[v3,0/4] Add Qualcomm SA8255p based firmware managed PCIe root complex

Based on received feedback, this patch series adds support with existing
Linux qcom-pcie.c driver to get PCIe host root complex functionality on
Qualcomm SA8255P auto platform.

1. Interface to allow requesting firmware to manage system resources and
performing PCIe Link up (devicetree binding in terms of power domain and
runtime PM APIs is used in driver)

2. SA8255P is using Synopsys Designware PCIe controller which supports MSI
controller. Using existing MSI controller based functionality by exporting
important pcie dwc core driver based MSI APIs, and using those from
pcie-qcom.c driver.

Below architecture is used on Qualcomm SA8255P auto platform to get ECAM
compliant PCIe controller based functionality. Here firmware VM based PCIe
driver takes care of resource management and performing PCIe link related
handling (D0 and D3cold). Linux pcie-qcom.c driver uses power domain to
request firmware VM to perform these operations using SCMI interface.
--------------------


                                   ┌────────────────────────┐                                               
                                   │                        │                                               
  ┌──────────────────────┐         │     SHARED MEMORY      │            ┌──────────────────────────┐       
  │     Firmware VM      │         │                        │            │         Linux VM         │       
  │ ┌─────────┐          │         │                        │            │    ┌────────────────┐    │       
  │ │ Drivers │ ┌──────┐ │         │                        │            │    │   PCIE Qcom    │    │       
  │ │ PCIE PHY◄─┤      │ │         │   ┌────────────────┐   │            │    │    driver      │    │       
  │ │         │ │ SCMI │ │         │   │                │   │            │    │                │    │       
  │ │PCIE CTL │ │      │ ├─────────┼───►    PCIE        ◄───┼─────┐      │    └──┬──────────▲──┘    │       
  │ │         ├─►Server│ │         │   │    SHMEM       │   │     │      │       │          │       │       
  │ │Clk, Vreg│ │      │ │         │   │                │   │     │      │    ┌──▼──────────┴──┐    │       
  │ │GPIO,GDSC│ └─▲──┬─┘ │         │   └────────────────┘   │     └──────┼────┤PCIE SCMI Inst  │    │       
  │ └─────────┘   │  │   │         │                        │            │    └──▲──────────┬──┘    │       
  │               │  │   │         │                        │            │       │          │       │       
  └───────────────┼──┼───┘         │                        │            └───────┼──────────┼───────┘       
                  │  │             │                        │                    │          │               
                  │  │             └────────────────────────┘                    │          │               
                  │  │                                                           │          │               
                  │  │                                                           │          │               
                  │  │                                                           │          │               
                  │  │                                                           │IRQ       │HVC            
              IRQ │  │HVC                                                        │          │               
                  │  │                                                           │          │               
                  │  │                                                           │          │               
                  │  │                                                           │          │               
┌─────────────────┴──▼───────────────────────────────────────────────────────────┴──────────▼──────────────┐
│                                                                                                          │
│                                                                                                          │
│                                      HYPERVISOR                                                          │
│                                                                                                          │
│                                                                                                          │
│                                                                                                          │
└──────────────────────────────────────────────────────────────────────────────────────────────────────────┘
                                                                                                            
  ┌─────────────┐    ┌─────────────┐  ┌──────────┐   ┌───────────┐   ┌─────────────┐  ┌────────────┐        
  │             │    │             │  │          │   │           │   │  PCIE       │  │   PCIE     │        
  │   CLOCK     │    │   REGULATOR │  │   GPIO   │   │   GDSC    │   │  PHY        │  │ controller │        
  └─────────────┘    └─────────────┘  └──────────┘   └───────────┘   └─────────────┘  └────────────┘        
                                                                                                            
----------
Changes in V3:
- Drop usage of PCIE host generic driver usage, and splitting of MSI functionality
- Modified existing pcie-qcom.c driver to add support for getting ECAM compliant and firmware managed
PCIe root complex functionality
Link to v2: https://lore.kernel.org/linux-arm-kernel/925d1eca-975f-4eec-bdf8-ca07a892361a@quicinc.com/T/

Changes in V2:
- Drop new PCIe Qcom ECAM driver, and use existing PCIe designware based MSI functionality
- Add power domain based functionality within existing ECAM driver
Link to v1: https://lore.kernel.org/all/d10199df-5fb3-407b-b404-a0a4d067341f@quicinc.com/T/                                                                                                      

Tested:
- Validated NVME functionality with PCIe0 on SA8255P-RIDE platform

Mayank Rana (3):
  PCI: dwc: Export dwc MSI controller related APIs
  PCI: qcom: Add firmware managed ECAM compliant PCIe root complex
    functionality
  dt-bindings: PCI: qcom,pcie-sa8255p: Document ECAM compliant PCIe root
    complex

 .../devicetree/bindings/pci/qcom,pcie-sa8255p.yaml | 100 +++++++++++++++++++++
 drivers/pci/controller/dwc/Kconfig                 |   1 +
 drivers/pci/controller/dwc/pcie-designware-host.c  |  38 ++++----
 drivers/pci/controller/dwc/pcie-designware.h       |  14 +++
 drivers/pci/controller/dwc/pcie-qcom.c             |  69 ++++++++++++--
 5 files changed, 199 insertions(+), 23 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/pci/qcom,pcie-sa8255p.yaml