Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Anup Patel <anup.patel@wdc.com>
To:     Palmer Dabbelt <palmer@dabbelt.com>,
        Palmer Dabbelt <palmerdabbelt@google.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        "Rafael J . Wysocki" <rjw@rjwysocki.net>,
        Pavel Machek <pavel@ucw.cz>, Rob Herring <robh+dt@kernel.org>
Cc:     Sandeep Tripathy <milun.tripathy@gmail.com>,
        Atish Patra <atish.patra@wdc.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        Liush <liush@allwinnertech.com>,
        Anup Patel <anup@brainfault.org>, devicetree@vger.kernel.org,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Anup Patel <anup.patel@wdc.com>, Rob Herring <robh@kernel.org>
Subject: [PATCH v8 7/8] dt-bindings: Add common bindings for ARM and RISC-V idle states
Date:   Mon, 11 Oct 2021 13:48:19 +0530
Message-Id: <20211011081820.1135261-8-anup.patel@wdc.com>
In-Reply-To: <20211011081820.1135261-1-anup.patel@wdc.com>
References: <20211011081820.1135261-1-anup.patel@wdc.com>
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
MIME-Version: 1.0
WDCIPOUTBOUND: EOP-TRUE
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?hI2IqGHLuciE90MhYxKgAtTh8OUkBYjMstGJ60fFWO9TI4QNeM/+CRb1VNyO?=
 =?us-ascii?Q?/Kdt44sgKWCHwpJFmVNJFQjrOHcjKtjkOXfEDvYFQbcolSl4gUOaG/D5O+43?=
 =?us-ascii?Q?CX3+glY7Em5vXo3w9cLt0UXmSJX5M+uE/WMcd2YPWLImK5Wp05tbA4xV7W2A?=
 =?us-ascii?Q?Bjj5ajU52we/qWcizrspLxvMaxx/b6WdcimKprnRE+B/EIqwooOBHD2YkAaa?=
 =?us-ascii?Q?R5ZbaqQimiJIf52kp3nXbAUD/DnCnbDA+2bGjOhxzmHXzgRHERei2cKzL4dM?=
 =?us-ascii?Q?l0cjxDt0jc3kN8XSK+sd6bCsPMohSc/6ub7nioHChZ9srtSXPUwYKriOY/9w?=
 =?us-ascii?Q?M2nqhz09aK3b8jKWz8B0q55hrjmOlj6kaPGXTv0qd3mInYVtSMVYUUlpzYdD?=
 =?us-ascii?Q?4gVV26bKsltChjtCnb9R8RM+mrkVpUSP/HzuY3ucof1LL3b8T9b8SdhbFT8I?=
 =?us-ascii?Q?qpYLQ1Fj1ZdgRw+uFNpKxVYeim4e3o1luti+oaFvJZpwwZ4X0oNsCxUXt3gl?=
 =?us-ascii?Q?t/QKEHh3VIFWUgMqqz+CYovOXOt4l0jyGfpgUvjF9Y/KDaVWnLFMih3Ulft3?=
 =?us-ascii?Q?XJ2ll4BZ7L4gYu80dpb5lwFR2+jsAHTt5y3w9aH7Q2vQZ3letjqX9/g8UDGF?=
 =?us-ascii?Q?hcg5X6feyV/6IHmhUlv9B3cGABsYSC/nkdBKqJtFsT2yYpYEMitSXmLoPYo+?=
 =?us-ascii?Q?mzNNduMtfHfUsEkBml/BcG/CEXdL0Wkd6faqG8jcpo42btbQYZe/+TaT+D61?=
 =?us-ascii?Q?ruPVc89rM3QGEkF9hgpzGvi9n+ZOG9JFVFfjq4+aO+0znMofnwLeuwsrPsGs?=
 =?us-ascii?Q?ha6kVvT23gbySht7+z7tN6mgMfiCfqx6nJ28RGSr7OVSB+xcAC9QeutDHAu+?=
 =?us-ascii?Q?bFVUCwef0Ew7lsMrEv9B/y9CvRH2R+c397mzwLko2nm9PB68jumarWGp47yQ?=
 =?us-ascii?Q?IHlMOxDvhoDgDJ2jp/tb2LVcAPWSySsG2tywAnAYY2o9qyJTxWPYATG5AFHc?=
 =?us-ascii?Q?DVzGWWVltmBARIf4BXl+nNJRd87vtfnBFzhHstEVSp82NAvIcIG5/8r47b5b?=
 =?us-ascii?Q?RWJt04v1Hx6aCuOzzMNTtiujcC2BIa5j2pQHjy10qNw8ibkvLHsa8K9IGawA?=
 =?us-ascii?Q?SJWNT0zuizIre0F/JytQtULej1DXvO4a0smrMjl89RFVeNZBdRxVMpILM+Rn?=
 =?us-ascii?Q?hEW0whUvazosCckOjh4UHoWrei6bJA2+4MAywdRfr+H0oi+NmCVoBLIBZhOx?=
 =?us-ascii?Q?PMR3qVGaDj8IzTCN+MKn2MzsT9Rnbf5tRvvaWYxuvy/quVWwr6A99qdoUL+C?=
 =?us-ascii?Q?HfW1e+7kXa3W0nKAOTL+0L7z?=
X-OriginatorOrg: wdc.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 97c8d3ee-055a-48c1-5bb1-08d98c8fd5e3
X-MS-Exchange-CrossTenant-AuthSource: CO6PR04MB7812.namprd04.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Oct 2021 08:19:24.9461
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: b61c8803-16f3-4c35-9b17-6f65f441df86
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: WlSd0r89ZVkiyiOrwkLJtD8cqTMeZdK0Y0nADlmUaBbgTAlvV1+78WQbAQNPcHLOo7+JmQZCxqot5/5Z9QPdig==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO6PR04MB7874
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

