diff options
Diffstat (limited to 'dts/Bindings/arm/msm')
| -rw-r--r-- | dts/Bindings/arm/msm/qcom,idle-state.txt | 84 | ||||
| -rw-r--r-- | dts/Bindings/arm/msm/qcom,saw2.txt | 40 | ||||
| -rw-r--r-- | dts/Bindings/arm/msm/timer.txt | 16 |
3 files changed, 128 insertions, 12 deletions
diff --git a/dts/Bindings/arm/msm/qcom,idle-state.txt b/dts/Bindings/arm/msm/qcom,idle-state.txt new file mode 100644 index 0000000000..06df04cc82 --- /dev/null +++ b/dts/Bindings/arm/msm/qcom,idle-state.txt @@ -0,0 +1,84 @@ +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.txt diff --git a/dts/Bindings/arm/msm/qcom,saw2.txt b/dts/Bindings/arm/msm/qcom,saw2.txt index 1505fb8e13..ae4afc6dcf 100644 --- a/dts/Bindings/arm/msm/qcom,saw2.txt +++ b/dts/Bindings/arm/msm/qcom,saw2.txt @@ -2,22 +2,31 @@ SPM AVS Wrapper 2 (SAW2) The SAW2 is a wrapper around the Subsystem Power Manager (SPM) and the Adaptive Voltage Scaling (AVS) hardware. The SPM is a programmable -micro-controller that transitions a piece of hardware (like a processor or +power-controller that transitions a piece of hardware (like a processor or subsystem) into and out of low power modes via a direct connection to the PMIC. It can also be wired up to interact with other processors in the system, notifying them when a low power state is entered or exited. +Multiple revisions of the SAW hardware are supported using these Device Nodes. +SAW2 revisions differ in the register offset and configuration data. Also, the +same revision of the SAW in different SoCs may have different configuration +data due the the differences in hardware capabilities. Hence the SoC name, the +version of the SAW hardware in that SoC and the distinction between cpu (big +or Little) or cache, may be needed to uniquely identify the SAW register +configuration and initialization data. The compatible string is used to +indicate this parameter. + PROPERTIES - compatible: Usage: required Value type: <string> - Definition: shall contain "qcom,saw2". A more specific value should be - one of: - "qcom,saw2-v1" - "qcom,saw2-v1.1" - "qcom,saw2-v2" - "qcom,saw2-v2.1" + Definition: Must have + "qcom,saw2" + A more specific value could be one of: + "qcom,apq8064-saw2-v1.1-cpu" + "qcom,msm8974-saw2-v2.1-cpu" + "qcom,apq8084-saw2-v2.1-cpu" - reg: Usage: required @@ -26,10 +35,23 @@ PROPERTIES the register region. An optional second element specifies the base address and size of the alias register region. +- regulator: + Usage: optional + Value type: boolean + Definition: Indicates that this SPM device acts as a regulator device + device for the core (CPU or Cache) the SPM is attached + to. -Example: +Example 1: - regulator@2099000 { + power-controller@2099000 { compatible = "qcom,saw2"; reg = <0x02099000 0x1000>, <0x02009000 0x1000>; + regulator; + }; + +Example 2: + saw0: power-controller@f9089000 { + compatible = "qcom,apq8084-saw2-v2.1-cpu", "qcom,saw2"; + reg = <0xf9089000 0x1000>, <0xf9009000 0x1000>; }; diff --git a/dts/Bindings/arm/msm/timer.txt b/dts/Bindings/arm/msm/timer.txt index 74607b6c11..5e10c34554 100644 --- a/dts/Bindings/arm/msm/timer.txt +++ b/dts/Bindings/arm/msm/timer.txt @@ -9,11 +9,17 @@ Properties: "qcom,scss-timer" - scorpion subsystem - interrupts : Interrupts for the debug timer, the first general purpose - timer, and optionally a second general purpose timer in that - order. + timer, and optionally a second general purpose timer, and + optionally as well, 2 watchdog interrupts, in that order. - reg : Specifies the base address of the timer registers. +- clocks: Reference to the parent clocks, one per output clock. The parents + must appear in the same order as the clock names. + +- clock-names: The name of the clocks as free-form strings. They should be in + the same order as the clocks. + - clock-frequency : The frequency of the debug timer and the general purpose timer(s) in Hz in that order. @@ -29,9 +35,13 @@ Example: compatible = "qcom,scss-timer", "qcom,msm-timer"; interrupts = <1 1 0x301>, <1 2 0x301>, - <1 3 0x301>; + <1 3 0x301>, + <1 4 0x301>, + <1 5 0x301>; reg = <0x0200a000 0x100>; clock-frequency = <19200000>, <32768>; + clocks = <&sleep_clk>; + clock-names = "sleep"; cpu-offset = <0x40000>; }; |