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., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <stddef.h>
  22 #include <string.h>
  23 #include <assert.h>
  24 #include <unistd.h>
  25 #include <gpxe/threewire.h>
  26
  27 /** @file
  28  *
  29  * Three-wire serial devices
  30  *
  31  */
  32
  33 /**
  34  * Read data from three-wire device
  35  *
  36  * @v nvs               NVS device
  37  * @v address           Address from which to read
  38  * @v data              Data buffer
  39  * @v len               Length of data buffer
  40  * @ret rc              Return status code
  41  */
  42 int threewire_read ( struct nvs_device *nvs, unsigned int address,
  43                      void *data, size_t len ) {
  44         struct spi_device *device = nvs_to_spi ( nvs );
  45         struct spi_bus *bus = device->bus;
  46         int rc;
  47
  48         assert ( bus->mode == SPI_MODE_THREEWIRE );
  49
  50         DBGC ( device, "3wire %p reading %zd bytes at %04x\n",
  51                device, len, address );
  52
  53         if ( ( rc = bus->rw ( bus, device, THREEWIRE_READ, address,
  54                               NULL, data, len ) ) != 0 ) {
  55                 DBGC ( device, "3wire %p could not read: %s\n",
  56                        device, strerror ( rc ) );
  57                 return rc;
  58         }
  59
  60         return 0;
  61 }
  62
  63 /**
  64  * Write data to three-wire device
  65  *
  66  * @v nvs               NVS device
  67  * @v address           Address from which to read
  68  * @v data              Data buffer
  69  * @v len               Length of data buffer
  70  * @ret rc              Return status code
  71  */
  72 int threewire_write ( struct nvs_device *nvs, unsigned int address,
  73                       const void *data, size_t len ) {
  74         struct spi_device *device = nvs_to_spi ( nvs );
  75         struct spi_bus *bus = device->bus;
  76         int rc;
  77
  78         assert ( bus->mode == SPI_MODE_THREEWIRE );
  79
  80         DBGC ( device, "3wire %p writing %zd bytes at %04x\n",
  81                device, len, address );
  82
  83         /* Enable device for writing */
  84         if ( ( rc = bus->rw ( bus, device, THREEWIRE_EWEN,
  85                               THREEWIRE_EWEN_ADDRESS, NULL, NULL, 0 ) ) != 0 ){
  86                 DBGC ( device, "3wire %p could not enable writing: %s\n",
  87                        device, strerror ( rc ) );
  88                 return rc;
  89         }
  90
  91         /* Write data */
  92         if ( ( rc = bus->rw ( bus, device, THREEWIRE_WRITE, address,
  93                               data, NULL, len ) ) != 0 ) {
  94                 DBGC ( device, "3wire %p could not write: %s\n",
  95                        device, strerror ( rc ) );
  96                 return rc;
  97         }
  98
  99         /* Our model of an SPI bus doesn't provide a mechanism for
 100          * "assert CS, wait for MISO to become high, so just wait for
 101          * long enough to ensure that the write has completed.
 102          */
 103         mdelay ( THREEWIRE_WRITE_MDELAY );
 104
 105         return 0;
 106 }
 107
 108 /**
 109  * Autodetect device address length
 110  *
 111  * @v device            SPI device
 112  * @ret rc              Return status code
 113  */
 114 int threewire_detect_address_len ( struct spi_device *device ) {
 115         struct nvs_device *nvs = &device->nvs;
 116         int rc;
 117
 118         DBGC ( device, "3wire %p autodetecting address length\n", device );
 119
 120         device->address_len = SPI_AUTODETECT_ADDRESS_LEN;
 121         if ( ( rc = threewire_read ( nvs, 0, NULL,
 122                                      ( 1 << nvs->word_len_log2 ) ) ) != 0 ) {
 123                 DBGC ( device, "3wire %p could not autodetect address "
 124                        "length: %s\n", device, strerror ( rc ) );
 125                 return rc;
 126         }
 127
 128         DBGC ( device, "3wire %p autodetected address length %d\n",
 129                device, device->address_len );
 130         return 0;
 131 }