powerpc/5200: update device tree binding documentation

This patch updates the mpc5200 binding documentation to match
actual usage conventions, to remove incorrect information, and
to remove topics which are more thoroughly described elsewhere.
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Reviewed-by: Wolfram Sang <w.sang@pengutronix.de>

Documentation/powerpc/dts-bindings/fsl/mpc5200.txt

+MPC5200 Device Tree Bindings
+----------------------------
+
+(c) 2006-2009 Secret Lab Technologies Ltd
+Grant Likely <grant.likely@secretlab.ca>
+
+Naming conventions
+------------------
+For mpc5200 on-chip devices, the format for each compatible value is
+<chip>-<device>[-<mode>].  The OS should be able to match a device driver
+to the device based solely on the compatible value.  If two drivers
+match on the compatible list; the 'most compatible' driver should be
+selected.
+
+The split between the MPC5200 and the MPC5200B leaves a bit of a
+conundrum.  How should the compatible property be set up to provide
+maximum compatibility information; but still accurately describe the
+chip?  For the MPC5200; the answer is easy.  Most of the SoC devices
+originally appeared on the MPC5200.  Since they didn't exist anywhere
+else; the 5200 compatible properties will contain only one item;
+"fsl,mpc5200-<device>".
+
+The 5200B is almost the same as the 5200, but not quite.  It fixes
+silicon bugs and it adds a small number of enhancements.  Most of the
+devices either provide exactly the same interface as on the 5200.  A few
+devices have extra functions but still have a backwards compatible mode.
+To express this information as completely as possible, 5200B device trees
+should have two items in the compatible list:
+	compatible = "fsl,mpc5200b-<device>","fsl,mpc5200-<device>";
+
+It is *strongly* recommended that 5200B device trees follow this convention
+(instead of only listing the base mpc5200 item).
+
+ie. ethernet on mpc5200: compatible = "fsl,mpc5200-fec";
+    ethernet on mpc5200b: compatible = "fsl,mpc5200b-fec", "fsl,mpc5200-fec";
+
+Modal devices, like PSCs, also append the configured function to the
+end of the compatible field.  ie. A PSC in i2s mode would specify
+"fsl,mpc5200-psc-i2s", not "fsl,mpc5200-i2s".  This convention is chosen to
+avoid naming conflicts with non-psc devices providing the same
+function.  For example, "fsl,mpc5200-spi" and "fsl,mpc5200-psc-spi" describe
+the mpc5200 simple spi device and a PSC spi mode respectively.
+
+At the time of writing, exact chip may be either 'fsl,mpc5200' or
+'fsl,mpc5200b'.
+
+The soc node
+------------
+This node describes the on chip SOC peripherals.  Every mpc5200 based
+board will have this node, and as such there is a common naming
+convention for SOC devices.
+
+Required properties:
+name			description
+----			-----------
+ranges			Memory range of the internal memory mapped registers.
+			Should be <0 [baseaddr] 0xc000>
+reg			Should be <[baseaddr] 0x100>
+compatible		mpc5200: "fsl,mpc5200-immr"
+			mpc5200b: "fsl,mpc5200b-immr"
+system-frequency	'fsystem' frequency in Hz; XLB, IPB, USB and PCI
+			clocks are derived from the fsystem clock.
+bus-frequency		IPB bus frequency in Hz.  Clock rate
+			used by most of the soc devices.
+
+soc child nodes
+---------------
+Any on chip SOC devices available to Linux must appear as soc5200 child nodes.
+
+Note: The tables below show the value for the mpc5200.  A mpc5200b device
+tree should use the "fsl,mpc5200b-<device>","fsl,mpc5200-<device>" form.
+
+Required soc5200 child nodes:
+name				compatible		Description
+----				----------		-----------
+cdm@<addr>			fsl,mpc5200-cdm		Clock Distribution
+interrupt-controller@<addr>	fsl,mpc5200-pic		need an interrupt
+							controller to boot
+bestcomm@<addr>			fsl,mpc5200-bestcomm	Bestcomm DMA controller
+
+Recommended soc5200 child nodes; populate as needed for your board
+name		compatible		Description
+----		----------		-----------
+timer@<addr>	fsl,mpc5200-gpt		 General purpose timers
+gpio@<addr>	fsl,mpc5200-gpio	 MPC5200 simple gpio controller
+gpio@<addr>	fsl,mpc5200-gpio-wkup	 MPC5200 wakeup gpio controller
+rtc@<addr>	fsl,mpc5200-rtc		 Real time clock
+mscan@<addr>	fsl,mpc5200-mscan	 CAN bus controller
