dt-bindings: memory-controller: add STM32 FMC2 EBI controller documentation

This patch adds the documentation of the device tree bindings for the STM32
FMC2 EBI controller.
Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/1591975362-22009-4-git-send-email-christophe.kerello@st.com

Documentation/devicetree/bindings/memory-controllers/st,stm32-fmc2-ebi.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/memory-controllers/st,stm32-fmc2-ebi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STMicroelectronics Flexible Memory Controller 2 (FMC2) Bindings
+
+description: |
+  The FMC2 functional block makes the interface with: synchronous and
+  asynchronous static devices (such as PSNOR, PSRAM or other memory-mapped
+  peripherals) and NAND flash memories.
+  Its main purposes are:
+    - to translate AXI transactions into the appropriate external device
+      protocol
+    - to meet the access time requirements of the external devices
+  All external devices share the addresses, data and control signals with the
+  controller. Each external device is accessed by means of a unique Chip
+  Select. The FMC2 performs only one access at a time to an external device.
+
+maintainers:
+  - Christophe Kerello <christophe.kerello@st.com>
+
+properties:
+  compatible:
+    const: st,stm32mp1-fmc2-ebi
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+  "#address-cells":
+    const: 2
+
+  "#size-cells":
+    const: 1
+
+  ranges:
+    description: |
+      Reflects the memory layout with four integer values per bank. Format:
+      <bank-number> 0 <address of the bank> <size>
+
+patternProperties:
+  "^.*@[0-4],[a-f0-9]+$":
+    type: object
+
+    properties:
+      reg:
+        description: Bank number, base address and size of the device.
+
+      st,fmc2-ebi-cs-transaction-type:
+        description: |
+          Select one of the transactions type supported
+          0: Asynchronous mode 1 SRAM/FRAM.
+          1: Asynchronous mode 1 PSRAM.
+          2: Asynchronous mode A SRAM/FRAM.
+          3: Asynchronous mode A PSRAM.
+          4: Asynchronous mode 2 NOR.
+          5: Asynchronous mode B NOR.
+          6: Asynchronous mode C NOR.
+          7: Asynchronous mode D NOR.
+          8: Synchronous read synchronous write PSRAM.
+          9: Synchronous read asynchronous write PSRAM.
+          10: Synchronous read synchronous write NOR.
+          11: Synchronous read asynchronous write NOR.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        minimum: 0
+        maximum: 11
+
+      st,fmc2-ebi-cs-cclk-enable:
+        description: Continuous clock enable (first bank must be configured
+          in synchronous mode). The FMC_CLK is generated continuously
+          during asynchronous and synchronous access. By default, the
+          FMC_CLK is only generated during synchronous access.
+        $ref: /schemas/types.yaml#/definitions/flag
+
+      st,fmc2-ebi-cs-mux-enable:
+        description: Address/Data multiplexed on databus (valid only with
+          NOR and PSRAM transactions type). By default, Address/Data
+          are not multiplexed.
+        $ref: /schemas/types.yaml#/definitions/flag
+
+      st,fmc2-ebi-cs-buswidth:
+        description: Data bus width
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [ 8, 16 ]
+        default: 16
+
+      st,fmc2-ebi-cs-waitpol-high:
+        description: Wait signal polarity (NWAIT signal active high).
+          By default, NWAIT is active low.
+        $ref: /schemas/types.yaml#/definitions/flag
+
+      st,fmc2-ebi-cs-waitcfg-enable:
+        description: The NWAIT signal indicates wheither the data from the
+          device are valid or if a wait state must be inserted when accessing
+          the device in synchronous mode. By default, the NWAIT signal is
+          active one data cycle before wait state.
+        $ref: /schemas/types.yaml#/definitions/flag
+
+      st,fmc2-ebi-cs-wait-enable:
+        description: The NWAIT signal is enabled (its level is taken into
+          account after the programmed latency period to insert wait states
+          if asserted). By default, the NWAIT signal is disabled.
+        $ref: /schemas/types.yaml#/definitions/flag
+
+      st,fmc2-ebi-cs-asyncwait-enable:
+        description: The NWAIT signal is taken into account during asynchronous
+          transactions. By default, the NWAIT signal is not taken into account
+          during asynchronous transactions.
+        $ref: /schemas/types.yaml#/definitions/flag
+
+      st,fmc2-ebi-cs-cpsize:
+        description: CRAM page size. The controller splits the burst access
+          when the memory page is reached. By default, no burst split when
+          crossing page boundary.
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [ 0, 128, 256, 512, 1024 ]
+        default: 0
+
+      st,fmc2-ebi-cs-byte-lane-setup-ns:
+        description: This property configures the byte lane setup timing
+          defined in nanoseconds from NBLx low to Chip Select NEx low.
