From ffb7da9aa25765b2115e7ff3ee4f6dafa60f5421 Mon Sep 17 00:00:00 2001
From: Sander Vanheule <sander@svanheule.net>
Date: Fri, 27 Dec 2024 14:55:31 +0100
Subject: [PATCH] net: mdio: Add Realtek Otto auxiliary controller

SoCs in Realtek's Otto platform such as the RTL8380, RTL8391, and
RTL9302 have a simple auxiliary MDIO controller that is commonly used to
manage RTL8231 GPIO expanders on switch devices.

Add a new MDIO controller driver supporting the RTL838x (maple), RTL839x
(cypress), and RTL930x (longan) SoCs.

Signed-off-by: Sander Vanheule <sander@svanheule.net>
---
 drivers/net/mdio/Kconfig                 |  10 ++
 drivers/net/mdio/Makefile                |   1 +
 drivers/net/mdio/mdio-realtek-otto-aux.c | 175 +++++++++++++++++++++++
 3 files changed, 186 insertions(+)
 create mode 100644 drivers/net/mdio/mdio-realtek-otto-aux.c

--- a/drivers/net/mdio/Kconfig
+++ b/drivers/net/mdio/Kconfig
@@ -207,6 +207,16 @@ config MDIO_REGMAP
 	  regmap. Users willing to use this driver must explicitly select
 	  REGMAP.
 
