spi: sh-msiof: Add R-Car Gen 2 and 3 fallback bindings

In the case of Renesas R-Car hardware we know that there are generations of
SoCs, e.g. Gen 2 and Gen 3. But beyond that it's not clear what the
relationship between IP blocks might be. For example, I believe that
r8a7790 is older than r8a7791 but that doesn't imply that the latter is a
descendant of the former or vice versa.

We can, however, by examining the documentation and behaviour of the
hardware at run-time observe that the current driver implementation appears
to be compatible with the IP blocks on SoCs within a given generation.

For the above reasons and convenience when enabling new SoCs a
per-generation fallback compatibility string scheme is being adopted for
drivers for Renesas SoCs.

Also:
* Deprecate renesas,sh-msiof. It seems poorly named as it is only
  compatible with SH-Mobile. It also appears unused in mainline.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/sh-msiof.txt

@@ -1,17 +1,23 @@
 Renesas MSIOF spi controller
 
 Required properties:
-- compatible           : "renesas,msiof-<soctype>" for SoCs,
-			 "renesas,sh-msiof" for SuperH, or
-			 "renesas,sh-mobile-msiof" for SH Mobile series.
-			 Examples with soctypes are:
-			 "renesas,msiof-r8a7790" (R-Car H2)
+- compatible           : "renesas,msiof-r8a7790" (R-Car H2)
 			 "renesas,msiof-r8a7791" (R-Car M2-W)
 			 "renesas,msiof-r8a7792" (R-Car V2H)
 			 "renesas,msiof-r8a7793" (R-Car M2-N)
 			 "renesas,msiof-r8a7794" (R-Car E2)
 			 "renesas,msiof-r8a7796" (R-Car M3-W)
 			 "renesas,msiof-sh73a0" (SH-Mobile AG5)
+			 "renesas,sh-mobile-msiof" (generic SH-Mobile compatibile device)
+			 "renesas,rcar-gen2-msiof" (generic R-Car Gen2 compatible device)
+			 "renesas,rcar-gen3-msiof" (generic R-Car Gen3 compatible device)
+			 "renesas,sh-msiof"      (deprecated)
+
+			 When compatible with the generic version, nodes
+			 must list the SoC-specific version corresponding
+			 to the platform first followed by the generic
+			 version.
+
 - reg                  : A list of offsets and lengths of the register sets for
 			 the device.
 			 If only one register set is present, it is to be used
@@ -61,7 +67,8 @@ Documentation/devicetree/bindings/pinctrl/renesas,*.
 Example:
 
 	msiof0: spi@e6e20000 {
-		compatible = "renesas,msiof-r8a7791";
+		compatible = "renesas,msiof-r8a7791",
+			     "renesas,rcar-gen2-msiof";
 		reg = <0 0xe6e20000 0 0x0064>;
 		interrupts = <0 156 IRQ_TYPE_LEVEL_HIGH>;
 		clocks = <&mstp0_clks R8A7791_CLK_MSIOF0>;

drivers/spi/spi-sh-msiof.c

@@ -973,14 +973,16 @@ static const struct sh_msiof_chipdata r8a779x_data = {
 };
 
 static const struct of_device_id sh_msiof_match[] = {
-	{ .compatible = "renesas,sh-msiof",        .data = &sh_data },
 	{ .compatible = "renesas,sh-mobile-msiof", .data = &sh_data },
 	{ .compatible = "renesas,msiof-r8a7790",   .data = &r8a779x_data },
 	{ .compatible = "renesas,msiof-r8a7791",   .data = &r8a779x_data },
 	{ .compatible = "renesas,msiof-r8a7792",   .data = &r8a779x_data },
 	{ .compatible = "renesas,msiof-r8a7793",   .data = &r8a779x_data },
 	{ .compatible = "renesas,msiof-r8a7794",   .data = &r8a779x_data },
+	{ .compatible = "renesas,rcar-gen2-msiof", .data = &r8a779x_data },
 	{ .compatible = "renesas,msiof-r8a7796",   .data = &r8a779x_data },
+	{ .compatible = "renesas,rcar-gen3-msiof", .data = &r8a779x_data },
+	{ .compatible = "renesas,sh-msiof",        .data = &sh_data }, // Deprecated
 	{},
 };
 MODULE_DEVICE_TABLE(of, sh_msiof_match);