1/*
2 * Copyright (C) 2004-2013 Synopsys, Inc. (www.synopsys.com)
3 *
4 * MDIO implementation for ARC EMAC
5 */
6
7#include <linux/delay.h>
8#include <linux/of_mdio.h>
9#include <linux/platform_device.h>
10
11#include "emac.h"
12
13/* Number of seconds we wait for "MDIO complete" flag to appear */
14#define ARC_MDIO_COMPLETE_POLL_COUNT	1
15
16/**
17 * arc_mdio_complete_wait - Waits until MDIO transaction is completed.
18 * @priv:	Pointer to ARC EMAC private data structure.
19 *
20 * returns:	0 on success, -ETIMEDOUT on a timeout.
21 */
22static int arc_mdio_complete_wait(struct arc_emac_priv *priv)
23{
24	unsigned int i;
25
26	for (i = 0; i < ARC_MDIO_COMPLETE_POLL_COUNT * 40; i++) {
27		unsigned int status = arc_reg_get(priv, R_STATUS);
28
29		status &= MDIO_MASK;
30
31		if (status) {
32			/* Reset "MDIO complete" flag */
33			arc_reg_set(priv, R_STATUS, status);
34			return 0;
35		}
36
37		msleep(25);
38	}
39
40	return -ETIMEDOUT;
41}
42
43/**
44 * arc_mdio_read - MDIO interface read function.
45 * @bus:	Pointer to MII bus structure.
46 * @phy_addr:	Address of the PHY device.
47 * @reg_num:	PHY register to read.
48 *
49 * returns:	The register contents on success, -ETIMEDOUT on a timeout.
50 *
51 * Reads the contents of the requested register from the requested PHY
52 * address.
53 */
54static int arc_mdio_read(struct mii_bus *bus, int phy_addr, int reg_num)
55{
56	struct arc_emac_priv *priv = bus->priv;
57	unsigned int value;
58	int error;
59
60	arc_reg_set(priv, R_MDIO,
61		    0x60020000 | (phy_addr << 23) | (reg_num << 18));
62
63	error = arc_mdio_complete_wait(priv);
64	if (error < 0)
65		return error;
66
67	value = arc_reg_get(priv, R_MDIO) & 0xffff;
68
69	dev_dbg(priv->dev, "arc_mdio_read(phy_addr=%i, reg_num=%x) = %x\n",
70		phy_addr, reg_num, value);
71
72	return value;
73}
74
75/**
76 * arc_mdio_write - MDIO interface write function.
77 * @bus:	Pointer to MII bus structure.
78 * @phy_addr:	Address of the PHY device.
79 * @reg_num:	PHY register to write to.
80 * @value:	Value to be written into the register.
81 *
82 * returns:	0 on success, -ETIMEDOUT on a timeout.
83 *
84 * Writes the value to the requested register.
85 */
86static int arc_mdio_write(struct mii_bus *bus, int phy_addr,
87			  int reg_num, u16 value)
88{
89	struct arc_emac_priv *priv = bus->priv;
90
91	dev_dbg(priv->dev,
92		"arc_mdio_write(phy_addr=%i, reg_num=%x, value=%x)\n",
93		phy_addr, reg_num, value);
94
95	arc_reg_set(priv, R_MDIO,
96		     0x50020000 | (phy_addr << 23) | (reg_num << 18) | value);
97
98	return arc_mdio_complete_wait(priv);
99}
100
101/**
102 * arc_mdio_probe - MDIO probe function.
103 * @priv:	Pointer to ARC EMAC private data structure.
104 *
105 * returns:	0 on success, -ENOMEM when mdiobus_alloc
106 * (to allocate memory for MII bus structure) fails.
107 *
108 * Sets up and registers the MDIO interface.
109 */
110int arc_mdio_probe(struct arc_emac_priv *priv)
111{
112	struct mii_bus *bus;
113	int error;
114
115	bus = mdiobus_alloc();
116	if (!bus)
117		return -ENOMEM;
118
119	priv->bus = bus;
120	bus->priv = priv;
121	bus->parent = priv->dev;
122	bus->name = "Synopsys MII Bus",
123	bus->read = &arc_mdio_read;
124	bus->write = &arc_mdio_write;
125
126	snprintf(bus->id, MII_BUS_ID_SIZE, "%s", bus->name);
127
128	error = of_mdiobus_register(bus, priv->dev->of_node);
129	if (error) {
130		dev_err(priv->dev, "cannot register MDIO bus %s\n", bus->name);
131		mdiobus_free(bus);
132		return error;
133	}
134
135	return 0;
136}
137
138/**
139 * arc_mdio_remove - MDIO remove function.
140 * @priv:	Pointer to ARC EMAC private data structure.
141 *
142 * Unregisters the MDIO and frees any associate memory for MII bus.
143 */
144int arc_mdio_remove(struct arc_emac_priv *priv)
145{
146	mdiobus_unregister(priv->bus);
147	mdiobus_free(priv->bus);
148	priv->bus = NULL;
149
150	return 0;
151}
152