common/miiphybb.c

   1 /*
   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  */
  41 static void miiphy_pre (char read, unsigned char addr, unsigned char reg)
  42 {
  43         int j;                  /* counter */
  44 #if !(defined(CONFIG_EP8248) || defined(CONFIG_EP82XXM))
  45         volatile ioport_t *iop = ioport_addr ((immap_t *) CFG_IMMR, MDIO_PORT);
  46 #endif
  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                 MDC (0);
  60                 MIIDELAY;
  61                 MDC (1);
  62                 MIIDELAY;
  63         }
  64
  65         /* send the start bit (01) and the read opcode (10) or write (10) */
  66         MDC (0);
  67         MDIO (0);
  68         MIIDELAY;
  69         MDC (1);
  70         MIIDELAY;
  71         MDC (0);
  72         MDIO (1);
  73         MIIDELAY;
  74         MDC (1);
  75         MIIDELAY;
  76         MDC (0);
  77         MDIO (read);
  78         MIIDELAY;
  79         MDC (1);
  80         MIIDELAY;
  81         MDC (0);
  82         MDIO (!read);
  83         MIIDELAY;
  84         MDC (1);
  85         MIIDELAY;
  86
  87         /* send the PHY address */
  88         for (j = 0; j < 5; j++) {
  89                 MDC (0);
  90                 if ((addr & 0x10) == 0) {
  91                         MDIO (0);
  92                 } else {
  93                         MDIO (1);
  94                 }
  95                 MIIDELAY;
  96                 MDC (1);
  97                 MIIDELAY;
  98                 addr <<= 1;
  99         }
 100
 101         /* send the register address */
 102         for (j = 0; j < 5; j++) {
 103                 MDC (0);
 104                 if ((reg & 0x10) == 0) {
 105                         MDIO (0);
 106                 } else {
 107                         MDIO (1);
 108                 }
 109                 MIIDELAY;
 110                 MDC (1);
 111                 MIIDELAY;
 112                 reg <<= 1;
 113         }
 114 }
 115
 116
 117 /*****************************************************************************
 118  *
 119  * Read a MII PHY register.
 120  *
 121  * Returns:
 122  *   0 on success
 123  */
 124 int bb_miiphy_read (char *devname, unsigned char addr,
 125                 unsigned char reg, unsigned short *value)
 126 {
 127         short rdreg;            /* register working value */
 128         int j;                  /* counter */
 129 #if !(defined(CONFIG_EP8248) || defined(CONFIG_EP82XXM))
 130         volatile ioport_t *iop = ioport_addr ((immap_t *) CFG_IMMR, MDIO_PORT);
 131 #endif
 132
 133         miiphy_pre (1, addr, reg);
 134
 135         /* tri-state our MDIO I/O pin so we can read */
 136         MDC (0);
 137         MDIO_TRISTATE;
 138         MIIDELAY;
 139         MDC (1);
 140         MIIDELAY;
 141
 142         /* check the turnaround bit: the PHY should be driving it to zero */
 143         if (MDIO_READ != 0) {
 144                 /* puts ("PHY didn't drive TA low\n"); */
 145                 for (j = 0; j < 32; j++) {
 146                         MDC (0);
 147                         MIIDELAY;
 148                         MDC (1);
 149                         MIIDELAY;
 150                 }
 151                 return (-1);
 152         }
 153
 154         MDC (0);
 155         MIIDELAY;
 156
 157         /* read 16 bits of register data, MSB first */
 158         rdreg = 0;
 159         for (j = 0; j < 16; j++) {
 160                 MDC (1);
 161                 MIIDELAY;
 162                 rdreg <<= 1;
 163                 rdreg |= MDIO_READ;
 164                 MDC (0);
 165                 MIIDELAY;
 166         }
 167
 168         MDC (1);
 169         MIIDELAY;
 170         MDC (0);
 171         MIIDELAY;
 172         MDC (1);
 173         MIIDELAY;
 174
 175         *value = rdreg;
 176
 177 #ifdef DEBUG
 178         printf ("miiphy_read(0x%x) @ 0x%x = 0x%04x\n", reg, addr, *value);
 179 #endif
 180
 181         return 0;
 182 }
 183
 184
 185 /*****************************************************************************
 186  *
 187  * Write a MII PHY register.
 188  *
 189  * Returns:
 190  *   0 on success
 191  */
 192 int bb_miiphy_write (char *devname, unsigned char addr,
 193                 unsigned char reg, unsigned short value)
 194 {
 195         int j;                  /* counter */
 196 #if !(defined(CONFIG_EP8248) || defined(CONFIG_EP82XXM))
 197         volatile ioport_t *iop = ioport_addr ((immap_t *) CFG_IMMR, MDIO_PORT);
 198 #endif
 199
 200         miiphy_pre (0, addr, reg);
 201
 202         /* send the turnaround (10) */
 203         MDC (0);
 204         MDIO (1);
 205         MIIDELAY;
 206         MDC (1);
 207         MIIDELAY;
 208         MDC (0);
 209         MDIO (0);
 210         MIIDELAY;
 211         MDC (1);
 212         MIIDELAY;
 213
 214         /* write 16 bits of register data, MSB first */
 215         for (j = 0; j < 16; j++) {
 216                 MDC (0);
 217                 if ((value & 0x00008000) == 0) {
 218                         MDIO (0);
 219                 } else {
 220                         MDIO (1);
 221                 }
 222                 MIIDELAY;
 223                 MDC (1);
 224                 MIIDELAY;
 225                 value <<= 1;
 226         }
 227
 228         /*
 229          * Tri-state the MDIO line.
 230          */
 231         MDIO_TRISTATE;
 232         MDC (0);
 233         MIIDELAY;
 234         MDC (1);
 235         MIIDELAY;
 236
 237         return 0;
 238 }
 239
 240 #endif /* CONFIG_BITBANGMII */