summaryrefslogtreecommitdiffstats
path: root/drivers/net/phy/mdio-bitbang.c
blob: 6428fcbbdd4bf4f6967e7eb3fee32e97fceba566 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
/*
 * Bitbanged MDIO support.
 *
 * Author: Scott Wood <scottwood@freescale.com>
 * Copyright (c) 2007 Freescale Semiconductor
 *
 * Based on CPM2 MDIO code which is:
 *
 * Copyright (c) 2003 Intracom S.A.
 *  by Pantelis Antoniou <panto@intracom.gr>
 *
 * 2005 (c) MontaVista Software, Inc.
 * Vitaly Bordug <vbordug@ru.mvista.com>
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2. This program is licensed "as is" without any warranty of any
 * kind, whether express or implied.
 */

#include <linux/module.h>
#include <linux/mdio-bitbang.h>
#include <linux/types.h>
#include <linux/delay.h>

#define MDIO_READ 2
#define MDIO_WRITE 1

#define MDIO_C45 (1<<15)
#define MDIO_C45_ADDR (MDIO_C45 | 0)
#define MDIO_C45_READ (MDIO_C45 | 3)
#define MDIO_C45_WRITE (MDIO_C45 | 1)

#define MDIO_SETUP_TIME 10
#define MDIO_HOLD_TIME 10

/* Minimum MDC period is 400 ns, plus some margin for error.  MDIO_DELAY
 * is done twice per period.
 */
#define MDIO_DELAY 250

/* The PHY may take up to 300 ns to produce data, plus some margin
 * for error.
 */
#define MDIO_READ_DELAY 350

/* MDIO must already be configured as output. */
static void mdiobb_send_bit(struct mdiobb_ctrl *ctrl, int val)
{
	const struct mdiobb_ops *ops = ctrl->ops;

	ops->set_mdio_data(ctrl, val);
	ndelay(MDIO_DELAY);
	ops->set_mdc(ctrl, 1);
	ndelay(MDIO_DELAY);
	ops->set_mdc(ctrl, 0);
}

/* MDIO must already be configured as input. */
static int mdiobb_get_bit(struct mdiobb_ctrl *ctrl)
{
	const struct mdiobb_ops *ops = ctrl->ops;

	ndelay(MDIO_DELAY);
	ops->set_mdc(ctrl, 1);
	ndelay(MDIO_READ_DELAY);
	ops->set_mdc(ctrl, 0);

	return ops->get_mdio_data(ctrl);
}

/* MDIO must already be configured as output. */
static void mdiobb_send_num(struct mdiobb_ctrl *ctrl, u16 val, int bits)
{
	int i;

	for (i = bits - 1; i >= 0; i--)
		mdiobb_send_bit(ctrl, (val >> i) & 1);
}

/* MDIO must already be configured as input. */
static u16 mdiobb_get_num(struct mdiobb_ctrl *ctrl, int bits)
{
	int i;
	u16 ret = 0;

	for (i = bits - 1; i >= 0; i--) {
		ret <<= 1;
		ret |= mdiobb_get_bit(ctrl);
	}

	return ret;
}

/* Utility to send the preamble, address, and
 * register (common to read and write).
 */
static void mdiobb_cmd(struct mdiobb_ctrl *ctrl, int op, u8 phy, u8 reg)
{
	const struct mdiobb_ops *ops = ctrl->ops;
	int i;

	ops->set_mdio_dir(ctrl, 1);

	/*
	 * Send a 32 bit preamble ('1's) with an extra '1' bit for good
	 * measure.  The IEEE spec says this is a PHY optional
	 * requirement.  The AMD 79C874 requires one after power up and
	 * one after a MII communications error.  This means that we are
	 * doing more preambles than we need, but it is safer and will be
	 * much more robust.
	 */

	for (i = 0; i < 32; i++)
		mdiobb_send_bit(ctrl, 1);

