[PATCH net-next v7 2/4] net: phy: mediatek: add phy driver for MT7628 built-in Fast Ethernet PHYs

The Fast Ethernet PHYs present in the MT7628 SoCs require an
undocumented bit to be set before they can establish 100mbps links.

This commit adds the Kconfig option MEDIATEK_FE_SOC_PHY and the
corresponding driver mtk-fe-soc.c.

Signed-off-by: Joris Vaisvila <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Reviewed-by: Daniel Golle <[email protected]>
---
 drivers/net/phy/mediatek/Kconfig      | 11 +++++-
 drivers/net/phy/mediatek/Makefile     |  1 +
 drivers/net/phy/mediatek/mtk-fe-soc.c | 52 +++++++++++++++++++++++++++
 3 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 drivers/net/phy/mediatek/mtk-fe-soc.c

diff --git a/drivers/net/phy/mediatek/Kconfig b/drivers/net/phy/mediatek/Kconfig
index b6d41bbbbc27..3b9cf82c0cb2 100644
--- a/drivers/net/phy/mediatek/Kconfig
+++ b/drivers/net/phy/mediatek/Kconfig
@@ -21,8 +21,17 @@ config MEDIATEK_GE_PHY
 	  common operations with MediaTek SoC built-in Gigabit
 	  Ethernet PHYs.
 
+config MEDIATEK_FE_SOC_PHY
+	tristate "MediaTek SoC Fast Ethernet PHYs"
+	depends on SOC_MT7620 || COMPILE_TEST
+	help
+	  Support for MediaTek MT7628 built-in Fast Ethernet PHYs.
+	  This driver only sets an initialization bit required for the PHY
+	  to establish 100 Mbps links. All other PHY operations are handled
+	  by the kernel's generic PHY code.
+
 config MEDIATEK_GE_SOC_PHY
-	tristate "MediaTek SoC Ethernet PHYs"
+	tristate "MediaTek SoC Gigabit Ethernet PHYs"
 	depends on ARM64 || ECONET || COMPILE_TEST
 	depends on ARCH_AIROHA || (ARCH_MEDIATEK && NVMEM_MTK_EFUSE) || \
 		   ECONET || COMPILE_TEST
diff --git a/drivers/net/phy/mediatek/Makefile b/drivers/net/phy/mediatek/Makefile
index ac57ecc799fc..6f9cacf7f906 100644
--- a/drivers/net/phy/mediatek/Makefile
+++ b/drivers/net/phy/mediatek/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_MEDIATEK_2P5GE_PHY)	+= mtk-2p5ge.o
+obj-$(CONFIG_MEDIATEK_FE_SOC_PHY)	+= mtk-fe-soc.o
 obj-$(CONFIG_MEDIATEK_GE_PHY)		+= mtk-ge.o
 obj-$(CONFIG_MEDIATEK_GE_SOC_PHY)	+= mtk-ge-soc.o
 obj-$(CONFIG_MTK_NET_PHYLIB)		+= mtk-phy-lib.o
diff --git a/drivers/net/phy/mediatek/mtk-fe-soc.c b/drivers/net/phy/mediatek/mtk-fe-soc.c
new file mode 100644
index 000000000000..0b0d6c1fefbd
--- /dev/null
+++ b/drivers/net/phy/mediatek/mtk-fe-soc.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for MT7628 Embedded Switch internal Fast Ethernet PHYs
+ */
+#include <linux/module.h>
+#include <linux/phy.h>
+
+#define MTK_FPHY_ID_MT7628	0x03a29410
+#define MTK_EXT_PAGE_ACCESS	0x1f
+
+static int mt7628_phy_read_page(struct phy_device *phydev)
+{
+	return __phy_read(phydev, MTK_EXT_PAGE_ACCESS);
+}
+
+static int mt7628_phy_write_page(struct phy_device *phydev, int page)
+{
+	return __phy_write(phydev, MTK_EXT_PAGE_ACCESS, page);
+}
+
+static int mt7628_phy_config_init(struct phy_device *phydev)
+{
+	/*
+	 * This undocumented bit is required for the PHYs to be able to
+	 * establish 100mbps links.
+	 */
+	return phy_modify_paged(phydev, 0x8000, 30, BIT(13), BIT(13));
+}
+
+static struct phy_driver mtk_soc_fe_phy_driver[] = {
+	{
+		PHY_ID_MATCH_EXACT(MTK_FPHY_ID_MT7628),
+		.name		= "MediaTek MT7628 PHY",
+		.config_init	= mt7628_phy_config_init,
+		.read_page	= mt7628_phy_read_page,
+		.write_page	= mt7628_phy_write_page,
+		.suspend	= genphy_suspend,
+		.resume		= genphy_resume,
+	},
+};
+
+module_phy_driver(mtk_soc_fe_phy_driver);
+static const struct mdio_device_id __maybe_unused mtk_soc_fe_phy_tbl[] = {
+	{ PHY_ID_MATCH_EXACT(MTK_FPHY_ID_MT7628) },
+	{ }
+};
+
+MODULE_DESCRIPTION("MediaTek SoC Fast Ethernet PHY driver");
+MODULE_AUTHOR("Joris Vaisvila <[email protected]>");
+MODULE_LICENSE("GPL");
+
+MODULE_DEVICE_TABLE(mdio, mtk_soc_fe_phy_tbl);
-- 
2.55.0