i2c: Check for ACPI resource conflicts

Check for ACPI resource conflicts in i2c bus drivers. I've included
all recent SMBus master drivers for PC hardware.

I've voluntarily left out:
* Drivers that don't run on PCs: they can't conflict with ACPI.
* Bit-banged bus device drivers: it's very unlikely that ACPI would
  deal with such buses.

Signed-off-by: Jean Delvare <jdelvare@suse.de>

drivers/i2c/busses/i2c-nforce2.c

@@ -51,6 +51,7 @@
 #include <linux/i2c.h>
 #include <linux/delay.h>
 #include <linux/dmi.h>
+#include <linux/acpi.h>
 #include <asm/io.h>
 
 MODULE_LICENSE("GPL");
@@ -343,6 +344,11 @@ static int __devinit nforce2_probe_smb (struct pci_dev *dev, int bar,
 		smbus->size = 64;
 	}
 
+	error = acpi_check_region(smbus->base, smbus->size,
+				  nforce2_driver.name);
+	if (error)
+		return -1;
+
 	if (!request_region(smbus->base, smbus->size, nforce2_driver.name)) {
 		dev_err(&smbus->adapter.dev, "Error requesting region %02x .. %02X for %s\n",
 			smbus->base, smbus->base+smbus->size-1, name);