net: dsa: LAN9303: add MDIO managed mode support

When the LAN9303 device is in MDIO manged mode, all register accesses must
be done via MDIO.

Please note: this code is compile time tested only due to the absence of such
configured hardware. It is based on a patch from Stefan Roese from 2014.

Signed-off-by: Juergen Borleis <jbe@pengutronix.de>
CC: devicetree@vger.kernel.org
CC: robh+dt@kernel.org
CC: mark.rutland@arm.com
CC: sr@denx.de
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/lan9303.txt

@@ -3,7 +3,10 @@ SMSC/MicroChip LAN9303 three port ethernet switch
 
 Required properties:
 
-- compatible: should be "smsc,lan9303-i2c"
+- compatible: should be
+  - "smsc,lan9303-i2c" for I2C managed mode
+    or
+  - "smsc,lan9303-mdio" for mdio managed mode
 
 Optional properties:
 
@@ -60,3 +63,43 @@ I2C managed mode:
 			};
 		};
 	};
+
+MDIO managed mode:
+
+	master: masterdevice@X {
+		status = "okay";
+		phy-handle = <&switch>;
+
+		mdio {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			switch: switch-phy@0 {
+				compatible = "smsc,lan9303-mdio";
+				reg = <0>;
+				reset-gpios = <&gpio7 6 GPIO_ACTIVE_LOW>;
+				reset-duration = <100>;
+
+				ports {
+					#address-cells = <1>;
+					#size-cells = <0>;
+
+					port@0 {
+						reg = <0>;
+						label = "cpu";
+						ethernet = <&master>;
+					};
+
+					port@1 { /* external port 1 */
+						reg = <1>;
+						label = "lan1;
+					};
+
+					port@2 { /* external port 2 */
+						reg = <2>;
+						label = "lan2";
+					};
+				};
+			};
+		};
+	};

drivers/net/dsa/Kconfig

@@ -66,4 +66,12 @@ config NET_DSA_SMSC_LAN9303_I2C
 	  Enable access functions if the SMSC/Microchip LAN9303 is configured
 	  for I2C managed mode.
 
+config NET_DSA_SMSC_LAN9303_MDIO
+	tristate "SMSC/Microchip LAN9303 3-ports 10/100 ethernet switch in MDIO managed mode"
+	depends on NET_DSA
+	select NET_DSA_SMSC_LAN9303
+	---help---
+	  Enable access functions if the SMSC/Microchip LAN9303 is configured
+	  for MDIO managed mode.
+
 endmenu

drivers/net/dsa/Makefile

@@ -5,6 +5,7 @@ obj-$(CONFIG_NET_DSA_QCA8K)	+= qca8k.o
 obj-$(CONFIG_NET_DSA_MT7530)	+= mt7530.o
 obj-$(CONFIG_NET_DSA_SMSC_LAN9303) += lan9303-core.o
 obj-$(CONFIG_NET_DSA_SMSC_LAN9303_I2C) += lan9303_i2c.o
+obj-$(CONFIG_NET_DSA_SMSC_LAN9303_MDIO) += lan9303_mdio.o
 obj-y				+= b53/
 obj-y				+= mv88e6xxx/
 obj-$(CONFIG_NET_DSA_LOOP)	+= dsa_loop.o dsa_loop_bdinfo.o

