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  */
22 static 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  */
54 static 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  */
86 static 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  * @pdev:	Pointer to platform device.
104  * @priv:	Pointer to ARC EMAC private data structure.
105  *
106  * returns:	0 on success, -ENOMEM when mdiobus_alloc
107  * (to allocate memory for MII bus structure) fails.
108  *
109  * Sets up and registers the MDIO interface.
110  */
111 int arc_mdio_probe(struct platform_device *pdev, struct arc_emac_priv *priv)
112 {
113 	struct mii_bus *bus;
114 	int error;
115 
116 	bus = mdiobus_alloc();
117 	if (!bus)
118 		return -ENOMEM;
119 
120 	priv->bus = bus;
121 	bus->priv = priv;
122 	bus->parent = priv->dev;
123 	bus->name = "Synopsys MII Bus",
124 	bus->read = &arc_mdio_read;
125 	bus->write = &arc_mdio_write;
126 
127 	snprintf(bus->id, MII_BUS_ID_SIZE, "%s", pdev->name);
128 
129 	error = of_mdiobus_register(bus, pdev->dev.of_node);
130 	if (error) {
131 		dev_err(priv->dev, "cannot register MDIO bus %s\n", bus->name);
132 		mdiobus_free(bus);
133 		return error;
134 	}
135 
136 	return 0;
137 }
138 
139 /**
140  * arc_mdio_remove - MDIO remove function.
141  * @priv:	Pointer to ARC EMAC private data structure.
142  *
143  * Unregisters the MDIO and frees any associate memory for MII bus.
144  */
145 int arc_mdio_remove(struct arc_emac_priv *priv)
146 {
147 	mdiobus_unregister(priv->bus);
148 	mdiobus_free(priv->bus);
149 	priv->bus = NULL;
150 
151 	return 0;
152 }
153