src/drivers/nvs/spi.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 <errno.h>
  28 #include <unistd.h>
  29 #include <ipxe/spi.h>
  30
  31 /** @file
  32  *
  33  * SPI devices
  34  *
  35  */
  36
  37 /**
  38  * Munge SPI device address into command
  39  *
  40  * @v command           SPI command
  41  * @v address           Address
  42  * @v munge_address     Device requires address munging
  43  * @ret command         Actual SPI command to use
  44  *
  45  * Some devices with 9-bit addresses (e.g. AT25040A EEPROM) use bit 3
  46  * of the command byte as address bit A8, rather than having a
  47  * two-byte address.  This function takes care of generating the
  48  * appropriate command.
  49  */
  50 static inline unsigned int spi_command ( unsigned int command,
  51                                          unsigned int address,
  52                                          int munge_address ) {
  53         return ( command | ( ( ( address >> 8 ) & munge_address ) << 3 ) );
  54 }
  55
  56 /**
  57  * Wait for SPI device to complete operation
  58  *
  59  * @v device            SPI device
  60  * @ret rc              Return status code
  61  */
  62 static int spi_wait ( struct spi_device *device ) {
  63         struct spi_bus *bus = device->bus;
  64         uint8_t status;
  65         int i;
  66         int rc;
  67
  68         for ( i = 0 ; i < 50 ; i++ ) {
  69                 udelay ( 20 );
  70                 if ( ( rc = bus->rw ( bus, device, SPI_RDSR, -1, NULL,
  71                                       &status, sizeof ( status ) ) ) != 0 )
  72                         return rc;
  73                 if ( ! ( status & SPI_STATUS_NRDY ) )
  74                         return 0;
  75         }
  76         DBG ( "SPI %p timed out\n", device );
  77         return -ETIMEDOUT;
  78 }
  79
  80 /**
  81  * Read data from SPI device
  82  *
  83  * @v nvs               NVS device
  84  * @v address           Address from which to read
  85  * @v data              Data buffer
  86  * @v len               Length of data buffer
  87  * @ret rc              Return status code
  88  */
  89 int spi_read ( struct nvs_device *nvs, unsigned int address,
  90                void *data, size_t len ) {
  91         struct spi_device *device = nvs_to_spi ( nvs );
  92         struct spi_bus *bus = device->bus;
  93         unsigned int command = spi_command ( SPI_READ, address,
  94                                              device->munge_address );
  95         int rc;
  96
  97         DBG ( "SPI %p reading %zd bytes from %#04x\n", device, len, address );
  98         if ( ( rc = bus->rw ( bus, device, command, address,
  99                               NULL, data, len ) ) != 0 ) {
 100                 DBG ( "SPI %p failed to read data from device\n", device );
 101                 return rc;
 102         }
 103
 104         return 0;
 105 }
 106
 107 /**
 108  * Write data to SPI device
 109  *
 110  * @v nvs               NVS device
 111  * @v address           Address from which to read
 112  * @v data              Data buffer
 113  * @v len               Length of data buffer
 114  * @ret rc              Return status code
 115  */
 116 int spi_write ( struct nvs_device *nvs, unsigned int address,
 117                 const void *data, size_t len ) {
 118         struct spi_device *device = nvs_to_spi ( nvs );
 119         struct spi_bus *bus = device->bus;
 120         unsigned int command = spi_command ( SPI_WRITE, address,
 121                                              device->munge_address );
 122         int rc;
 123
 124         DBG ( "SPI %p writing %zd bytes to %#04x\n", device, len, address );
 125
 126         if ( ( rc = bus->rw ( bus, device, SPI_WREN, -1,
 127                               NULL, NULL, 0 ) ) != 0 ) {
 128                 DBG ( "SPI %p failed to write-enable device\n", device );
 129                 return rc;
 130         }
 131
 132         if ( ( rc = bus->rw ( bus, device, command, address,
 133                               data, NULL, len ) ) != 0 ) {
 134                 DBG ( "SPI %p failed to write data to device\n", device );
 135                 return rc;
 136         }
 137
 138         if ( ( rc = spi_wait ( device ) ) != 0 ) {
 139                 DBG ( "SPI %p failed to complete write operation\n", device );
 140                 return rc;
 141         }
 142
 143         return 0;
 144 }
 145