i2c-algo-bit: Improve debugging

Improve the debugging features of the i2c-algo-bit driver:
* Make it possible to compile the driver without debugging support
  at all, making it much smaller.
* Use dev_dbg() for debugging messages where possible, and dev_err()
  for error messages.
* Remove redundant debugging messages.

These changes allowed for minor code cleanups, which are included
as well.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/i2c/algos/i2c-algo-bit.c

@@ -33,19 +33,30 @@
 
 
 /* ----- global defines ----------------------------------------------- */
-#define DEB(x) if (i2c_debug>=1) x;
-#define DEB2(x) if (i2c_debug>=2) x;
-#define DEBSTAT(x) if (i2c_debug>=3) x; /* print several statistical values*/
-#define DEBPROTO(x) if (i2c_debug>=9) { x; }
- 	/* debug the protocol by showing transferred bits */
 
+#ifdef DEBUG
+#define bit_dbg(level, dev, format, args...) \
+	do { \
+		if (i2c_debug >= level) \
+			dev_dbg(dev, format, ##args); \
+	} while (0)
+#else
+#define bit_dbg(level, dev, format, args...) \
+	do {} while (0)
+#endif /* DEBUG */
 
 /* ----- global variables ---------------------------------------------	*/
 
-/* module parameters:
- */
-static int i2c_debug;
 static int bit_test;	/* see if the line-setting functions work	*/
+module_param(bit_test, bool, 0);
+MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck");
+
+#ifdef DEBUG
+static int i2c_debug = 1;
+module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(i2c_debug,
+		 "debug level - 0 off; 1 normal; 2 verbose; 3 very verbose");
+#endif
 
 /* --- setting states on the bus with the right timing: ---------------	*/
 
@@ -98,7 +109,11 @@ static int sclhi(struct i2c_algo_bit_data *adap)
 		}
 		cond_resched();
 	}
-	DEBSTAT(printk(KERN_DEBUG "needed %ld jiffies\n", jiffies-start));
+#ifdef DEBUG
+	if (jiffies != start && i2c_debug >= 3)
+		pr_debug("i2c-algo-bit: needed %ld jiffies for SCL to go "
+			 "high\n", jiffies - start);
+#endif
 
 done:
 	udelay(adap->udelay);
@@ -110,7 +125,6 @@ done:
 static void i2c_start(struct i2c_algo_bit_data *adap) 
 {
 	/* assert: scl, sda are high */
-	DEBPROTO(printk("S "));
 	setsda(adap, 0);
 	udelay(adap->udelay);
 	scllo(adap);
@@ -119,7 +133,6 @@ static void i2c_start(struct i2c_algo_bit_data *adap)
 static void i2c_repstart(struct i2c_algo_bit_data *adap) 
 {
 	/* assert: scl is low */
-	DEBPROTO(printk(" Sr "));
 	sdahi(adap);
 	sclhi(adap);
 	setsda(adap, 0);
@@ -130,7 +143,6 @@ static void i2c_repstart(struct i2c_algo_bit_data *adap)
 
 static void i2c_stop(struct i2c_algo_bit_data *adap) 
 {
-	DEBPROTO(printk("P\n"));
 	/* assert: scl is low */
 	sdalo(adap);
 	sclhi(adap); 
@@ -147,7 +159,7 @@ static void i2c_stop(struct i2c_algo_bit_data *adap)
  * 0 if the device did not ack
  * -ETIMEDOUT if an error occurred (while raising the scl line)
  */
-static int i2c_outb(struct i2c_adapter *i2c_adap, char c)
+static int i2c_outb(struct i2c_adapter *i2c_adap, unsigned char c)
 {
 	int i;
 	int sb;
@@ -156,12 +168,12 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, char c)
 
