2 files changed, 26 insertions, 22 deletions

diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index fc16f9d268a..d9d0ec49e60 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -57,19 +57,19 @@ static int bit_test;	/* see if the line-setting functions work	*/
 static inline void sdalo(struct i2c_algo_bit_data *adap)
 {
         setsda(adap,0);
-        udelay(adap->udelay);
+        udelay((adap->udelay + 1) / 2);
 }
 
 static inline void sdahi(struct i2c_algo_bit_data *adap)
 {
         setsda(adap,1);
-        udelay(adap->udelay);
+        udelay((adap->udelay + 1) / 2);
 }
 
 static inline void scllo(struct i2c_algo_bit_data *adap)
 {
         setscl(adap,0);
-        udelay(adap->udelay);
+        udelay(adap->udelay / 2);
 }
 
 /*
@@ -111,18 +111,19 @@ static void i2c_start(struct i2c_algo_bit_data *adap)
 {
         /* assert: scl, sda are high */
         DEBPROTO(printk("S "));
-        sdalo(adap);
+        setsda(adap, 0);
+        udelay(adap->udelay);
         scllo(adap);
 }
 
 static void i2c_repstart(struct i2c_algo_bit_data *adap) 
 {
-        /* scl, sda may not be high */
+        /* assert: scl is low */
         DEBPROTO(printk(" Sr "));
-        setsda(adap,1);
+        sdahi(adap);
         sclhi(adap);
-        
-        sdalo(adap);
+        setsda(adap, 0);
+        udelay(adap->udelay);
         scllo(adap);
 }
 
@@ -133,7 +134,8 @@ static void i2c_stop(struct i2c_algo_bit_data *adap)
         /* assert: scl is low */
         sdalo(adap);
         sclhi(adap); 
-        sdahi(adap);
+        setsda(adap, 1);
+        udelay(adap->udelay);
 }
 
 
@@ -156,18 +158,16 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, char c)
         for ( i=7 ; i>=0 ; i-- ) {
                 sb = c & ( 1 << i );
                 setsda(adap,sb);
-                udelay(adap->udelay);
+                udelay((adap->udelay + 1) / 2);
                 DEBPROTO(printk(KERN_DEBUG "%d",sb!=0));
                 if (sclhi(adap)<0) { /* timed out */
-                        sdahi(adap); /* we don't want to block the net */
                         DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x, timeout at bit #%d\n", c&0xff, i));
                         return -ETIMEDOUT;
                 };
                 /* do arbitration here: 
                  * if ( sb && ! getsda(adap) ) -> ouch! Get out of here.
                  */
-                setscl(adap, 0 );
-                udelay(adap->udelay);
+                scllo(adap);
         }
         sdahi(adap);
         if (sclhi(adap)<0){ /* timeout */
@@ -204,7 +204,8 @@ static int i2c_inb(struct i2c_adapter *i2c_adap)
                 indata *= 2;
                 if ( getsda(adap) ) 
                         indata |= 0x01;
-                scllo(adap);
+                setscl(adap, 0);
+                udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
         }
         /* assert: scl is low */
         DEB2(printk(KERN_DEBUG "i2c_inb: 0x%02x\n", indata & 0xff));
@@ -315,9 +316,9 @@ static int try_address(struct i2c_adapter *i2c_adap,
                 if (ret == 1 || i == retries)
                         break;
                 i2c_stop(adap);
-                udelay(5/*adap->udelay*/);
-                i2c_start(adap);
                 udelay(adap->udelay);
+                yield();
+                i2c_start(adap);
         }
         DEB2(if (i)
              printk(KERN_DEBUG "i2c-algo-bit.o: Used %d tries to %s client at 0x%02x : %s\n",
@@ -377,20 +378,21 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
                 if (msg->flags & I2C_M_NO_RD_ACK)
                         continue;
 
+                /* assert: sda is high */
                 if ( count > 0 ) {              /* send ack */
-                        sdalo(adap);
+                        setsda(adap, 0);
+                        udelay((adap->udelay + 1) / 2);
                         DEBPROTO(printk(" Am "));
                 } else {
-                        sdahi(adap);    /* neg. ack on last byte */
+                        /* neg. ack on last byte */
+                        udelay((adap->udelay + 1) / 2);
                         DEBPROTO(printk(" NAm "));
                 }
                 if (sclhi(adap)<0) {    /* timeout */
-                        sdahi(adap);
                         printk(KERN_ERR "i2c-algo-bit.o: readbytes: Timeout at ack\n");
                         return -ETIMEDOUT;
                 };
                 scllo(adap);
-                sdahi(adap);
 
                 /* Some SMBus transactions require that we receive the
                    transaction length as the first read byte. */
diff --git a/include/linux/i2c-algo-bit.h b/include/linux/i2c-algo-bit.h
index d91dab88635..9ee0f800592 100644
--- a/include/linux/i2c-algo-bit.h
+++ b/include/linux/i2c-algo-bit.h
@@ -38,8 +38,10 @@ struct i2c_algo_bit_data {
         int  (*getscl) (void *data);
 
         /* local settings */
-        int udelay;             /* half-clock-cycle time in microsecs */
-                                /* i.e. clock is (500 / udelay) KHz */
+        int udelay;             /* half clock cycle time in us,
+                                   minimum 2 us for fast-mode I2C,
+                                   minimum 5 us for standard-mode I2C and SMBus,
+                                   maximum 50 us for SMBus */
         int timeout;            /* in jiffies */
 };