[PATCH v2 1/3] net: phy: mdio: add IPQ40xx MDIO driver

[Robert Marko]

This patch adds the driver for the MDIO interface
inside of Qualcomm IPQ40xx series SoC-s.

Signed-off-by: Christian Lamparter <chunkeey@xxxxxxxxx>
Signed-off-by: Robert Marko <robert.marko@xxxxxxxxxx>
Cc: Luka Perkov <luka.perkov@xxxxxxxxxx>
---
Changes from v1 to v2:
* Remove magic default value
* Remove lockdep_assert_held
* Add C45 check
* Simplify the driver
* Drop device and mii_bus structs from private struct
* Use devm_mdiobus_alloc_size()

 drivers/net/phy/Kconfig        |   7 ++
 drivers/net/phy/Makefile       |   1 +
 drivers/net/phy/mdio-ipq40xx.c | 176 +++++++++++++++++++++++++++++++++
 3 files changed, 184 insertions(+)
 create mode 100644 drivers/net/phy/mdio-ipq40xx.c

diff --git a/drivers/net/phy/Kconfig b/drivers/net/phy/Kconfig
index 3fa33d27eeba..815d52fa6080 100644
--- a/drivers/net/phy/Kconfig
+++ b/drivers/net/phy/Kconfig
@@ -157,6 +157,13 @@ config MDIO_I2C
 
 	  This is library mode.
 