 	/* assert: scl is low */
 	for ( i=7 ; i>=0 ; i-- ) {
-		sb = c & ( 1 << i );
+		sb = (c >> i) & 1;
 		setsda(adap,sb);
 		udelay((adap->udelay + 1) / 2);
-		DEBPROTO(printk(KERN_DEBUG "%d",sb!=0));
 		if (sclhi(adap)<0) { /* timed out */
-			DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x, timeout at bit #%d\n", c&0xff, i));
+			bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
+				"timeout at bit #%d\n", (int)c, i);
 			return -ETIMEDOUT;
 		};
 		/* do arbitration here: 
@@ -171,17 +183,17 @@ static int i2c_outb(struct i2c_adapter *i2c_adap, char c)
 	}
 	sdahi(adap);
 	if (sclhi(adap)<0){ /* timeout */
-	    DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x, timeout at ack\n", c&0xff));
-	    return -ETIMEDOUT;
+		bit_dbg(1, &i2c_adap->dev, "i2c_outb: 0x%02x, "
+			"timeout at ack\n", (int)c);
+		return -ETIMEDOUT;
 	};
 	/* read ack: SDA should be pulled down by slave */
-	ack=getsda(adap);	/* ack: sda is pulled low ->success.	 */
-	DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x , getsda() = %d\n", c & 0xff, ack));
+	ack = !getsda(adap);    /* ack: sda is pulled low -> success */
+	bit_dbg(2, &i2c_adap->dev, "i2c_outb: 0x%02x %s\n", (int)c,
+		ack ? "A" : "NA");
 
-	DEBPROTO( printk(KERN_DEBUG "[%2.2x]",c&0xff) );
-	DEBPROTO(if (0==ack){ printk(KERN_DEBUG " A ");} else printk(KERN_DEBUG " NA ") );
 	scllo(adap);
-	return 0==ack;		/* return 1 if device acked	 */
+	return ack;
 	/* assert: scl is low (sda undef) */
 }
 
@@ -198,7 +210,8 @@ static int i2c_inb(struct i2c_adapter *i2c_adap)
 	sdahi(adap);
 	for (i=0;i<8;i++) {
 		if (sclhi(adap)<0) { /* timeout */
-			DEB2(printk(KERN_DEBUG " i2c_inb: timeout at bit #%d\n", 7-i));
+			bit_dbg(1, &i2c_adap->dev, "i2c_inb: timeout at bit "
+				"#%d\n", 7 - i);
 			return -ETIMEDOUT;
 		};
 		indata *= 2;
@@ -208,10 +221,7 @@ static int i2c_inb(struct i2c_adapter *i2c_adap)
 		udelay(i == 7 ? adap->udelay / 2 : adap->udelay);
 	}
 	/* assert: scl is low */
-	DEB2(printk(KERN_DEBUG "i2c_inb: 0x%02x\n", indata & 0xff));
-
-	DEBPROTO(printk(KERN_DEBUG " 0x%02x", indata & 0xff));
-	return (int) (indata & 0xff);
+	return indata;
 }
 
 /*
@@ -222,73 +232,67 @@ static int test_bus(struct i2c_algo_bit_data *adap, char* name) {
 	int scl,sda;
 
 	if (adap->getscl==NULL)
-		printk(KERN_INFO "i2c-algo-bit.o: Testing SDA only, "
-			"SCL is not readable.\n");
+		pr_info("%s: Testing SDA only, SCL is not readable\n", name);
 
 	sda=getsda(adap);
 	scl=(adap->getscl==NULL?1:getscl(adap));
-	printk(KERN_DEBUG "i2c-algo-bit.o: (0) scl=%d, sda=%d\n",scl,sda);
 	if (!scl || !sda ) {
-		printk(KERN_WARNING "i2c-algo-bit.o: %s seems to be busy.\n", name);
+		printk(KERN_WARNING "%s: bus seems to be busy\n", name);
 		goto bailout;
 	}
 
