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., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 #include <stddef.h>
  20 #include <errno.h>
  21 #include <timer.h>
  22 #include <gpxe/spi.h>
  23
  24 /** @file
  25  *
  26  * SPI devices
  27  *
  28  */
  29
  30 /**
  31  * Munge SPI device address into command
  32  *
  33  * @v command           SPI command
  34  * @v address           Address
  35  * @v munge_address     Device requires address munging
  36  * @ret command         Actual SPI command to use
  37  *
  38  * Some devices with 9-bit addresses (e.g. AT25040A EEPROM) use bit 3
  39  * of the command byte as address bit A8, rather than having a
  40  * two-byte address.  This function takes care of generating the
  41  * appropriate command.
  42  */
  43 static inline unsigned int spi_command ( unsigned int command,
  44                                          unsigned int address,
  45                                          int munge_address ) {
  46         return ( command | ( ( ( address >> 8 ) & munge_address ) << 3 ) );
  47 }
  48
  49 /**
  50  * Wait for SPI device to complete operation
  51  *
  52  * @v device            SPI device
  53  * @ret rc              Return status code
  54  */
  55 static int spi_wait ( struct spi_device *device ) {
  56         struct spi_bus *bus = device->bus;
  57         uint8_t status;
  58         int i;
  59         int rc;
  60
  61         for ( i = 0 ; i < 50 ; i++ ) {
  62                 udelay ( 20 );
  63                 if ( ( rc = bus->rw ( bus, device, SPI_RDSR, -1, NULL,
  64                                       &status, sizeof ( status ) ) ) != 0 )
  65                         return rc;
  66                 if ( ! ( status & SPI_STATUS_NRDY ) )
  67                         return 0;
  68         }
  69         DBG ( "SPI %p timed out\n", device );
  70         return -ETIMEDOUT;
  71 }
  72
  73 /**
  74  * Read data from SPI device
  75  *
  76  * @v nvs               NVS device
  77  * @v address           Address from which to read
  78  * @v data              Data buffer
  79  * @v len               Length of data buffer
  80  * @ret rc              Return status code
  81  */
  82 int spi_read ( struct nvs_device *nvs, unsigned int address,
  83                void *data, unsigned int len ) {
  84         struct spi_device *device = nvs_to_spi ( nvs );
  85         struct spi_bus *bus = device->bus;
  86         unsigned int command = spi_command ( SPI_READ, address,
  87                                              device->munge_address );
  88         int rc;
  89
  90         DBG ( "SPI %p reading %d bytes from %#04x\n", device, len, address );
  91         if ( ( rc = bus->rw ( bus, device, command, address,
  92                               NULL, data, len ) ) != 0 ) {
  93                 DBG ( "SPI %p failed to read data from device\n", device );
  94                 return rc;
  95         }
  96
  97         return 0;
  98 }
  99
 100 /**
 101  * Write data to SPI device
 102  *
 103  * @v nvs               NVS device
 104  * @v address           Address from which to read
 105  * @v data              Data buffer
 106  * @v len               Length of data buffer
 107  * @ret rc              Return status code
 108  */
 109 int spi_write ( struct nvs_device *nvs, unsigned int address,
 110                 const void *data, unsigned int len ) {
 111         struct spi_device *device = nvs_to_spi ( nvs );
 112         struct spi_bus *bus = device->bus;
 113         unsigned int command = spi_command ( SPI_WRITE, address,
 114                                              device->munge_address );
 115         int rc;
 116
 117         DBG ( "SPI %p writing %d bytes to %#04x\n", device, len, address );
 118
 119         if ( ( rc = bus->rw ( bus, device, SPI_WREN, -1,
 120                               NULL, NULL, 0 ) ) != 0 ) {
 121                 DBG ( "SPI %p failed to write-enable device\n", device );
 122                 return rc;
 123         }
 124
 125         if ( ( rc = bus->rw ( bus, device, command, address,
 126                               data, NULL, len ) ) != 0 ) {
 127                 DBG ( "SPI %p failed to write data to device\n", device );
 128                 return rc;
 129         }
 130
 131         if ( ( rc = spi_wait ( device ) ) != 0 ) {
 132                 DBG ( "SPI %p failed to complete write operation\n", device );
 133                 return rc;
 134         }
 135
 136         return 0;
 137 }
 138