Модуль управления памятью ввода-вывода IOMMU: список регистров

  MODE_SEL

0: Prefetch
1: Debug Mode
It is used to chose prefetch mode or Debug mode.

  Unused

  VA_CONFIG

0: Read operation
1: Write operation

  Unused

  VA_CONFIG_START

0: No operation or operation completes
1: Start
After the operation completes, the bit can clear to 0 automatically.
Read operation process:
a) Write IOMMU_VA_REG[31:0];
b) Write IOMMU_VA_CONFIG_REG[8] to 0;
c) Write IOMMU_VA_CONFIG_REG[0] to 1 to start read-process;
d) Query IOMMU_VA_CONFIG_REG[0] until it is 0;
e) Read IOMMU_VA_DATA_REG[31:0];
Write operation process:
a) Write IOMMU_VA_REG[31:0];
b) Write IOMMU_VA_DATA_REG[31:0];
c) Write IOMMU_VA_CONFIG_REG[8] to 1;
d) Write IOMMU_VA_CONFIG_REG[0] to 1 to start write-process;
e) Query IOMMU_VA_CONFIG_REG[0] until it is 0;

Команда U-Boot для чтения регистра

Bit fields structure

typedef union  iommu_va_config_reg
{
  struct
  {
   unsigned va_config_start : 1;
   unsigned unused0 : 7;
   unsigned va_config : 1;
   unsigned unused1 : 22;
   unsigned mode_sel : 1;
  } b;
   unsigned long w;
} IOMMU_VA_CONFIG_REG