i2c: rework kernel config I2C_ACPI

Commit da3c6647(I2C/ACPI: Clean up I2C ACPI code and Add CONFIG_I2C_ACPI
config) adds a new kernel config I2C_ACPI and make I2C core built in
when the config is selected. This is wrong because distributions
etc generally compile I2C as a module and the commit broken that.
This patch is to rename I2C_ACPI to ACPI_I2C_OPREGION. New config
only controls ACPI I2C operation region code and depends on I2C=y.
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[wsa: removed unrelated change for Kconfig]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/i2c/Kconfig

@@ -23,17 +23,14 @@ config I2C
 	  This I2C support can also be built as a module.  If so, the module
 	  will be called i2c-core.
 
-config I2C_ACPI
-	bool "I2C ACPI support"
-	select I2C
-	depends on ACPI
+config ACPI_I2C_OPREGION
+	bool "ACPI I2C Operation region support"
+	depends on I2C=y && ACPI
 	default y
 	help
-	  Say Y here if you want to enable ACPI I2C support. This includes support
-	  for automatic enumeration of I2C slave devices and support for ACPI I2C
-	  Operation Regions. Operation Regions allow firmware (BIOS) code to
-	  access I2C slave devices, such as smart batteries through an I2C host
-	  controller driver.
+	  Say Y here if you want to enable ACPI I2C operation region support.
+	  Operation Regions allow firmware (BIOS) code to access I2C slave devices,
+	  such as smart batteries through an I2C host controller driver.
 
 if I2C
 

drivers/i2c/Makefile

@@ -3,7 +3,7 @@
 #
 
 i2ccore-y := i2c-core.o
-i2ccore-$(CONFIG_I2C_ACPI)	+= i2c-acpi.o
+i2ccore-$(CONFIG_ACPI)	 	+= i2c-acpi.o
 
 obj-$(CONFIG_I2C_BOARDINFO)	+= i2c-boardinfo.o
 obj-$(CONFIG_I2C)		+= i2ccore.o

drivers/i2c/i2c-acpi.c

@@ -126,6 +126,7 @@ void acpi_i2c_register_devices(struct i2c_adapter *adap)
 		dev_warn(&adap->dev, "failed to enumerate I2C slaves\n");
 }
 
+#ifdef CONFIG_ACPI_I2C_OPREGION
 static int acpi_gsb_i2c_read_bytes(struct i2c_client *client,
 		u8 cmd, u8 *data, u8 data_len)
 {
@@ -360,3 +361,4 @@ void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter)
 
 	acpi_bus_detach_private_data(handle);
 }
+#endif

include/linux/i2c.h

@@ -577,16 +577,20 @@ static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node
 }
 #endif /* CONFIG_OF */
 
-#ifdef CONFIG_I2C_ACPI
-int acpi_i2c_install_space_handler(struct i2c_adapter *adapter);
-void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter);
+#ifdef CONFIG_ACPI
 void acpi_i2c_register_devices(struct i2c_adapter *adap);
 #else
 static inline void acpi_i2c_register_devices(struct i2c_adapter *adap) { }
+#endif /* CONFIG_ACPI */
+
+#ifdef CONFIG_ACPI_I2C_OPREGION
+int acpi_i2c_install_space_handler(struct i2c_adapter *adapter);
+void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter);
+#else
 static inline void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter)
 { }
 static inline int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
 { return 0; }
-#endif
+#endif /* CONFIG_ACPI_I2C_OPREGION */
 
 #endif /* _LINUX_I2C_H */