1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2004-2013 Synopsys, Inc. (www.synopsys.com)
4 *
5 * MDIO implementation for ARC EMAC
6 */
7
8#include <linux/delay.h>
9#include <linux/of_mdio.h>
10#include <linux/platform_device.h>
11#include <linux/gpio/consumer.h>
12
13#include "emac.h"
14
15/* Number of seconds we wait for "MDIO complete" flag to appear */
16#define ARC_MDIO_COMPLETE_POLL_COUNT	1
17
18/**
19 * arc_mdio_complete_wait - Waits until MDIO transaction is completed.
20 * @priv:	Pointer to ARC EMAC private data structure.
21 *
22 * returns:	0 on success, -ETIMEDOUT on a timeout.
23 */
24static int arc_mdio_complete_wait(struct arc_emac_priv *priv)
25{
26	unsigned int i;
27
28	for (i = 0; i < ARC_MDIO_COMPLETE_POLL_COUNT * 40; i++) {
29		unsigned int status = arc_reg_get(priv, R_STATUS);
30
31		status &= MDIO_MASK;
32
33		if (status) {
34			/* Reset "MDIO complete" flag */
35			arc_reg_set(priv, R_STATUS, status);
36			return 0;
37		}
38
39		msleep(25);
40	}
41
42	return -ETIMEDOUT;
43}
44
45/**
46 * arc_mdio_read - MDIO interface read function.
47 * @bus:	Pointer to MII bus structure.
48 * @phy_addr:	Address of the PHY device.
49 * @reg_num:	PHY register to read.
50 *
51 * returns:	The register contents on success, -ETIMEDOUT on a timeout.
52 *
53 * Reads the contents of the requested register from the requested PHY
54 * address.
55 */
56static int arc_mdio_read(struct mii_bus *bus, int phy_addr, int reg_num)
57{
58	struct arc_emac_priv *priv = bus->priv;
59	unsigned int value;
60	int error;
61
62	arc_reg_set(priv, R_MDIO,
63		    0x60020000 | (phy_addr << 23) | (reg_num << 18));
64
65	error = arc_mdio_complete_wait(priv);
66	if (error < 0)
67		return error;
68
69	value = arc_reg_get(priv, R_MDIO) & 0xffff;
70
71	dev_dbg(priv->dev, "arc_mdio_read(phy_addr=%i, reg_num=%x) = %x\n",
72		phy_addr, reg_num, value);
73
74	return value;
75}
76
77/**
78 * arc_mdio_write - MDIO interface write function.
79 * @bus:	Pointer to MII bus structure.
80 * @phy_addr:	Address of the PHY device.
81 * @reg_num:	PHY register to write to.
82 * @value:	Value to be written into the register.
83 *
84 * returns:	0 on success, -ETIMEDOUT on a timeout.
85 *
86 * Writes the value to the requested register.
87 */
88static int arc_mdio_write(struct mii_bus *bus, int phy_addr,
89			  int reg_num, u16 value)
90{
91	struct arc_emac_priv *priv = bus->priv;
92
93	dev_dbg(priv->dev,
94		"arc_mdio_write(phy_addr=%i, reg_num=%x, value=%x)\n",
95		phy_addr, reg_num, value);
96
97	arc_reg_set(priv, R_MDIO,
98		    0x50020000 | (phy_addr << 23) | (reg_num << 18) | value);
99
100	return arc_mdio_complete_wait(priv);
101}
102
103/**
104 * arc_mdio_reset
105 * @bus: points to the mii_bus structure
106 * Description: reset the MII bus
107 */
108static int arc_mdio_reset(struct mii_bus *bus)
109{
110	struct arc_emac_priv *priv = bus->priv;
111	struct arc_emac_mdio_bus_data *data = &priv->bus_data;
112
113	if (data->reset_gpio) {
114		gpiod_set_value_cansleep(data->reset_gpio, 1);
115		msleep(data->msec);
116		gpiod_set_value_cansleep(data->reset_gpio, 0);
117	}
118
119	return 0;
120}
121
122/**
123 * arc_mdio_probe - MDIO probe function.
124 * @priv:	Pointer to ARC EMAC private data structure.
125 *
126 * returns:	0 on success, -ENOMEM when mdiobus_alloc
127 * (to allocate memory for MII bus structure) fails.
128 *
129 * Sets up and registers the MDIO interface.
130 */
131int arc_mdio_probe(struct arc_emac_priv *priv)
132{
133	struct arc_emac_mdio_bus_data *data = &priv->bus_data;
134	struct device_node *np = priv->dev->of_node;
135	const char *name = "Synopsys MII Bus";
136	struct mii_bus *bus;
137	int error;
138
139	bus = mdiobus_alloc();
140	if (!bus)
141		return -ENOMEM;
142
143	priv->bus = bus;
144	bus->priv = priv;
145	bus->parent = priv->dev;
146	bus->name = name;
147	bus->read = &arc_mdio_read;
148	bus->write = &arc_mdio_write;
149	bus->reset = &arc_mdio_reset;
150
151	/* optional reset-related properties */
152	data->reset_gpio = devm_gpiod_get_optional(priv->dev, "phy-reset",
153						   GPIOD_OUT_LOW);
154	if (IS_ERR(data->reset_gpio)) {
155		mdiobus_free(bus);
156		return dev_err_probe(priv->dev, PTR_ERR(data->reset_gpio),
157				     "Failed to request gpio\n");
158	}
159
160	of_property_read_u32(np, "phy-reset-duration", &data->msec);
161	/* A sane reset duration should not be longer than 1s */
162	if (data->msec > 1000)
163		data->msec = 1;
164
165	snprintf(bus->id, MII_BUS_ID_SIZE, "%s", bus->name);
166
167	error = of_mdiobus_register(bus, priv->dev->of_node);
168	if (error) {
169		mdiobus_free(bus);
170		return dev_err_probe(priv->dev, error,
171				     "cannot register MDIO bus %s\n", name);
172	}
173
174	return 0;
175}
176
177/**
178 * arc_mdio_remove - MDIO remove function.
179 * @priv:	Pointer to ARC EMAC private data structure.
180 *
181 * Unregisters the MDIO and frees any associate memory for MII bus.
182 */
183int arc_mdio_remove(struct arc_emac_priv *priv)
184{
185	mdiobus_unregister(priv->bus);
186	mdiobus_free(priv->bus);
187	priv->bus = NULL;
188
189	return 0;
190}
191