Documentation/loongarch/irq-chip-model.rst

   1 .. SPDX-License-Identifier: GPL-2.0
   2
   3 =======================================
   4 IRQ chip model (hierarchy) of LoongArch
   5 =======================================
   6
   7 Currently, LoongArch based processors (e.g. Loongson-3A5000) can only work together
   8 with LS7A chipsets. The irq chips in LoongArch computers include CPUINTC (CPU Core
   9 Interrupt Controller), LIOINTC (Legacy I/O Interrupt Controller), EIOINTC (Extended
  10 I/O Interrupt Controller), HTVECINTC (Hyper-Transport Vector Interrupt Controller),
  11 PCH-PIC (Main Interrupt Controller in LS7A chipset), PCH-LPC (LPC Interrupt Controller
  12 in LS7A chipset) and PCH-MSI (MSI Interrupt Controller).
  13
  14 CPUINTC is a per-core controller (in CPU), LIOINTC/EIOINTC/HTVECINTC are per-package
  15 controllers (in CPU), while PCH-PIC/PCH-LPC/PCH-MSI are controllers out of CPU (i.e.,
  16 in chipsets). These controllers (in other words, irqchips) are linked in a hierarchy,
  17 and there are two models of hierarchy (legacy model and extended model).
  18
  19 Legacy IRQ model
  20 ================
  21
  22 In this model, IPI (Inter-Processor Interrupt) and CPU Local Timer interrupt go
  23 to CPUINTC directly, CPU UARTS interrupts go to LIOINTC, while all other devices
  24 interrupts go to PCH-PIC/PCH-LPC/PCH-MSI and gathered by HTVECINTC, and then go
  25 to LIOINTC, and then CPUINTC::
  26
  27      +-----+     +---------+     +-------+
  28      | IPI | --> | CPUINTC | <-- | Timer |
  29      +-----+     +---------+     +-------+
  30                       ^
  31                       |
  32                  +---------+     +-------+
  33                  | LIOINTC | <-- | UARTs |
  34                  +---------+     +-------+
  35                       ^
  36                       |
  37                 +-----------+
  38                 | HTVECINTC |
  39                 +-----------+
  40                  ^         ^
  41                  |         |
  42            +---------+ +---------+
  43            | PCH-PIC | | PCH-MSI |
  44            +---------+ +---------+
  45              ^     ^           ^
  46              |     |           |
  47      +---------+ +---------+ +---------+
  48      | PCH-LPC | | Devices | | Devices |
  49      +---------+ +---------+ +---------+
  50           ^
  51           |
  52      +---------+
  53      | Devices |
  54      +---------+
  55
  56 Extended IRQ model
  57 ==================
  58
  59 In this model, IPI (Inter-Processor Interrupt) and CPU Local Timer interrupt go
  60 to CPUINTC directly, CPU UARTS interrupts go to LIOINTC, while all other devices
  61 interrupts go to PCH-PIC/PCH-LPC/PCH-MSI and gathered by EIOINTC, and then go to
  62 to CPUINTC directly::
  63
  64           +-----+     +---------+     +-------+
  65           | IPI | --> | CPUINTC | <-- | Timer |
  66           +-----+     +---------+     +-------+
  67                        ^       ^
  68                        |       |
  69                 +---------+ +---------+     +-------+
  70                 | EIOINTC | | LIOINTC | <-- | UARTs |
  71                 +---------+ +---------+     +-------+
  72                  ^       ^
  73                  |       |
  74           +---------+ +---------+
  75           | PCH-PIC | | PCH-MSI |
  76           +---------+ +---------+
  77             ^     ^           ^
  78             |     |           |
  79     +---------+ +---------+ +---------+
  80     | PCH-LPC | | Devices | | Devices |
  81     +---------+ +---------+ +---------+
  82          ^
  83          |
  84     +---------+
  85     | Devices |
  86     +---------+
  87
  88 ACPI-related definitions
  89 ========================
  90
  91 CPUINTC::
  92
  93   ACPI_MADT_TYPE_CORE_PIC;
  94   struct acpi_madt_core_pic;
  95   enum acpi_madt_core_pic_version;
  96
  97 LIOINTC::
  98
  99   ACPI_MADT_TYPE_LIO_PIC;
 100   struct acpi_madt_lio_pic;
 101   enum acpi_madt_lio_pic_version;
 102
 103 EIOINTC::
 104
 105   ACPI_MADT_TYPE_EIO_PIC;
 106   struct acpi_madt_eio_pic;
 107   enum acpi_madt_eio_pic_version;
 108
 109 HTVECINTC::
 110
 111   ACPI_MADT_TYPE_HT_PIC;
 112   struct acpi_madt_ht_pic;
 113   enum acpi_madt_ht_pic_version;
 114
 115 PCH-PIC::
 116
 117   ACPI_MADT_TYPE_BIO_PIC;
 118   struct acpi_madt_bio_pic;
 119   enum acpi_madt_bio_pic_version;
 120
 121 PCH-MSI::
 122
 123   ACPI_MADT_TYPE_MSI_PIC;
 124   struct acpi_madt_msi_pic;
 125   enum acpi_madt_msi_pic_version;
 126
 127 PCH-LPC::
 128
 129   ACPI_MADT_TYPE_LPC_PIC;
 130   struct acpi_madt_lpc_pic;
 131   enum acpi_madt_lpc_pic_version;
 132
 133 References
 134 ==========
 135
 136 Documentation of Loongson-3A5000:
 137
 138   https://github.com/loongson/LoongArch-Documentation/releases/latest/download/Loongson-3A5000-usermanual-1.02-CN.pdf (in Chinese)
 139
 140   https://github.com/loongson/LoongArch-Documentation/releases/latest/download/Loongson-3A5000-usermanual-1.02-EN.pdf (in English)
 141
 142 Documentation of Loongson's LS7A chipset:
 143
 144   https://github.com/loongson/LoongArch-Documentation/releases/latest/download/Loongson-7A1000-usermanual-2.00-CN.pdf (in Chinese)
 145
 146   https://github.com/loongson/LoongArch-Documentation/releases/latest/download/Loongson-7A1000-usermanual-2.00-EN.pdf (in English)
 147
 148 .. Note::
 149     - CPUINTC is CSR.ECFG/CSR.ESTAT and its interrupt controller described
 150       in Section 7.4 of "LoongArch Reference Manual, Vol 1";
 151     - LIOINTC is "Legacy I/OInterrupts" described in Section 11.1 of
 152       "Loongson 3A5000 Processor Reference Manual";
 153     - EIOINTC is "Extended I/O Interrupts" described in Section 11.2 of
 154       "Loongson 3A5000 Processor Reference Manual";
 155     - HTVECINTC is "HyperTransport Interrupts" described in Section 14.3 of
 156       "Loongson 3A5000 Processor Reference Manual";
 157     - PCH-PIC/PCH-MSI is "Interrupt Controller" described in Section 5 of
 158       "Loongson 7A1000 Bridge User Manual";
 159     - PCH-LPC is "LPC Interrupts" described in Section 24.3 of
 160       "Loongson 7A1000 Bridge User Manual".