MAC_CR_ADD_ | MAC_CR_ASD_);
+ /* Set duplex mode */
+ if (phydev->duplex)
+ data |= MAC_CR_DPX_;
+ else
+ data &= ~MAC_CR_DPX_;
+ /* Set bus speed */
+ switch (phydev->speed) {
+ case 10:
+ data &= ~MAC_CR_CFG_H_;
+ data &= ~MAC_CR_CFG_L_;
+ break;
+ case 100:
+ data &= ~MAC_CR_CFG_H_;
+ data |= MAC_CR_CFG_L_;
+ break;
+ case 1000:
+ data |= MAC_CR_CFG_H_;
+ data |= MAC_CR_CFG_L_;
+ break;
+ }
+ /* Set interface mode */
+ if (phyifc == PHY_INTERFACE_MODE_RGMII ||
+ phyifc == PHY_INTERFACE_MODE_RGMII_ID ||
+ phyifc == PHY_INTERFACE_MODE_RGMII_RXID ||
+ phyifc == PHY_INTERFACE_MODE_RGMII_TXID)
+ /* RGMII */
+ data &= ~MAC_CR_MII_EN_;
+ else
+ /* GMII */
+ data |= MAC_CR_MII_EN_;
+ lan743x_csr_write(adapter, MAC_CR, data);
+ } else {
+ phydev = phy_find_first(adapter->mdiobus);
+ if (!phydev)
+ goto return_error;
+
+ ret = phy_connect_direct(netdev, phydev,
+ lan743x_phy_link_status_change,
+ PHY_INTERFACE_MODE_GMII);
+ /* Note: We cannot use phyifc here because this would be SGMII
+ * on a standard PC.
+ */
+ if (ret)
+ goto return_error;
+ }
+
+ if (phynode)
+ of_node_put(phynode);

/* MAC doesn't support 1000T Half */
phy_remove_link_mode(phydev, ETHTOOL_LINK_MODE_1000baseT_Half_BIT);
@@ -1004,10 +1077,13 @@ static int lan743x_phy_open(struct lan743x_adapter *adapter)
phy->fc_autoneg = phydev->autoneg;

phy_start(phydev);
- phy_start_aneg(phydev);
+ if (!fixed_link)
+ phy_start_aneg(phydev);
return 0;

return_error:
+ if (phynode)
+ of_node_put(phynode);
return ret;
}

diff --git a/drivers/net/ethernet/microchip/lan743x_main.h b/drivers/net/ethernet/microchip/lan743x_main.h
index 3b02eeae5f45..e49f6b6cd440 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.h
+++ b/drivers/net/ethernet/microchip/lan743x_main.h
@@ -104,10 +104,14 @@
((value << 0) & FCT_FLOW_CTL_ON_THRESHOLD_)

#define MAC_CR (0x100)
+#define MAC_CR_MII_EN_ BIT(19)
#define MAC_CR_EEE_EN_ BIT(17)
#define MAC_CR_ADD_ BIT(12)
#define MAC_CR_ASD_ BIT(11)
#define MAC_CR_CNTR_RST_ BIT(5)
+#define MAC_CR_DPX_ BIT(3)
+#define MAC_CR_CFG_H_ BIT(2)
+#define MAC_CR_CFG_L_ BIT(1)
#define MAC_CR_RST_ BIT(0)

#define MAC_RX (0x104)
--
2.20.1