mtd: rawnand: denali: decouple controller and NAND chips

Currently, this driver sticks to the legacy NAND model because it was
upstreamed before commit 2d472ab ("mtd: nand: document the NAND
controller/NAND chip DT representation"). However, relying on the
dummy_controller is already deprecated.

Switch over to the new controller/chip representation.

The struct denali_nand_info has been split into denali_controller
and denali_chip, to contain the controller data, per-chip data,
respectively.

One problem is, this commit changes the DT binding. So, as always,
the backward compatibility must be taken into consideration.

In the new binding, the controller node expects

  #address-cells = <1>;
  #size-cells = <0>;

... since the child nodes represent NAND chips.

In the old binding, the controller node may have subnodes, but they
are MTD partitions.

The denali_dt_is_legacy_binding() exploits it to distinguish old/new
platforms.

Going forward, the old binding is only allowed for existing DT files.
I updated the binding document.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Documentation/devicetree/bindings/mtd/denali-nand.txt

@@ -7,34 +7,48 @@ Required properties:
       "socionext,uniphier-denali-nand-v5b"  - for Socionext UniPhier (v5b)
   - reg : should contain registers location and length for data and reg.
   - reg-names: Should contain the reg names "nand_data" and "denali_reg"
+  - #address-cells: should be 1. The cell encodes the chip select connection.
+  - #size-cells : should be 0.
   - interrupts : The interrupt number.
   - clocks: should contain phandle of the controller core clock, the bus
     interface clock, and the ECC circuit clock.
   - clock-names: should contain "nand", "nand_x", "ecc"
 
-Optional properties:
-  - nand-ecc-step-size: see nand.txt for details.  If present, the value must be
-      512        for "altr,socfpga-denali-nand"
-      1024       for "socionext,uniphier-denali-nand-v5a"
-      1024       for "socionext,uniphier-denali-nand-v5b"
-  - nand-ecc-strength: see nand.txt for details.  Valid values are:
-      8, 15      for "altr,socfpga-denali-nand"
-      8, 16, 24  for "socionext,uniphier-denali-nand-v5a"
-      8, 16      for "socionext,uniphier-denali-nand-v5b"
-  - nand-ecc-maximize: see nand.txt for details
-
-The device tree may optionally contain sub-nodes describing partitions of the
+Sub-nodes:
+  Sub-nodes represent available NAND chips.
+
+  Required properties:
+    - reg: should contain the bank ID of the controller to which each chip
+      select is connected.
+
+  Optional properties:
+    - nand-ecc-step-size: see nand.txt for details.
+      If present, the value must be
+        512        for "altr,socfpga-denali-nand"
+        1024       for "socionext,uniphier-denali-nand-v5a"
+        1024       for "socionext,uniphier-denali-nand-v5b"
+    - nand-ecc-strength: see nand.txt for details. Valid values are:
+        8, 15      for "altr,socfpga-denali-nand"
+        8, 16, 24  for "socionext,uniphier-denali-nand-v5a"
+        8, 16      for "socionext,uniphier-denali-nand-v5b"
+    - nand-ecc-maximize: see nand.txt for details
+
+The chip nodes may optionally contain sub-nodes describing partitions of the
 address space. See partition.txt for more detail.
 
 Examples:
 
 nand: nand@ff900000 {
 	#address-cells = <1>;
-	#size-cells = <1>;
+	#size-cells = <0>;
 	compatible = "altr,socfpga-denali-nand";
 	reg = <0xff900000 0x20>, <0xffb80000 0x1000>;
 	reg-names = "nand_data", "denali_reg";
 	clocks = <&nand_clk>, <&nand_x_clk>, <&nand_ecc_clk>;
 	clock-names = "nand", "nand_x", "ecc";
 	interrupts = <0 144 4>;
+
+	nand@0 {
+		reg = <0>;
+	}
 };