From c6773e1436ba3adda0a6456dbe54ba1320a095be Mon Sep 17 00:00:00 2001
From: Björn Stenberg <bjorn@haxx.se>
Date: Tue, 23 Apr 2002 09:13:23 +0000
Subject: Moved driver to 'drivers' subdir

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@189 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/drivers/i2c.c | 212 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 212 insertions(+)
 create mode 100644 firmware/drivers/i2c.c

(limited to 'firmware/drivers/i2c.c')

diff --git a/firmware/drivers/i2c.c b/firmware/drivers/i2c.c
new file mode 100644
index 0000000000..3a5603ddd4
--- /dev/null
+++ b/firmware/drivers/i2c.c
@@ -0,0 +1,212 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2002 by Linus Nielsen Feltzing
+ *
+ * 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 "lcd.h"
+#include "sh7034.h"
+#include "debug.h"
+
+#define PB13 0x2000
+#define PB7  0x0080
+#define PB5  0x0020
+
+/* cute little functions */
+#define SDA_LO  (PBDR &= ~PB7)
+#define SDA_HI  (PBDR |= PB7)
+#define SDA_INPUT (PBIOR &= ~PB7)
+#define SDA_OUTPUT (PBIOR |= PB7)
+#define SDA     (PBDR & PB7)
+
+#define SCL_INPUT (PBIOR &= ~PB13)
+#define SCL_OUTPUT (PBIOR |= PB13)
+#define SCL_LO  (PBDR &= ~PB13)
+#define SCL_HI  (PBDR |= PB13)
+#define SCL     (PBDR & PB13)
+
+/* arbitrary delay loop */
+#define DELAY   do { int _x; for(_x=0;_x<20;_x++);} while (0)
+
+void i2c_start(void)
+{
+    SDA_OUTPUT;
+    SDA_HI;
+    SCL_HI;
+    SDA_LO;
+    DELAY;
+    SCL_LO;
+}
+
+void i2c_stop(void)
+{
+   SDA_LO;
+   SCL_HI;
+   DELAY;
+   SDA_HI;
+}
+
+void i2c_init(void)
+{
+   int i;
+
+   /* make PB5, PB7 & PB13 general I/O */
+   PBCR1 &= ~0x0c00; /* PB13 */
+   PBCR2 &= ~0xcc00; /* PB5 abd PB7 */
+
+   /* PB5 is "MAS enable". make it output and high */
+   PBIOR |= PB5;
+   PBDR |= PB5;
+
+   /* Set the clock line to an output */
+   PBIOR |= PB13;
+   
+   SDA_OUTPUT;
+   SDA_HI;
+   SCL_LO;
+   for (i=0;i<3;i++)
+      i2c_stop();
+}
+
+void i2c_ack(int bit)
+{
+    /* Here's the deal. The MAS is slow, and sometimes needs to wait
+       before it can receive the acknowledge. Therefore it forces the clock
+       low until it is ready. We need to poll the clock line until it goes
+       high before we release the ack. */
+    
+    SCL_LO;      /* Set the clock low */
+    if ( bit )
+        SDA_HI;
+    else
+        SDA_LO;
+    
+    SCL_INPUT;   /* Set the clock to input */
+    while(!SCL); /* and wait for the MAS to release it */
+
+    DELAY;
+    SCL_OUTPUT;
+    SCL_LO;
+}
+
+int i2c_getack(void)
+{
+    unsigned short x;
+
+    /* Here's the deal. The MAS is slow, and sometimes needs to wait
+       before it can send the acknowledge. Therefore it forces the clock
+       low until it is ready. We need to poll the clock line until it goes
+       high before we read the ack. */
+    
+    SDA_LO;      /* First, discharge the data line */
+    SDA_INPUT;   /* And set to input */
+    SCL_LO;      /* Set the clock low */
+    SCL_INPUT;   /* Set the clock to input */
+    while(!SCL); /* and wait for the MAS to release it */
+
+    x = SDA;
+    if (x)
+        /* ack failed */
+        return 0;
+    SCL_OUTPUT;
+    SCL_LO;
+    SDA_HI;
+    SDA_OUTPUT;
+    return 1;
+}
+
+void i2c_outb(unsigned char byte)
+{
+   int i;
+
+   /* clock out each bit, MSB first */
+   for ( i=0x80; i; i>>=1 ) {
+      if ( i & byte )
+         SDA_HI;
+      else
+         SDA_LO;
+      SCL_HI;
+      SCL_LO;
+   }
+
+   SDA_HI;
+}
+
+unsigned char i2c_inb(int ack)
+{
+   int i;
+   unsigned char byte = 0;
+
+   /* clock in each bit, MSB first */
+   for ( i=0x80; i; i>>=1 ) {
+       /* Tricky business. Here we discharge the data line by driving it low
+          and then set it to input to see if it stays low or goes high */
+       SDA_LO;      /* First, discharge the data line */
+       SDA_INPUT;   /* And set to input */
+       SCL_HI;
+       if ( SDA )
+           byte |= i;
+       SCL_LO;
+       SDA_OUTPUT;
+   }
+   
+   i2c_ack(ack);
+   
+   return byte;
+}
+
+int i2c_write(int address, unsigned char* buf, int count )
+{
+    int i,x=0;
+
+    i2c_start();
+    i2c_outb(address & 0xfe);
+    if (i2c_getack())
+    {
+        for (i=0; i<count; i++)
+        {
+            i2c_outb(buf[i]);
+            if (!i2c_getack())
+            {
+                x=-2;
+                break;
+            }
+        }
+    }
+    else
+    {
+        debugf("i2c_write() - no ack\n");
+        x=-1;
+    }
+    i2c_stop();
+    return x;
+}
+
+int i2c_read(int address, unsigned char* buf, int count )
+{
+    int i,x=0;
+    
+    i2c_start();
+    i2c_outb(address | 1);
+    if (i2c_getack()) {
+        for (i=0; i<count; i++) {
+            buf[i] = i2c_inb(0);
+        }
+    }
+    else
+        x=-1;
+    i2c_stop();
+    return x;
+}
-- 
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