drivers/net/dsa/lan9303_mdio.c

@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2017 Pengutronix, Juergen Borleis <kernel@pengutronix.de>
+ *
+ * Partially based on a patch from
+ * Copyright (c) 2014 Stefan Roese <sr@denx.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mdio.h>
+#include <linux/phy.h>
+#include <linux/of.h>
+
+#include "lan9303.h"
+
+/* Generate phy-addr and -reg from the input address */
+#define PHY_ADDR(x) ((((x) >> 6) + 0x10) & 0x1f)
+#define PHY_REG(x) (((x) >> 1) & 0x1f)
+
+struct lan9303_mdio {
+	struct mdio_device *device;
+	struct lan9303 chip;
+};
+
+static void lan9303_mdio_real_write(struct mdio_device *mdio, int reg, u16 val)
+{
+	mdio->bus->write(mdio->bus, PHY_ADDR(reg), PHY_REG(reg), val);
+}
+
+static int lan9303_mdio_write(void *ctx, uint32_t reg, uint32_t val)
+{
+	struct lan9303_mdio *sw_dev = (struct lan9303_mdio *)ctx;
+
+	mutex_lock(&sw_dev->device->bus->mdio_lock);
+	lan9303_mdio_real_write(sw_dev->device, reg, val & 0xffff);
+	lan9303_mdio_real_write(sw_dev->device, reg + 2, (val >> 16) & 0xffff);
+	mutex_unlock(&sw_dev->device->bus->mdio_lock);
+
+	return 0;
+}
+
+static u16 lan9303_mdio_real_read(struct mdio_device *mdio, int reg)
+{
+	return mdio->bus->read(mdio->bus, PHY_ADDR(reg), PHY_REG(reg));
+}
+
+static int lan9303_mdio_read(void *ctx, uint32_t reg, uint32_t *val)
+{
+	struct lan9303_mdio *sw_dev = (struct lan9303_mdio *)ctx;
+
+	mutex_lock(&sw_dev->device->bus->mdio_lock);
+	*val = lan9303_mdio_real_read(sw_dev->device, reg);
+	*val |= (lan9303_mdio_real_read(sw_dev->device, reg + 2) << 16);
+	mutex_unlock(&sw_dev->device->bus->mdio_lock);
+
+	return 0;
+}
+
+static const struct regmap_config lan9303_mdio_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 32,
+	.reg_stride = 1,
+	.can_multi_write = true,
+	.max_register = 0x0ff, /* address bits 0..1 are not used */
+	.reg_format_endian = REGMAP_ENDIAN_LITTLE,
+
+	.volatile_table = &lan9303_register_set,
+	.wr_table = &lan9303_register_set,
+	.rd_table = &lan9303_register_set,
+
+	.reg_read = lan9303_mdio_read,
+	.reg_write = lan9303_mdio_write,
+
+	.cache_type = REGCACHE_NONE,
+};
+
+static int lan9303_mdio_probe(struct mdio_device *mdiodev)
+{
+	struct lan9303_mdio *sw_dev;
+	int ret;
+
+	sw_dev = devm_kzalloc(&mdiodev->dev, sizeof(struct lan9303_mdio),
+			      GFP_KERNEL);
+	if (!sw_dev)
+		return -ENOMEM;
+
+	sw_dev->chip.regmap = devm_regmap_init(&mdiodev->dev, NULL, sw_dev,
+						&lan9303_mdio_regmap_config);
+	if (IS_ERR(sw_dev->chip.regmap)) {
+		ret = PTR_ERR(sw_dev->chip.regmap);
+		dev_err(&mdiodev->dev, "regmap init failed: %d\n", ret);
+		return ret;
+	}
+
+	/* link forward and backward */
+	sw_dev->device = mdiodev;
+	dev_set_drvdata(&mdiodev->dev, sw_dev);
+	sw_dev->chip.dev = &mdiodev->dev;
+
+	ret = lan9303_probe(&sw_dev->chip, mdiodev->dev.of_node);
+	if (ret != 0)
+		return ret;
+
+	dev_info(&mdiodev->dev, "LAN9303 MDIO driver loaded successfully\n");
+
+	return 0;
+}
+
+static void lan9303_mdio_remove(struct mdio_device *mdiodev)
+{
+	struct lan9303_mdio *sw_dev = dev_get_drvdata(&mdiodev->dev);
+
+	if (!sw_dev)
+		return;
+
+	lan9303_remove(&sw_dev->chip);
+}
+
+/*-------------------------------------------------------------------------*/
+
+static const struct of_device_id lan9303_mdio_of_match[] = {
+	{ .compatible = "smsc,lan9303-mdio" },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, lan9303_mdio_of_match);
+
+static struct mdio_driver lan9303_mdio_driver = {
+	.mdiodrv.driver = {
+		.name = "LAN9303_MDIO",
+		.of_match_table = of_match_ptr(lan9303_mdio_of_match),
+	},
+	.probe  = lan9303_mdio_probe,
+	.remove = lan9303_mdio_remove,
+};
+mdio_module_driver(lan9303_mdio_driver);
+
+MODULE_AUTHOR("Stefan Roese <sr@denx.de>, Juergen Borleis <kernel@pengutronix.de>");
+MODULE_DESCRIPTION("Driver for SMSC/Microchip LAN9303 three port ethernet switch in MDIO managed mode");
+MODULE_LICENSE("GPL v2");