The RISC-V CPU idle states will be described in under the
/cpus/idle-states DT node in the same way as ARM CPU idle
states.

This patch adds common bindings documentation for both ARM
and RISC-V idle states.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Rob Herring <robh@kernel.org>
---
 .../bindings/arm/msm/qcom,idle-state.txt      |   2 +-
 .../devicetree/bindings/arm/psci.yaml         |   2 +-
 .../bindings/{arm => cpu}/idle-states.yaml    | 228 ++++++++++++++++--
 .../devicetree/bindings/riscv/cpus.yaml       |   6 +
 4 files changed, 219 insertions(+), 19 deletions(-)
 rename Documentation/devicetree/bindings/{arm => cpu}/idle-states.yaml (74%)

diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
index 6ce0b212ec6d..606b4b1b709d 100644
--- a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
+++ b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
@@ -81,4 +81,4 @@ Example:
 		};
 	};
 
-[1]. Documentation/devicetree/bindings/arm/idle-states.yaml
+[1]. Documentation/devicetree/bindings/cpu/idle-states.yaml
diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml
index 8b77cf83a095..dd83ef278af0 100644
--- a/Documentation/devicetree/bindings/arm/psci.yaml
+++ b/Documentation/devicetree/bindings/arm/psci.yaml
@@ -101,7 +101,7 @@ properties:
       bindings in [1]) must specify this property.
 
