net: phy: add MediaTek Gigabit Ethernet PHY driver

Add support for MediaTek Gigabit Ethernet PHYs found in MT7530 and
MT7531 switches.
The initialization procedure is from the vendor driver, but due to lack
of documentation, the function of some register values remains unknown.

Signed-off-by: DENG Qingfang <dqfext@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/Kconfig

@@ -207,6 +207,11 @@ config MARVELL_88X2222_PHY
 	  Support for the Marvell 88X2222 Dual-port Multi-speed Ethernet
 	  Transceiver.
 
+config MEDIATEK_GE_PHY
+	tristate "MediaTek Gigabit Ethernet PHYs"
+	help
+	  Supports the MediaTek Gigabit Ethernet PHYs.
+
 config MICREL_PHY
 	tristate "Micrel PHYs"
 	help

drivers/net/phy/Makefile

@@ -64,6 +64,7 @@ obj-$(CONFIG_LXT_PHY)		+= lxt.o
 obj-$(CONFIG_MARVELL_10G_PHY)	+= marvell10g.o
 obj-$(CONFIG_MARVELL_PHY)	+= marvell.o
 obj-$(CONFIG_MARVELL_88X2222_PHY)	+= marvell-88x2222.o
+obj-$(CONFIG_MEDIATEK_GE_PHY)	+= mediatek-ge.o
 obj-$(CONFIG_MESON_GXL_PHY)	+= meson-gxl.o
 obj-$(CONFIG_MICREL_KS8995MA)	+= spi_ks8995.o
 obj-$(CONFIG_MICREL_PHY)	+= micrel.o

drivers/net/phy/mediatek-ge.c

@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include <linux/bitfield.h>
+#include <linux/module.h>
+#include <linux/phy.h>
+
+#define MTK_EXT_PAGE_ACCESS		0x1f
+#define MTK_PHY_PAGE_STANDARD		0x0000
+#define MTK_PHY_PAGE_EXTENDED		0x0001
+#define MTK_PHY_PAGE_EXTENDED_2		0x0002
+#define MTK_PHY_PAGE_EXTENDED_3		0x0003
+#define MTK_PHY_PAGE_EXTENDED_2A30	0x2a30
+#define MTK_PHY_PAGE_EXTENDED_52B5	0x52b5
+
+static int mtk_gephy_read_page(struct phy_device *phydev)
+{
+	return __phy_read(phydev, MTK_EXT_PAGE_ACCESS);
+}
+
+static int mtk_gephy_write_page(struct phy_device *phydev, int page)
+{
+	return __phy_write(phydev, MTK_EXT_PAGE_ACCESS, page);
+}
+
+static void mtk_gephy_config_init(struct phy_device *phydev)
+{
+	/* Disable EEE */
+	phy_write_mmd(phydev, MDIO_MMD_AN, MDIO_AN_EEE_ADV, 0);
+
+	/* Enable HW auto downshift */
+	phy_modify_paged(phydev, MTK_PHY_PAGE_EXTENDED, 0x14, 0, BIT(4));
+
+	/* Increase SlvDPSready time */
+	phy_select_page(phydev, MTK_PHY_PAGE_EXTENDED_52B5);
+	__phy_write(phydev, 0x10, 0xafae);
+	__phy_write(phydev, 0x12, 0x2f);
+	__phy_write(phydev, 0x10, 0x8fae);
+	phy_restore_page(phydev, MTK_PHY_PAGE_STANDARD, 0);
+
+	/* Adjust 100_mse_threshold */
+	phy_write_mmd(phydev, MDIO_MMD_VEND1, 0x123, 0xffff);
+
+	/* Disable mcc */
+	phy_write_mmd(phydev, MDIO_MMD_VEND1, 0xa6, 0x300);
+}
+
+static int mt7530_phy_config_init(struct phy_device *phydev)
+{
+	mtk_gephy_config_init(phydev);
+
+	/* Increase post_update_timer */
+	phy_write_paged(phydev, MTK_PHY_PAGE_EXTENDED_3, 0x11, 0x4b);
+
+	return 0;
+}
+
+static int mt7531_phy_config_init(struct phy_device *phydev)
+{
+	if (phydev->interface != PHY_INTERFACE_MODE_INTERNAL)
+		return -EINVAL;
+
+	mtk_gephy_config_init(phydev);
+
+	/* PHY link down power saving enable */
+	phy_set_bits(phydev, 0x17, BIT(4));
+	phy_clear_bits_mmd(phydev, MDIO_MMD_VEND1, 0xc6, 0x300);
+
+	/* Set TX Pair delay selection */
+	phy_write_mmd(phydev, MDIO_MMD_VEND1, 0x13, 0x404);
+	phy_write_mmd(phydev, MDIO_MMD_VEND1, 0x14, 0x404);
+
+	return 0;
+}
+
+static struct phy_driver mtk_gephy_driver[] = {
+	{
+		PHY_ID_MATCH_EXACT(0x03a29412),
+		.name		= "MediaTek MT7530 PHY",
+		.config_init	= mt7530_phy_config_init,
+		/* Interrupts are handled by the switch, not the PHY
+		 * itself.
+		 */
+		.config_intr	= genphy_no_config_intr,
+		.handle_interrupt = genphy_handle_interrupt_no_ack,
+		.read_page	= mtk_gephy_read_page,
+		.write_page	= mtk_gephy_write_page,
+	},
+	{
+		PHY_ID_MATCH_EXACT(0x03a29441),
+		.name		= "MediaTek MT7531 PHY",
+		.config_init	= mt7531_phy_config_init,
+		/* Interrupts are handled by the switch, not the PHY
+		 * itself.
+		 */
+		.config_intr	= genphy_no_config_intr,
+		.handle_interrupt = genphy_handle_interrupt_no_ack,
+		.read_page	= mtk_gephy_read_page,
+		.write_page	= mtk_gephy_write_page,
+	},
+};
+
+module_phy_driver(mtk_gephy_driver);
+
+static struct mdio_device_id __maybe_unused mtk_gephy_tbl[] = {
+	{ PHY_ID_MATCH_VENDOR(0x03a29400) },
+	{ }
+};
+
+MODULE_DESCRIPTION("MediaTek Gigabit Ethernet PHY driver");
+MODULE_AUTHOR("DENG, Qingfang <dqfext@gmail.com>");
+MODULE_LICENSE("GPL");
+
+MODULE_DEVICE_TABLE(mdio, mtk_gephy_tbl);