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>
diff --git a/drivers/i2c/busses/i2c-ali15x3.c b/drivers/i2c/busses/i2c-ali15x3.c
index e922c39..a030abd 100644
--- a/drivers/i2c/busses/i2c-ali15x3.c
+++ b/drivers/i2c/busses/i2c-ali15x3.c
@@ -68,6 +68,7 @@
 #include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
+#include <linux/acpi.h>
 #include <asm/io.h>
 
 /* ALI15X3 SMBus address offsets */
@@ -166,6 +167,10 @@
 	if(force_addr)
 		ali15x3_smba = force_addr & ~(ALI15X3_SMB_IOSIZE - 1);
 
+	if (acpi_check_region(ali15x3_smba, ALI15X3_SMB_IOSIZE,
+			      ali15x3_driver.name))
+		return -EBUSY;
+
 	if (!request_region(ali15x3_smba, ALI15X3_SMB_IOSIZE,
 			    ali15x3_driver.name)) {
 		dev_err(&ALI15X3_dev->dev,