       [1] Kernel documentation - ARM idle states bindings
-        Documentation/devicetree/bindings/arm/idle-states.yaml
+        Documentation/devicetree/bindings/cpu/idle-states.yaml
 
 patternProperties:
   "^power-domain-":
diff --git a/Documentation/devicetree/bindings/arm/idle-states.yaml b/Documentation/devicetree/bindings/cpu/idle-states.yaml
similarity index 74%
rename from Documentation/devicetree/bindings/arm/idle-states.yaml
rename to Documentation/devicetree/bindings/cpu/idle-states.yaml
index 52bce5dbb11f..74466f160cb2 100644
--- a/Documentation/devicetree/bindings/arm/idle-states.yaml
+++ b/Documentation/devicetree/bindings/cpu/idle-states.yaml
@@ -1,25 +1,30 @@
 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
 %YAML 1.2
 ---
-$id: http://devicetree.org/schemas/arm/idle-states.yaml#
+$id: http://devicetree.org/schemas/cpu/idle-states.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
-title: ARM idle states binding description
+title: Idle states binding description
 
 maintainers:
   - Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+  - Anup Patel <anup.patel@wdc.com>
 
 description: |+
   ==========================================
   1 - Introduction
   ==========================================
 
-  ARM systems contain HW capable of managing power consumption dynamically,
-  where cores can be put in different low-power states (ranging from simple wfi
-  to power gating) according to OS PM policies. The CPU states representing the
-  range of dynamic idle states that a processor can enter at run-time, can be
-  specified through device tree bindings representing the parameters required to
-  enter/exit specific idle states on a given processor.
+  ARM and RISC-V systems contain HW capable of managing power consumption
+  dynamically, where cores can be put in different low-power states (ranging
+  from simple wfi to power gating) according to OS PM policies. The CPU states
+  representing the range of dynamic idle states that a processor can enter at
+  run-time, can be specified through device tree bindings representing the
+  parameters required to enter/exit specific idle states on a given processor.
+
+  ==========================================
+  2 - ARM idle states
+  ==========================================
 
   According to the Server Base System Architecture document (SBSA, [3]), the
   power states an ARM CPU can be put into are identified by the following list:
@@ -43,8 +48,23 @@ description: |+
   The device tree binding definition for ARM idle states is the subject of this
   document.
 
+  ==========================================
+  3 - RISC-V idle states
+  ==========================================
+
+  On RISC-V systems, the HARTs (or CPUs) [6] can be put in platform specific
+  suspend (or idle) states (ranging from simple WFI, power gating, etc). The
+  RISC-V SBI v0.3 (or higher) [7] hart state management extension provides a
+  standard mechanism for OS to request HART state transitions.
+
+  The platform specific suspend (or idle) states of a hart can be either
+  retentive or non-rententive in nature. A retentive suspend state will
+  preserve HART registers and CSR values for all privilege modes whereas
+  a non-retentive suspend state will not preserve HART registers and CSR
+  values.
+
   ===========================================
-  2 - idle-states definitions
+  4 - idle-states definitions
   ===========================================
 
   Idle states are characterized for a specific system through a set of
@@ -211,10 +231,10 @@ description: |+
   properties specification that is the subject of the following sections.
 
   ===========================================
-  3 - idle-states node
+  5 - idle-states node
   ===========================================
 
-  ARM processor idle states are defined within the idle-states node, which is
+  The processor idle states are defined within the idle-states node, which is
   a direct child of the cpus node [1] and provides a container where the
   processor idle states, defined as device tree nodes, are listed.
 
@@ -223,7 +243,7 @@ description: |+
   just supports idle_standby, an idle-states node is not required.
 
   ===========================================
-  4 - References
+  6 - References
   ===========================================
 
   [1] ARM Linux Kernel documentation - CPUs bindings
@@ -238,9 +258,15 @@ description: |+
   [4] ARM Architecture Reference Manuals
       http://infocenter.arm.com/help/index.jsp
 
-  [6] ARM Linux Kernel documentation - Booting AArch64 Linux
+  [5] ARM Linux Kernel documentation - Booting AArch64 Linux
       Documentation/arm64/booting.rst
 
+  [6] RISC-V Linux Kernel documentation - CPUs bindings
+      Documentation/devicetree/bindings/riscv/cpus.yaml
+
+  [7] RISC-V Supervisor Binary Interface (SBI)
+      http://github.com/riscv/riscv-sbi-doc/riscv-sbi.adoc
+
 properties:
   $nodename:
     const: idle-states
@@ -253,7 +279,7 @@ properties:
       On ARM 32-bit systems this property is optional
 
       This assumes that the "enable-method" property is set to "psci" in the cpu
-      node[6] that is responsible for setting up CPU idle management in the OS
+      node[5] that is responsible for setting up CPU idle management in the OS
       implementation.
     const: psci
 
@@ -265,8 +291,8 @@ patternProperties:
       as follows.
 
