sys/arch/acorn26/ioc/ssn.c

   1 /*      $NetBSD: ssn.c,v 1.5.6.3 2004/09/21 13:11:20 skrll Exp $        */
   2
   3 /*-
   4  * Copyright (c) 2002 Ben Harris
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. The name of the author may not be used to endorse or promote products
  16  *    derived from this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #include <sys/cdefs.h>
  31 __KERNEL_RCSID(0, "$NetBSD: ssn.c,v 1.5.6.3 2004/09/21 13:11:20 skrll Exp $");
  32
  33 #include <sys/param.h>
  34 #include <sys/device.h>
  35 #include <sys/systm.h>
  36
  37 #include <machine/bus.h>
  38
  39 #include <acorn26/iobus/iocreg.h>
  40 #include <acorn26/iobus/iocvar.h>
  41
  42 #include <dev/ic/ds.h>
  43
  44 struct ssn_softc {
  45         struct device sc_dev;
  46         struct ds_handle sc_dsh;
  47         struct device *sc_ioc;
  48         int sc_timebase;
  49 };
  50
  51 static int ssn_match(struct device *, struct cfdata *, void *);
  52 static void ssn_attach(struct device *, struct device *, void *);
  53
  54 CFATTACH_DECL(ssn, sizeof(struct ssn_softc),
  55     ssn_match, ssn_attach, NULL, NULL);
  56
  57 static int ds_ioc_read_bit(void *);
  58 static void ds_ioc_write_bit(void *, int);
  59 static void ds_ioc_reset(void *);
  60
  61 static int ds_crc(const u_int8_t *data, size_t len);
  62
  63 static int
  64 ssn_match(struct device *parent, struct cfdata *cf, void *aux)
  65 {
  66
  67         return (1);
  68 }
  69
  70 static void
  71 ssn_attach(struct device *parent, struct device *self, void *aux)
  72 {
  73         struct ssn_softc *sc = (void *)self;
  74         int i;
  75         u_int8_t rombuf[8];
  76
  77         sc->sc_ioc = parent;
  78         sc->sc_dsh.ds_read_bit = ds_ioc_read_bit;
  79         sc->sc_dsh.ds_write_bit = ds_ioc_write_bit;
  80         sc->sc_dsh.ds_reset = ds_ioc_reset;
  81         sc->sc_dsh.ds_hw_handle = sc;
  82
  83         sc->sc_dsh.ds_reset(sc->sc_dsh.ds_hw_handle);
  84
  85         ds_write_byte(&sc->sc_dsh, DS_ROM_READ);
  86         for (i=0; i<8; ++i)
  87                 rombuf[i] = ds_read_byte(&sc->sc_dsh);
  88
  89         printf(": ROM %02x %02x%02x%02x%02x%02x%02x %02x CRC %02x\n",
  90             rombuf[7], rombuf[6], rombuf[5], rombuf[4],
  91             rombuf[3], rombuf[2], rombuf[1], rombuf[0], ds_crc(rombuf, 8));
  92
  93 }
  94
  95 static int
  96 ds_ioc_read_bit(void *cookie)
  97 {
  98         struct ssn_softc *sc = cookie;
  99         int result;
 100
 101         /*
 102          * Read is 1--15us low, >60us high.
 103          * Sample 15us after falling edge.
 104          */
 105         ioc_ctl_write(sc->sc_ioc, 0, IOC_CTL_SSN);
 106         ioc_ctl_write(sc->sc_ioc, IOC_CTL_SSN, IOC_CTL_SSN);
 107         result = (ioc_ctl_read(sc->sc_ioc) & IOC_CTL_SSN) != 0;
 108         DELAY(60);
 109         return result;
 110 }
 111
 112 static void
 113 ds_ioc_write_bit(void *cookie, int bit)
 114 {
 115         struct ssn_softc *sc = cookie;
 116
 117         if (!bit) {
 118                 /* Write 0 is 60--120us low, >1us high. */
 119                 ioc_ctl_write(sc->sc_ioc, 0, IOC_CTL_SSN);
 120                 DELAY(60);
 121                 ioc_ctl_write(sc->sc_ioc, IOC_CTL_SSN, IOC_CTL_SSN);
 122                 DELAY(1);
 123         } else {
 124                 /* Write 1 is 1--15us low, >60us high. */
 125                 ioc_ctl_write(sc->sc_ioc, 0, IOC_CTL_SSN);
 126                 ioc_ctl_write(sc->sc_ioc, IOC_CTL_SSN, IOC_CTL_SSN);
 127                 DELAY(60);
 128         }
 129 }
 130
 131 static void
 132 ds_ioc_reset(void *cookie)
 133 {
 134         struct ssn_softc *sc = cookie;
 135         int t_pdh, t_pdl;
 136
 137         /* Reset pulse is >480us low, then >480us high. */
 138         ioc_ctl_write(sc->sc_ioc, 0, IOC_CTL_SSN);
 139         DELAY(480);
 140         ioc_ctl_write(sc->sc_ioc, IOC_CTL_SSN, IOC_CTL_SSN);
 141         DELAY(60);
 142         if ((ioc_ctl_read(sc->sc_ioc) & IOC_CTL_SSN) != 0) {
 143                 printf(": No presence pulse\n");
 144                 return;
 145         }
 146         DELAY(420);
 147         /* Reset again, and time it this time. */
 148         ioc_ctl_write(sc->sc_ioc, 0, IOC_CTL_SSN);
 149         DELAY(480);
 150         ioc_ctl_write(sc->sc_ioc, IOC_CTL_SSN, IOC_CTL_SSN);
 151         t_pdh = 0;
 152         while ((ioc_ctl_read(sc->sc_ioc) & IOC_CTL_SSN) != 0)
 153                 t_pdh++;
 154         t_pdl = 0;
 155         while ((ioc_ctl_read(sc->sc_ioc) & IOC_CTL_SSN) == 0)
 156                 t_pdl++;
 157         DELAY(480);
 158         printf(": t_PDH = %d, t_PDL = %d", t_pdh, t_pdl);
 159         sc->sc_timebase = (t_pdh + t_pdl) / 5 + 1;
 160 }
 161
 162 #define DS_CRC_POLY 0x8c
 163
 164 static int
 165 ds_crc(const u_int8_t *buf, size_t len)
 166 {
 167         u_int8_t c, crc, carry;
 168         size_t i, j;
 169
 170         crc = 0;
 171
 172         for (i = 0; i < len; i++) {
 173                 c = buf[i];
 174                 for (j = 0; j < 8; j++) {
 175                         carry = (crc ^ c) & 0x01;
 176                         crc >>= 1;
 177                         c >>= 1;
 178                         if (carry)
 179                                 crc ^= DS_CRC_POLY;
 180                 }
 181         }
 182         return (crc);
 183 }