	/* send the start bit (01) and the read opcode (10) or write (10).
	   Clause 45 operation uses 00 for the start and 11, 10 for
	   read/write */
	mdiobb_send_bit(ctrl, 0);
	if (op & MDIO_C45)
		mdiobb_send_bit(ctrl, 0);
	else
		mdiobb_send_bit(ctrl, 1);
	mdiobb_send_bit(ctrl, (op >> 1) & 1);
	mdiobb_send_bit(ctrl, (op >> 0) & 1);

	mdiobb_send_num(ctrl, phy, 5);
	mdiobb_send_num(ctrl, reg, 5);
}

/* In clause 45 mode all commands are prefixed by MDIO_ADDR to specify the
   lower 16 bits of the 21 bit address. This transfer is done identically to a
   MDIO_WRITE except for a different code. To enable clause 45 mode or
   MII_ADDR_C45 into the address. Theoretically clause 45 and normal devices
   can exist on the same bus. Normal devices should ignore the MDIO_ADDR
   phase. */
static int mdiobb_cmd_addr(struct mdiobb_ctrl *ctrl, int phy, u32 addr)
{
	unsigned int dev_addr = (addr >> 16) & 0x1F;
	unsigned int reg = addr & 0xFFFF;
	mdiobb_cmd(ctrl, MDIO_C45_ADDR, phy, dev_addr);

	/* send the turnaround (10) */
	mdiobb_send_bit(ctrl, 1);
	mdiobb_send_bit(ctrl, 0);

	mdiobb_send_num(ctrl, reg, 16);

	ctrl->ops->set_mdio_dir(ctrl, 0);
	mdiobb_get_bit(ctrl);

	return dev_addr;
}

static int mdiobb_read(struct mii_bus *bus, int phy, int reg)
{
	struct mdiobb_ctrl *ctrl = bus->priv;
	int ret, i;

	if (reg & MII_ADDR_C45) {
		reg = mdiobb_cmd_addr(ctrl, phy, reg);
		mdiobb_cmd(ctrl, MDIO_C45_READ, phy, reg);
	} else
		mdiobb_cmd(ctrl, MDIO_READ, phy, reg);

	ctrl->ops->set_mdio_dir(ctrl, 0);

	/* check the turnaround bit: the PHY should be driving it to zero */
	if (mdiobb_get_bit(ctrl) != 0) {
		/* PHY didn't drive TA low -- flush any bits it
		 * may be trying to send.
		 */
		for (i = 0; i < 32; i++)
			mdiobb_get_bit(ctrl);

		return 0xffff;
	}

	ret = mdiobb_get_num(ctrl, 16);
	mdiobb_get_bit(ctrl);
	return ret;
}

static int mdiobb_write(struct mii_bus *bus, int phy, int reg, u16 val)
{
	struct mdiobb_ctrl *ctrl = bus->priv;

	if (reg & MII_ADDR_C45) {
		reg = mdiobb_cmd_addr(ctrl, phy, reg);
		mdiobb_cmd(ctrl, MDIO_C45_WRITE, phy, reg);
	} else
		mdiobb_cmd(ctrl, MDIO_WRITE, phy, reg);

	/* send the turnaround (10) */
	mdiobb_send_bit(ctrl, 1);
	mdiobb_send_bit(ctrl, 0);

	mdiobb_send_num(ctrl, val, 16);

	ctrl->ops->set_mdio_dir(ctrl, 0);
	mdiobb_get_bit(ctrl);
	return 0;
}

static int mdiobb_reset(struct mii_bus *bus)
{
	struct mdiobb_ctrl *ctrl = bus->priv;
	if (ctrl->reset)
		ctrl->reset(bus);
	return 0;
}

struct mii_bus *alloc_mdio_bitbang(struct mdiobb_ctrl *ctrl)
{
	struct mii_bus *bus;

	bus = mdiobus_alloc();
	if (!bus)
		return NULL;

	__module_get(ctrl->ops->owner);

	bus->read = mdiobb_read;
	bus->write = mdiobb_write;
	bus->reset = mdiobb_reset;
	bus->priv = ctrl;

	return bus;
}
EXPORT_SYMBOL(alloc_mdio_bitbang);

void free_mdio_bitbang(struct mii_bus *bus)
{
	struct mdiobb_ctrl *ctrl = bus->priv;

	module_put(ctrl->ops->owner);
	mdiobus_unregister(bus);
	mdiobus_free(bus);
}
EXPORT_SYMBOL(free_mdio_bitbang);

MODULE_LICENSE("GPL");