       The idle state entered by executing the wfi instruction (idle_standby
-      SBSA,[3][4]) is considered standard on all ARM platforms and therefore
-      must not be listed.
+      SBSA,[3][4]) is considered standard on all ARM and RISC-V platforms and
+      therefore must not be listed.
 
       In addition to the properties listed above, a state node may require
       additional properties specific to the entry-method defined in the
@@ -275,7 +301,27 @@ patternProperties:
 
     properties:
       compatible:
-        const: arm,idle-state
+        oneOf:
+          - const: arm,idle-state
+          - const: riscv,idle-state
+
+      arm,psci-suspend-param:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: |
+          power_state parameter to pass to the ARM PSCI suspend call.
+
+          Device tree nodes that require usage of PSCI CPU_SUSPEND function
+          (i.e. idle states node with entry-method property is set to "psci")
+          must specify this property.
+
+      riscv,sbi-suspend-param:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: |
+          suspend_type parameter to pass to the RISC-V SBI HSM suspend call.
+
+          This property is required in idle state nodes of device tree meant
+          for RISC-V systems. For more details on the suspend_type parameter
+          refer the SBI specifiation v0.3 (or higher) [7].
 
       local-timer-stop:
         description:
@@ -317,6 +363,8 @@ patternProperties:
         description:
           A string used as a descriptive name for the idle state.
 
+    additionalProperties: false
+
     required:
       - compatible
       - entry-latency-us
@@ -658,4 +706,150 @@ examples:
         };
     };
 