 	sdalo(adap);
 	sda=getsda(adap);
 	scl=(adap->getscl==NULL?1:getscl(adap));
-	printk(KERN_DEBUG "i2c-algo-bit.o: (1) scl=%d, sda=%d\n",scl,sda);
 	if ( 0 != sda ) {
-		printk(KERN_WARNING "i2c-algo-bit.o: SDA stuck high!\n");
+		printk(KERN_WARNING "%s: SDA stuck high!\n", name);
 		goto bailout;
 	}
 	if ( 0 == scl ) {
-		printk(KERN_WARNING "i2c-algo-bit.o: SCL unexpected low "
-			"while pulling SDA low!\n");
+		printk(KERN_WARNING "%s: SCL unexpected low "
+		       "while pulling SDA low!\n", name);
 		goto bailout;
 	}		
 
 	sdahi(adap);
 	sda=getsda(adap);
 	scl=(adap->getscl==NULL?1:getscl(adap));
-	printk(KERN_DEBUG "i2c-algo-bit.o: (2) scl=%d, sda=%d\n",scl,sda);
 	if ( 0 == sda ) {
-		printk(KERN_WARNING "i2c-algo-bit.o: SDA stuck low!\n");
+		printk(KERN_WARNING "%s: SDA stuck low!\n", name);
 		goto bailout;
 	}
 	if ( 0 == scl ) {
-		printk(KERN_WARNING "i2c-algo-bit.o: SCL unexpected low "
-			"while pulling SDA high!\n");
+		printk(KERN_WARNING "%s: SCL unexpected low "
+		       "while pulling SDA high!\n", name);
 		goto bailout;
 	}
 
 	scllo(adap);
 	sda=getsda(adap);
 	scl=(adap->getscl==NULL?0:getscl(adap));
-	printk(KERN_DEBUG "i2c-algo-bit.o: (3) scl=%d, sda=%d\n",scl,sda);
 	if ( 0 != scl ) {
-		printk(KERN_WARNING "i2c-algo-bit.o: SCL stuck high!\n");
+		printk(KERN_WARNING "%s: SCL stuck high!\n", name);
 		goto bailout;
 	}
 	if ( 0 == sda ) {
-		printk(KERN_WARNING "i2c-algo-bit.o: SDA unexpected low "
-			"while pulling SCL low!\n");
+		printk(KERN_WARNING "%s: SDA unexpected low "
+		       "while pulling SCL low!\n", name);
 		goto bailout;
 	}
 	
 	sclhi(adap);
 	sda=getsda(adap);
 	scl=(adap->getscl==NULL?1:getscl(adap));
-	printk(KERN_DEBUG "i2c-algo-bit.o: (4) scl=%d, sda=%d\n",scl,sda);
 	if ( 0 == scl ) {
-		printk(KERN_WARNING "i2c-algo-bit.o: SCL stuck low!\n");
+		printk(KERN_WARNING "%s: SCL stuck low!\n", name);
 		goto bailout;
 	}
 	if ( 0 == sda ) {
-		printk(KERN_WARNING "i2c-algo-bit.o: SDA unexpected low "
-			"while pulling SCL high!\n");
+		printk(KERN_WARNING "%s: SDA unexpected low "
+		       "while pulling SCL high!\n", name);
 		goto bailout;
 	}
-	printk(KERN_INFO "i2c-algo-bit.o: %s passed test.\n",name);
+	pr_info("%s: Test OK\n", name);
 	return 0;
 bailout:
 	sdahi(adap);
@@ -315,32 +319,31 @@ static int try_address(struct i2c_adapter *i2c_adap,
 		ret = i2c_outb(i2c_adap,addr);
 		if (ret == 1 || i == retries)
 			break;
+		bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
 		i2c_stop(adap);
 		udelay(adap->udelay);
 		yield();
+		bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
 		i2c_start(adap);
 	}
-	DEB2(if (i)
-	     printk(KERN_DEBUG "i2c-algo-bit.o: Used %d tries to %s client at 0x%02x : %s\n",
-		    i+1, addr & 1 ? "read" : "write", addr>>1,
-		    ret==1 ? "success" : ret==0 ? "no ack" : "failed, timeout?" )
-	    );
+	if (i && ret)
+		bit_dbg(1, &i2c_adap->dev, "Used %d tries to %s client at "
+			"0x%02x: %s\n", i + 1,
+			addr & 1 ? "read from" : "write to", addr >> 1,
+			ret == 1 ? "success" : "failed, timeout?");
 	return ret;
 }
 
