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-amd756.c b/drivers/i2c/busses/i2c-amd756.c
index bd4f638..26acc65 100644
--- a/drivers/i2c/busses/i2c-amd756.c
+++ b/drivers/i2c/busses/i2c-amd756.c
@@ -45,6 +45,7 @@
 #include <linux/ioport.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
+#include <linux/acpi.h>
 #include <asm/io.h>
 
 /* AMD756 SMBus address offsets */
@@ -368,6 +369,11 @@
 		amd756_ioport += SMB_ADDR_OFFSET;
 	}
 
+	error = acpi_check_region(amd756_ioport, SMB_IOSIZE,
+				  amd756_driver.name);
+	if (error)
+		return error;
+
 	if (!request_region(amd756_ioport, SMB_IOSIZE, amd756_driver.name)) {
 		dev_err(&pdev->dev, "SMB region 0x%x already in use!\n",
 			amd756_ioport);