[PATCH net-next v1] r8169: implement get_module functions for rtl8127atf

Fabio Baltieri
2026-04-04T20:13:37Z

Implement get_module_info and get_module_eeprom for supported devices,
right now that's the rtl8127atf.

This enables using ethtool to retrieve the transceiver identification
and diagnostic data.

Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
---

Hi,

Realtek released a new out of tree driver for the rtl8127 and it
includes some code that exposes the I2C controller connected to the SFP
port.

This patch implements get_module_info and get_module_eeprom based on the
information found on that driver, it allows ethtool to fetch the SFP
module information, which is useful both to identify the module and to
track the health of fiber optic transceivers.

The logic for the SFF standard and i2c address selection is borrowed
directly from the aquantia/atlantic driver, I don't have a lot of stuff
to test it but I was able to trigger all code paths from a fiber optic
transceiver and an SFP cable I have available.

Demo:

# Fiber transceiver
$ sudo ethtool -m eth1
Identifier : 0x03 (SFP)
Extended identifier : 0x04 (GBIC/SFP defined by 2-wire interface ID)
Connector : 0x07 (LC)
Transceiver codes : 0x10 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
Transceiver type : 10G Ethernet: 10G Base-SR
Encoding : 0x06 (64B/66B)
BR Nominal : 10300MBd
Rate identifier : 0x00 (unspecified)
Length (SMF) : 0km
Length (OM2) : 80m
Length (OM1) : 30m
Length (Copper or Active cable) : 0m
Length (OM3) : 300m
Laser wavelength : 850nm
Vendor name : QSFPTEK
Vendor OUI : 00:0a:0d
Vendor PN : QT-SFP+-SR
Vendor rev :
Option values : 0x00 0x1a
Option : TX_DISABLE implemented
BR margin max : 10%
BR margin min : 88%
Vendor SN : QT8250805131
Date code : 250806
Optical diagnostics support : Yes
Laser bias current : 5.880 mA
Laser output power : 0.5431 mW / -2.65 dBm
Receiver signal average optical power : 0.6912 mW / -1.60 dBm
Module temperature : 20.70 degrees C / 69.25 degrees F
Module voltage : 3.3000 V
...

# DAC
$ sudo ethtool -m eth1
Identifier : 0x03 (SFP)
Extended identifier : 0x04 (GBIC/SFP defined by 2-wire interface ID)
Connector : 0x21 (Copper pigtail)
Transceiver codes : 0x00 0x00 0x00 0x00 0x00 0x04 0x00 0x00 0x00
Transceiver type : Passive Cable
Encoding : 0x00 (unspecified)
BR Nominal : 10300MBd
Rate identifier : 0x00 (unspecified)
Length (SMF) : 0km
Length (OM2) : 0m
Length (OM1) : 0m
Length (Copper or Active cable) : 1m
Length (OM3) : 0m
Passive Cu cmplnce. : 0x01 (SFF-8431 appendix E [SFF-8472 rev10.4 only])
Vendor name : OEM
Vendor OUI : 00:40:20
Vendor PN : SFP-H10GB-CU1M
Vendor rev : R
Option values : 0x00 0x00
BR margin max : 0%
BR margin min : 0%
Vendor SN : CSC240415030053
Date code : 240508
...

# No module
$ sudo ethtool -m eth1
netlink error: Input/output error

Cheers,
Fabio

drivers/net/ethernet/realtek/r8169_main.c | 177 ++++++++++++++++++++++
1 file changed, 177 insertions(+)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 58788d196c57..45ec0b5c1c21 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -2411,6 +2411,181 @@ static int rtl8169_set_link_ksettings(struct net_device *ndev,
return 0;
}

