Generic I2C: fix various problems with this (now) unused driver

Explicit if SDA is input or output in static functions
Do not use logf() but return codes
Check for overflow when adding an interface
Indent on 4 spaces
Rewrite i2c_read_data() and i2c_write_data() using goto for error cases
Make subaddress optional (not sent if == -1)

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19360 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 93 insertions, 58 deletions

diff --git a/firmware/drivers/generic_i2c.c b/firmware/drivers/generic_i2c.c
index 2e5f202307..0dcc957260 100644
--- a/firmware/drivers/generic_i2c.c
+++ b/firmware/drivers/generic_i2c.c
@@ -23,14 +23,17 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include "debug.h"
-#include "logf.h"
 #include "generic_i2c.h"
 
+#define MAX_I2C_INTERFACES 5
+
 int i2c_num_ifs = 0;
-struct i2c_interface *i2c_if[5];
+struct i2c_interface *i2c_if[MAX_I2C_INTERFACES];
 
 static void i2c_start(struct i2c_interface *iface)
 {
+    iface->sda_output();
+
     iface->sda_hi();
     iface->scl_hi();
     iface->sda_lo();
@@ -40,6 +43,8 @@ static void i2c_start(struct i2c_interface *iface)
 
 static void i2c_stop(struct i2c_interface *iface)
 {
+    iface->sda_output();
+
     iface->sda_lo();
     iface->scl_hi();
     iface->delay_su_sto();
@@ -48,6 +53,7 @@ static void i2c_stop(struct i2c_interface *iface)
 
 static void i2c_ack(struct i2c_interface *iface, bool ack)
 {
+    iface->sda_output();
     iface->scl_lo();
     if ( ack )
         iface->sda_lo();
@@ -67,10 +73,10 @@ static int i2c_getack(struct i2c_interface *iface)
     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();
@@ -83,7 +89,9 @@ static unsigned char i2c_inb(struct i2c_interface *iface, bool ack)
 {
     int i;
     unsigned char byte = 0;
-    
+
+    iface->sda_input();
+
     /* clock in each bit, MSB first */
     for ( i=0x80; i; i>>=1 ) {
         iface->sda_input();
@@ -95,27 +103,29 @@ static unsigned char i2c_inb(struct i2c_interface *iface, bool ack)
         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();
+    int i;
+
+    iface->sda_output();
+
+    /* 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();
@@ -140,27 +150,36 @@ int i2c_write_data(int bus_address, int address,
     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)) {
+    if (!i2c_getack(iface))
+    {
+        ret = -2;
+        goto end;
+    }
+
+    if (address != -1)
+    {
         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;
+        if (!i2c_getack(iface))
+        {
+            ret = -3;
+            goto end;
+        }
+    }
+
+    for(i = 0;i < count;i++)
+    {
+        i2c_outb(iface, buf[i]);
+        if (!i2c_getack(iface))
+        {
+            ret = -4;
+            break;
         }
-    } else {
-        logf("i2c_write_data() - no ack\n");
-        ret = -1;
     }
-    
+
+end:
     i2c_stop(iface);
     return ret;
 }
@@ -173,34 +192,50 @@ int i2c_read_data(int bus_address, int address,
     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 {
+
+    if (address != -1)
+    {
+        i2c_start(iface);
+        i2c_outb(iface, iface->address & 0xfe);
+        if (!i2c_getack(iface))
+        {
             ret = -2;
+            goto end;
+        }
+        i2c_outb(iface, address);
+        if (!i2c_getack(iface))
+        {
+            ret = -3;
+            goto end;
         }
-    } else {
-        ret = -1;
     }
-    
+
+    i2c_start(iface);
+    i2c_outb(iface, iface->address | 1);
+    if (!i2c_getack(iface))
+    {
+        ret = -4;
+        goto end;
+    }
+
+    for(i = 0;i < count-1;i++)
+        buf[i] = i2c_inb(iface, true);
+
+    buf[i] = i2c_inb(iface, false);
+
+end:
     i2c_stop(iface);
     return ret;
 }
 
-void i2c_add_node(struct i2c_interface *iface)
+int i2c_add_node(struct i2c_interface *iface)
 {
+    if (i2c_num_ifs == MAX_I2C_INTERFACES)
+        return -1;
+
     i2c_if[i2c_num_ifs++] = iface;
+
+    iface->scl_output();
+
+    return 0;
 }
diff --git a/firmware/export/generic_i2c.h b/firmware/export/generic_i2c.h
index 7b598039fa..f38728589d 100644
--- a/firmware/export/generic_i2c.h
+++ b/firmware/export/generic_i2c.h
@@ -47,7 +47,7 @@ struct i2c_interface
     void (*delay_thigh)(void);  /* SCL high period (tHIGH)     4.0us/0.6us */
 };
 
-extern void i2c_add_node(struct i2c_interface *iface);
+extern int 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,