drivers/spi/mpc8xxx_spi.c

   1 /*
   2  * Copyright (c) 2006 Ben Warren, Qstreams Networks Inc.
   3  * With help from the common/soft_spi and cpu/mpc8260 drivers
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 #include <common.h>
  25 #if defined(CONFIG_MPC8XXX_SPI) && defined(CONFIG_HARD_SPI)
  26
  27 #include <malloc.h>
  28 #include <spi.h>
  29 #include <asm/mpc8xxx_spi.h>
  30
  31 #define SPI_EV_NE       (0x80000000 >> 22)      /* Receiver Not Empty */
  32 #define SPI_EV_NF       (0x80000000 >> 23)      /* Transmitter Not Full */
  33
  34 #define SPI_MODE_LOOP   (0x80000000 >> 1)       /* Loopback mode */
  35 #define SPI_MODE_REV    (0x80000000 >> 5)       /* Reverse mode - MSB first */
  36 #define SPI_MODE_MS     (0x80000000 >> 6)       /* Always master */
  37 #define SPI_MODE_EN     (0x80000000 >> 7)       /* Enable interface */
  38
  39 #define SPI_TIMEOUT     1000
  40
  41 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
  42                 unsigned int max_hz, unsigned int mode)
  43 {
  44         struct spi_slave *slave;
  45
  46         if (!spi_cs_is_valid(bus, cs))
  47                 return NULL;
  48
  49         slave = malloc(sizeof(struct spi_slave));
  50         if (!slave)
  51                 return NULL;
  52
  53         slave->bus = bus;
  54         slave->cs = cs;
  55
  56         /*
  57          * TODO: Some of the code in spi_init() should probably move
  58          * here, or into spi_claim_bus() below.
  59          */
  60
  61         return slave;
  62 }
  63
  64 void spi_free_slave(struct spi_slave *slave)
  65 {
  66         free(slave);
  67 }
  68
  69 void spi_init(void)
  70 {
  71         volatile spi8xxx_t *spi = &((immap_t *) (CFG_IMMR))->spi;
  72
  73         /*
  74          * SPI pins on the MPC83xx are not muxed, so all we do is initialize
  75          * some registers
  76          */
  77         spi->mode = SPI_MODE_REV | SPI_MODE_MS | SPI_MODE_EN;
  78         spi->mode = (spi->mode & 0xfff0ffff) | (1 << 16); /* Use SYSCLK / 8
  79                                                              (16.67MHz typ.) */
  80         spi->event = 0xffffffff;        /* Clear all SPI events */
  81         spi->mask = 0x00000000; /* Mask  all SPI interrupts */
  82         spi->com = 0;           /* LST bit doesn't do anything, so disregard */
  83 }
  84
  85 int spi_claim_bus(struct spi_slave *slave)
  86 {
  87         return 0;
  88 }
  89
  90 void spi_release_bus(struct spi_slave *slave)
  91 {
  92
  93 }
  94
  95 int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
  96                 void *din, unsigned long flags)
  97 {
  98         volatile spi8xxx_t *spi = &((immap_t *) (CFG_IMMR))->spi;
  99         unsigned int tmpdout, tmpdin, event;
 100         int numBlks = bitlen / 32 + (bitlen % 32 ? 1 : 0);
 101         int tm, isRead = 0;
 102         unsigned char charSize = 32;
 103
 104         debug("spi_xfer: slave %u:%u dout %08X din %08X bitlen %u\n",
 105               slave->bus, slave->cs, *(uint *) dout, *(uint *) din, bitlen);
 106
 107         if (flags & SPI_XFER_BEGIN)
 108                 spi_cs_activate(slave);
 109
 110         spi->event = 0xffffffff;        /* Clear all SPI events */
 111
 112         /* handle data in 32-bit chunks */
 113         while (numBlks--) {
 114                 tmpdout = 0;
 115                 charSize = (bitlen >= 32 ? 32 : bitlen);
 116
 117                 /* Shift data so it's msb-justified */
 118                 tmpdout = *(u32 *) dout >> (32 - charSize);
 119
 120                 /* The LEN field of the SPMODE register is set as follows:
 121                  *
 122                  * Bit length             setting
 123                  * len <= 4               3
 124                  * 4 < len <= 16          len - 1
 125                  * len > 16               0
 126                  */
 127
 128                 if (bitlen <= 16) {
 129                         if (bitlen <= 4)
 130                                 spi->mode = (spi->mode & 0xff0fffff) |
 131                                             (3 << 20);
 132                         else
 133                                 spi->mode = (spi->mode & 0xff0fffff) |
 134                                             ((bitlen - 1) << 20);
 135                 } else {
 136                         spi->mode = (spi->mode & 0xff0fffff);
 137                         /* Set up the next iteration if sending > 32 bits */
 138                         bitlen -= 32;
 139                         dout += 4;
 140                 }
 141
 142                 spi->tx = tmpdout;      /* Write the data out */
 143                 debug("*** spi_xfer: ... %08x written\n", tmpdout);
 144
 145                 /*
 146                  * Wait for SPI transmit to get out
 147                  * or time out (1 second = 1000 ms)
 148                  * The NE event must be read and cleared first
 149                  */
 150                 for (tm = 0, isRead = 0; tm < SPI_TIMEOUT; ++tm) {
 151                         event = spi->event;
 152                         if (event & SPI_EV_NE) {
 153                                 tmpdin = spi->rx;
 154                                 spi->event |= SPI_EV_NE;
 155                                 isRead = 1;
 156
 157                                 *(u32 *) din = (tmpdin << (32 - charSize));
 158                                 if (charSize == 32) {
 159                                         /* Advance output buffer by 32 bits */
 160                                         din += 4;
 161                                 }
 162                         }
 163                         /*
 164                          * Only bail when we've had both NE and NF events.
 165                          * This will cause timeouts on RO devices, so maybe
 166                          * in the future put an arbitrary delay after writing
 167                          * the device.  Arbitrary delays suck, though...
 168                          */
 169                         if (isRead && (event & SPI_EV_NF))
 170                                 break;
 171                 }
 172                 if (tm >= SPI_TIMEOUT)
 173                         puts("*** spi_xfer: Time out during SPI transfer");
 174
 175                 debug("*** spi_xfer: transfer ended. Value=%08x\n", tmpdin);
 176         }
 177
 178         if (flags & SPI_XFER_END)
 179                 spi_cs_deactivate(slave);
 180
 181         return 0;
 182 }
 183 #endif                          /* CONFIG_HARD_SPI */