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wdenkaffae2b2002-08-17 09:36:01 +00001/*
2 * (C) Copyright 2001
3 * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
4 *
5 * See file CREDITS for list of people who contributed to this
6 * project.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21 * MA 02111-1307 USA
22 */
23
24/*
25 * This provides a bit-banged interface to the ethernet MII management
26 * channel.
27 */
28
29#include <common.h>
30#include <ioports.h>
31#include <ppc_asm.tmpl>
32
33#ifdef CONFIG_BITBANGMII
34
35
36/*****************************************************************************
37 *
38 * Utility to send the preamble, address, and register (common to read
39 * and write).
40 */
41static void miiphy_pre(char read,
42 unsigned char addr,
43 unsigned char reg)
44{
45 int j; /* counter */
46 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, MDIO_PORT);
47
48 /*
49 * Send a 32 bit preamble ('1's) with an extra '1' bit for good measure.
50 * The IEEE spec says this is a PHY optional requirement. The AMD
51 * 79C874 requires one after power up and one after a MII communications
52 * error. This means that we are doing more preambles than we need,
53 * but it is safer and will be much more robust.
54 */
55
56 MDIO_ACTIVE;
57 MDIO(1);
58 for(j = 0; j < 32; j++)
59 {
60 MDC(0);
61 MIIDELAY;
62 MDC(1);
63 MIIDELAY;
64 }
65
66 /* send the start bit (01) and the read opcode (10) or write (10) */
67 MDC(0); MDIO(0); MIIDELAY; MDC(1); MIIDELAY;
68 MDC(0); MDIO(1); MIIDELAY; MDC(1); MIIDELAY;
69 MDC(0); MDIO(read); MIIDELAY; MDC(1); MIIDELAY;
70 MDC(0); MDIO(!read); MIIDELAY; MDC(1); MIIDELAY;
71
72 /* send the PHY address */
73 for(j = 0; j < 5; j++)
74 {
75 MDC(0);
76 if((addr & 0x10) == 0)
77 {
78 MDIO(0);
79 }
80 else
81 {
82 MDIO(1);
83 }
84 MIIDELAY;
85 MDC(1);
86 MIIDELAY;
87 addr <<= 1;
88 }
89
90 /* send the register address */
91 for(j = 0; j < 5; j++)
92 {
93 MDC(0);
94 if((reg & 0x10) == 0)
95 {
96 MDIO(0);
97 }
98 else
99 {
100 MDIO(1);
101 }
102 MIIDELAY;
103 MDC(1);
104 MIIDELAY;
105 reg <<= 1;
106 }
107}
108
109
110/*****************************************************************************
111 *
112 * Read a MII PHY register.
113 *
114 * Returns:
115 * 0 on success
116 */
117int miiphy_read(unsigned char addr,
118 unsigned char reg,
119 unsigned short *value)
120{
121 short rdreg; /* register working value */
122 int j; /* counter */
123 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, MDIO_PORT);
124
125 miiphy_pre(1, addr, reg);
126
127 /* tri-state our MDIO I/O pin so we can read */
128 MDC(0);
129 MDIO_TRISTATE;
130 MIIDELAY;
131 MDC(1);
132 MIIDELAY;
133
134 /* check the turnaround bit: the PHY should be driving it to zero */
135 if(MDIO_READ != 0)
136 {
137 /* printf("PHY didn't drive TA low\n"); */
138 for(j = 0; j < 32; j++)
139 {
140 MDC(0);
141 MIIDELAY;
142 MDC(1);
143 MIIDELAY;
144 }
145 return(-1);
146 }
147
148 MDC(0);
149 MIIDELAY;
150
151 /* read 16 bits of register data, MSB first */
152 rdreg = 0;
153 for(j = 0; j < 16; j++)
154 {
155 MDC(1);
156 MIIDELAY;
157 rdreg <<= 1;
158 rdreg |= MDIO_READ;
159 MDC(0);
160 MIIDELAY;
161 }
162
163 MDC(1);
164 MIIDELAY;
165 MDC(0);
166 MIIDELAY;
167 MDC(1);
168 MIIDELAY;
169
170 *value = rdreg;
171
172#ifdef DEBUG
173 printf ("miiphy_read(0x%x) @ 0x%x = 0x%04x\n", reg, addr, *value);
174#endif
175
176 return 0;
177}
178
179
180/*****************************************************************************
181 *
182 * Write a MII PHY register.
183 *
184 * Returns:
185 * 0 on success
186 */
187int miiphy_write(unsigned char addr,
188 unsigned char reg,
189 unsigned short value)
190{
191 int j; /* counter */
192 volatile ioport_t *iop = ioport_addr((immap_t *)CFG_IMMR, MDIO_PORT);
193
194 miiphy_pre(0, addr, reg);
195
196 /* send the turnaround (10) */
197 MDC(0); MDIO(1); MIIDELAY; MDC(1); MIIDELAY;
198 MDC(0); MDIO(0); MIIDELAY; MDC(1); MIIDELAY;
199
200 /* write 16 bits of register data, MSB first */
201 for(j = 0; j < 16; j++)
202 {
203 MDC(0);
204 if((value & 0x00008000) == 0)
205 {
206 MDIO(0);
207 }
208 else
209 {
210 MDIO(1);
211 }
212 MIIDELAY;
213 MDC(1);
214 MIIDELAY;
215 value <<= 1;
216 }
217
218 /*
219 * Tri-state the MDIO line.
220 */
221 MDIO_TRISTATE;
222 MDC(0);
223 MIIDELAY;
224 MDC(1);
225 MIIDELAY;
226
227 return 0;
228}
229
230#endif /* CONFIG_BITBANGMII */
231