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 */
arc_mdio_complete_wait(struct arc_emac_priv * priv)24 static 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 */
arc_mdio_read(struct mii_bus * bus,int phy_addr,int reg_num)56 static 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 */
arc_mdio_write(struct mii_bus * bus,int phy_addr,int reg_num,u16 value)88 static 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 */
arc_mdio_reset(struct mii_bus * bus)108 static 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 */
arc_mdio_probe(struct arc_emac_priv * priv)131 int 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 device_node *mdio_node;
137 struct mii_bus *bus;
138 int error;
139
140 bus = mdiobus_alloc();
141 if (!bus)
142 return -ENOMEM;
143
144 priv->bus = bus;
145 bus->priv = priv;
146 bus->parent = priv->dev;
147 bus->name = name;
148 bus->read = &arc_mdio_read;
149 bus->write = &arc_mdio_write;
150 bus->reset = &arc_mdio_reset;
151
152 /* optional reset-related properties */
153 data->reset_gpio = devm_gpiod_get_optional(priv->dev, "phy-reset",
154 GPIOD_OUT_LOW);
155 if (IS_ERR(data->reset_gpio)) {
156 mdiobus_free(bus);
157 return dev_err_probe(priv->dev, PTR_ERR(data->reset_gpio),
158 "Failed to request gpio\n");
159 }
160
161 of_property_read_u32(np, "phy-reset-duration", &data->msec);
162 /* A sane reset duration should not be longer than 1s */
163 if (data->msec > 1000)
164 data->msec = 1;
165
166 snprintf(bus->id, MII_BUS_ID_SIZE, "%s", bus->name);
167
168 /* Backwards compatibility for EMAC nodes without MDIO subnode. */
169 mdio_node = of_get_child_by_name(np, "mdio");
170 if (!mdio_node)
171 mdio_node = of_node_get(np);
172
173 error = of_mdiobus_register(bus, mdio_node);
174 of_node_put(mdio_node);
175 if (error) {
176 mdiobus_free(bus);
177 return dev_err_probe(priv->dev, error,
178 "cannot register MDIO bus %s\n", name);
179 }
180
181 return 0;
182 }
183
184 /**
185 * arc_mdio_remove - MDIO remove function.
186 * @priv: Pointer to ARC EMAC private data structure.
187 *
188 * Unregisters the MDIO and frees any associate memory for MII bus.
189 */
arc_mdio_remove(struct arc_emac_priv * priv)190 int arc_mdio_remove(struct arc_emac_priv *priv)
191 {
192 mdiobus_unregister(priv->bus);
193 mdiobus_free(priv->bus);
194 priv->bus = NULL;
195
196 return 0;
197 }
198