Add fallback compatibility string for R-Car Gen 1, 2 and 3.

In the case of Renesas R-Car hardware we know that there are generations of
SoCs, e.g. Gen 1 and 2. But beyond that its not clear what the relationship
between IP blocks might be. For example, I believe that r8a7779 is older
than r8a7778 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 being adopted for
drivers for Renesas SoCs.

Signed-off-by: Simon Horman <[email protected]>
---
Based on libata/for-next
---
 Documentation/devicetree/bindings/ata/sata_rcar.txt | 15 ++++++++++++---
 drivers/ata/sata_rcar.c                             | 12 ++++++++++++
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/ata/sata_rcar.txt 
b/Documentation/devicetree/bindings/ata/sata_rcar.txt
index 0764f9ab63dc..b44048176938 100644
--- a/Documentation/devicetree/bindings/ata/sata_rcar.txt
+++ b/Documentation/devicetree/bindings/ata/sata_rcar.txt
@@ -1,14 +1,23 @@
 * Renesas R-Car SATA
 
 Required properties:
-- compatible           : should contain one of the following:
+- compatible           : should contain one or more of the following:
                          - "renesas,sata-r8a7779" for R-Car H1
-                           ("renesas,rcar-sata" is deprecated)
                          - "renesas,sata-r8a7790-es1" for R-Car H2 ES1
                          - "renesas,sata-r8a7790" for R-Car H2 other than ES1
                          - "renesas,sata-r8a7791" for R-Car M2-W
                          - "renesas,sata-r8a7793" for R-Car M2-N
                          - "renesas,sata-r8a7795" for R-Car H3
+                         - "renesas,rcar-gen1-sata" for a generic R-Car Gen1 
compatible device
+                         - "renesas,rcar-gen2-sata" for a generic R-Car Gen2 
compatible device
+                         - "renesas,rcar-gen3-sata" for a generic R-Car Gen3 
compatible device
+                         - "renesas,rcar-sata" is 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                  : address and length of the SATA registers;
 - interrupts           : must consist of one interrupt specifier.
 - clocks               : must contain a reference to the functional clock.
@@ -16,7 +25,7 @@ Required properties:
 Example:
 
 sata0: sata@ee300000 {
-       compatible = "renesas,sata-r8a7791";
+       compatible = "renesas,sata-r8a7791", "renesas,rcar-gen2-sata";
        reg = <0 0xee300000 0 0x2000>;
        interrupt-parent = <&gic>;
        interrupts = <0 105 IRQ_TYPE_LEVEL_HIGH>;
diff --git a/drivers/ata/sata_rcar.c b/drivers/ata/sata_rcar.c
index f72d601e300a..09d4ba3f0bc4 100644
--- a/drivers/ata/sata_rcar.c
+++ b/drivers/ata/sata_rcar.c
@@ -858,6 +858,18 @@ static struct of_device_id sata_rcar_match[] = {
                .compatible = "renesas,sata-r8a7795",
                .data = (void *)RCAR_GEN2_SATA
        },
+       {
+               .compatible = "renesas,rcar-gen1-sata",
+               .data = (void *)RCAR_GEN1_SATA
+       },
+       {
+               .compatible = "renesas,rcar-gen2-sata",
+               .data = (void *)RCAR_GEN2_SATA
+       },
+       {
+               .compatible = "renesas,rcar-gen3-sata",
+               .data = (void *)RCAR_GEN2_SATA
+       },
        { },
 };
 MODULE_DEVICE_TABLE(of, sata_rcar_match);
-- 
2.1.4

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