drivers/spi/soft_spi.c

   1 /*
   2  * (C) Copyright 2002
   3  * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
   4  *
   5  * Influenced by code from:
   6  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   7  *
   8  * See file CREDITS for list of people who contributed to this
   9  * project.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License as
  13  * published by the Free Software Foundation; either version 2 of
  14  * the License, or (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, write to the Free Software
  23  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  24  * MA 02111-1307 USA
  25  */
  26
  27 #include <common.h>
  28 #include <spi.h>
  29
  30 #include <malloc.h>
  31
  32 /*-----------------------------------------------------------------------
  33  * Definitions
  34  */
  35
  36 #ifdef DEBUG_SPI
  37 #define PRINTD(fmt,args...)     printf (fmt ,##args)
  38 #else
  39 #define PRINTD(fmt,args...)
  40 #endif
  41
  42 struct soft_spi_slave {
  43         struct spi_slave slave;
  44         unsigned int mode;
  45 };
  46
  47 static inline struct soft_spi_slave *to_soft_spi(struct spi_slave *slave)
  48 {
  49         return container_of(slave, struct soft_spi_slave, slave);
  50 }
  51
  52 /*=====================================================================*/
  53 /*                         Public Functions                            */
  54 /*=====================================================================*/
  55
  56 /*-----------------------------------------------------------------------
  57  * Initialization
  58  */
  59 void spi_init (void)
  60 {
  61 #ifdef  SPI_INIT
  62         volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
  63
  64         SPI_INIT;
  65 #endif
  66 }
  67
  68 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
  69                 unsigned int max_hz, unsigned int mode)
  70 {
  71         struct soft_spi_slave *ss;
  72
  73         if (!spi_cs_is_valid(bus, cs))
  74                 return NULL;
  75
  76         ss = malloc(sizeof(struct soft_spi_slave));
  77         if (!ss)
  78                 return NULL;
  79
  80         ss->slave.bus = bus;
  81         ss->slave.cs = cs;
  82         ss->mode = mode;
  83
  84         /* TODO: Use max_hz to limit the SCK rate */
  85
  86         return &ss->slave;
  87 }
  88
  89 void spi_free_slave(struct spi_slave *slave)
  90 {
  91         struct soft_spi_slave *ss = to_soft_spi(slave);
  92
  93         free(ss);
  94 }
  95
  96 int spi_claim_bus(struct spi_slave *slave)
  97 {
  98 #ifdef CONFIG_SYS_IMMR
  99         volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
 100 #endif
 101         struct soft_spi_slave *ss = to_soft_spi(slave);
 102
 103         /*
 104          * Make sure the SPI clock is in idle state as defined for
 105          * this slave.
 106          */
 107         if (ss->mode & SPI_CPOL)
 108                 SPI_SCL(1);
 109         else
 110                 SPI_SCL(0);
 111
 112         return 0;
 113 }
 114
 115 void spi_release_bus(struct spi_slave *slave)
 116 {
 117         /* Nothing to do */
 118 }
 119
 120 /*-----------------------------------------------------------------------
 121  * SPI transfer
 122  *
 123  * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
 124  * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
 125  *
 126  * The source of the outgoing bits is the "dout" parameter and the
 127  * destination of the input bits is the "din" parameter.  Note that "dout"
 128  * and "din" can point to the same memory location, in which case the
 129  * input data overwrites the output data (since both are buffered by
 130  * temporary variables, this is OK).
 131  */
 132 int  spi_xfer(struct spi_slave *slave, unsigned int bitlen,
 133                 const void *dout, void *din, unsigned long flags)
 134 {
 135 #ifdef CONFIG_SYS_IMMR
 136         volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
 137 #endif
 138         struct soft_spi_slave *ss = to_soft_spi(slave);
 139         uchar           tmpdin  = 0;
 140         uchar           tmpdout = 0;
 141         const u8        *txd = dout;
 142         u8              *rxd = din;
 143         int             cpol = ss->mode & SPI_CPOL;
 144         int             cpha = ss->mode & SPI_CPHA;
 145         unsigned int    j;
 146
 147         PRINTD("spi_xfer: slave %u:%u dout %08X din %08X bitlen %u\n",
 148                 slave->bus, slave->cs, *(uint *)txd, *(uint *)rxd, bitlen);
 149
 150         if (flags & SPI_XFER_BEGIN)
 151                 spi_cs_activate(slave);
 152
 153         for(j = 0; j < bitlen; j++) {
 154                 /*
 155                  * Check if it is time to work on a new byte.
 156                  */
 157                 if((j % 8) == 0) {
 158                         tmpdout = *txd++;
 159                         if(j != 0) {
 160                                 *rxd++ = tmpdin;
 161                         }
 162                         tmpdin  = 0;
 163                 }
 164
 165                 if (!cpha)
 166                         SPI_SCL(!cpol);
 167                 SPI_SDA(tmpdout & 0x80);
 168                 SPI_DELAY;
 169                 if (cpha)
 170                         SPI_SCL(!cpol);
 171                 else
 172                         SPI_SCL(cpol);
 173                 tmpdin  <<= 1;
 174                 tmpdin  |= SPI_READ;
 175                 tmpdout <<= 1;
 176                 SPI_DELAY;
 177                 if (cpha)
 178                         SPI_SCL(cpol);
 179         }
 180         /*
 181          * If the number of bits isn't a multiple of 8, shift the last
 182          * bits over to left-justify them.  Then store the last byte
 183          * read in.
 184          */
 185         if((bitlen % 8) != 0)
 186                 tmpdin <<= 8 - (bitlen % 8);
 187         *rxd++ = tmpdin;
 188
 189         if (flags & SPI_XFER_END)
 190                 spi_cs_deactivate(slave);
 191
 192         return(0);
 193 }