Device tree bindings for OMAP general purpose memory controllers (GPMC)
The actual devices are instantiated from the child nodes of a GPMC node.
Required properties:
compatible: Should be set to one of the following:
ti,omap2420-gpmc (omap2420) ti,omap2430-gpmc (omap2430) ti,omap3430-gpmc (omap3430 & omap3630) ti,omap4430-gpmc (omap4430 & omap4460 & omap543x) ti,am3352-gpmc (am335x devices)reg: A resource specifier for the register space
(see the example below)ti,hwmods: Should be set to “ti,gpmc” until the DT transition is
completed.#address-cells: Must be set to 2 to allow memory address translation
#size-cells: Must be set to 1 to allow CS address passing
gpmc,num-cs: The maximum number of chip-select lines that controller
can support.gpmc,num-waitpins: The maximum number of wait pins that controller can
support.ranges: Must be set up to reflect the memory layout with four
integer values for each chip-select line in use: <cs-number> 0 <physical address of mapping> <size> Currently, calculated values derived from the contents of the per-CS register GPMC_CONFIG7 (as set up by the bootloader) are used for the physical address decoding. As this will change in the future, filling correct values here is a requirement.
Timing properties for child nodes. All are optional and default to 0.
gpmc,sync-clk-ps: Minimum clock period for synchronous mode, in picoseconds
Chip-select signal timings (in nanoseconds) corresponding to GPMC_CONFIG2:
gpmc,cs-on-ns: Assertion time
gpmc,cs-rd-off-ns: Read deassertion time
gpmc,cs-wr-off-ns: Write deassertion time
ADV signal timings (in nanoseconds) corresponding to GPMC_CONFIG3:
gpmc,adv-on-ns: Assertion time
gpmc,adv-rd-off-ns: Read deassertion time
gpmc,adv-wr-off-ns: Write deassertion time
WE signals timings (in nanoseconds) corresponding to GPMC_CONFIG4:
gpmc,we-on-ns Assertion time
gpmc,we-off-ns: Deassertion time
OE signals timings (in nanoseconds) corresponding to GPMC_CONFIG4:
gpmc,oe-on-ns: Assertion time
gpmc,oe-off-ns: Deassertion time
Access time and cycle time timings (in nanoseconds) corresponding to
GPMC_CONFIG5:gpmc,page-burst-access-ns: Multiple access word delay
gpmc,access-ns: Start-cycle to first data valid delay
gpmc,rd-cycle-ns: Total read cycle time
gpmc,wr-cycle-ns: Total write cycle time
gpmc,bus-turnaround-ns: Turn-around time between successive accesses
gpmc,cycle2cycle-delay-ns: Delay between chip-select pulses
gpmc,clk-activation-ns: GPMC clock activation time
gpmc,wait-monitoring-ns: Start of wait monitoring with regard to valid
data
Boolean timing parameters. If property is present parameter enabled and
disabled if omitted:
- gpmc,adv-extra-delay: ADV signal is delayed by half GPMC clock
- gpmc,cs-extra-delay: CS signal is delayed by half GPMC clock
- gpmc,cycle2cycle-diffcsen: Add “cycle2cycle-delay” between successive
accesses to a different CS - gpmc,cycle2cycle-samecsen: Add “cycle2cycle-delay” between successive
accesses to the same CS - gpmc,oe-extra-delay: OE signal is delayed by half GPMC clock
- gpmc,we-extra-delay: WE signal is delayed by half GPMC clock
- gpmc,time-para-granularity: Multiply all access times by 2
The following are only applicable to OMAP3+ and AM335x:
- gpmc,wr-access-ns: In synchronous write mode, for single or
burst accesses, defines the number of GPMC_FCLK cycles from start access time to the GPMC_CLK rising edge used by the memory device for the first data capture. - gpmc,wr-data-mux-bus-ns: In address-data multiplex mode, specifies
the time when the first data is driven on the address-data bus.
GPMC chip-select settings properties for child nodes. All are optional.
- gpmc,burst-length Page/burst length. Must be 4, 8 or 16.
- gpmc,burst-wrap Enables wrap bursting
- gpmc,burst-read Enables read page/burst mode
- gpmc,burst-write Enables write page/burst mode
- gpmc,device-nand Device is NAND
- gpmc,device-width Total width of device(s) connected to a GPMC
chip-select in bytes. The GPMC supports 8-bit and 16-bit devices and so this property must be 1 or 2. - gpmc,mux-add-data Address and data multiplexing configuration.
Valid values are 1 for address-address-data multiplexing mode and 2 for address-data multiplexing mode. - gpmc,sync-read Enables synchronous read. Defaults to asynchronous
is this is not set. - gpmc,sync-write Enables synchronous writes. Defaults to asynchronous
is this is not set. - gpmc,wait-pin Wait-pin used by client. Must be less than
"gpmc,num-waitpins". - gpmc,wait-on-read Enables wait monitoring on reads.
- gpmc,wait-on-write Enables wait monitoring on writes.
Example for an AM33xx board:
gpmc: gpmc@50000000 {
compatible = "ti,am3352-gpmc";
ti,hwmods = "gpmc";
reg = <0x50000000 0x2000>;
interrupts = <100>;
gpmc,num-cs = <8>;
gpmc,num-waitpins = <2>;
#address-cells = <2>;
#size-cells = <1>;
ranges = <0 0 0x08000000 0x10000000>; /* CS0 @addr 0x8000000, size 0x10000000 */
/* child nodes go here */
};
