diff options
Diffstat (limited to 'Documentation/powerpc/mpc52xx-device-tree-bindings.txt')
| -rw-r--r-- | Documentation/powerpc/mpc52xx-device-tree-bindings.txt | 277 |
1 files changed, 0 insertions, 277 deletions
diff --git a/Documentation/powerpc/mpc52xx-device-tree-bindings.txt b/Documentation/powerpc/mpc52xx-device-tree-bindings.txt deleted file mode 100644 index 6f12f1c79c0..00000000000 --- a/Documentation/powerpc/mpc52xx-device-tree-bindings.txt +++ /dev/null @@ -1,277 +0,0 @@ -MPC5200 Device Tree Bindings ----------------------------- - -(c) 2006-2007 Secret Lab Technologies Ltd -Grant Likely <grant.likely at secretlab.ca> - -********** DRAFT *********** -* WARNING: Do not depend on the stability of these bindings just yet. -* The MPC5200 device tree conventions are still in flux -* Keep an eye on the linuxppc-dev mailing list for more details -********** DRAFT *********** - -I - Introduction -================ -Boards supported by the arch/powerpc architecture require device tree be -passed by the boot loader to the kernel at boot time. The device tree -describes what devices are present on the board and how they are -connected. The device tree can either be passed as a binary blob (as -described in Documentation/powerpc/booting-without-of.txt), or passed -by Open Firmware (IEEE 1275) compatible firmware using an OF compatible -client interface API. - -This document specifies the requirements on the device-tree for mpc5200 -based boards. These requirements are above and beyond the details -specified in either the Open Firmware spec or booting-without-of.txt - -All new mpc5200-based boards are expected to match this document. In -cases where this document is not sufficient to support a new board port, -this document should be updated as part of adding the new board support. - -II - Philosophy -=============== -The core of this document is naming convention. The whole point of -defining this convention is to reduce or eliminate the number of -special cases required to support a 5200 board. If all 5200 boards -follow the same convention, then generic 5200 support code will work -rather than coding special cases for each new board. - -This section tries to capture the thought process behind why the naming -convention is what it is. - -1. names ---------- -There is strong convention/requirements already established for children -of the root node. 'cpus' describes the processor cores, 'memory' -describes memory, and 'chosen' provides boot configuration. Other nodes -are added to describe devices attached to the processor local bus. - -Following convention already established with other system-on-chip -processors, 5200 device trees should use the name 'soc5200' for the -parent node of on chip devices, and the root node should be its parent. - -Child nodes are typically named after the configured function. ie. -the FEC node is named 'ethernet', and a PSC in uart mode is named 'serial'. - -2. device_type property ------------------------ -similar to the node name convention above; the device_type reflects the -configured function of a device. ie. 'serial' for a uart and 'spi' for -an spi controller. However, while node names *should* reflect the -configured function, device_type *must* match the configured function -exactly. - -3. compatible property ----------------------- -Since device_type isn't enough to match devices to drivers, there also -needs to be a naming convention for the compatible property. Compatible -is an list of device descriptions sorted from specific to generic. For -the mpc5200, the required 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; -"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; -"mpc5200b-<device>\0mpc5200-<device>". It is *strongly* recommended -that 5200B device trees follow this convention (instead of only listing -the base mpc5200 item). - -If another chip appear on the market with one of the mpc5200 SoC -devices, then the compatible list should include mpc5200-<device>. - -ie. ethernet on mpc5200: compatible = "mpc5200-ethernet" - ethernet on mpc5200b: compatible = "mpc5200b-ethernet\0mpc5200-ethernet" - -Modal devices, like PSCs, also append the configured function to the -end of the compatible field. ie. A PSC in i2s mode would specify -"mpc5200-psc-i2s", not "mpc5200-i2s". This convention is chosen to -avoid naming conflicts with non-psc devices providing the same -function. For example, "mpc5200-spi" and "mpc5200-psc-spi" describe -the mpc5200 simple spi device and a PSC spi mode respectively. - -If the soc device is more generic and present on other SOCs, the -compatible property can specify the more generic device type also. - -ie. mscan: compatible = "mpc5200-mscan\0fsl,mscan"; - -At the time of writing, exact chip may be