iAudio X5: Enable reading of DS2411 serial number. See it under System|Debug|View HW info.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12723 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 206 insertions, 0 deletions

diff --git a/firmware/target/coldfire/iaudio/x5/ds2411-x5.c b/firmware/target/coldfire/iaudio/x5/ds2411-x5.c
new file mode 100644
index 0000000000..a8b2ae705c
--- /dev/null
+++ b/firmware/target/coldfire/iaudio/x5/ds2411-x5.c
@@ -0,0 +1,206 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2007 by Michael Sevakis
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include "config.h"
+#include "system.h"
+#include "cpu.h"
+#include "ds2411.h"
+#include "logf.h"
+
+/* Delay factor that depends on CPU frequency */
+static unsigned int ds2411_delay_factor = 0;
+
+#define DS2411_BIT (1 << 22)
+
+/* Delay the specified number of microseconds - plus a tiny bit */
+#define DELAY(uS)                \
+    asm volatile(                   \
+        "move.l %[x], %%d0      \n" \
+        "mulu.l %[factor], %%d0 \n" \
+    "1:                         \n" \
+        "subq.l #1, %%d0        \n" \
+        "bhi.s  1b              \n" \
+        : : [factor]"d"(ds2411_delay_factor), [x]"d"(uS) : "d0");
+
+/* Calculate the CRC of a byte */
+static unsigned char ds2411_calc_crc(unsigned char byte)
+{
+    /* POLYNOMIAL = X^8 + X^5 + X^4 + 1 */
+    static const unsigned char eor[8] =
+    {
+        0x5e, /* 01011110 */
+        0xbc, /* 10111100 */
+        0x61, /* 01100001 */
+        0xc2, /* 11000010 */
+        0x9d, /* 10011101 */
+        0x23, /* 00100011 */
+        0x46, /* 01000110 */
+        0x8c, /* 10001100 */
+    };
+
+    unsigned char crc = 0;
+    int i = 0;
+
+    do
+    {
+        if (byte & (1 << i))
+            crc ^= eor[i];
+    }
+    while (++i < 8);
+
+    return crc;
+} /* ds2411_calc_crc */
+
+/* Write a byte to the DS2411 - LSb first */
+static void ds2411_write_byte(unsigned char data)
+{
+    int i = 0;
+
+    do
+    {
+        if (data & 0x01)
+        {
+            /* Write a "1": Hold line low, then leave line pulled up and wait
+               out the remainder of Tslot */
+            or_l(DS2411_BIT, &GPIO_ENABLE);
+            DELAY(6);
+            and_l(~DS2411_BIT, &GPIO_ENABLE);
+            DELAY(60);
+        }
+        else
+        {
+            /* Write a "0": Hold line low, then leave line pulled up and wait
+               out the remainder of Tslot which is just Trec */
+            or_l(DS2411_BIT, &GPIO_ENABLE);
+            DELAY(60);
+            and_l(~DS2411_BIT, &GPIO_ENABLE);
+            DELAY(6);
+        }
+
+        data >>= 1;
+    }
+    while (++i < 8);
+} /* ds2411_write_byte */
+
+/* Read a byte from the DS2411 - LSb first */
+static unsigned char ds2411_read_byte(void)
+{
+    int i = 0;
+    unsigned data = 0;
+
+    do
+    {
+        /* Hold line low to begin bit read: Tf + Trl */
+        or_l(DS2411_BIT, &GPIO_ENABLE);
+        DELAY(6);
+
+        /* Set line high and delay before sampling within the master
+           sampling window: Tmsr - max 15us from Trl start */
+        and_l(~DS2411_BIT, &GPIO_ENABLE);
+        DELAY(9);
+
+        /* Sample data line */
+        if ((GPIO_READ & DS2411_BIT) != 0)
+            data |= 1 << i;
+
+        /* Wait out the remainder of Tslot */
+        DELAY(60);   
+    }
+    while (++i < 8);
+
+    return data;
+} /* ds2411_read_byte */
+
+/*
+ * Byte 0:    8-bit family code (01h)
+ * Bytes 1-6: 48-bit serial number
+ * Byte 7:    8-bit CRC code
+ */
+int ds2411_read_id(struct ds2411_id *id)
+{
+    int i;
+    unsigned char crc;
+
+    /* Initialize delay factor based on loop time: 3*(uS-1) + 3 */
+    ds2411_delay_factor = MIN(cpu_frequency / (1000000*3), 1);
+
+    /* Init GPIO 1 wire bus for bit banging with a pullup resistor where 
+     * it is set low as output and switched between input and output mode.
+     * Required for bidirectional communication on a single wire.
+     */
+    or_l(DS2411_BIT, &GPIO_FUNCTION);   /* Set pin as GPIO            */
+    and_l(~DS2411_BIT, &GPIO_ENABLE);   /* Set as input               */
+    and_l(~DS2411_BIT, &GPIO_OUT);      /* Set low when set as output */
+
+    /* Delay 100us to stabilize */
+    DELAY(100);
+
+    /* Issue reset pulse - 480uS or more to ensure standard (not overdrive)
+       mode - we don't have the timing accuracy for that. */
+    or_l(DS2411_BIT, &GPIO_ENABLE);
+    /* Delay 560us: (Trstlmin + Trstlmax) / 2*/
+    DELAY(560);
+    and_l(~DS2411_BIT, &GPIO_ENABLE);
+    /* Delay 66us: Tpdhmax + 6 */
+    DELAY(66);
+
+    /* Read presence pulse - line should be pulled low at proper time by the
+       slave device */
+    if (GPIO_READ & DS2411_BIT)
+    {
+        logf("ds2411: no presence pulse");
+        return DS2411_NO_PRESENCE;
+    }
+
+    /* Trsth + 1 - 66 = Tpdhmax + Tpdlmax + Trecmin + 1 - 66 */
+    DELAY(240);
+
+    /* ds2411 should be ready for data transfer */
+
+    /* Send Read ROM command */
+    ds2411_write_byte(0x33);
+
+    /* Read ROM serial number and CRC */
+    i = 0, crc = 0;
+
+    do
+    {
+        unsigned char byte = ds2411_read_byte();
+        ((unsigned char *)id)[i] = byte;
+        crc = ds2411_calc_crc(crc ^ byte);
+    }
+    while (++i < 8);
+
+    /* Check that family code is ok */
+    if (id->family_code != 0x01)
+    {
+        logf("ds2411: invalid family code=%02X", (unsigned)id->family_code);
+        return DS2411_INVALID_FAMILY_CODE;
+    }
+
+    /* Check that CRC was ok */
+    if (crc != 0) /* Because last loop eors the CRC with the resulting CRC */
+    {
+        logf("ds2411: invalid CRC=%02X", (unsigned)id->crc);
+        return DS2411_INVALID_CRC;
+    }
+
+    /* Good ID read */
+    return DS2411_OK;
+} /* ds2411_read_id */