arch/ppc/boot/simple/iic.c

   1 /* Minimal support functions to read configuration from IIC EEPROMS
   2  * on MPC8xx boards.  Originally written for RPGC RPX-Lite.
   3  * Dan Malek (dmalek@jlc.net).
   4  */
   5 #include <linux/types.h>
   6 #include <asm/uaccess.h>
   7 #include <asm/mpc8xx.h>
   8 #include <asm/commproc.h>
   9
  10
  11 /* IIC functions.
  12  * These are just the basic master read/write operations so we can
  13  * examine serial EEPROM.
  14  */
  15 void    iic_read(uint devaddr, u_char *buf, uint offset, uint count);
  16
  17 static  int     iic_init_done;
  18
  19 static void
  20 iic_init(void)
  21 {
  22         volatile iic_t *iip;
  23         volatile i2c8xx_t *i2c;
  24         volatile cpm8xx_t       *cp;
  25         volatile immap_t        *immap;
  26         uint    dpaddr;
  27
  28         immap = (immap_t *)IMAP_ADDR;
  29         cp = (cpm8xx_t *)&(immap->im_cpm);
  30
  31         /* Reset the CPM.  This is necessary on the 860 processors
  32          * that may have started the SCC1 ethernet without relocating
  33          * the IIC.
  34          * This also stops the Ethernet in case we were loaded by a
  35          * BOOTP rom monitor.
  36          */
  37         cp->cp_cpcr = (CPM_CR_RST | CPM_CR_FLG);
  38
  39         /* Wait for it.
  40         */
  41         while (cp->cp_cpcr & (CPM_CR_RST | CPM_CR_FLG));
  42
  43         /* Remove any microcode patches.  We will install our own
  44          * later.
  45          */
  46         cp->cp_cpmcr1 = 0;
  47         cp->cp_cpmcr2 = 0;
  48         cp->cp_cpmcr3 = 0;
  49         cp->cp_cpmcr4 = 0;
  50         cp->cp_rccr = 0;
  51
  52         iip = (iic_t *)&cp->cp_dparam[PROFF_IIC];
  53         i2c = (i2c8xx_t *)&(immap->im_i2c);
  54
  55         /* Initialize Port B IIC pins.
  56         */
  57         cp->cp_pbpar |= 0x00000030;
  58         cp->cp_pbdir |= 0x00000030;
  59         cp->cp_pbodr |= 0x00000030;
  60
  61         /* Initialize the parameter ram.
  62         */
  63
  64         /* Allocate space for a two transmit and one receive buffer
  65          * descriptor in the DP ram.
  66          * For now, this address seems OK, but it may have to
  67          * change with newer versions of the firmware.
  68          */
  69         dpaddr = 0x0840;
  70
  71         /* Set up the IIC parameters in the parameter ram.
  72         */
  73         iip->iic_tbase = dpaddr;
  74         iip->iic_rbase = dpaddr + (2 * sizeof(cbd_t));
  75
  76         iip->iic_tfcr = SMC_EB;
  77         iip->iic_rfcr = SMC_EB;
  78
  79         /* This should really be done by the reader/writer.
  80         */
  81         iip->iic_mrblr = 128;
  82
  83         /* Initialize Tx/Rx parameters.
  84         */
  85         cp->cp_cpcr = mk_cr_cmd(CPM_CR_CH_I2C, CPM_CR_INIT_TRX) | CPM_CR_FLG;
  86         while (cp->cp_cpcr & CPM_CR_FLG);
  87
  88         /* Select an arbitrary address.  Just make sure it is unique.
  89         */
  90         i2c->i2c_i2add = 0x34;
  91
  92         /* Make clock run maximum slow.
  93         */
  94         i2c->i2c_i2brg = 7;
  95
  96         /* Disable interrupts.
  97         */
  98         i2c->i2c_i2cmr = 0;
  99         i2c->i2c_i2cer = 0xff;
 100
 101         /* Enable SDMA.
 102         */
 103         immap->im_siu_conf.sc_sdcr = 1;
 104
 105         iic_init_done = 1;
 106 }
 107
 108 /* Read from IIC.
 109  * Caller provides device address, memory buffer, and byte count.
