[mii] Add bit-bashing interface
[ipxe.git] / src / drivers / bitbash / mii_bit.c
1 /*
2 * Copyright (C) 2018 Sylvie Barlow <sylvie.c.barlow@gmail.com>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 * 02110-1301, USA.
18 *
19 * You can also choose to distribute this program under the terms of
20 * the Unmodified Binary Distribution Licence (as given in the file
21 * COPYING.UBDL), provided that you have satisfied its requirements.
22 */
23
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25
26 #include <stdint.h>
27 #include <unistd.h>
28 #include <ipxe/bitbash.h>
29 #include <ipxe/mii_bit.h>
30
31 /**
32 * Transfer bits over MII bit-bashing interface
33 *
34 * @v basher Bit basher
35 * @v mask Mask
36 * @v write Data to write
37 * @ret read Data read
38 */
39 static uint32_t mii_bit_xfer ( struct bit_basher *basher,
40 uint32_t mask, uint32_t write ) {
41 uint32_t read = 0;
42 int bit;
43
44 for ( ; mask ; mask >>= 1 ) {
45
46 /* Delay */
47 udelay ( 1 );
48
49 /* Write bit to basher */
50 write_bit ( basher, MII_BIT_MDIO, ( write & mask ) );
51
52 /* Read bit from basher */
53 bit = read_bit ( basher, MII_BIT_MDIO );
54 read <<= 1;
55 read |= ( bit & 1 );
56
57 /* Set clock high */
58 write_bit ( basher, MII_BIT_MDC, 1 );
59
60 /* Delay */
61 udelay ( 1 );
62
63 /* Set clock low */
64 write_bit ( basher, MII_BIT_MDC, 0 );
65 }
66 return read;
67 }
68
69 /**
70 * Read or write via MII bit-bashing interface
71 *
72 * @v basher Bit basher
73 * @v phy PHY address
74 * @v reg Register address
75 * @v data Data to write
76 * @v cmd Command
77 * @ret data Data read
78 */
79 static unsigned int mii_bit_rw ( struct bit_basher *basher,
80 unsigned int phy, unsigned int reg,
81 unsigned int data, unsigned int cmd ) {
82
83 /* Initiate drive for write */
84 write_bit ( basher, MII_BIT_DRIVE, 1 );
85
86 /* Write start */
87 mii_bit_xfer ( basher, MII_BIT_START_MASK, MII_BIT_START );
88
89 /* Write command */
90 mii_bit_xfer ( basher, MII_BIT_CMD_MASK, cmd );
91
92 /* Write PHY address */
93 mii_bit_xfer ( basher, MII_BIT_PHY_MASK, phy );
94
95 /* Write register address */
96 mii_bit_xfer ( basher, MII_BIT_REG_MASK, reg );
97
98 /* Switch drive to read if applicable */
99 write_bit ( basher, MII_BIT_DRIVE, ( cmd & MII_BIT_CMD_RW ) );
100
101 /* Allow space for turnaround */
102 mii_bit_xfer ( basher, MII_BIT_SWITCH_MASK, MII_BIT_SWITCH );
103
104 /* Read or write data */
105 data = mii_bit_xfer (basher, MII_BIT_DATA_MASK, data );
106
107 /* Initiate drive for read */
108 write_bit ( basher, MII_BIT_DRIVE, 0 );
109
110 return data;
111 }
112
113 /**
114 * Read from MII register
115 *
116 * @v mdio MII interface
117 * @v phy PHY address
118 * @v reg Register address
119 * @ret data Data read, or negative error
120 */
121 static int mii_bit_read ( struct mii_interface *mdio, unsigned int phy,
122 unsigned int reg ) {
123 struct mii_bit_basher *miibit =
124 container_of ( mdio, struct mii_bit_basher, mdio );
125 struct bit_basher *basher = &miibit->basher;
126
127 return mii_bit_rw ( basher, phy, reg, 0, MII_BIT_CMD_READ );
128 }
129
130 /**
131 * Write to MII register
132 *
133 * @v mdio MII interface
134 * @v phy PHY address
135 * @v reg Register address
136 * @v data Data to write
137 * @ret rc Return status code
138 */
139 static int mii_bit_write ( struct mii_interface *mdio, unsigned int phy,
140 unsigned int reg, unsigned int data ) {
141 struct mii_bit_basher *miibit =
142 container_of ( mdio, struct mii_bit_basher, mdio );
143 struct bit_basher *basher = &miibit->basher;
144
145 mii_bit_rw ( basher, phy, reg, data, MII_BIT_CMD_WRITE );
146 return 0;
147 }
148
149 /** MII bit basher operations */
150 static struct mii_operations mii_bit_op = {
151 .read = mii_bit_read,
152 .write = mii_bit_write,
153 };
154
155 /**
156 * Initialise bit-bashing interface
157 *
158 * @v miibit MII bit basher
159 */
160 void init_mii_bit_basher ( struct mii_bit_basher *miibit ) {
161 mdio_init ( &miibit->mdio, &mii_bit_op );
162 };