kernel: rtl8366-smi: add Realtek switch management via mii-bus

Current version of rtl8366-smi module only supports Realtek switch
managment via two gpio lines. This adds Realtek switch
management via mii_bus. Tested on a Tp-link Archer C2 v1 (Mediatek
SoC mt7620a based)

dts-file configuration should look like this:

rtl8367rb {
	compatible = "realtek,rtl8367b";
	realtek,extif1 = <1 0 1 1 1 1 1 1 2>;
	mii-bus = <&mdio0>;
};

&ethernet {
	status = "okay";
	mtd-mac-address = <&rom 0xf100>;
	pinctrl-names = "default";
	pinctrl-0 = <&rgmii1_pins &rgmii2_pins &mdio_pins>;

	port@5 {
		status = "okay";
		mediatek,fixed-link = <1000 1 1 1>;
		phy-mode = "rgmii";
	};

	mdio0: mdio-bus {
		status = "okay";
	};
};

Signed-off-by: Serge Vasilugin <vasilugin@yandex.ru>
Signed-off-by: Franz Flasch <franz.flasch@gmx.at>

target/linux/generic/files/drivers/net/phy/rtl8366_smi.c

@@ -199,7 +199,7 @@ static int rtl8366_smi_read_byte1(struct rtl8366_smi *smi, u8 *data)
 	return 0;
 }
 
-int rtl8366_smi_read_reg(struct rtl8366_smi *smi, u32 addr, u32 *data)
+static int __rtl8366_smi_read_reg(struct rtl8366_smi *smi, u32 addr, u32 *data)
 {
 	unsigned long flags;
 	u8 lo = 0;
@@ -240,6 +240,101 @@ int rtl8366_smi_read_reg(struct rtl8366_smi *smi, u32 addr, u32 *data)
 
 	return ret;
 }
+/* Read/write via mdiobus */
+#define MDC_MDIO_CTRL0_REG		31
+#define MDC_MDIO_START_REG		29
+#define MDC_MDIO_CTRL1_REG		21
+#define MDC_MDIO_ADDRESS_REG		23
+#define MDC_MDIO_DATA_WRITE_REG		24
+#define MDC_MDIO_DATA_READ_REG		25
+
+#define MDC_MDIO_START_OP		0xFFFF
+#define MDC_MDIO_ADDR_OP		0x000E
+#define MDC_MDIO_READ_OP		0x0001
+#define MDC_MDIO_WRITE_OP		0x0003
+#define MDC_REALTEK_PHY_ADDR		0x0
+
+int __rtl8366_mdio_read_reg(struct rtl8366_smi *smi, u32 addr, u32 *data)
+{
+	u32 phy_id = MDC_REALTEK_PHY_ADDR;
+	struct mii_bus *mbus = smi->ext_mbus;
+
+	BUG_ON(in_interrupt());
+
+	mutex_lock(&mbus->mdio_lock);
+	/* Write Start command to register 29 */
+	mbus->write(mbus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
+
+	/* Write address control code to register 31 */
+	mbus->write(mbus, phy_id, MDC_MDIO_CTRL0_REG, MDC_MDIO_ADDR_OP);
+
+	/* Write Start command to register 29 */
+	mbus->write(mbus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
+
+	/* Write address to register 23 */
+	mbus->write(mbus, phy_id, MDC_MDIO_ADDRESS_REG, addr);
+
+	/* Write Start command to register 29 */
+	mbus->write(mbus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
+
+	/* Write read control code to register 21 */
+	mbus->write(mbus, phy_id, MDC_MDIO_CTRL1_REG, MDC_MDIO_READ_OP);
+
+	/* Write Start command to register 29 */
+	mbus->write(smi->ext_mbus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
+
+	/* Read data from register 25 */
+	*data = mbus->read(mbus, phy_id, MDC_MDIO_DATA_READ_REG);
+
+	mutex_unlock(&mbus->mdio_lock);
+
+	return 0;
+}
+
+static int __rtl8366_mdio_write_reg(struct rtl8366_smi *smi, u32 addr, u32 data)
+{
+	u32 phy_id = MDC_REALTEK_PHY_ADDR;
+	struct mii_bus *mbus = smi->ext_mbus;
+
+	BUG_ON(in_interrupt());
+
+	mutex_lock(&mbus->mdio_lock);
+
+	/* Write Start command to register 29 */
+	mbus->write(mbus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
+
+	/* Write address control code to register 31 */
+	mbus->write(mbus, phy_id, MDC_MDIO_CTRL0_REG, MDC_MDIO_ADDR_OP);
+
+	/* Write Start command to register 29 */
+	mbus->write(mbus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
+
+	/* Write address to register 23 */
+	mbus->write(mbus, phy_id, MDC_MDIO_ADDRESS_REG, addr);
+
+	/* Write Start command to register 29 */
+	mbus->write(mbus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
+
+	/* Write data to register 24 */
+	mbus->write(mbus, phy_id, MDC_MDIO_DATA_WRITE_REG, data);
+
+	/* Write Start command to register 29 */
+	mbus->write(mbus, phy_id, MDC_MDIO_START_REG, MDC_MDIO_START_OP);
+
+	/* Write data control code to register 21 */
+	mbus->write(mbus, phy_id, MDC_MDIO_CTRL1_REG, MDC_MDIO_WRITE_OP);
+
+	mutex_unlock(&mbus->mdio_lock);
+	return 0;
+}
+
+int rtl8366_smi_read_reg(struct rtl8366_smi *smi, u32 addr, u32 *data)
+{
+	if (smi->ext_mbus)
+		return __rtl8366_mdio_read_reg(smi, addr, data);
+	else
+		return __rtl8366_smi_read_reg(smi, addr, data);
+}
 EXPORT_SYMBOL_GPL(rtl8366_smi_read_reg);
 