+  - |
+    // Example 3 (RISC-V 64-bit, 4-cpu systems, two clusters):
+
+    cpus {
+        #size-cells = <0>;
+        #address-cells = <1>;
+
+        cpu@0 {
+            device_type = "cpu";
+            compatible = "riscv";
+            reg = <0x0>;
+            riscv,isa = "rv64imafdc";
+            mmu-type = "riscv,sv48";
+            cpu-idle-states = <&CPU_RET_0_0 &CPU_NONRET_0_0
+                            &CLUSTER_RET_0 &CLUSTER_NONRET_0>;
+
+            cpu_intc0: interrupt-controller {
+                #interrupt-cells = <1>;
+                compatible = "riscv,cpu-intc";
+                interrupt-controller;
+            };
+        };
+
+        cpu@1 {
+            device_type = "cpu";
+            compatible = "riscv";
+            reg = <0x1>;
+            riscv,isa = "rv64imafdc";
+            mmu-type = "riscv,sv48";
+            cpu-idle-states = <&CPU_RET_0_0 &CPU_NONRET_0_0
+                            &CLUSTER_RET_0 &CLUSTER_NONRET_0>;
+
+            cpu_intc1: interrupt-controller {
+                #interrupt-cells = <1>;
+                compatible = "riscv,cpu-intc";
+                interrupt-controller;
+            };
+        };
+
+        cpu@10 {
+            device_type = "cpu";
+            compatible = "riscv";
+            reg = <0x10>;
+            riscv,isa = "rv64imafdc";
+            mmu-type = "riscv,sv48";
+            cpu-idle-states = <&CPU_RET_1_0 &CPU_NONRET_1_0
+                            &CLUSTER_RET_1 &CLUSTER_NONRET_1>;
+
+            cpu_intc10: interrupt-controller {
+                #interrupt-cells = <1>;
+                compatible = "riscv,cpu-intc";
+                interrupt-controller;
+            };
+        };
+
+        cpu@11 {
+            device_type = "cpu";
+            compatible = "riscv";
+            reg = <0x11>;
+            riscv,isa = "rv64imafdc";
+            mmu-type = "riscv,sv48";
+            cpu-idle-states = <&CPU_RET_1_0 &CPU_NONRET_1_0
+                            &CLUSTER_RET_1 &CLUSTER_NONRET_1>;
+
+            cpu_intc11: interrupt-controller {
+                #interrupt-cells = <1>;
+                compatible = "riscv,cpu-intc";
+                interrupt-controller;
+            };
+        };
+
+        idle-states {
+            CPU_RET_0_0: cpu-retentive-0-0 {
+                compatible = "riscv,idle-state";
+                riscv,sbi-suspend-param = <0x10000000>;
+                entry-latency-us = <20>;
+                exit-latency-us = <40>;
+                min-residency-us = <80>;
+            };
+
+            CPU_NONRET_0_0: cpu-nonretentive-0-0 {
+                compatible = "riscv,idle-state";
+                riscv,sbi-suspend-param = <0x90000000>;
+                entry-latency-us = <250>;
+                exit-latency-us = <500>;
+                min-residency-us = <950>;
+            };
+
+            CLUSTER_RET_0: cluster-retentive-0 {
+                compatible = "riscv,idle-state";
+                riscv,sbi-suspend-param = <0x11000000>;
+                local-timer-stop;
+                entry-latency-us = <50>;
+                exit-latency-us = <100>;
+                min-residency-us = <250>;
+                wakeup-latency-us = <130>;
+            };
+
+            CLUSTER_NONRET_0: cluster-nonretentive-0 {
+                compatible = "riscv,idle-state";
+                riscv,sbi-suspend-param = <0x91000000>;
+                local-timer-stop;
+                entry-latency-us = <600>;
+                exit-latency-us = <1100>;
+                min-residency-us = <2700>;
+                wakeup-latency-us = <1500>;
+            };
+
+            CPU_RET_1_0: cpu-retentive-1-0 {
+                compatible = "riscv,idle-state";
+                riscv,sbi-suspend-param = <0x10000010>;
+                entry-latency-us = <20>;
+                exit-latency-us = <40>;
+                min-residency-us = <80>;
+            };
+
+            CPU_NONRET_1_0: cpu-nonretentive-1-0 {
+                compatible = "riscv,idle-state";
+                riscv,sbi-suspend-param = <0x90000010>;
+                entry-latency-us = <250>;
+                exit-latency-us = <500>;
+                min-residency-us = <950>;
+            };
+
+            CLUSTER_RET_1: cluster-retentive-1 {
+                compatible = "riscv,idle-state";
+                riscv,sbi-suspend-param = <0x11000010>;
+                local-timer-stop;
+                entry-latency-us = <50>;
+                exit-latency-us = <100>;
+                min-residency-us = <250>;
+                wakeup-latency-us = <130>;
+            };
+
+            CLUSTER_NONRET_1: cluster-nonretentive-1 {
+                compatible = "riscv,idle-state";
+                riscv,sbi-suspend-param = <0x91000010>;
+                local-timer-stop;
+                entry-latency-us = <600>;
+                exit-latency-us = <1100>;
+                min-residency-us = <2700>;
+                wakeup-latency-us = <1500>;
+            };
+        };
+    };
+
 ...
diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
index e534f6a7cfa1..482936630525 100644
--- a/Documentation/devicetree/bindings/riscv/cpus.yaml
+++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
@@ -95,6 +95,12 @@ properties:
       - compatible
       - interrupt-controller
 
+  cpu-idle-states:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    description: |
+      List of phandles to idle state nodes supported
+      by this hart (see ./idle-states.yaml).
+
 required:
   - riscv,isa
   - interrupt-controller
-- 
2.25.1