Message-Id: <20211224144835.39193-1-david@ixit.cz>
Date:   Fri, 24 Dec 2021 15:48:34 +0100
From:   David Heidelberg <david@...t.cz>
To:     Rob Herring <robh+dt@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Cc:     ~okias/devicetree@...ts.sr.ht, David Heidelberg <david@...t.cz>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3] dt-bindings: arm: merge qcom,idle-state with idle-state

Merge Qualcomm specific idle-state binding with generic one.

Signed-off-by: David Heidelberg <david@...t.cz>

---
v3:
 - integrate into idle-state.yml
 - orig. patch name was:
   "[v2] dt-bindings: arm/msm/qcom,idle-state convert to YAML"

Signed-off-by: David Heidelberg <david@...t.cz>
---
 .../devicetree/bindings/arm/idle-states.yaml  | 107 ++++++++++++++++++
 .../bindings/arm/msm/qcom,idle-state.txt      |  84 --------------
 2 files changed, 107 insertions(+), 84 deletions(-)
 delete mode 100644 Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt

diff --git a/Documentation/devicetree/bindings/arm/idle-states.yaml b/Documentation/devicetree/bindings/arm/idle-states.yaml
index 52bce5dbb11f..fde1557f2332 100644
--- a/Documentation/devicetree/bindings/arm/idle-states.yaml
+++ b/Documentation/devicetree/bindings/arm/idle-states.yaml
@@ -241,6 +241,64 @@ description: |+
   [6] ARM Linux Kernel documentation - Booting AArch64 Linux
       Documentation/arm64/booting.rst
 
+  ===========================================
+  5 - Qualcomm specific STATES
+  ===========================================
+
+  cpuidle-qcom is the cpuidle driver for Qualcomm SoCs and uses these idle
+  states. Idle states have different enter/exit latency and residency values.
+  The idle states supported by the QCOM SoC are defined as -
+
+    * Standby
+    * Retention
+    * Standalone Power Collapse (Standalone PC or SPC)
+    * Power Collapse (PC)
+
+  Standby: Standby does a little more in addition to architectural clock gating.
+  When the WFI instruction is executed the ARM core would gate its internal
+  clocks. In addition to gating the clocks, QCOM cpus use this instruction as a
+  trigger to execute the SPM state machine. The SPM state machine waits for the
+  interrupt to trigger the core back in to active. This triggers the cache
+  hierarchy to enter standby states, when all cpus are idle. An interrupt brings
+  the SPM state machine out of its wait, the next step is to ensure that the
+  cache hierarchy is also out of standby, and then the cpu is allowed to resume
+  execution. This state is defined as a generic ARM WFI state by the ARM cpuidle
+  driver and is not defined in the DT. The SPM state machine should be
+  configured to execute this state by default and after executing every other
+  state below.
+
+  Retention: Retention is a low power state where the core is clock gated and
+  the memory and the registers associated with the core are retained. The
+  voltage may be reduced to the minimum value needed to keep the processor
+  registers active. The SPM should be configured to execute the retention
+  sequence and would wait for interrupt, before restoring the cpu to execution
+  state. Retention may have a slightly higher latency than Standby.
+
+  Standalone PC: A cpu can power down and warmboot if there is a sufficient time
+  between the time it enters idle and the next known wake up. SPC mode is used
+  to indicate a core entering a power down state without consulting any other
+  cpu or the system resources. This helps save power only on that core.  The SPM
+  sequence for this idle state is programmed to power down the supply to the
+  core, wait for the interrupt, restore power to the core, and ensure the
+  system state including cache hierarchy is ready before allowing core to
+  resume. Applying power and resetting the core causes the core to warmboot
+  back into Elevation Level (EL) which trampolines the control back to the
+  kernel. Entering a power down state for the cpu, needs to be done by trapping
+  into a EL. Failing to do so, would result in a crash enforced by the warm boot
+  code in the EL for the SoC. On SoCs with write-back L1 cache, the cache has to
+  be flushed in s/w, before powering down the core.
+
+  Power Collapse: This state is similar to the SPC mode, but distinguishes
+  itself in that the cpu acknowledges and permits the SoC to enter deeper sleep
+  modes. In a hierarchical power domain SoC, this means L2 and other caches can
+  be flushed, system bus, clocks - lowered, and SoC main XO clock gated and
+  voltages reduced, provided all cpus enter this state.  Since the span of low
+  power modes possible at this state is vast, the exit latency and the residency
+  of this low power mode would be considered high even though at a cpu level,
+  this essentially is cpu power down. The SPM in this state also may handshake
+  with the Resource power manager (RPM) processor in the SoC to indicate a
+  complete application processor subsystem shut down.
+
 properties:
   $nodename:
     const: idle-states
@@ -323,6 +381,44 @@ patternProperties:
       - exit-latency-us
       - min-residency-us
 