 110  */
 111 static  u_char  iitemp[32];
 112
 113 void
 114 iic_read(uint devaddr, u_char *buf, uint offset, uint count)
 115 {
 116         volatile iic_t          *iip;
 117         volatile i2c8xx_t       *i2c;
 118         volatile cbd_t          *tbdf, *rbdf;
 119         volatile cpm8xx_t       *cp;
 120         volatile immap_t        *immap;
 121         u_char                  *tb;
 122         uint                    temp;
 123
 124         /* If the interface has not been initialized, do that now.
 125         */
 126         if (!iic_init_done)
 127                 iic_init();
 128
 129         immap = (immap_t *)IMAP_ADDR;
 130         cp = (cpm8xx_t *)&(immap->im_cpm);
 131
 132         iip = (iic_t *)&cp->cp_dparam[PROFF_IIC];
 133         i2c = (i2c8xx_t *)&(immap->im_i2c);
 134
 135         tbdf = (cbd_t *)&cp->cp_dpmem[iip->iic_tbase];
 136         rbdf = (cbd_t *)&cp->cp_dpmem[iip->iic_rbase];
 137
 138         /* Send a "dummy write" operation.  This is a write request with
 139          * only the offset sent, followed by another start condition.
 140          * This will ensure we start reading from the first location
 141          * of the EEPROM.
 142          */
 143         tb = iitemp;
 144         tb = (u_char *)(((uint)tb + 15) & ~15);
 145         tbdf->cbd_bufaddr = (int)tb;
 146         *tb = devaddr & 0xfe;   /* Device address */
 147         *(tb+1) = offset;               /* Offset */
 148         tbdf->cbd_datlen = 2;           /* Length */
 149         tbdf->cbd_sc =
 150               BD_SC_READY | BD_SC_LAST | BD_SC_WRAP | BD_IIC_START;
 151
 152         i2c->i2c_i2mod = 1;     /* Enable */
 153         i2c->i2c_i2cer = 0xff;
 154         i2c->i2c_i2com = 0x81;  /* Start master */
 155
 156         /* Wait for IIC transfer.
 157         */
 158 #if 0
 159         while ((i2c->i2c_i2cer & 3) == 0);
 160
 161         if (tbdf->cbd_sc & BD_SC_READY)
 162                 printf("IIC ra complete but tbuf ready\n");
 163 #else
 164         temp = 10000000;
 165         while ((tbdf->cbd_sc & BD_SC_READY) && (temp != 0))
 166                 temp--;
 167 #if 0
 168         /* We can't do this...there is no serial port yet!
 169         */
 170         if (temp == 0) {
 171                 printf("Timeout reading EEPROM\n");
 172                 return;
 173         }
 174 #endif
 175 #endif
 176
 177         /* Chip errata, clear enable.
 178         */
 179         i2c->i2c_i2mod = 0;
 180
 181         /* To read, we need an empty buffer of the proper length.
 182          * All that is used is the first byte for address, the remainder
 183          * is just used for timing (and doesn't really have to exist).
 184          */
 185         tbdf->cbd_bufaddr = (int)tb;
 186         *tb = devaddr | 1;      /* Device address */
 187         rbdf->cbd_bufaddr = (uint)buf;          /* Desination buffer */
 188         tbdf->cbd_datlen = rbdf->cbd_datlen = count + 1;        /* Length */
 189         tbdf->cbd_sc = BD_SC_READY | BD_SC_LAST | BD_SC_WRAP | BD_IIC_START;
 190         rbdf->cbd_sc = BD_SC_EMPTY | BD_SC_WRAP;
 191
 192         /* Chip bug, set enable here.
 193         */
 194         i2c->i2c_i2mod = 1;     /* Enable */
 195         i2c->i2c_i2cer = 0xff;
 196         i2c->i2c_i2com = 0x81;  /* Start master */
 197
 198         /* Wait for IIC transfer.
 199         */
 200 #if 0
 201         while ((i2c->i2c_i2cer & 1) == 0);
 202
 203         if (rbdf->cbd_sc & BD_SC_EMPTY)
 204                 printf("IIC read complete but rbuf empty\n");
 205 #else
 206         temp = 10000000;
 207         while ((tbdf->cbd_sc & BD_SC_READY) && (temp != 0))
 208                 temp--;
 209 #endif
 210
 211         /* Chip errata, clear enable.
 212         */
 213         i2c->i2c_i2mod = 0;
 214 }