[RFC PATCH v15 02/11] ARM: qcom: Add Subsystem Power Manager (SPM) driver

[Kumar Gala]

On Mar 9, 2015, at 10:16 AM, Lina Iyer <lina.iyer at linaro.org> wrote:

> SPM is a hardware block that controls the peripheral logic surrounding
> the application cores (cpu/l$). When the core executes WFI instruction,
> the SPM takes over the putting the core in low power state as
> configured. The wake up for the SPM is an interrupt at the GIC, which
> then completes the rest of low power mode sequence and brings the core
> out of low power mode.
> 
> The SPM has a set of control registers that configure the SPMs
> individually based on the type of the core and the runtime conditions.
> SPM is a finite state machine block to which a sequence is provided and
> it interprets the bytes and executes them in sequence. Each low power
> mode that the core can enter into is provided to the SPM as a sequence.
> 
> Configure the SPM to set the core (cpu or L2) into its low power mode,
> the index of the first command in the sequence is set in the SPM_CTL
> register. When the core executes ARM wfi instruction, it triggers the
> SPM state machine to start executing from that index. The SPM state
> machine waits until the interrupt occurs and starts executing the rest
> of the sequence until it hits the end of the sequence. The end of the
> sequence jumps the core out of its low power mode.
> 
> Add support for an idle driver to set up the SPM to place the core in
> Standby or Standalone power collapse mode when the core is idle.
> 
> Based on work by: Mahesh Sivasubramanian <msivasub at codeaurora.org>,
> Ai Li <ali at codeaurora.org>, Praveen Chidambaram <pchidamb at codeaurora.org>
> Original tree available at -
> git://codeaurora.org/quic/la/kernel/msm-3.10.git
> 
> Cc: Stephen Boyd <sboyd at codeaurora.org>
> Cc: Arnd Bergmann <arnd at arndb.de>
> Cc: Kevin Hilman <khilman at linaro.org>
> Cc: Daniel Lezcano <daniel.lezcano at linaro.org>
> Signed-off-by: Lina Iyer <lina.iyer at linaro.org>
> ---
> .../devicetree/bindings/arm/msm/qcom,saw2.txt      |  31 +-
> drivers/soc/qcom/Kconfig                           |   7 +
> drivers/soc/qcom/Makefile                          |   1 +
> drivers/soc/qcom/spm.c                             | 422 +++++++++++++++++++++
> 4 files changed, 455 insertions(+), 6 deletions(-)
> create mode 100644 drivers/soc/qcom/spm.c
> 
> diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt b/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
> index 1505fb8..690c3c0 100644
> --- a/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
> +++ b/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
> @@ -2,11 +2,20 @@ 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:
> @@ -14,10 +23,13 @@ PROPERTIES
> 	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"
> +			"qcom,saw2-v1"
> +			"qcom,saw2-v1.1"
> +			"qcom,saw2-v2"
> +			"qcom,saw2-v2.1"
> +			"qcom,apq8064-saw2-v1.1-cpu"
> +			"qcom,msm8974-saw2-v2.1-cpu"
> +			"qcom,apq8084-saw2-v2.1-cpu”
> 

We don’t seem to use the "qcom,saw2-v1*” variants so should we just drop them?


> - reg:
> 	Usage: required
> @@ -26,10 +38,17 @@ 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:
> 
> -	regulator at 2099000 {
> +	power-controller at 2099000 {
> 		compatible = "qcom,saw2";
> 		reg = <0x02099000 0x1000>, <0x02009000 0x1000>;
> +		regulator;
> 	};

- k

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