+  "^(ret|spc|pc)$":
+    type: object
+    description:
+      Each state node represents a domain idle state description.
+
+    properties:
+      compatible:
+        items:
+          - enum:
+              - qcom,idle-state-ret
+              - qcom,idle-state-spc
+              - qcom,idle-state-pc
+          - const: arm,idle-state
+
+      entry-latency-us:
+        description:
+          The worst case latency in microseconds required to enter the idle
+          state. Note that, the exit-latency-us duration may be guaranteed only
+          after the entry-latency-us has passed.
+
+      exit-latency-us:
+        description:
+          The worst case latency in microseconds required to exit the idle
+          state.
+
+      min-residency-us:
+        description:
+          The minimum residency duration in microseconds after which the idle
+          state will yield power benefits, after overcoming the overhead while
+          entering the idle state.
+
+    required:
+      - compatible
+      - entry-latency-us
+      - exit-latency-us
+      - min-residency-us
+
+
 additionalProperties: false
 
 examples:
@@ -658,4 +754,15 @@ examples:
         };
     };
 
+  - |
+    // Example 3 - QCOM SPC
+    idle-states {
+      cpu_spc: spc {
+        compatible = "qcom,idle-state-spc", "arm,idle-state";
+        entry-latency-us = <150>;
+        exit-latency-us = <200>;
+        min-residency-us = <2000>;
+      };
+    };
+
 ...
diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt b/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
deleted file mode 100644
index 6ce0b212ec6d..000000000000
--- a/Documentation/devicetree/bindings/arm/msm/qcom,idle-state.txt
+++ /dev/null
@@ -1,84 +0,0 @@
-QCOM Idle States for cpuidle driver
-
-ARM provides idle-state node to define the cpuidle states, as defined in [1].
-cpuidle-qcom is the cpuidle driver for Qualcomm SoCs and uses these idle
-states. Idle states have different enter/exit latency and residency values.
-The idle states supported by the QCOM SoC are defined as -
-
-    * Standby
-    * Retention
-    * Standalone Power Collapse (Standalone PC or SPC)
-    * Power Collapse (PC)
-
-Standby: Standby does a little more in addition to architectural clock gating.
-When the WFI instruction is executed the ARM core would gate its internal
-clocks. In addition to gating the clocks, QCOM cpus use this instruction as a
-trigger to execute the SPM state machine. The SPM state machine waits for the
-interrupt to trigger the core back in to active. This triggers the cache
-hierarchy to enter standby states, when all cpus are idle. An interrupt brings
-the SPM state machine out of its wait, the next step is to ensure that the
-cache hierarchy is also out of standby, and then the cpu is allowed to resume
-execution. This state is defined as a generic ARM WFI state by the ARM cpuidle
-driver and is not defined in the DT. The SPM state machine should be
-configured to execute this state by default and after executing every other
-state below.
-
-Retention: Retention is a low power state where the core is clock gated and
-the memory and the registers associated with the core are retained. The
-voltage may be reduced to the minimum value needed to keep the processor
-registers active. The SPM should be configured to execute the retention
-sequence and would wait for interrupt, before restoring the cpu to execution
-state. Retention may have a slightly higher latency than Standby.
-
-Standalone PC: A cpu can power down and warmboot if there is a sufficient time
-between the time it enters idle and the next known wake up. SPC mode is used
-to indicate a core entering a power down state without consulting any other
-cpu or the system resources. This helps save power only on that core.  The SPM
-sequence for this idle state is programmed to power down the supply to the
-core, wait for the interrupt, restore power to the core, and ensure the
-system state including cache hierarchy is ready before allowing core to
-resume. Applying power and resetting the core causes the core to warmboot
-back into Elevation Level (EL) which trampolines the control back to the
-kernel. Entering a power down state for the cpu, needs to be done by trapping
-into a EL. Failing to do so, would result in a crash enforced by the warm boot
-code in the EL for the SoC. On SoCs with write-back L1 cache, the cache has to
-be flushed in s/w, before powering down the core.
-
-Power Collapse: This state is similar to the SPC mode, but distinguishes
-itself in that the cpu acknowledges and permits the SoC to enter deeper sleep
-modes. In a hierarchical power domain SoC, this means L2 and other caches can
-be flushed, system bus, clocks - lowered, and SoC main XO clock gated and
-voltages reduced, provided all cpus enter this state.  Since the span of low
-power modes possible at this state is vast, the exit latency and the residency
-of this low power mode would be considered high even though at a cpu level,
-this essentially is cpu power down. The SPM in this state also may handshake
-with the Resource power manager (RPM) processor in the SoC to indicate a
-complete application processor subsystem shut down.
-
-The idle-state for QCOM SoCs are distinguished by the compatible property of
-the idle-states device node.
-
-The devicetree representation of the idle state should be -
-
-Required properties:
-
-- compatible: Must be one of -
-			"qcom,idle-state-ret",
-			"qcom,idle-state-spc",
-			"qcom,idle-state-pc",
-		and "arm,idle-state".
-
-Other required and optional properties are specified in [1].
-
-Example:
-
-	idle-states {
-		CPU_SPC: spc {
-			compatible = "qcom,idle-state-spc", "arm,idle-state";
-			entry-latency-us = <150>;
-			exit-latency-us = <200>;
-			min-residency-us = <2000>;
-		};
-	};
-
-[1]. Documentation/devicetree/bindings/arm/idle-states.yaml
-- 
2.34.1

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