[PATCH] net: phy: Add TJA1100 BroadR-Reach PHY driver.

[Kirill Kranke <kranke.kirill@gmail.com>]

Current generic PHY driver does not work with TJA1100 BroadR-REACH PHY
properly. TJA1100 does not have any standard ability enabled at MII_BMSR
register. Instead it has BroadR-REACH ability at MII_ESTATUS enabled, which
is not handled by generic driver yet. Therefore generic driver is unable to
guess required link speed, duplex etc. Device is started up with 10Mbps
halfduplex which is incorrect.

BroadR-REACH able flag is not specified in IEEE802.3-2015. Which is why I
did not add BroadR-REACH able flag support at generic driver. Once
BroadR-REACH able flag gets into IEEE802.3 it should be reasonable to
support it in the generic PHY driver.

Signed-off-by: Kirill Kranke <kranke.kirill@gmail.com>

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 343989f..7014eb7 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -422,6 +422,14 @@ config TERANETICS_PHY
 	---help---
 	  Currently supports the Teranetics TN2020
 
+config TJA1100_PHY
+	tristate "NXP TJA1100 PHY"
+	help
+	  Support of NXP TJA1100 BroadR-REACH ethernet PHY.
+	  Generic driver is not suitable for TJA1100 PHY while the PHY does not
+	  advertise any standard IEEE capabilities. It uses BroadR-REACH able
+	  flag instead. This driver configures capabilities of the PHY properly.
+
 config VITESSE_PHY
 	tristate "Vitesse PHYs"
 	---help---
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 5805c0b..4d2a69d 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -83,5 +83,6 @@ obj-$(CONFIG_ROCKCHIP_PHY)	+= rockchip.o
 obj-$(CONFIG_SMSC_PHY)		+= smsc.o
 obj-$(CONFIG_STE10XP)		+= ste10Xp.o
 obj-$(CONFIG_TERANETICS_PHY)	+= teranetics.o
+obj-$(CONFIG_TJA1100_PHY)	+= tja1100.o
 obj-$(CONFIG_VITESSE_PHY)	+= vitesse.o
 obj-$(CONFIG_XILINX_GMII2RGMII) += xilinx_gmii2rgmii.o
diff --git a/drivers/net/phy/tja1100.c b/drivers/net/phy/tja1100.c
new file mode 100644
index 0000000..cddf4d7
--- /dev/null
+++ b/drivers/net/phy/tja1100.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+/* tja1100.c: TJA1100 BoardR-REACH PHY driver.
+ *
+ * Copyright (c) 2017 Kirill Kranke <kirill.kranke@gmail.com>
+ * Author: Kirill Kranke <kirill.kranke@gmail.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/phy.h>
+
+static int tja1100_phy_config_init(struct phy_device *phydev)
+{
+	phydev->autoneg = AUTONEG_DISABLE;
+	phydev->speed = SPEED_100;
+	phydev->duplex = DUPLEX_FULL;
+
+	return 0;
+}
+
+static int tja1100_phy_config_aneg(struct phy_device *phydev)
+{
+	if (phydev->autoneg == AUTONEG_ENABLE) {
+		phydev_err(phydev, "autonegotiation is not supported\n");
+		return -EINVAL;
+	}
+
+	if (phydev->speed != SPEED_100 || phydev->duplex != DUPLEX_FULL) {
+		phydev_err(phydev, "only 100MBps Full Duplex allowed\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct phy_driver tja1100_phy_driver[] = {
+	{
+		.phy_id = 0x0180dc48,
+		.phy_id_mask = 0xfffffff0,
+		.name = "NXP TJA1100",
+
+		/* TJA1100 has only 100BASE-BroadR-REACH ability specified
+		 * at MII_ESTATUS register. Standard modes are not
+		 * supported. Therefore BroadR-REACH allow only 100Mbps
+		 * full duplex without autoneg.
+		 */
+		.features = SUPPORTED_100baseT_Full | SUPPORTED_MII,
+
+		.config_aneg = tja1100_phy_config_aneg,
+		.config_init = tja1100_phy_config_init,
+
+		.suspend = genphy_suspend,
+		.resume = genphy_resume,
+	}
+};
+
+module_phy_driver(tja1100_phy_driver);
+
+MODULE_DESCRIPTION("NXP TJA1100 driver");
+MODULE_AUTHOR("Kirill Kranke <kkranke@topcon.com>");
+MODULE_LICENSE("GPL");
+
+static struct mdio_device_id __maybe_unused nxp_tbl[] = {
+	{ 0x0180dc48, 0xfffffff0 },
+	{}
+};
+
+MODULE_DEVICE_TABLE(mdio, nxp_tbl);