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diff --git a/Documentation/devicetree/bindings/bus/qcom,ebi2.yaml b/Documentation/devicetree/bindings/bus/qcom,ebi2.yaml new file mode 100644 index 000000000000..1b1fb3538e6e --- /dev/null +++ b/Documentation/devicetree/bindings/bus/qcom,ebi2.yaml @@ -0,0 +1,239 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/bus/qcom,ebi2.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Qualcomm External Bus Interface 2 (EBI2) + +description: | + The EBI2 contains two peripheral blocks: XMEM and LCDC. The XMEM handles any + external memory (such as NAND or other memory-mapped peripherals) whereas + LCDC handles LCD displays. + + As it says it connects devices to an external bus interface, meaning address + lines (up to 9 address lines so can only address 1KiB external memory space), + data lines (16 bits), OE (output enable), ADV (address valid, used on some + NOR flash memories), WE (write enable). This on top of 6 different chip selects + (CS0 thru CS5) so that in theory 6 different devices can be connected. + + Apparently this bus is clocked at 64MHz. It has dedicated pins on the package + and the bus can only come out on these pins, however if some of the pins are + unused they can be left unconnected or remuxed to be used as GPIO or in some + cases other orthogonal functions as well. + + Also CS1 and CS2 has -A and -B signals. Why they have that is unclear to me. + + The chip selects have the following memory range assignments. This region of + memory is referred to as "Chip Peripheral SS FPB0" and is 168MB big. + + Chip Select Physical address base + CS0 GPIO134 0x1a800000-0x1b000000 (8MB) + CS1 GPIO39 (A) / GPIO123 (B) 0x1b000000-0x1b800000 (8MB) + CS2 GPIO40 (A) / GPIO124 (B) 0x1b800000-0x1c000000 (8MB) + CS3 GPIO133 0x1d000000-0x25000000 (128 MB) + CS4 GPIO132 0x1c800000-0x1d000000 (8MB) + CS5 GPIO131 0x1c000000-0x1c800000 (8MB) + + The APQ8060 Qualcomm Application Processor User Guide, 80-N7150-14 Rev. A, + August 6, 2012 contains some incomplete documentation of the EBI2. + + FIXME: the manual mentions "write precharge cycles" and "precharge cycles". + We have not been able to figure out which bit fields these correspond to + in the hardware, or what valid values exist. The current hypothesis is that + this is something just used on the FAST chip selects and that the SLOW + chip selects are understood fully. There is also a "byte device enable" + flag somewhere for 8bit memories. + + FIXME: The chipselects have SLOW and FAST configuration registers. It's a bit + unclear what this means, if they are mutually exclusive or can be used + together, or if some chip selects are hardwired to be FAST and others are SLOW + by design. + + The XMEM registers are totally undocumented but could be partially decoded + because the Cypress AN49576 Antioch Westbridge apparently has suspiciously + similar register layout, see: http://www.cypress.com/file/105771/download + +maintainers: + - Bjorn Andersson <andersson@kernel.org> + +properties: + compatible: + enum: + - qcom,apq8060-ebi2 + - qcom,msm8660-ebi2 + + reg: + items: + - description: EBI2 config region + - description: XMEM config region + + reg-names: + items: + - const: ebi2 + - const: xmem + + ranges: true + + clocks: + items: + - description: EBI_2X clock + - description: EBI clock + + clock-names: + items: + - const: ebi2x + - const: ebi2 + + '#address-cells': + const: 2 + + '#size-cells': + const: 1 + +required: + - compatible + - reg + - reg-names + - ranges + - clocks + - clock-names + - '#address-cells' + - '#size-cells' + +patternProperties: + "^.