+
+      st,fmc2-ebi-cs-address-setup-ns:
+        description: This property defines the duration of the address setup
+          phase in nanoseconds used for asynchronous read/write transactions.
+
+      st,fmc2-ebi-cs-address-hold-ns:
+        description: This property defines the duration of the address hold
+          phase in nanoseconds used for asynchronous multiplexed read/write
+          transactions.
+
+      st,fmc2-ebi-cs-data-setup-ns:
+        description: This property defines the duration of the data setup phase
+          in nanoseconds used for asynchronous read/write transactions.
+
+      st,fmc2-ebi-cs-bus-turnaround-ns:
+        description: This property defines the delay in nanoseconds between the
+          end of current read/write transaction and the next transaction.
+
+      st,fmc2-ebi-cs-data-hold-ns:
+        description: This property defines the duration of the data hold phase
+          in nanoseconds used for asynchronous read/write transactions.
+
+      st,fmc2-ebi-cs-clk-period-ns:
+        description: This property defines the FMC_CLK output signal period in
+          nanoseconds.
+
+      st,fmc2-ebi-cs-data-latency-ns:
+        description: This property defines the data latency before reading or
+          writing the first data in nanoseconds.
+
+      st,fmc2_ebi-cs-write-address-setup-ns:
+        description: This property defines the duration of the address setup
+          phase in nanoseconds used for asynchronous write transactions.
+
+      st,fmc2-ebi-cs-write-address-hold-ns:
+        description: This property defines the duration of the address hold
+          phase in nanoseconds used for asynchronous multiplexed write
+          transactions.
+
+      st,fmc2-ebi-cs-write-data-setup-ns:
+        description: This property defines the duration of the data setup
+          phase in nanoseconds used for asynchronous write transactions.
+
+      st,fmc2-ebi-cs-write-bus-turnaround-ns:
+        description: This property defines the delay between the end of current
+          write transaction and the next transaction in nanoseconds.
+
+      st,fmc2-ebi-cs-write-data-hold-ns:
+        description: This property defines the duration of the data hold phase
+          in nanoseconds used for asynchronous write transactions.
+
+      st,fmc2-ebi-cs-max-low-pulse-ns:
+        description: This property defines the maximum chip select low pulse
+          duration in nanoseconds for synchronous transactions. When this timing
+          reaches 0, the controller splits the current access, toggles NE to
+          allow device refresh and restarts a new access.
+
+    required:
+      - reg
+
+required:
+  - "#address-cells"
+  - "#size-cells"
+  - compatible
+  - reg
+  - clocks
+  - ranges
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/stm32mp1-clks.h>
+    #include <dt-bindings/reset/stm32mp1-resets.h>
+    memory-controller@58002000 {
+      #address-cells = <2>;
+      #size-cells = <1>;
+      compatible = "st,stm32mp1-fmc2-ebi";
+      reg = <0x58002000 0x1000>;
+      clocks = <&rcc FMC_K>;
+      resets = <&rcc FMC_R>;
+
+      ranges = <0 0 0x60000000 0x04000000>, /* EBI CS 1 */
+               <1 0 0x64000000 0x04000000>, /* EBI CS 2 */
+               <2 0 0x68000000 0x04000000>, /* EBI CS 3 */
+               <3 0 0x6c000000 0x04000000>, /* EBI CS 4 */
+               <4 0 0x80000000 0x10000000>; /* NAND */
+
+      psram@0,0 {
+        compatible = "mtd-ram";
+        reg = <0 0x00000000 0x100000>;
+        bank-width = <2>;
+
+        st,fmc2-ebi-cs-transaction-type = <1>;
+        st,fmc2-ebi-cs-address-setup-ns = <60>;
+        st,fmc2-ebi-cs-data-setup-ns = <30>;
+        st,fmc2-ebi-cs-bus-turnaround-ns = <5>;
+      };
+
+      nand-controller@4,0 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        compatible = "st,stm32mp1-fmc2-nfc";
+        reg = <4 0x00000000 0x1000>,
+              <4 0x08010000 0x1000>,
+              <4 0x08020000 0x1000>,
+              <4 0x01000000 0x1000>,
+              <4 0x09010000 0x1000>,
+              <4 0x09020000 0x1000>;
+        interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
+        dmas = <&mdma1 20 0x2 0x12000a02 0x0 0x0>,
+               <&mdma1 20 0x2 0x12000a08 0x0 0x0>,
+               <&mdma1 21 0x2 0x12000a0a 0x0 0x0>;
+        dma-names = "tx", "rx", "ecc";
+
+        nand@0 {
+          reg = <0>;
+          nand-on-flash-bbt;
+          #address-cells = <1>;
+          #size-cells = <1>;
+        };
+      };
+    };
+
+...