 static int __rtl8366_smi_write_reg(struct rtl8366_smi *smi,
@@ -291,6 +386,9 @@ static int __rtl8366_smi_write_reg(struct rtl8366_smi *smi,
 
 int rtl8366_smi_write_reg(struct rtl8366_smi *smi, u32 addr, u32 data)
 {
+	if (smi->ext_mbus)
+		return __rtl8366_mdio_write_reg(smi, addr, data);
+	else
 		return __rtl8366_smi_write_reg(smi, addr, data, true);
 }
 EXPORT_SYMBOL_GPL(rtl8366_smi_write_reg);
@@ -1282,6 +1380,7 @@ static int __rtl8366_smi_init(struct rtl8366_smi *smi, const char *name)
 {
 	int err;
 
+	if (!smi->ext_mbus) {
 		err = gpio_request(smi->gpio_sda, name);
 		if (err) {
 			printk(KERN_ERR "rtl8366_smi: gpio_request failed for %u, err=%d\n",
@@ -1295,6 +1394,7 @@ static int __rtl8366_smi_init(struct rtl8366_smi *smi, const char *name)
 				smi->gpio_sck, err);
 			goto err_free_sda;
 		}
+	}
 
 	spin_lock_init(&smi->lock);
 
@@ -1317,8 +1417,10 @@ static void __rtl8366_smi_cleanup(struct rtl8366_smi *smi)
 	if (smi->hw_reset)
 		smi->hw_reset(smi, true);
 
+	if (!smi->ext_mbus) {
 		gpio_free(smi->gpio_sck);
 		gpio_free(smi->gpio_sda);
+	}
 }
 
 enum rtl8366_type rtl8366_smi_detect(struct rtl8366_platform_data *pdata)
@@ -1371,8 +1473,11 @@ int rtl8366_smi_init(struct rtl8366_smi *smi)
 	if (err)
 		goto err_out;
 
+	if (!smi->ext_mbus)
 		dev_info(smi->parent, "using GPIO pins %u (SDA) and %u (SCK)\n",
 			 smi->gpio_sda, smi->gpio_sck);
+	else
+		dev_info(smi->parent, "using MDIO bus '%s'\n", smi->ext_mbus->name);
 
 	err = smi->ops->detect(smi);
 	if (err) {
@@ -1437,7 +1542,25 @@ int rtl8366_smi_probe_of(struct platform_device *pdev, struct rtl8366_smi *smi)
 {
 	int sck = of_get_named_gpio(pdev->dev.of_node, "gpio-sck", 0);
 	int sda = of_get_named_gpio(pdev->dev.of_node, "gpio-sda", 0);
+	struct device_node *np = pdev->dev.of_node;
+	struct device_node *mdio_node;
 
+	mdio_node = of_parse_phandle(np, "mii-bus", 0);
+	if (!mdio_node) {
+		dev_err(&pdev->dev, "cannot find mdio node phandle");
+		goto try_gpio;
+	}
+
+	smi->ext_mbus = of_mdio_find_bus(mdio_node);
+	if (!smi->ext_mbus) {
+		dev_err(&pdev->dev,
+			"cannot find mdio bus from bus handle");
+		goto try_gpio;
+	}
+
+	return 0;
+
+try_gpio:
 	if (!gpio_is_valid(sck) || !gpio_is_valid(sda)) {
 		dev_err(&pdev->dev, "gpios missing in devictree\n");
 		return -EINVAL;

target/linux/generic/files/drivers/net/phy/rtl8366_smi.h

@@ -63,6 +63,7 @@ struct rtl8366_smi {
 	u16			dbg_reg;
 	u8			dbg_vlan_4k_page;
 #endif
+	struct mii_bus		*ext_mbus;
 };
 
 struct rtl8366_vlan_mc {