*@[0-5],[0-9a-f]+$": + type: object + additionalProperties: true + properties: + reg: + maxItems: 1 + + # SLOW chip selects + qcom,xmem-recovery-cycles: + $ref: /schemas/types.yaml#/definitions/uint32 + description: > + The time the memory continues to drive the data bus after OE + is de-asserted, in order to avoid contention on the data bus. + They are inserted when reading one CS and switching to another + CS or read followed by write on the same CS. Minimum value is + actually 1, so a value of 0 will still yield 1 recovery cycle. + minimum: 0 + maximum: 15 + + qcom,xmem-write-hold-cycles: + $ref: /schemas/types.yaml#/definitions/uint32 + description: > + The extra cycles inserted after every write minimum 1. The + data out is driven from the time WE is asserted until CS is + asserted. With a hold of 1 (value = 0), the CS stays active + for 1 extra cycle, etc. + minimum: 0 + maximum: 15 + + qcom,xmem-write-delta-cycles: + $ref: /schemas/types.yaml#/definitions/uint32 + description: > + The initial latency for write cycles inserted for the first + write to a page or burst memory. + minimum: 0 + maximum: 255 + + qcom,xmem-read-delta-cycles: + $ref: /schemas/types.yaml#/definitions/uint32 + description: > + The initial latency for read cycles inserted for the first + read to a page or burst memory. + minimum: 0 + maximum: 255 + + qcom,xmem-write-wait-cycles: + $ref: /schemas/types.yaml#/definitions/uint32 + description: > + The number of wait cycles for every write access. + minimum: 0 + maximum: 15 + + qcom,xmem-read-wait-cycles: + $ref: /schemas/types.yaml#/definitions/uint32 + description: > + The number of wait cycles for every read access. + minimum: 0 + maximum: 15 + + + # FAST chip selects + qcom,xmem-address-hold-enable: + $ref: /schemas/types.yaml#/definitions/uint32 + description: > + Holds the address for an extra cycle to meet hold time + requirements with ADV assertion, when set to 1. + enum: [ 0, 1 ] + + qcom,xmem-adv-to-oe-recovery-cycles: + $ref: /schemas/types.yaml#/definitions/uint32 + description: > + The number of cycles elapsed before an OE assertion, with + respect to the cycle where ADV (address valid) is asserted. + minimum: 0 + maximum: 3 + + qcom,xmem-read-hold-cycles: + $ref: /schemas/types.yaml#/definitions/uint32 + description: > + The length in cycles of the first segment of a read transfer. + For a single read transfer this will be the time from CS + assertion to OE assertion. + minimum: 0 + maximum: 15 + + required: + - reg + +additionalProperties: false + +examples: + - | + #include <dt-bindings/clock/qcom,gcc-msm8660.h> + #include <dt-bindings/interrupt-controller/irq.h> + #include <dt-bindings/gpio/gpio.h> + + external-bus@1a100000 { + compatible = "qcom,msm8660-ebi2"; + reg = <0x1a100000 0x1000>, <0x1a110000 0x1000>; + reg-names = "ebi2", "xmem"; + ranges = <0 0x0 0x1a800000 0x00800000>, + <1 0x0 0x1b000000 0x00800000>, + <2 0x0 0x1b800000 0x00800000>, + <3 0x0 0x1d000000 0x08000000>, + <4 0x0 0x1c800000 0x00800000>, + <5 0x0 0x1c000000 0x00800000>; + + clocks = <&gcc EBI2_2X_CLK>, <&gcc EBI2_CLK>; + clock-names = "ebi2x", "ebi2"; + + #address-cells = <2>; + #size-cells = <1>; + + ethernet@2,0 { + compatible = "smsc,lan9221", "smsc,lan9115"; + reg = <2 0x0 0x100>; + + interrupts-extended = <&pm8058_gpio 7 IRQ_TYPE_EDGE_FALLING>, + <&tlmm 29 IRQ_TYPE_EDGE_RISING>; + reset-gpios = <&tlmm 30 GPIO_ACTIVE_LOW>; + + phy-mode = "mii"; + reg-io-width = <2>; + smsc,force-external-phy; + smsc,irq-push-pull; + + /* SLOW chipselect config */ + qcom,xmem-recovery-cycles = <0>; + qcom,xmem-write-hold-cycles = <3>; + qcom,xmem-write-delta-cycles = <31>; + qcom,xmem-read-delta-cycles = <28>; + qcom,xmem-write-wait-cycles = <9>; + qcom,xmem-read-wait-cycles = <9>; + }; + }; |