can: sja1000: generic OF platform bus driver

This patch adds a generic driver for SJA1000 chips on the OpenFirmware
platform bus found on embedded PowerPC systems. You need a SJA1000 node
definition in your flattened device tree source (DTS) file similar to:

  can@3,100 {
  	compatible = "nxp,sja1000";
  	reg = <3 0x100 0x80>;
  	interrupts = <2 0>;
  	interrupt-parent = <&mpic>;
  	nxp,external-clock-frequency = <16000000>;
  };

See also Documentation/powerpc/dts-bindings/can/sja1000.txt.

CC: devicetree-discuss@ozlabs.org
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/can/Kconfig

@@ -51,6 +51,15 @@ config CAN_SJA1000_PLATFORM
 	  boards from Phytec (http://www.phytec.de) like the PCM027,
 	  PCM038.
 
+config CAN_SJA1000_OF_PLATFORM
+	depends on CAN_SJA1000 && PPC_OF
+	tristate "Generic OF Platform Bus based SJA1000 driver"
+	---help---
+	  This driver adds support for the SJA1000 chips connected to
+	  the OpenFirmware "platform bus" found on embedded systems with
+	  OpenFirmware bindings, e.g. if you have a PowerPC based system
+	  you may want to enable this option.
+
 config CAN_EMS_PCI
 	tristate "EMS CPC-PCI and CPC-PCIe Card"
 	depends on PCI && CAN_SJA1000