+config MDIO_IPQ40XX
+	tristate "Qualcomm IPQ40xx MDIO interface"
+	depends on HAS_IOMEM && OF
+	help
+	  This driver supports the MDIO interface found in Qualcomm
+	  IPQ40xx series Soc-s.
+
 config MDIO_IPQ8064
 	tristate "Qualcomm IPQ8064 MDIO interface support"
 	depends on HAS_IOMEM && OF_MDIO
diff --git a/drivers/net/phy/Makefile b/drivers/net/phy/Makefile
index 2f5c7093a65b..36aafc6128c4 100644
--- a/drivers/net/phy/Makefile
+++ b/drivers/net/phy/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_MDIO_CAVIUM)	+= mdio-cavium.o
 obj-$(CONFIG_MDIO_GPIO)		+= mdio-gpio.o
 obj-$(CONFIG_MDIO_HISI_FEMAC)	+= mdio-hisi-femac.o
 obj-$(CONFIG_MDIO_I2C)		+= mdio-i2c.o
+obj-$(CONFIG_MDIO_IPQ40XX)	+= mdio-ipq40xx.o
 obj-$(CONFIG_MDIO_IPQ8064)	+= mdio-ipq8064.o
 obj-$(CONFIG_MDIO_MOXART)	+= mdio-moxart.o
 obj-$(CONFIG_MDIO_MSCC_MIIM)	+= mdio-mscc-miim.o
diff --git a/drivers/net/phy/mdio-ipq40xx.c b/drivers/net/phy/mdio-ipq40xx.c
new file mode 100644
index 000000000000..d8c11c621f20
--- /dev/null
+++ b/drivers/net/phy/mdio-ipq40xx.c
@@ -0,0 +1,176 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/* Copyright (c) 2015, The Linux Foundation. All rights reserved. */
+/* Copyright (c) 2020 Sartura Ltd. */
+
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/of_mdio.h>
+#include <linux/phy.h>
+#include <linux/platform_device.h>
+
+#define MDIO_CTRL_0_REG		0x40
+#define MDIO_CTRL_1_REG		0x44
+#define MDIO_CTRL_2_REG		0x48
+#define MDIO_CTRL_3_REG		0x4c
+#define MDIO_CTRL_4_REG		0x50
+#define MDIO_CTRL_4_ACCESS_BUSY		BIT(16)
+#define MDIO_CTRL_4_ACCESS_START		BIT(8)
+#define MDIO_CTRL_4_ACCESS_CODE_READ		0
+#define MDIO_CTRL_4_ACCESS_CODE_WRITE	1
+
+#define IPQ40XX_MDIO_RETRY	1000
+#define IPQ40XX_MDIO_DELAY	10
+
+struct ipq40xx_mdio_data {
+	void __iomem	*membase;
+};
+
+static int ipq40xx_mdio_wait_busy(struct mii_bus *bus)
+{
+	struct ipq40xx_mdio_data *priv = bus->priv;
+	int i;
+
+	for (i = 0; i < IPQ40XX_MDIO_RETRY; i++) {
+		unsigned int busy;
+
+		busy = readl(priv->membase + MDIO_CTRL_4_REG) &
+			MDIO_CTRL_4_ACCESS_BUSY;
+		if (!busy)
+			return 0;
+
+		/* BUSY might take to be cleard by 15~20 times of loop */
+		udelay(IPQ40XX_MDIO_DELAY);
+	}
+
+	dev_err(bus->parent, "MDIO operation timed out\n");
+
+	return -ETIMEDOUT;
+}
+
+static int ipq40xx_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
+{
+	struct ipq40xx_mdio_data *priv = bus->priv;
+	int value = 0;
+	unsigned int cmd = 0;
+
+	/* Reject clause 45 */
+	if (regnum & MII_ADDR_C45)
+		return -EOPNOTSUPP;
+
+	if (ipq40xx_mdio_wait_busy(bus))
+		return -ETIMEDOUT;
+
+	/* issue the phy address and reg */
+	writel((mii_id << 8) | regnum, priv->membase + MDIO_CTRL_1_REG);
+
+	cmd = MDIO_CTRL_4_ACCESS_START | MDIO_CTRL_4_ACCESS_CODE_READ;
+
+	/* issue read command */
+	writel(cmd, priv->membase + MDIO_CTRL_4_REG);
+
+	/* Wait read complete */
+	if (ipq40xx_mdio_wait_busy(bus))
+		return -ETIMEDOUT;
+
+	/* Read data */
+	value = readl(priv->membase + MDIO_CTRL_3_REG);
+
+	return value;
+}
+
+static int ipq40xx_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
+							 u16 value)
+{
+	struct ipq40xx_mdio_data *priv = bus->priv;
+	unsigned int cmd = 0;
+
+	/* Reject clause 45 */
+	if (regnum & MII_ADDR_C45)
+		return -EOPNOTSUPP;
+
+	if (ipq40xx_mdio_wait_busy(bus))
+		return -ETIMEDOUT;
+
+	/* issue the phy address and reg */
+	writel((mii_id << 8) | regnum, priv->membase + MDIO_CTRL_1_REG);
+
+	/* issue write data */
+	writel(value, priv->membase + MDIO_CTRL_2_REG);
+
+	cmd = MDIO_CTRL_4_ACCESS_START | MDIO_CTRL_4_ACCESS_CODE_WRITE;
+	/* issue write command */
+	writel(cmd, priv->membase + MDIO_CTRL_4_REG);
+
+	/* Wait write complete */
+	if (ipq40xx_mdio_wait_busy(bus))
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int ipq40xx_mdio_probe(struct platform_device *pdev)
+{
+	struct ipq40xx_mdio_data *priv;
+	struct mii_bus *bus;
+	int ret;
+
+	bus = devm_mdiobus_alloc_size(&pdev->dev, sizeof(*priv));
+	if (!bus)
+		return -ENOMEM;
+
+	priv = bus->priv;
+
+	priv->membase = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->membase))
+		return PTR_ERR(priv->membase);
+
+	bus->name = "ipq40xx_mdio";
+	bus->read = ipq40xx_mdio_read;
+	bus->write = ipq40xx_mdio_write;
+	bus->parent = &pdev->dev;
+	snprintf(bus->id, MII_BUS_ID_SIZE, "%s%d", pdev->name, pdev->id);
+
+	ret = of_mdiobus_register(bus, pdev->dev.of_node);
+	if (ret) {
+		dev_err(&pdev->dev, "Cannot register MDIO bus!\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, bus);
+
+	return 0;
+}
+
+static int ipq40xx_mdio_remove(struct platform_device *pdev)
+{
+	struct mii_bus *bus = platform_get_drvdata(pdev);
+
+	mdiobus_unregister(bus);
+
+	return 0;
+}
+
+static const struct of_device_id ipq40xx_mdio_dt_ids[] = {
+	{ .compatible = "qcom,ipq40xx-mdio" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ipq40xx_mdio_dt_ids);
+
+static struct platform_driver ipq40xx_mdio_driver = {
+	.probe = ipq40xx_mdio_probe,
+	.remove = ipq40xx_mdio_remove,
+	.driver = {
+		.name = "ipq40xx-mdio",
+		.of_match_table = ipq40xx_mdio_dt_ids,
+	},
+};
+
+module_platform_driver(ipq40xx_mdio_driver);
+
+MODULE_DESCRIPTION("IPQ40XX MDIO interface driver");
+MODULE_AUTHOR("Qualcomm Atheros");
+MODULE_LICENSE("Dual BSD/GPL");
-- 
2.26.0