 static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 {
-	char c;
-	const char *temp = msg->buf;
+	const unsigned char *temp = msg->buf;
 	int count = msg->len;
 	unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK; 
 	int retval;
 	int wrcount=0;
 
 	while (count > 0) {
-		c = *temp;
-		DEB2(dev_dbg(&i2c_adap->dev, "sendbytes: writing %2.2X\n", c&0xff));
-		retval = i2c_outb(i2c_adap,c);
+		retval = i2c_outb(i2c_adap, *temp);
 		if ((retval>0) || (nak_ok && (retval==0)))  { /* ok or ignored NAK */
 			count--; 
 			temp++;
@@ -359,7 +362,7 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 	int inval;
 	int rdcount=0;   	/* counts bytes read */
 	struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
-	char *temp = msg->buf;
+	unsigned char *temp = msg->buf;
 	int count = msg->len;
 
 	while (count > 0) {
@@ -368,28 +371,26 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 			*temp = inval;
 			rdcount++;
 		} else {   /* read timed out */
-			printk(KERN_ERR "i2c-algo-bit.o: readbytes: i2c_inb timed out.\n");
 			break;
 		}
 
 		temp++;
 		count--;
 
-		if (msg->flags & I2C_M_NO_RD_ACK)
+		if (msg->flags & I2C_M_NO_RD_ACK) {
+			bit_dbg(2, &i2c_adap->dev, "i2c_inb: 0x%02x\n",
+				inval);
 			continue;
+		}
 
 		/* assert: sda is high */
-		if ( count > 0 ) {		/* send ack */
+		if (count)		/* send ack */
 			setsda(adap, 0);
-			udelay((adap->udelay + 1) / 2);
-			DEBPROTO(printk(" Am "));
-		} else {
-			/* neg. ack on last byte */
-			udelay((adap->udelay + 1) / 2);
-			DEBPROTO(printk(" NAm "));
-		}
+		udelay((adap->udelay + 1) / 2);
+		bit_dbg(2, &i2c_adap->dev, "i2c_inb: 0x%02x %s\n", inval,
+			count ? "A" : "NA");
 		if (sclhi(adap)<0) {	/* timeout */
-			printk(KERN_ERR "i2c-algo-bit.o: readbytes: Timeout at ack\n");
+			dev_err(&i2c_adap->dev, "readbytes: timeout at ack\n");
 			return -ETIMEDOUT;
 		};
 		scllo(adap);
@@ -398,8 +399,8 @@ static int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 		   transaction length as the first read byte. */
 		if (rdcount == 1 && (msg->flags & I2C_M_RECV_LEN)) {
 			if (inval <= 0 || inval > I2C_SMBUS_BLOCK_MAX) {
-				printk(KERN_ERR "i2c-algo-bit: readbytes: "
-				       "invalid block length (%d)\n", inval);
+				dev_err(&i2c_adap->dev, "readbytes: invalid "
+					"block length (%d)\n", inval);
 				return -EREMOTEIO;
 			}
 			/* The original count value accounts for the extra
@@ -434,27 +435,31 @@ static int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
 	if ( (flags & I2C_M_TEN)  ) { 
 		/* a ten bit address */
 		addr = 0xf0 | (( msg->addr >> 7) & 0x03);
-		DEB2(printk(KERN_DEBUG "addr0: %d\n",addr));
+		bit_dbg(2, &i2c_adap->dev, "addr0: %d\n", addr);
 		/* try extended address code...*/
 		ret = try_address(i2c_adap, addr, retries);
 		if ((ret != 1) && !nak_ok)  {
-			printk(KERN_ERR "died at extended address code.\n");
+			dev_err(&i2c_adap->dev,
+				"died at extended address code\n");
 			return -EREMOTEIO;
 		}
 		/* the remaining 8 bit address */
 		ret = i2c_outb(i2c_adap,msg->addr & 0x7f);
 		if ((ret != 1) && !nak_ok) {
 			/* the chip did not ack / xmission error occurred */
-			printk(KERN_ERR "died at 2nd address code.\n");
+			dev_err(&i2c_adap->dev, "died at 2nd address code\n");
 			return -EREMOTEIO;
 		}
 		if ( flags & I2C_M_RD ) {
+			bit_dbg(3, &i2c_adap->dev, "emitting repeated "
+				"start condition\n");
 			i2c_repstart(adap);
 			/* okay, now switch into reading mode */
 			addr |= 0x01;
 			ret = try_address(i2c_adap, addr, retries);
 			if ((ret!=1) && !nak_ok) {
-				printk(KERN_ERR "died at extended address code.\n");
+				dev_err(&i2c_adap->dev,
+					"died at repeated address code\n");
 				return -EREMOTEIO;
 			}
 		}
@@ -481,25 +486,31 @@ static int bit_xfer(struct i2c_adapter *i2c_adap,
 	int i,ret;
 	unsigned short nak_ok;
 
