dt-bindings: ata: ahci: Add platform capability properties

In case if the platform doesn't have BIOS or a comprehensive firmware
installed then the HBA capability flags will be left uninitialized. As a
good alternative we suggest to define the DT-properties with the AHCI
platform capabilities describing all the HW-init flags of the
corresponding capability register. Luckily there aren't too many of them.
SSS - Staggered Spin-up support and MPS - Mechanical Presence Switch
support determine the corresponding feature availability for the whole HBA
by means of the "hba-cap" property. Each port can have the "hba-port-cap"
property initialized indicating that the port supports some of the next
functionalities: HPCP - HotPlug capable port, MPSP - Mechanical Presence
Switch attached to a port, CPD - Cold Plug detection, ESP - External SATA
Port (eSATA), FBSCP - FIS-based switching capable port.
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

Documentation/devicetree/bindings/ata/ahci-common.yaml

@@ -58,6 +58,14 @@ properties:
   phy-names:
     const: sata-phy
 
+  hba-cap:
+    $ref: '/schemas/types.yaml#/definitions/uint32'
+    description:
+      Bitfield of the HBA generic platform capabilities like Staggered
+      Spin-up or Mechanical Presence Switch support. It can be used to
+      appropriately initialize the HWinit fields of the HBA CAP register
+      in case if the system firmware hasn't done it.
+
   ports-implemented:
     $ref: '/schemas/types.yaml#/definitions/uint32'
     description:
@@ -101,6 +109,14 @@ $defs:
       target-supply:
         description: Power regulator for SATA port target device
 
+      hba-port-cap:
+        $ref: '/schemas/types.yaml#/definitions/uint32'
+        description:
+          Bitfield of the HBA port-specific platform capabilities like Hot
+          plugging, eSATA, FIS-based Switching, etc (see AHCI specification
+          for details). It can be used to initialize the HWinit fields of
+          the PxCMD register in case if the system firmware hasn't done it.
+
     required:
       - reg
 

Documentation/devicetree/bindings/ata/ahci-platform.yaml

@@ -111,6 +111,8 @@ examples:
   - |
     #include <dt-bindings/interrupt-controller/arm-gic.h>
     #include <dt-bindings/clock/berlin2q.h>
+    #include <dt-bindings/ata/ahci.h>
+
     sata@f7e90000 {
         compatible = "marvell,berlin2q-ahci", "generic-ahci";
         reg = <0xf7e90000 0x1000>;
@@ -119,15 +121,23 @@ examples:
         #address-cells = <1>;
         #size-cells = <0>;
 
+        hba-cap = <HBA_SMPS>;
+
         sata0: sata-port@0 {
             reg = <0>;
+
             phys = <&sata_phy 0>;
             target-supply = <&reg_sata0>;
+
+            hba-port-cap = <(HBA_PORT_FBSCP | HBA_PORT_ESP)>;
         };
 
         sata1: sata-port@1 {
             reg = <1>;
+
             phys = <&sata_phy 1>;
             target-supply = <&reg_sata1>;
+
+            hba-port-cap = <(HBA_PORT_HPCP | HBA_PORT_MPSP | HBA_PORT_FBSCP)>;
         };
     };

include/dt-bindings/ata/ahci.h

+/* SPDX-License-Identifier: GPL-2.0-only or BSD-2-Clause */
+/*
+ * This header provides constants for most AHCI bindings.
+ */
+
+#ifndef _DT_BINDINGS_ATA_AHCI_H
+#define _DT_BINDINGS_ATA_AHCI_H
+
+/* Host Bus Adapter generic platform capabilities */
+#define HBA_SSS		(1 << 27)
+#define HBA_SMPS	(1 << 28)
+
+/* Host Bus Adapter port-specific platform capabilities */
+#define HBA_PORT_HPCP	(1 << 18)
+#define HBA_PORT_MPSP	(1 << 19)
+#define HBA_PORT_CPD	(1 << 20)
+#define HBA_PORT_ESP	(1 << 21)
+#define HBA_PORT_FBSCP	(1 << 22)
+
+#endif