[PATCH] I2C: Yet another it87 patch.

Ok, after writing up something in the way of a perl script to make some
sense of the data for voltages, and finding that there is no sense to
make, I took a longer look at things.

The it87 driver in 2.5.x is doing some, down right /odd/ math on the
numbers for the in_input* readings, and the 2.4.x driver is doing
something quite different.

And while it might be possible to get sane numbers out of the 2.5.x
driver, people /expect/ to get the numbers that they were getting from
2.4.x.

So this patch puts things back to the simpler calculations done by the
2.4.x lm-sensors drivers, and my script confirms that the numbers come
out right.

drivers/i2c/chips/it87.c

@@ -99,46 +99,8 @@ static int temp_type = 0x2a;
 
 #define IT87_REG_CHIPID        0x58
 
-static inline u8 IN_TO_REG(long val, int inNum)
-{
-	/* to avoid floating point, we multiply everything by 100.
-	 val is guaranteed to be positive, so we can achieve the effect of 
-	 rounding by (...*10+5)/10.  Note that the *10 is hidden in the 
-	 /250 (which should really be /2500).
-	 At the end, we need to /100 because we *100 everything and we need
-	 to /10 because of the rounding thing, so we /1000.   */
-	if (inNum <= 1)
-		return (u8)
-		    SENSORS_LIMIT(((val * 210240 - 13300) / 250 + 5) / 1000, 
-				  0, 255);
-	else if (inNum == 2)
-		return (u8)
-		    SENSORS_LIMIT(((val * 157370 - 13300) / 250 + 5) / 1000, 
-				  0, 255);
-	else if (inNum == 3)
-		return (u8)
-		    SENSORS_LIMIT(((val * 101080 - 13300) / 250 + 5) / 1000, 
-				  0, 255);
-	else
-		return (u8) SENSORS_LIMIT(((val * 41714 - 13300) / 250 + 5)
-					  / 1000, 0, 255);
-}
-
-static inline long IN_FROM_REG(u8 val, int inNum)
-{
-	/* to avoid floating point, we multiply everything by 100.
-	 val is guaranteed to be positive, so we can achieve the effect of
-	 rounding by adding 0.5.  Or, to avoid fp math, we do (...*10+5)/10.
-	 We need to scale with *100 anyway, so no need to /100 at the end. */
-	if (inNum <= 1)
-		return (long) (((250000 * val + 13300) / 210240 * 10 + 5) /10);
-	else if (inNum == 2)
-		return (long) (((250000 * val + 13300) / 157370 * 10 + 5) /10);
-	else if (inNum == 3)
-		return (long) (((250000 * val + 13300) / 101080 * 10 + 5) /10);
-	else
-		return (long) (((250000 * val + 13300) / 41714 * 10 + 5) /10);
-}
+#define IN_TO_REG(val)  (SENSORS_LIMIT((((val) * 10 + 8)/16),0,255))
+#define IN_FROM_REG(val) (((val) *  16) / 10)
 
 static inline u8 FAN_TO_REG(long rpm, int div)
 {
@@ -279,7 +241,7 @@ static ssize_t show_in(struct device *dev, char *buf, int nr)
 	struct i2c_client *client = to_i2c_client(dev);
 	struct it87_data *data = i2c_get_clientdata(client);
 	it87_update_client(client);
-	return sprintf(buf, "%ld\n", IN_FROM_REG(data->in[nr], nr)*10 );
+	return sprintf(buf, "%d\n", IN_FROM_REG(data->in[nr])*10 );
 }
 
 static ssize_t show_in_min(struct device *dev, char *buf, int nr)
@@ -287,7 +249,7 @@ static ssize_t show_in_min(struct device *dev, char *buf, int nr)
 	struct i2c_client *client = to_i2c_client(dev);
 	struct it87_data *data = i2c_get_clientdata(client);
 	it87_update_client(client);
-	return sprintf(buf, "%ld\n", IN_FROM_REG(data->in_min[nr], nr)*10 );
+	return sprintf(buf, "%d\n", IN_FROM_REG(data->in_min[nr])*10 );
 }
 
 static ssize_t show_in_max(struct device *dev, char *buf, int nr)
@@ -295,7 +257,7 @@ static ssize_t show_in_max(struct device *dev, char *buf, int nr)
 	struct i2c_client *client = to_i2c_client(dev);
 	struct it87_data *data = i2c_get_clientdata(client);
 	it87_update_client(client);
-	return sprintf(buf, "%ld\n", IN_FROM_REG(data->in_max[nr], nr)*10 );
+	return sprintf(buf, "%d\n", IN_FROM_REG(data->in_max[nr])*10 );
 }
 
