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 };