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 = spi_alloc_slave(struct soft_spi_slave, bus, cs);
  77         if (!ss)
  78                 return NULL;
  79
  80         ss->mode = mode;
  81
  82         /* TODO: Use max_hz to limit the SCK rate */
  83
  84         return &ss->slave;
  85 }
  86
  87 void spi_free_slave(struct spi_slave *slave)
  88 {
  89         struct soft_spi_slave *ss = to_soft_spi(slave);
  90
  91         free(ss);
  92 }
  93
  94 int spi_claim_bus(struct spi_slave *slave)
  95 {
  96 #ifdef CONFIG_SYS_IMMR
  97         volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
  98 #endif
  99         struct soft_spi_slave *ss = to_soft_spi(slave);
 100
 101         /*
 102          * Make sure the SPI clock is in idle state as defined for
 103          * this slave.
 104          */
 105         if (ss->mode & SPI_CPOL)
 106                 SPI_SCL(1);
 107         else
 108                 SPI_SCL(0);
 109
 110         return 0;
 111 }
 112
 113 void spi_release_bus(struct spi_slave *slave)
 114 {
 115         /* Nothing to do */
 116 }
 117
 118 /*-----------------------------------------------------------------------
 119  * SPI transfer
 120  *
 121  * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
 122  * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
 123  *
 124  * The source of the outgoing bits is the "dout" parameter and the
 125  * destination of the input bits is the "din" parameter.  Note that "dout"
 126  * and "din" can point to the same memory location, in which case the
 127  * input data overwrites the output data (since both are buffered by
 128  * temporary variables, this is OK).
 129  */
 130 int  spi_xfer(struct spi_slave *slave, unsigned int bitlen,
 131                 const void *dout, void *din, unsigned long flags)
 132 {
 133 #ifdef CONFIG_SYS_IMMR
 134         volatile immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
 135 #endif
 136         struct soft_spi_slave *ss = to_soft_spi(slave);
 137         uchar           tmpdin  = 0;
 138         uchar           tmpdout = 0;
 139         const u8        *txd = dout;
 140         u8              *rxd = din;
 141         int             cpol = ss->mode & SPI_CPOL;
 142         int             cpha = ss->mode & SPI_CPHA;
 143         unsigned int    j;
 144
 145         PRINTD("spi_xfer: slave %u:%u dout %08X din %08X bitlen %u\n",
 146                 slave->bus, slave->cs, *(uint *)txd, *(uint *)rxd, bitlen);
 147
 148         if (flags & SPI_XFER_BEGIN)
 149                 spi_cs_activate(slave);
 150
 151         for(j = 0; j < bitlen; j++) {
 152                 /*
 153                  * Check if it is time to work on a new byte.
 154                  */
 155                 if((j % 8) == 0) {
 156                         tmpdout = *txd++;
 157                         if(j != 0) {
 158                                 *rxd++ = tmpdin;
 159                         }
 160                         tmpdin  = 0;
 161                 }
 162
 163                 if (!cpha)
 164                         SPI_SCL(!cpol);
 165                 SPI_SDA(tmpdout & 0x80);
 166                 SPI_DELAY;
 167                 if (cpha)
 168                         SPI_SCL(!cpol);
 169                 else
 170                         SPI_SCL(cpol);
 171                 tmpdin  <<= 1;
 172                 tmpdin  |= SPI_READ;
 173                 tmpdout <<= 1;
 174                 SPI_DELAY;
 175                 if (cpha)
 176                         SPI_SCL(cpol);
 177         }
 178         /*
 179          * If the number of bits isn't a multiple of 8, shift the last
 180          * bits over to left-justify them.  Then store the last byte
 181          * read in.
 182          */
 183         if((bitlen % 8) != 0)
 184                 tmpdin <<= 8 - (bitlen % 8);
 185         *rxd++ = tmpdin;
 186
 187         if (flags & SPI_XFER_END)
 188                 spi_cs_deactivate(slave);
 189
 190         return(0);
 191 }