either 'mpc5200' or -'mpc5200b'. - -Device drivers should always try to match as generically as possible. - -III - Structure -=============== -The device tree for an mpc5200 board follows the structure defined in -booting-without-of.txt with the following additional notes: - -0) the root node ----------------- -Typical root description node; see booting-without-of - -1) The cpus node ----------------- -The cpus node follows the basic layout described in booting-without-of. -The bus-frequency property holds the XLB bus frequency -The clock-frequency property holds the core frequency - -2) The memory node ------------------- -Typical memory description node; see booting-without-of. - -3) The soc5200 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 type description ----- ---- ----------- -device_type string must be "soc" -ranges int should be <0 baseaddr baseaddr+10000> -reg int must be <baseaddr 10000> -compatible string mpc5200: "mpc5200-soc" - mpc5200b: "mpc5200b-soc\0mpc5200-soc" -system-frequency int Fsystem frequency; source of all - other clocks. -bus-frequency int IPB bus frequency in HZ. Clock rate - used by most of the soc devices. -#interrupt-cells int must be <3>. - -Recommended properties: -name type description ----- ---- ----------- -model string Exact model of the chip; - ie: model="fsl,mpc5200" -revision string Silicon revision of chip - ie: revision="M08A" - -The 'model' and 'revision' properties are *strongly* recommended. Having -them presence acts as a bit of a safety net for working around as yet -undiscovered bugs on one version of silicon. For example, device drivers -can use the model and revision properties to decide if a bug fix should -be turned on. - -4) soc5200 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 "mpc5200b-<device>\0mpc5200-<device> form. - -Required soc5200 child nodes: -name device_type compatible Description ----- ----------- ---------- ----------- -cdm@<addr> cdm mpc5200-cmd Clock Distribution -pic@<addr> interrupt-controller mpc5200-pic need an interrupt - controller to boot -bestcomm@<addr> dma-controller mpc5200-bestcomm 5200 pic also requires - the bestcomm device - -Recommended soc5200 child nodes; populate as needed for your board -name device_type compatible Description ----- ----------- ---------- ----------- -gpt@<addr> gpt fsl,mpc5200-gpt General purpose timers -gpt@<addr> gpt fsl,mpc5200-gpt-gpio General purpose - timers in GPIO mode -gpio@<addr> fsl,mpc5200-gpio MPC5200 simple gpio - controller -gpio@<addr> fsl,mpc5200-gpio-wkup MPC5200 wakeup gpio - controller -rtc@<addr> rtc mpc5200-rtc Real time clock -mscan@<addr> mscan mpc5200-mscan CAN bus controller -pci@<addr> pci mpc5200-pci PCI bridge -serial@<addr> serial mpc5200-psc-uart PSC in serial mode -i2s@<addr> sound mpc5200-psc-i2s PSC in i2s mode -ac97@<addr> sound mpc5200-psc-ac97 PSC in ac97 mode -spi@<addr> spi mpc5200-psc-spi PSC in spi mode -irda@<addr> irda mpc5200-psc-irda PSC in IrDA mode -spi@<addr> spi mpc5200-spi MPC5200 spi device -ethernet@<addr> network mpc5200-fec MPC5200 ethernet device -ata@<addr> ata mpc5200-ata IDE ATA interface -i2c@<addr> i2c mpc5200-i2c I2C controller -usb@<addr> usb-ohci-be mpc5200-ohci,ohci-be USB controller -xlb@<addr> xlb mpc5200-xlb XLB arbitrator - -Important child node properties -name type description ----- ---- ----------- -cell-index int When multiple devices are present, is the - index of the device in the hardware (ie. There - are 6 PSC on the 5200 numbered PSC1 to PSC6) - PSC1 has 'cell-index = <0>' - PSC4 has 'cell-index = <3>' - -5) General Purpose Timer nodes (child of soc5200 node) -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'. - -6) PSC nodes (child of soc5200 node) -PSC nodes can define the optional 'port-number' property to force assignment -order of serial ports. For example, PSC5 might be physically connected to -the port labeled 'COM1' and PSC1 wired to 'COM1'. In this case, PSC5 would -have a "port-number = <0>" property, and PSC1 would have "port-number = <1>". - -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. - -7) GPIO controller 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 unsused. - -8) 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. - -IV - Extra Notes -================ - -1. Interrupt mapping --------------------- -The mpc5200 pic driver 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] - -2. Shared registers -------------------- -Some SoC devices share registers between them. ie. the i2c devices use -a single clock control register, and almost all device are affected by -the port_config register. Devices which need to manipulate shared regs -should look to the parent SoC node. The soc node is responsible -for arbitrating all shared register access. |