+config MDIO_REALTEK_OTTO_AUX
+	tristate "Realtek Otto auxiliary MDIO interface support"
+	default MACH_REALTEK_RTL
+	depends on MACH_REALTEK_RTL
+	depends on MFD_SYSCON
+	select MDIO_DEVRES
+	help
+	  This driver supports the auxilairy MDIO bus on RTL838x SoCs. This bus
+	  is typically used to attach RTL8231 GPIO extenders.
+
 config MDIO_THUNDER
 	tristate "ThunderX SOCs MDIO buses"
 	depends on 64BIT
--- a/drivers/net/mdio/Makefile
+++ b/drivers/net/mdio/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_MDIO_MSCC_MIIM)		+= mdio-ms
 obj-$(CONFIG_MDIO_MVUSB)		+= mdio-mvusb.o
 obj-$(CONFIG_MDIO_OCTEON)		+= mdio-octeon.o
 obj-$(CONFIG_MDIO_REGMAP)		+= mdio-regmap.o
+obj-$(CONFIG_MDIO_REALTEK_OTTO_AUX)	+= mdio-realtek-otto-aux.o
 obj-$(CONFIG_MDIO_SMBUS)		+= mdio-smbus.o
 obj-$(CONFIG_MDIO_SUN4I)		+= mdio-sun4i.o
 obj-$(CONFIG_MDIO_THUNDER)		+= mdio-thunder.o
--- /dev/null
+++ b/drivers/net/mdio/mdio-realtek-otto-aux.c
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/mfd/core.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_mdio.h>
+#include <linux/mod_devicetable.h>
+#include <linux/phy.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define RTL8380_EXT_GPIO_INDIRECT_ACCESS	0xA09C
+#define RTL8390_EXT_GPIO_INDIRECT_ACCESS	0x0224
+#define RTL9300_EXT_GPIO_INDIRECT_ACCESS	0xC620
+#define RTL9310_EXT_GPIO_INDIRECT_ACCESS	0x07F4
+
+#define RTL83XX_AUX_MDIO_DATA_OFFSET		16
+#define RTL83XX_AUX_MDIO_RCMD_FAIL		0
+
+#define RTL93XX_AUX_MDIO_DATA_OFFSET		12
+#define RTL93XX_AUX_MDIO_RCMD_FAIL		BIT(28)
+
+#define REALTEK_AUX_MDIO_REG			GENMASK(11, 7)
+#define REALTEK_AUX_MDIO_PHY_ADDR		GENMASK(6, 2)
+#define REALTEK_AUX_MDIO_WRITE			BIT(1)
+#define REALTEK_AUX_MDIO_READ			0
+#define REALTEK_AUX_MDIO_EXEC			BIT(0)
+
+struct realtek_aux_mdio_info {
+	unsigned int cmd_reg;
+	unsigned int data_offset;
+	unsigned int rcmd_fail_mask;
+	unsigned int timeout_us;
+};
+
+static const struct realtek_aux_mdio_info info_rtl838x = {
+	.cmd_reg = RTL8380_EXT_GPIO_INDIRECT_ACCESS,
+	.data_offset = RTL83XX_AUX_MDIO_DATA_OFFSET,
+	.rcmd_fail_mask = RTL83XX_AUX_MDIO_RCMD_FAIL,
+	.timeout_us = 1700,
+};
+
+static const struct realtek_aux_mdio_info info_rtl839x = {
+	.cmd_reg = RTL8390_EXT_GPIO_INDIRECT_ACCESS,
+	.data_offset = RTL83XX_AUX_MDIO_DATA_OFFSET,
+	.rcmd_fail_mask = RTL83XX_AUX_MDIO_RCMD_FAIL,
+	.timeout_us = 4120,
+};
+
+static const struct realtek_aux_mdio_info info_rtl930x = {
+	.cmd_reg = RTL9300_EXT_GPIO_INDIRECT_ACCESS,
+	.data_offset = RTL93XX_AUX_MDIO_DATA_OFFSET,
+	.rcmd_fail_mask = RTL93XX_AUX_MDIO_RCMD_FAIL,
+	.timeout_us = 19000,
+};
+
+static const struct realtek_aux_mdio_info info_rtl931x = {
+	.cmd_reg = RTL9310_EXT_GPIO_INDIRECT_ACCESS,
+	.data_offset = RTL93XX_AUX_MDIO_DATA_OFFSET,
+	.rcmd_fail_mask = RTL93XX_AUX_MDIO_RCMD_FAIL,
+	.timeout_us = 19000,
+};
+
+struct realtek_aux_mdio_ctrl {
+	struct device *dev;
+	struct regmap *map;
+	const struct realtek_aux_mdio_info *info;
+};
+
+#define mii_bus_to_ctrl(bus)	((struct realtek_aux_mdio_ctrl *) bus->priv)
+
+static int realtek_aux_mdio_cmd(struct realtek_aux_mdio_ctrl *ctrl, int addr, int regnum,
+		u32 rw_bit, u16 *data)
+{
+	unsigned int cmd;
+	int err;
+
+	cmd = rw_bit | REALTEK_AUX_MDIO_EXEC;
+	cmd |= FIELD_PREP(REALTEK_AUX_MDIO_PHY_ADDR, addr);
+	cmd |= FIELD_PREP(REALTEK_AUX_MDIO_REG, regnum);
+
+	if (rw_bit == REALTEK_AUX_MDIO_WRITE)
+		cmd |= *data << ctrl->info->data_offset;
+
+	err = regmap_write(ctrl->map, ctrl->info->cmd_reg, cmd);
+	if (err)
+		return err;
+
+	err = regmap_read_poll_timeout_atomic(ctrl->map, ctrl->info->cmd_reg, cmd,
+			!(cmd & REALTEK_AUX_MDIO_EXEC), 3, ctrl->info->timeout_us);
+	if (err)
+		return err;
+
+	if (rw_bit == REALTEK_AUX_MDIO_READ) {
+		if (cmd & ctrl->info->rcmd_fail_mask)
+			return -EIO;
+
+		*data = (cmd >> ctrl->info->data_offset) & GENMASK(15, 0);
+	}
+
+	return 0;
+}
+
+static int realtek_aux_mdio_read(struct mii_bus *bus, int addr, int regnum)
+{
+	struct realtek_aux_mdio_ctrl *ctrl = mii_bus_to_ctrl(bus);
+	u16 data;
+	int err;
+
+	err = realtek_aux_mdio_cmd(ctrl, addr, regnum, REALTEK_AUX_MDIO_READ, &data);
+
+	if (err)
+		return err;
+	else
+		return data;
+}
+
+static int realtek_aux_mdio_write(struct mii_bus *bus, int addr, int regnum, u16 val)
+{
+	struct realtek_aux_mdio_ctrl *ctrl = mii_bus_to_ctrl(bus);
+
+	return realtek_aux_mdio_cmd(ctrl, addr, regnum, REALTEK_AUX_MDIO_WRITE, &val);
+}
+
+static int realtek_aux_mdio_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct realtek_aux_mdio_ctrl *ctrl;
+	struct mii_bus *bus;
+
+	bus = devm_mdiobus_alloc_size(&pdev->dev, sizeof(*ctrl));
+	if (!bus)
+		return -ENOMEM;
+
+	ctrl = bus->priv;
+	ctrl->dev = &pdev->dev;
+	ctrl->info = (const struct realtek_aux_mdio_info *) device_get_match_data(ctrl->dev);
+	ctrl->map = syscon_node_to_regmap(np->parent);
+	if (IS_ERR(ctrl->map))
+		return PTR_ERR(ctrl->map);
+
+	bus->name = "Realtek auxiliary MDIO bus";
+	snprintf(bus->id, MII_BUS_ID_SIZE, "realtek-aux-mdio") ;
+	bus->parent = ctrl->dev;
+	bus->read = realtek_aux_mdio_read;
+	bus->write = realtek_aux_mdio_write;
+	/* Don't have interrupts */
+	for (unsigned int i = 0; i < PHY_MAX_ADDR; i++)
+		bus->irq[i] = PHY_POLL;
+
+	return devm_of_mdiobus_register(ctrl->dev, bus, np);
+}
+
+static const struct of_device_id realtek_aux_mdio_of_match[] = {
+	{
+		.compatible = "realtek,rtl8380-aux-mdio",
+		.data = &info_rtl838x,
+	},
+	{
+		.compatible = "realtek,rtl8390-aux-mdio",
+		.data = &info_rtl839x,
+	},
+	{
+		.compatible = "realtek,rtl9300-aux-mdio",
+		.data = &info_rtl930x,
+	},
+	{
+		.compatible = "realtek,rtl9310-aux-mdio",
+		.data = &info_rtl931x,
+	},
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, realtek_aux_mdio_of_match);
+
+static struct platform_driver realtek_aux_mdio_driver = {
+	.driver = {
+		.name = "realtek-otto-aux-mdio",
+		.of_match_table = realtek_aux_mdio_of_match
+	},
+	.probe = realtek_aux_mdio_probe,
+};
+module_platform_driver(realtek_aux_mdio_driver);
+
+MODULE_AUTHOR("Sander Vanheule <sander@svanheule.net>");
+MODULE_DESCRIPTION("Realtek otto auxiliary MDIO bus");
+MODULE_LICENSE("GPL v2");
