1// SPDX-License-Identifier: GPL-2.0
  2/* MOXA ART Ethernet (RTL8201CP) MDIO interface driver
  3 *
  4 * Copyright (C) 2013 Jonas Jensen <jonas.jensen@gmail.com>
  5 */
  6
  7#include <linux/delay.h>
  8#include <linux/kernel.h>
  9#include <linux/module.h>
 10#include <linux/mutex.h>
 11#include <linux/of_address.h>
 12#include <linux/of_mdio.h>
 13#include <linux/phy.h>
 14#include <linux/platform_device.h>
 15#include <linux/regulator/consumer.h>
 16
 17#define REG_PHY_CTRL            0
 18#define REG_PHY_WRITE_DATA      4
 19
 20/* REG_PHY_CTRL */
 21#define MIIWR                   BIT(27) /* init write sequence (auto cleared)*/
 22#define MIIRD                   BIT(26)
 23#define REGAD_MASK              0x3e00000
 24#define PHYAD_MASK              0x1f0000
 25#define MIIRDATA_MASK           0xffff
 26
 27/* REG_PHY_WRITE_DATA */
 28#define MIIWDATA_MASK           0xffff
 29
 30struct moxart_mdio_data {
 31	void __iomem		*base;
 32};
 33
 34static int moxart_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
 35{
 36	struct moxart_mdio_data *data = bus->priv;
 37	u32 ctrl = 0;
 38	unsigned int count = 5;
 39
 40	dev_dbg(&bus->dev, "%s\n", __func__);
 41
 42	ctrl |= MIIRD | ((mii_id << 16) & PHYAD_MASK) |
 43		((regnum << 21) & REGAD_MASK);
 44
 45	writel(ctrl, data->base + REG_PHY_CTRL);
 46
 47	do {
 48		ctrl = readl(data->base + REG_PHY_CTRL);
 49
 50		if (!(ctrl & MIIRD))
 51			return ctrl & MIIRDATA_MASK;
 52
 53		mdelay(10);
 54		count--;
 55	} while (count > 0);
 56
 57	dev_dbg(&bus->dev, "%s timed out\n", __func__);
 58
 59	return -ETIMEDOUT;
 60}
 61
 62static int moxart_mdio_write(struct mii_bus *bus, int mii_id,
 63			     int regnum, u16 value)
 64{
 65	struct moxart_mdio_data *data = bus->priv;
 66	u32 ctrl = 0;
 67	unsigned int count = 5;
 68
 69	dev_dbg(&bus->dev, "%s\n", __func__);
 70
 71	ctrl |= MIIWR | ((mii_id << 16) & PHYAD_MASK) |
 72		((regnum << 21) & REGAD_MASK);
 73
 74	value &= MIIWDATA_MASK;
 75
 76	writel(value, data->base + REG_PHY_WRITE_DATA);
 77	writel(ctrl, data->base + REG_PHY_CTRL);
 78
 79	do {
 80		ctrl = readl(data->base + REG_PHY_CTRL);
 81
 82		if (!(ctrl & MIIWR))
 83			return 0;
 84
 85		mdelay(10);
 86		count--;
 87	} while (count > 0);
 88
 89	dev_dbg(&bus->dev, "%s timed out\n", __func__);
 90
 91	return -ETIMEDOUT;
 92}
 93
 94static int moxart_mdio_reset(struct mii_bus *bus)
 95{
 96	int data, i;
 97
 98	for (i = 0; i < PHY_MAX_ADDR; i++) {
 99		data = moxart_mdio_read(bus, i, MII_BMCR);
100		if (data < 0)
101			continue;
102
103		data |= BMCR_RESET;
104		if (moxart_mdio_write(bus, i, MII_BMCR, data) < 0)
105			continue;
106	}
107
108	return 0;
109}
110
111static int moxart_mdio_probe(struct platform_device *pdev)
112{
113	struct device_node *np = pdev->dev.of_node;
114	struct mii_bus *bus;
115	struct moxart_mdio_data *data;
116	int ret, i;
117
118	bus = mdiobus_alloc_size(sizeof(*data));
119	if (!bus)
120		return -ENOMEM;
121
122	bus->name = "MOXA ART Ethernet MII";
123	bus->read = &moxart_mdio_read;
124	bus->write = &moxart_mdio_write;
125	bus->reset = &moxart_mdio_reset;
126	snprintf(bus->id, MII_BUS_ID_SIZE, "%s-%d-mii", pdev->name, pdev->id);
127	bus->parent = &pdev->dev;
128
129	/* Setting PHY_IGNORE_INTERRUPT here even if it has no effect,
130	 * of_mdiobus_register() sets these PHY_POLL.
131	 * Ideally, the interrupt from MAC controller could be used to
132	 * detect link state changes, not polling, i.e. if there was
133	 * a way phy_driver could set PHY_HAS_INTERRUPT but have that
134	 * interrupt handled in ethernet drivercode.
135	 */
136	for (i = 0; i < PHY_MAX_ADDR; i++)
137		bus->irq[i] = PHY_IGNORE_INTERRUPT;
138
139	data = bus->priv;
140	data->base = devm_platform_ioremap_resource(pdev, 0);
141	if (IS_ERR(data->base)) {
142		ret = PTR_ERR(data->base);
143		goto err_out_free_mdiobus;
144	}
145
146	ret = of_mdiobus_register(bus, np);
147	if (ret < 0)
148		goto err_out_free_mdiobus;
149
150	platform_set_drvdata(pdev, bus);
151
152	return 0;
153
154err_out_free_mdiobus:
155	mdiobus_free(bus);
156	return ret;
157}
158
159static int moxart_mdio_remove(struct platform_device *pdev)
160{
161	struct mii_bus *bus = platform_get_drvdata(pdev);
162
163	mdiobus_unregister(bus);
164	mdiobus_free(bus);
165
166	return 0;
167}
168
169static const struct of_device_id moxart_mdio_dt_ids[] = {
170	{ .compatible = "moxa,moxart-mdio" },
171	{ }
172};
173MODULE_DEVICE_TABLE(of, moxart_mdio_dt_ids);
174
175static struct platform_driver moxart_mdio_driver = {
176	.probe = moxart_mdio_probe,
177	.remove = moxart_mdio_remove,
178	.driver = {
179		.name = "moxart-mdio",
180		.of_match_table = moxart_mdio_dt_ids,
181	},
182};
183
184module_platform_driver(moxart_mdio_driver);
185
186MODULE_DESCRIPTION("MOXA ART MDIO interface driver");
187MODULE_AUTHOR("Jonas Jensen <jonas.jensen@gmail.com>");
188MODULE_LICENSE("GPL v2");