+#define R8127_SDS_I2C_CON 0xe200
+#define R8127_SDS_I2C_TAR 0xe204
+#define R8127_SDS_I2C_DATA_CMD 0xe210
+#define R8127_SDS_I2C_FS_SCL_HCNT 0xe21c
+#define R8127_SDS_I2C_FS_SCL_LCNT 0xe220
+#define R8127_SDS_I2C_INTR_STAT 0xe22c
+#define R8127_SDS_I2C_EN 0xe26c
+#define R8127_SDS_I2C_STATUS 0xe270
+
+#define R8127_SDS_I2C_STATUS_ACTIVITY BIT(0)
+#define R8127_SDS_I2C_RX_FIFO_NOT_EMPTY BIT(3)
+#define R8127_SDS_I2C_STAT_TX_ABRT BIT(6)
+
+#define R8127_SDS_I2C_CMD_READ BIT(8)
+#define R8127_SDS_I2C_CMD_STOP BIT(9)
+#define R8127_SDS_I2C_CMD_RESTART BIT(10)
+
+#define SFF_8472_ID_ADDR 0x50
+#define SFF_8472_DIAGNOSTICS_ADDR 0x51
+
+#define SFF_8472_COMP_ADDR 0x5e
+#define SFF_8472_DOM_TYPE_ADDR 0x5c
+
+#define SFF_8472_ADDRESS_CHANGE_REQ_MASK 0x4
+
+static void r8127_sfp_sds_i2c_init(struct rtl8169_private *tp, u8 addr)
+{
+ r8168_mac_ocp_write(tp, R8127_SDS_I2C_EN, 0);
+ r8168_mac_ocp_write(tp, R8127_SDS_I2C_CON, 0x65);
+ r8168_mac_ocp_write(tp, R8127_SDS_I2C_TAR, addr);
+ r8168_mac_ocp_write(tp, R8127_SDS_I2C_FS_SCL_HCNT, 0x23a);
+ r8168_mac_ocp_write(tp, R8127_SDS_I2C_FS_SCL_LCNT, 0x23a);
+ r8168_mac_ocp_write(tp, R8127_SDS_I2C_EN, 1);
+}
+
+static void r8127_sfp_sds_i2c_disable(struct rtl8169_private *tp)
+{
+ r8168_mac_ocp_write(tp, R8127_SDS_I2C_EN, 0);
+}
+
+DECLARE_RTL_COND(r8127_sfp_sds_i2c_idle_cond)
+{
+ u16 val;
+
+ val = r8168_mac_ocp_read(tp, R8127_SDS_I2C_STATUS);
+
+ return val & R8127_SDS_I2C_STATUS_ACTIVITY;
+}
+
+DECLARE_RTL_COND(r8127_sfp_sds_i2c_rx_fifo_cond)
+{
+ u16 val;
+
+ val = r8168_mac_ocp_read(tp, R8127_SDS_I2C_STATUS);
+
+ return val & R8127_SDS_I2C_RX_FIFO_NOT_EMPTY;
+}
+
+static int r8127_sfp_sds_i2c_read(struct rtl8169_private *tp,
+ u8 addr, u8 off, u8 *buf, u16 len)
+{
+ u16 intr_stat;
+ int ret = 0;
+
+ r8127_sfp_sds_i2c_init(tp, addr);
+
+ r8168_mac_ocp_write(tp, R8127_SDS_I2C_DATA_CMD, off);
+
+ if (!rtl_loop_wait_low(tp, &r8127_sfp_sds_i2c_idle_cond, 10, 100)) {
+ ret = -EIO;
+ goto out;
+ }
+
+ intr_stat = r8168_mac_ocp_read(tp, R8127_SDS_I2C_INTR_STAT);
+ if (intr_stat & R8127_SDS_I2C_STAT_TX_ABRT) {
+ /* NACK */
+ ret = -EIO;
+ goto out;
+ }
+
+ for (int i = 0; i < len; i++) {
+ u16 data = R8127_SDS_I2C_CMD_READ;
+
+ if (i == len - 1)
+ data |= R8127_SDS_I2C_CMD_STOP;
+ if (i == 0)
+ data |= R8127_SDS_I2C_CMD_RESTART;
+
+ r8168_mac_ocp_write(tp, R8127_SDS_I2C_DATA_CMD, data);
+
