hwmon: (it87) Check for fan2 and fan3 availability

The fan2 and fan3 input and output pins can be used as GPIOs. Check
their function before exposing their sysfs attributes and accessing
their registers.
Signed-off-by: NJean Delvare <khali@linux-fr.org>

drivers/hwmon/it87.c

@@ -125,6 +125,7 @@ superio_exit(void)
 
 /* Logical device 7 registers (IT8712F and later) */
 #define IT87_SIO_GPIO3_REG	0x27
+#define IT87_SIO_GPIO5_REG	0x29
 #define IT87_SIO_PINX2_REG	0x2c	/* Pin selection */
 #define IT87_SIO_VID_REG	0xfc	/* VID value */
 
@@ -245,8 +246,9 @@ struct it87_sio_data {
 	/* Values read from Super-I/O config space */
 	u8 revision;
 	u8 vid_value;
+	/* Features skipped based on config or DMI */
 	u8 skip_vid;
-	/* Values set based on DMI strings */
+	u8 skip_fan;
 	u8 skip_pwm;
 };
 
@@ -1044,6 +1046,19 @@ static int __init it87_find(unsigned short *address,
 			sio_data->skip_vid = 1;
 		}
 
+		/* Check if fan3 is there or not */
+		if (reg & (1 << 6))
+			sio_data->skip_pwm |= (1 << 2);
+		if (reg & (1 << 7))
+			sio_data->skip_fan |= (1 << 2);
+
+		/* Check if fan2 is there or not */
+		reg = superio_inb(IT87_SIO_GPIO5_REG);
+		if (reg & (1 << 1))
+			sio_data->skip_pwm |= (1 << 1);
+		if (reg & (1 << 2))
+			sio_data->skip_fan |= (1 << 1);
+
 		if ((sio_data->type == it8718 || sio_data->type == it8720)
 		 && !(sio_data->skip_vid))
 			sio_data->vid_value = superio_inb(IT87_SIO_VID_REG);
@@ -1367,8 +1382,10 @@ static int __devinit it87_check_pwm(struct device *dev)
 /* Called when we have found a new IT87. */
 static void __devinit it87_init_device(struct platform_device *pdev)
 {
+	struct it87_sio_data *sio_data = pdev->dev.platform_data;
 	struct it87_data *data = platform_get_drvdata(pdev);
 	int tmp, i;
+	u8 mask;
 
 	/* initialize to sane defaults:
 	 * - if the chip is in manual pwm mode, this will be overwritten with
@@ -1414,10 +1431,11 @@ static void __devinit it87_init_device(struct platform_device *pdev)
 	}
 
 	/* Check if tachometers are reset manually or by some reason */
+	mask = 0x70 & ~(sio_data->skip_fan << 4);
 	data->fan_main_ctrl = it87_read_value(data, IT87_REG_FAN_MAIN_CTRL);
-	if ((data->fan_main_ctrl & 0x70) == 0) {
+	if ((data->fan_main_ctrl & mask) == 0) {
 		/* Enable all fan tachometers */
-		data->fan_main_ctrl |= 0x70;
+		data->fan_main_ctrl |= mask;
 		it87_write_value(data, IT87_REG_FAN_MAIN_CTRL, data->fan_main_ctrl);
 	}
 	data->has_fan = (data->fan_main_ctrl >> 4) & 0x07;
@@ -1440,6 +1458,9 @@ static void __devinit it87_init_device(struct platform_device *pdev)
 		}
 	}
 
+	/* Fan input pins may be used for alternative functions */
+	data->has_fan &= ~sio_data->skip_fan;
+
 	/* Set current fan mode registers and the default settings for the
 	 * other mode registers */
 	for (i = 0; i < 3; i++) {