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