+ if (!rtl_loop_wait_high(tp, &r8127_sfp_sds_i2c_rx_fifo_cond,
+ 10, 1000)) {
+ ret = -ETIMEDOUT;
+ goto out;
+ }
+
+ buf[i] = r8168_mac_ocp_read(tp, R8127_SDS_I2C_DATA_CMD);
+ }
+
+out:
+ r8127_sfp_sds_i2c_disable(tp);
+
+ return ret;
+}
+
+static int rtl8169_get_module_info(struct net_device *ndev,
+ struct ethtool_modinfo *modinfo)
+{
+ struct rtl8169_private *tp = netdev_priv(ndev);
+ u8 compliance_val, dom_type;
+ int ret;
+
+ if (!tp->sfp_mode)
+ return -EOPNOTSUPP;
+
+ ret = r8127_sfp_sds_i2c_read(tp, SFF_8472_ID_ADDR,
+ SFF_8472_COMP_ADDR, &compliance_val, 1);
+ if (ret)
+ return ret;
+
+ ret = r8127_sfp_sds_i2c_read(tp, SFF_8472_ID_ADDR,
+ SFF_8472_DOM_TYPE_ADDR, &dom_type, 1);
+ if (ret)
+ return ret;
+
+ if (dom_type & SFF_8472_ADDRESS_CHANGE_REQ_MASK || compliance_val == 0x00) {
+ modinfo->type = ETH_MODULE_SFF_8079;
+ modinfo->eeprom_len = ETH_MODULE_SFF_8079_LEN;
+ } else {
+ modinfo->type = ETH_MODULE_SFF_8472;
+ modinfo->eeprom_len = ETH_MODULE_SFF_8472_LEN;
+ }
+
+ return 0;
+}
+
+static int rtl8169_get_module_eeprom(struct net_device *ndev,
+ struct ethtool_eeprom *ee, unsigned char *data)
+{
+ struct rtl8169_private *tp = netdev_priv(ndev);
+ unsigned int first, last, len;
+ int ret;
+
+ if (!tp->sfp_mode)
+ return -EOPNOTSUPP;
+
+ first = ee->offset;
+ last = ee->offset + ee->len;
+
+ if (first < ETH_MODULE_SFF_8079_LEN) {
+ len = min(last, ETH_MODULE_SFF_8079_LEN);
+ len -= first;
+
+ ret = r8127_sfp_sds_i2c_read(tp, SFF_8472_ID_ADDR,
+ first, data, len);
+ if (ret)
+ return ret;
+
+ first += len;
+ data += len;
+ }
+ if (first < ETH_MODULE_SFF_8472_LEN && last > ETH_MODULE_SFF_8079_LEN) {
+ len = min(last, ETH_MODULE_SFF_8472_LEN);
+ len -= first;
+ first -= ETH_MODULE_SFF_8079_LEN;
+
+ ret = r8127_sfp_sds_i2c_read(tp, SFF_8472_DIAGNOSTICS_ADDR,
+ first, data, len);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
static const struct ethtool_ops rtl8169_ethtool_ops = {
.supported_coalesce_params = ETHTOOL_COALESCE_USECS |
ETHTOOL_COALESCE_MAX_FRAMES,
@@ -2437,6 +2612,8 @@ static const struct ethtool_ops rtl8169_ethtool_ops = {
.set_pauseparam = rtl8169_set_pauseparam,
.get_eth_mac_stats = rtl8169_get_eth_mac_stats,
.get_eth_ctrl_stats = rtl8169_get_eth_ctrl_stats,
+ .get_module_info = rtl8169_get_module_info,
+ .get_module_eeprom = rtl8169_get_module_eeprom,
};

static const struct rtl_chip_info *rtl8169_get_chip_version(u32 xid, bool gmii)
--
2.47.3