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Introduction

============

Resource Power Manager (RPM)

RPM is a dedicated hardware engine for managing shared SoC resources,

which includes buses, clocks, power rails, etc.  The goal of RPM is

to achieve the maximum power savings while satisfying the SoC's

operational and performance requirements.  RPM accepts resource

requests from multiple RPM masters.  It arbitrates and aggregates the

requests, and configures the shared resources.  The RPM masters are

the application processor, the modem processor, as well as some

hardware accelerators.

The RPM driver provides an API for interacting with RPM.  Kernel code

calls the RPM driver to request RPM-managed, shared resources.

Kernel code can also register with the driver for RPM notifications,

which are sent when the status of shared resources change.

Hardware description

====================

RPM exposes a separate region of registers to each of the RPM masters.

In general, each register represents some shared resource(s).  At a

very basic level, a master requests resources by writing to the

registers, then generating an interrupt to RPM.  RPM processes the

request, writes acknowledgment to the registers, then generates an

interrupt to the master.

In addition to the master-specific regions, RPM also exposes a shared

region that contains the current status of the shared resources.  Only

RPM can write to the status region, but every master can read from it.

RPM contains internal logics that aggregate and arbitrate among

requests from the various RPM masters.  It interfaces with the PMIC,

the bus arbitration block, and the clock controller block in order to

configure the shared resources.

Software description

====================

The RPM driver encapsulates the low level RPM interactions, which

rely on reading/writing registers and generating/processing

interrupts, and provides a higher level synchronuous set/clear/get

interface.  Most functions take an array of id-value pairs.

The ids identify the RPM registers which would correspond to some

RPM resources, the values specify the new resource values.

The RPM driver synchronizes accesses to RPM.  It protects against

simultaneous accesses from multiple tasks, on SMP cores, in task

contexts, and in atomic contexts.

Design

======

Design goals:

- Encapsulate low level RPM interactions.

- Provide a synchronuous set/clear/get interface.

- Synchronize simultaneous software accesses to RPM.

Power Management

================

RPM is part of the power management architecture for MSM 8660.  RPM

manages shared system resources to lower system power.

SMP/multi-core

==============

The RPM driver uses mutex to synchronize client accesses among tasks.

It uses spinlocks to synchronize accesses from atomic contexts and

SMP cores.

Security

========

None.

Performance

===========

None.

Interface

=========

msm_rpm_get_status():

The function reads the shared status region and returns the current

resource values, which are the arbitrated/aggregated results across

all RPM masters.

msm_rpm_set():

The function makes a resource request to RPM.

msm_rpm_set_noirq():

The function is similar to msm_rpm_set() except that it must be

called with interrupts masked.  If possible, use msm_rpm_set()

instead, to maximize CPU throughput.

msm_rpm_clear():

The function makes a resource request to RPM to clear resource values.

Once the values are cleared, the resources revert back to their default

values for this RPM master.  RPM internally uses the default values as

the requests from this RPM master when arbitrating and aggregating with

requests from other RPM masters.

msm_rpm_clear_noirq():

The function is similar to msm_rpm_clear() except that it must be

called with interrupts masked.  If possible, use msm_rpm_clear()

instead, to maximize CPU throughput.

msm_rpm_register_notification():

The function registers for RPM notification.  When the specified

resources change their status on RPM, RPM sends out notifications

and the driver will "up" the semaphore in struct

msm_rpm_notification.

msm_rpm_unregister_notification():

The function unregisters a notification.

msm_rpm_init():

The function initializes the RPM driver with platform specific data.

Driver parameters

=================

None.

Config options

==============

MSM_RPM

Dependencies

============

None.

User space utilities

====================

None.

Other

=====

None.

Known issues

============

None.

To do

=====

None.

  This also affects writes to the tval register, due to the implicit

  counter read.

- hisilicon,erratum-161010101 : A boolean property. Indicates the

  presence of Hisilicon erratum 161010101, which says that reading the

  counters is unreliable in some cases, and reads may return a value 32

  beyond the correct value. This also affects writes to the tval

  registers, due to the implicit counter read.

** Optional properties:

- arm,cpu-registers-not-fw-configured : Firmware does not initialize

- HDK device:

  compatible = "qcom,hdk"

- IPC device:

  compatible = "qcom,ipc"

Boards (SoC type + board variant):

compatible = "qcom,apq8016"

compatible = "qcom,apq8017-mtp"

compatible = "qcom,apq8053-cdp"

compatible = "qcom,apq8053-mtp"

compatible = "qcom,apq8053-ipc"

compatible = "qcom,mdm9630-cdp"

compatible = "qcom,mdm9630-mtp"

compatible = "qcom,mdm9630-sim"

compatible = "qcom,msm8953-sim"

compatible = "qcom,msm8953-cdp"

compatible = "qcom,msm8953-mtp"

compatible = "qcom,msm8953-ipc"

compatible = "qcom,msm8953-qrd"

compatible = "qcom,msm8953-qrd-sku3"

compatible = "qcom,sdm450-mtp"

	Usage:      required

	Value type: <stringlist>

	Definition: Address names. Must be "osm_l3_base", "osm_pwrcl_base",

		    "osm_perfcl_base".

		    "osm_perfcl_base", and "cpr_rc".

		    Must be specified in the same order as the corresponding

		    addresses are specified in the reg property.

- vdd_l3_mx_ao-supply

	Usage:      required

	Value type: <phandle>

	Definition: Phandle to the MX active-only regulator device.

- vdd_pwrcl_mx_ao-supply

	Usage:      required

	Value type: <phandle>

	Definition: Phandle to the MX active-only regulator device.

- qcom,mx-turbo-freq

	Usage:      required

	Value type: <array>

	Definition: List of frequencies for the 3 clock domains (following the

		    order of L3, power, and performance clusters) that denote

		    the lowest rate that requires a TURBO vote on the MX rail.

- l3-devs

	Usage: optional

	Value type: <phandle>

		compatible = "qcom,clk-cpu-osm";

		reg = <0x17d41000 0x1400>,

			<0x17d43000 0x1400>,

			<0x17d45800 0x1400>;

		reg-names = "osm_l3_base", "osm_pwrcl_base", "osm_perfcl_base";

			<0x17d45800 0x1400>,

			<0x784248 0x4>;

		reg-names = "osm_l3_base", "osm_pwrcl_base", "osm_perfcl_base",

							"cpr_rc";

		vdd_l3_mx_ao-supply = <&pm8998_s6_level_ao>;

		vdd_pwrcl_mx_ao-supply = <&pm8998_s6_level_ao>;

		l3-devs = <&phandle0 &phandle1 &phandle2>;

		qcom,mx-turbo-freq = <1478400000 1689600000 3300000001>;

		l3-devs = <&l3_cpu0 &l3_cpu4 &l3_cdsp>;

		clock-names = "xo_ao";

		clocks = <&clock_rpmh RPMH_CXO_CLK_A>;

Qualcomm Technologies, Inc. QDSS bridge Driver

This device will enable routing debug data from modem

subsystem to APSS host.

Required properties:

-compatible : "qcom,qdss-mhi".

-qcom,mhi : phandle of MHI Device to connect to.

Example:

	qcom,qdss-mhi {

		compatible = "qcom,qdss-mhi";

		qcom,mhi = <&mhi_0>;

	};