src/drivers/nvs/threewire.c

   1 /*
   2  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
   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 <stddef.h>
  27 #include <string.h>
  28 #include <assert.h>
  29 #include <unistd.h>
  30 #include <ipxe/threewire.h>
  31
  32 /** @file
  33  *
  34  * Three-wire serial devices
  35  *
  36  */
  37
  38 /**
  39  * Read data from three-wire device
  40  *
  41  * @v nvs               NVS device
  42  * @v address           Address from which to read
  43  * @v data              Data buffer
  44  * @v len               Length of data buffer
  45  * @ret rc              Return status code
  46  */
  47 int threewire_read ( struct nvs_device *nvs, unsigned int address,
  48                      void *data, size_t len ) {
  49         struct spi_device *device = nvs_to_spi ( nvs );
  50         struct spi_bus *bus = device->bus;
  51         int rc;
  52
  53         assert ( bus->mode == SPI_MODE_THREEWIRE );
  54
  55         DBGC ( device, "3wire %p reading %zd bytes at %04x\n",
  56                device, len, address );
  57
  58         if ( ( rc = bus->rw ( bus, device, THREEWIRE_READ, address,
  59                               NULL, data, len ) ) != 0 ) {
  60                 DBGC ( device, "3wire %p could not read: %s\n",
  61                        device, strerror ( rc ) );
  62                 return rc;
  63         }
  64
  65         return 0;
  66 }
  67
  68 /**
  69  * Write data to three-wire device
  70  *
  71  * @v nvs               NVS device
  72  * @v address           Address from which to read
  73  * @v data              Data buffer
  74  * @v len               Length of data buffer
  75  * @ret rc              Return status code
  76  */
  77 int threewire_write ( struct nvs_device *nvs, unsigned int address,
  78                       const void *data, size_t len ) {
  79         struct spi_device *device = nvs_to_spi ( nvs );
  80         struct spi_bus *bus = device->bus;
  81         int rc;
  82
  83         assert ( bus->mode == SPI_MODE_THREEWIRE );
  84
  85         DBGC ( device, "3wire %p writing %zd bytes at %04x\n",
  86                device, len, address );
  87
  88         /* Enable device for writing */
  89         if ( ( rc = bus->rw ( bus, device, THREEWIRE_EWEN,
  90                               THREEWIRE_EWEN_ADDRESS, NULL, NULL, 0 ) ) != 0 ){
  91                 DBGC ( device, "3wire %p could not enable writing: %s\n",
  92                        device, strerror ( rc ) );
  93                 return rc;
  94         }
  95
  96         /* Write data */
  97         if ( ( rc = bus->rw ( bus, device, THREEWIRE_WRITE, address,
  98                               data, NULL, len ) ) != 0 ) {
  99                 DBGC ( device, "3wire %p could not write: %s\n",
 100                        device, strerror ( rc ) );
 101                 return rc;
 102         }
 103
 104         /* Our model of an SPI bus doesn't provide a mechanism for
 105          * "assert CS, wait for MISO to become high, so just wait for
 106          * long enough to ensure that the write has completed.
 107          */
 108         mdelay ( THREEWIRE_WRITE_MDELAY );
 109
 110         return 0;
 111 }
 112
 113 /**
 114  * Autodetect device address length
 115  *
 116  * @v device            SPI device
 117  * @ret rc              Return status code
 118  */
 119 int threewire_detect_address_len ( struct spi_device *device ) {
 120         struct nvs_device *nvs = &device->nvs;
 121         int rc;
 122
 123         DBGC ( device, "3wire %p autodetecting address length\n", device );
 124
 125         device->address_len = SPI_AUTODETECT_ADDRESS_LEN;
 126         if ( ( rc = threewire_read ( nvs, 0, NULL,
 127                                      ( 1 << nvs->word_len_log2 ) ) ) != 0 ) {
 128                 DBGC ( device, "3wire %p could not autodetect address "
 129                        "length: %s\n", device, strerror ( rc ) );
 130                 return rc;
 131         }
 132
 133         DBGC ( device, "3wire %p autodetected address length %d\n",
 134                device, device->address_len );
 135         return 0;
 136 }