Generic bitbang I2C driver

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8782 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 257 insertions, 0 deletions

diff --git a/firmware/drivers/generic_i2c.c b/firmware/drivers/generic_i2c.c
new file mode 100755
index 0000000000..8475f00ee6
--- /dev/null
+++ b/firmware/drivers/generic_i2c.c
@@ -0,0 +1,204 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2006 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 "config.h"
+#include "cpu.h"
+#include <stdbool.h>
+#include <stdlib.h>
+#include "debug.h"
+#include "logf.h"
+#include "generic_i2c.h"
+
+int i2c_num_ifs = 0;
+struct i2c_interface *i2c_if[5];
+
+static void i2c_start(struct i2c_interface *iface)
+{
+    iface->sda_hi();
+    iface->scl_hi();
+    iface->sda_lo();
+    iface->delay_hd_sta();
+    iface->scl_lo();
+}
+
+static void i2c_stop(struct i2c_interface *iface)
+{
+    iface->sda_lo();
+    iface->scl_hi();
+    iface->delay_su_sto();
+    iface->sda_hi();
+}
+
+static void i2c_ack(struct i2c_interface *iface, bool ack)
+{
+    iface->scl_lo();
+    if ( ack )
+        iface->sda_lo();
+    else
+        iface->sda_hi();
+
+    iface->delay_su_dat();
+    iface->scl_hi();
+    iface->delay_thigh();
+    iface->scl_lo();
+}
+
+static int i2c_getack(struct i2c_interface *iface)
+{
+    int ret = 1;
+
+    iface->sda_input();
+    iface->delay_su_dat();
+    iface->scl_hi();
+    
+    if (iface->sda())
+        ret = 0; /* ack failed */
+    
+    iface->delay_thigh();
+    iface->scl_lo();
+    iface->sda_hi();
+    iface->sda_output();
+    iface->delay_hd_dat();
+    return ret;
+}
+
+static unsigned char i2c_inb(struct i2c_interface *iface, bool ack)
+{
+    int i;
+    unsigned char byte = 0;
+    
+    /* clock in each bit, MSB first */
+    for ( i=0x80; i; i>>=1 ) {
+        iface->sda_input();
+        iface->scl_hi();
+        iface->delay_thigh();
+        if (iface->sda())
+            byte |= i;
+        iface->scl_lo();
+        iface->delay_hd_dat();
+        iface->sda_output();
+    }
+    
+    i2c_ack(iface, ack);
+    
+    return byte;
+}
+
+static void i2c_outb(struct i2c_interface *iface, unsigned char byte)
+{
+   int i;
+
+   /* clock out each bit, MSB first */
+   for (i=0x80; i; i>>=1) {
+       if (i & byte)
+           iface->sda_hi();
+       else
+           iface->sda_lo();
+       iface->delay_su_dat();
+       iface->scl_hi();
+       iface->delay_thigh();
+       iface->scl_lo();
+       iface->delay_hd_dat();
+   }
+
+   iface->sda_hi();
+}
+
+static struct i2c_interface *find_if(int address)
+{
+    int i;
+
+    for(i = 0;i < i2c_num_ifs;i++) {
+        if(i2c_if[i]->address == address)
+            return i2c_if[i];
+    }
+    return NULL;
+}
+
+int i2c_write_data(int bus_address, int address,
+                   const unsigned char* buf, int count)
+{
+    int i;
+    int ret = 0;
+    struct i2c_interface *iface = find_if(bus_address);
+    if(!iface)
+        return -1;
+    
+    i2c_start(iface);
+    i2c_outb(iface, iface->address & 0xfe);
+    if (i2c_getack(iface)) {
+        i2c_outb(iface, address);
+        if (i2c_getack(iface)) {
+            for(i = 0;i < count;i++) {
+                i2c_outb(iface, buf[i]);
+                if (!i2c_getack(iface)) {
+                    ret = -3;
+                    break;
+                }
+            }
+        } else {
+            ret = -2;
+        }
+    } else {
+        logf("i2c_write_data() - no ack\n");
+        ret = -1;
+    }
+    
+    i2c_stop(iface);
+    return ret;
+}
+
+int i2c_read_data(int bus_address, int address,
+                  unsigned char* buf, int count)
+{
+    int i;
+    int ret = 0;
+    struct i2c_interface *iface = find_if(bus_address);
+    if(!iface)
+        return -1;
+    
+    i2c_start(iface);
+    i2c_outb(iface, iface->address & 0xfe);
+    if (i2c_getack(iface)) {
+        i2c_outb(iface, address);
+        if (i2c_getack(iface)) {
+            i2c_start(iface);
+            i2c_outb(iface, iface->address | 1);
+            if (i2c_getack(iface)) {
+                for(i = 0;i < count-1;i++)
+                    buf[i] = i2c_inb(iface, true);
+                
+                buf[i] = i2c_inb(iface, false);
+            } else {
+                ret = -3;
+            }
+        } else {
+            ret = -2;
+        }
+    } else {
+        ret = -1;
+    }
+    
+    i2c_stop(iface);
+    return ret;
+}
+
+void i2c_add_node(struct i2c_interface *iface)
+{
+    i2c_if[i2c_num_ifs++] = iface;
+}
diff --git a/firmware/export/generic_i2c.h b/firmware/export/generic_i2c.h
new file mode 100755
index 0000000000..5570d940fb
--- /dev/null
+++ b/firmware/export/generic_i2c.h
@@ -0,0 +1,53 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2006 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.
+ *
+ ****************************************************************************/
+#ifndef _GEN_I2C_
+#define _GEN_I2C_
+
+struct i2c_interface
+{
+    unsigned char address; /* Address of the chip that this interface
+                              describes */
+
+    void (*scl_hi)(void);  /* Drive SCL high, might sleep on clk stretch */
+    void (*scl_lo)(void);  /* Drive SCL low */
+    void (*sda_hi)(void);  /* Drive SDA high */
+    void (*sda_lo)(void);  /* Drive SDA low */
+    void (*sda_input)(void);  /* Set SDA as input */
+    void (*sda_output)(void); /* Set SDA as output */
+    void (*scl_input)(void);  /* Set SCL as input */
+    void (*scl_output)(void); /* Set SCL as output */
+    int (*scl)(void);      /* Read SCL, returns 0 or non-zero */
+    int (*sda)(void);      /* Read SDA, returns 0 or non-zero */
+
+    /* These are the delays specified in the I2C specification, the
+       time pairs to the right are the minimum 100kHz and 400kHz specs */
+    void (*delay_hd_sta)(void); /* START SDA hold (tHD:SDA)    4.0us/0.6us */
+    void (*delay_hd_dat)(void); /* SDA hold (tHD:DAT)          5.0us/0us   */
+    void (*delay_su_dat)(void); /* SDA setup (tSU:DAT)         250ns/100ns */
+    void (*delay_su_sto)(void); /* STOP setup (tSU:STO)        4.0us/0.6us */
+    void (*delay_su_sta)(void); /* Rep. START setup (tSU:STA)  4.7us/0.6us */
+    void (*delay_thigh)(void);  /* SCL high period (tHIGH)     4.0us/0.6us */
+};
+
+extern void i2c_add_node(struct i2c_interface *iface);
+extern int i2c_write_data(int bus_address, int address,
+                          const unsigned char* buf, int count);
+extern int i2c_read_data(int bus_address, int address,
+                         unsigned char* buf, int count);
+#endif