i2c: Make I2C available on UML

Remove the global dependency of the I2C subsystem on HAS_IOMEM and
move the dependency to the i2c/busses submenu, with an exception for
i2c-stub.

The generic I2C part does not need to have HAS_IOMEM set and thus now
becomes available in UML, so the I2C subsystem can now be used, e.g.
by the i2c-stub driver, for development of I2C device drivers.

[JD: Some adjustments.]

[Heiko Carstens: Keep I2C disabled on S390.]

Signed-off-by: Peter Huewe <[e-mail]>
Signed-off-by: Jean Delvare <[e-mail]>

drivers/i2c/Kconfig

···
 
 menuconfig I2C
 	tristate "I2C support"
-	depends on HAS_IOMEM
+	depends on !S390
 	select RT_MUTEXES
 	---help---
 	  I2C (pronounce: I-squared-C) is a slow serial bus protocol used in
···
 
 config I2C_MUX
 	tristate "I2C bus multiplexing support"
+	depends on HAS_IOMEM
 	help
 	  Say Y here if you want the I2C core to support the ability to
 	  handle multiplexed I2C bus topologies, by presenting each
···
 source drivers/i2c/algos/Kconfig
 source drivers/i2c/busses/Kconfig
 
+config I2C_STUB
+	tristate "I2C/SMBus Test Stub"
+	depends on EXPERIMENTAL && m
+	default 'n'
+	help
+	  This module may be useful to developers of SMBus client drivers,
+	  especially for certain kinds of sensor chips.
+
+	  If you do build this module, be sure to read the notes and warnings
+	  in <file:Documentation/i2c/i2c-stub>.
+
+	  If you don't know what to do here, definitely say N.
+
 config I2C_DEBUG_CORE
 	bool "I2C Core debugging messages"
 	help
···
 
 config I2C_DEBUG_BUS
 	bool "I2C Bus debugging messages"
+	depends on HAS_IOMEM
 	help
 	  Say Y here if you want the I2C bus drivers to produce a bunch of
 	  debug messages to the system log.  Select this if you are having

drivers/i2c/busses/Kconfig

···
 #
 
 menu "I2C Hardware Bus support"
+	depends on HAS_IOMEM
 
 comment "PC SMBus host controller drivers"
 	depends on PCI
···
 	depends on SIBYTE_SB1xxx_SOC
 	help
 	  Supports the SiByte SOC on-chip I2C interfaces (2 channels).
-
-config I2C_STUB
-	tristate "I2C/SMBus Test Stub"
-	depends on EXPERIMENTAL && m
-	default 'n'
-	help
-	  This module may be useful to developers of SMBus client drivers,
-	  especially for certain kinds of sensor chips.
-
-	  If you do build this module, be sure to read the notes and warnings
-	  in <file:Documentation/i2c/i2c-stub>.
-
-	  If you don't know what to do here, definitely say N.
 
 config SCx200_I2C
 	tristate "NatSemi SCx200 I2C using GPIO pins (DEPRECATED)"