+	bit_dbg(3, &i2c_adap->dev, "emitting start condition\n");
 	i2c_start(adap);
 	for (i=0;i<num;i++) {
 		pmsg = &msgs[i];
 		nak_ok = pmsg->flags & I2C_M_IGNORE_NAK; 
 		if (!(pmsg->flags & I2C_M_NOSTART)) {
 			if (i) {
+				bit_dbg(3, &i2c_adap->dev, "emitting "
+					"repeated start condition\n");
 				i2c_repstart(adap);
 			}
 			ret = bit_doAddress(i2c_adap, pmsg);
 			if ((ret != 0) && !nak_ok) {
-			    DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: NAK from device addr %2.2x msg #%d\n"
-					,msgs[i].addr,i));
+				bit_dbg(1, &i2c_adap->dev, "NAK from "
+					"device addr 0x%02x msg #%d\n",
+					msgs[i].addr, i);
 				goto bailout;
 			}
 		}
 		if (pmsg->flags & I2C_M_RD ) {
 			/* read bytes into buffer*/
 			ret = readbytes(i2c_adap, pmsg);
-			DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: read %d bytes.\n",ret));
+			if (ret >= 1)
+				bit_dbg(2, &i2c_adap->dev, "read %d byte%s\n",
+					ret, ret == 1 ? "" : "s");
 			if (ret < pmsg->len) {
 				if (ret >= 0)
 					ret = -EREMOTEIO;
@@ -508,7 +519,9 @@ static int bit_xfer(struct i2c_adapter *i2c_adap,
 		} else {
 			/* write bytes from buffer */
 			ret = sendbytes(i2c_adap, pmsg);
-			DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: wrote %d bytes.\n",ret));
+			if (ret >= 1)
+				bit_dbg(2, &i2c_adap->dev, "wrote %d byte%s\n",
+					ret, ret == 1 ? "" : "s");
 			if (ret < pmsg->len) {
 				if (ret >= 0)
 					ret = -EREMOTEIO;
@@ -519,6 +532,7 @@ static int bit_xfer(struct i2c_adapter *i2c_adap,
 	ret = i;
 
 bailout:
+	bit_dbg(3, &i2c_adap->dev, "emitting stop condition\n");
 	i2c_stop(adap);
 	return ret;
 }
@@ -552,8 +566,6 @@ static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
 			return -ENODEV;
 	}
 
-	DEB2(dev_dbg(&adap->dev, "hw routines registered.\n"));
-
 	/* register new adapter to i2c module... */
 	adap->algo = &i2c_bit_algo;
 
@@ -590,10 +602,3 @@ EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
 MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
 MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
 MODULE_LICENSE("GPL");
-
-module_param(bit_test, bool, 0);
-module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
-
-MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck");
-MODULE_PARM_DESC(i2c_debug,
-		 "debug level - 0 off; 1 normal; 2,3 more verbose; 9 bit-protocol");