 static ssize_t set_in_min(struct device *dev, const char *buf, 
@@ -304,7 +266,7 @@ static ssize_t set_in_min(struct device *dev, const char *buf,
 	struct i2c_client *client = to_i2c_client(dev);
 	struct it87_data *data = i2c_get_clientdata(client);
 	unsigned long val = simple_strtoul(buf, NULL, 10)/10;
-	data->in_min[nr] = IN_TO_REG(val,nr);
+	data->in_min[nr] = IN_TO_REG(val);
 	it87_write_value(client, IT87_REG_VIN_MIN(nr), 
 			data->in_min[nr]);
 	return count;
@@ -315,7 +277,7 @@ static ssize_t set_in_max(struct device *dev, const char *buf,
 	struct i2c_client *client = to_i2c_client(dev);
 	struct it87_data *data = i2c_get_clientdata(client);
 	unsigned long val = simple_strtoul(buf, NULL, 10)/10;
-	data->in_max[nr] = IN_TO_REG(val,nr);
+	data->in_max[nr] = IN_TO_REG(val);
 	it87_write_value(client, IT87_REG_VIN_MAX(nr), 
 			data->in_max[nr]);
 	return count;
@@ -855,37 +817,37 @@ static void it87_init_client(struct i2c_client *client, struct it87_data *data)
 	   This sets fan-divs to 2, among others */
 	it87_write_value(client, IT87_REG_CONFIG, 0x80);
 	it87_write_value(client, IT87_REG_VIN_MIN(0),
-			 IN_TO_REG(IT87_INIT_IN_MIN_0, 0));
+			 IN_TO_REG(IT87_INIT_IN_MIN_0));
 	it87_write_value(client, IT87_REG_VIN_MAX(0),
-			 IN_TO_REG(IT87_INIT_IN_MAX_0, 0));
+			 IN_TO_REG(IT87_INIT_IN_MAX_0));
 	it87_write_value(client, IT87_REG_VIN_MIN(1),
-			 IN_TO_REG(IT87_INIT_IN_MIN_1, 1));
+			 IN_TO_REG(IT87_INIT_IN_MIN_1));
 	it87_write_value(client, IT87_REG_VIN_MAX(1),
-			 IN_TO_REG(IT87_INIT_IN_MAX_1, 1));
+			 IN_TO_REG(IT87_INIT_IN_MAX_1));
 	it87_write_value(client, IT87_REG_VIN_MIN(2),
-			 IN_TO_REG(IT87_INIT_IN_MIN_2, 2));
+			 IN_TO_REG(IT87_INIT_IN_MIN_2));
 	it87_write_value(client, IT87_REG_VIN_MAX(2),
-			 IN_TO_REG(IT87_INIT_IN_MAX_2, 2));
+			 IN_TO_REG(IT87_INIT_IN_MAX_2));
 	it87_write_value(client, IT87_REG_VIN_MIN(3),
-			 IN_TO_REG(IT87_INIT_IN_MIN_3, 3));
+			 IN_TO_REG(IT87_INIT_IN_MIN_3));
 	it87_write_value(client, IT87_REG_VIN_MAX(3),
-			 IN_TO_REG(IT87_INIT_IN_MAX_3, 3));
+			 IN_TO_REG(IT87_INIT_IN_MAX_3));
 	it87_write_value(client, IT87_REG_VIN_MIN(4),
-			 IN_TO_REG(IT87_INIT_IN_MIN_4, 4));
+			 IN_TO_REG(IT87_INIT_IN_MIN_4));
 	it87_write_value(client, IT87_REG_VIN_MAX(4),
-			 IN_TO_REG(IT87_INIT_IN_MAX_4, 4));
+			 IN_TO_REG(IT87_INIT_IN_MAX_4));
 	it87_write_value(client, IT87_REG_VIN_MIN(5),
-			 IN_TO_REG(IT87_INIT_IN_MIN_5, 5));
+			 IN_TO_REG(IT87_INIT_IN_MIN_5));
 	it87_write_value(client, IT87_REG_VIN_MAX(5),
-			 IN_TO_REG(IT87_INIT_IN_MAX_5, 5));
+			 IN_TO_REG(IT87_INIT_IN_MAX_5));
 	it87_write_value(client, IT87_REG_VIN_MIN(6),
-			 IN_TO_REG(IT87_INIT_IN_MIN_6, 6));
+			 IN_TO_REG(IT87_INIT_IN_MIN_6));
 	it87_write_value(client, IT87_REG_VIN_MAX(6),
-			 IN_TO_REG(IT87_INIT_IN_MAX_6, 6));
+			 IN_TO_REG(IT87_INIT_IN_MAX_6));
 	it87_write_value(client, IT87_REG_VIN_MIN(7),
-			 IN_TO_REG(IT87_INIT_IN_MIN_7, 7));
+			 IN_TO_REG(IT87_INIT_IN_MIN_7));
 	it87_write_value(client, IT87_REG_VIN_MAX(7),
-			 IN_TO_REG(IT87_INIT_IN_MAX_7, 7));
+			 IN_TO_REG(IT87_INIT_IN_MAX_7));
 	/* Note: Battery voltage does not have limit registers */
 	it87_write_value(client, IT87_REG_FAN_MIN(1),
 			 FAN_TO_REG(IT87_INIT_FAN_MIN_1, 2));