+pci@<addr>	fsl,mpc5200-pci		 PCI bridge
+serial@<addr>	fsl,mpc5200-psc-uart	 PSC in serial mode
+i2s@<addr>	fsl,mpc5200-psc-i2s	 PSC in i2s mode
+ac97@<addr>	fsl,mpc5200-psc-ac97	 PSC in ac97 mode
+spi@<addr>	fsl,mpc5200-psc-spi	 PSC in spi mode
+irda@<addr>	fsl,mpc5200-psc-irda	 PSC in IrDA mode
+spi@<addr>	fsl,mpc5200-spi		 MPC5200 spi device
+ethernet@<addr>	fsl,mpc5200-fec		 MPC5200 ethernet device
+ata@<addr>	fsl,mpc5200-ata		 IDE ATA interface
+i2c@<addr>	fsl,mpc5200-i2c		 I2C controller
+usb@<addr>	fsl,mpc5200-ohci,ohci-be USB controller
+xlb@<addr>	fsl,mpc5200-xlb		 XLB arbitrator
+
+fsl,mpc5200-gpt nodes
+---------------------
+On the mpc5200 and 5200b, GPT0 has a watchdog timer function.  If the board
+design supports the internal wdt, then the device node for GPT0 should
+include the empty property 'fsl,has-wdt'.
+
+An mpc5200-gpt can be used as a single line GPIO controller.  To do so,
+add the following properties to the gpt node:
+	gpio-controller;
+	#gpio-cells = <2>;
+When referencing the GPIO line from another node, the first cell must always
+be zero and the second cell represents the gpio flags and described in the
+gpio device tree binding.
+
+An mpc5200-gpt can be used as a single line edge sensitive interrupt
+controller.  To do so, add the following properties to the gpt node:
+	interrupt-controller;
+	#interrupt-cells = <1>;
+When referencing the IRQ line from another node, the cell represents the
+sense mode; 1 for edge rising, 2 for edge falling.
+
+fsl,mpc5200-psc nodes
+---------------------
+The PSCs should include a cell-index which is the index of the PSC in
+hardware.  cell-index is used to determine which shared SoC registers to
+use when setting up PSC clocking.  cell-index number starts at '0'.  ie:
+	PSC1 has 'cell-index = <0>'
+	PSC4 has 'cell-index = <3>'
+
+PSC in i2s mode:  The mpc5200 and mpc5200b PSCs are not compatible when in
+i2s mode.  An 'mpc5200b-psc-i2s' node cannot include 'mpc5200-psc-i2s' in the
+compatible field.
+
+
+fsl,mpc5200-gpio and fsl,mpc5200-gpio-wkup nodes
+------------------------------------------------
+Each GPIO controller node should have the empty property gpio-controller and
+#gpio-cells set to 2. First cell is the GPIO number which is interpreted
+according to the bit numbers in the GPIO control registers. The second cell
+is for flags which is currently unused.
+
+fsl,mpc5200-fec nodes
+---------------------
+The FEC node can specify one of the following properties to configure
+the MII link:
+- fsl,7-wire-mode - An empty property that specifies the link uses 7-wire
+                    mode instead of MII
+- current-speed   - Specifies that the MII should be configured for a fixed
+                    speed.  This property should contain two cells.  The
+                    first cell specifies the speed in Mbps and the second
+                    should be '0' for half duplex and '1' for full duplex
+- phy-handle      - Contains a phandle to an Ethernet PHY.
+
+Interrupt controller (fsl,mpc5200-pic) node
+-------------------------------------------
+The mpc5200 pic binding splits hardware IRQ numbers into two levels.  The
+split reflects the layout of the PIC hardware itself, which groups
+interrupts into one of three groups; CRIT, MAIN or PERP.  Also, the
+Bestcomm dma engine has it's own set of interrupt sources which are
+cascaded off of peripheral interrupt 0, which the driver interprets as a
+fourth group, SDMA.
+
+The interrupts property for device nodes using the mpc5200 pic consists
+of three cells; <L1 L2 level>
+
+    L1 := [CRIT=0, MAIN=1, PERP=2, SDMA=3]
+    L2 := interrupt number; directly mapped from the value in the
+          "ICTL PerStat, MainStat, CritStat Encoded Register"
+    level := [LEVEL_HIGH=0, EDGE_RISING=1, EDGE_FALLING=2, LEVEL_LOW=3]
+
+For external IRQs, use the following interrupt property values (how to
+specify external interrupts is a frequently asked question):
+External interrupts:
+	external irq0:	interrupts = <0 0 n>;
+	external irq1:	interrupts = <1 1 n>;
+	external irq2:	interrupts = <1 2 n>;
+	external irq3:	interrupts = <1 3 n>;
+'n' is sense (0: level high, 1: edge rising, 2: edge falling 3: level low)
+