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-viapro.c b/drivers/i2c/busses/i2c-viapro.c
index 7957ce5..faef995 100644
--- a/drivers/i2c/busses/i2c-viapro.c
+++ b/drivers/i2c/busses/i2c-viapro.c
@@ -50,6 +50,7 @@
 #include <linux/ioport.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
+#include <linux/acpi.h>
 #include <asm/io.h>
 
 static struct pci_dev *vt596_pdev;
@@ -356,6 +357,10 @@
 	}
 
 found:
+	error = acpi_check_region(vt596_smba, 8, vt596_driver.name);
+	if (error)
+		return error;
+
 	if (!request_region(vt596_smba, 8, vt596_driver.name)) {
 		dev_err(&pdev->dev, "SMBus region 0x%x already in use!\n",
 			vt596_smba);