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>

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

@@ -0,0 +1,53 @@
+Memory mapped SJA1000 CAN controller from NXP (formerly Philips)
+
+Required properties:
+
+- compatible : should be "nxp,sja1000".
+
+- reg : should specify the chip select, address offset and size required
+	to map the registers of the SJA1000. The size is usually 0x80.
+
+- interrupts: property with a value describing the interrupt source
+	(number and sensitivity) required for the SJA1000.
+
+Optional properties:
+
+- nxp,external-clock-frequency : Frequency of the external oscillator
+	clock in Hz. Note that the internal clock frequency used by the
+	SJA1000 is half of that value. If not specified, a default value
+	of 16000000 (16 MHz) is used.
+
+- nxp,tx-output-mode : operation mode of the TX output control logic:
+	<0x0> : bi-phase output mode
+	<0x1> : normal output mode (default)
+	<0x2> : test output mode
+	<0x3> : clock output mode
+
+- nxp,tx-output-config : TX output pin configuration:
+	<0x01> : TX0 invert
+	<0x02> : TX0 pull-down (default)
+	<0x04> : TX0 pull-up
+	<0x06> : TX0 push-pull
+	<0x08> : TX1 invert
+	<0x10> : TX1 pull-down
+	<0x20> : TX1 pull-up
+	<0x30> : TX1 push-pull
+
+- nxp,clock-out-frequency : clock frequency in Hz on the CLKOUT pin.
+	If not specified or if the specified value is 0, the CLKOUT pin
+	will be disabled.
+
+- nxp,no-comparator-bypass : Allows to disable the CAN input comperator.
+
+For futher information, please have a look to the SJA1000 data sheet.
+
+Examples:
+
+can@3,100 {
+	compatible = "nxp,sja1000";
+	reg = <3 0x100 0x80>;
+	interrupts = <2 0>;
+	interrupt-parent = <&mpic>;
+	nxp,external-clock-frequency = <16000000>;
+};
+