| 1. Introduction | |
| --------------- | |
| **SpiDxe** driver implements MARVELL_SPI_MASTER_PROTOCOL in order to manage SPI | |
| controller on Marvell A8k boards. It exposes below functionalities: | |
| - create and setup SPI slaves | |
| - raw transfer over SPI bus | |
| 2. SpiDxe driver design | |
| ----------------------- | |
| 2.1 MARVELL_SPI_MASTER_PROTOCOL | |
| ----------------------- | |
| First member of SPI_MASTER protocol is Init function, implemented for SPI | |
| master controller initialization. | |
| ->Init() | |
| // | |
| //Initializes the host controller to execute SPI commands. | |
| // | |
| param[IN] This Pointer to the MARVELL_SPI_MASTER_PROTOCOL instance | |
| return EFI_SUCCESS Opcode initialization on the SPI host | |
| controller completed. | |
| return EFI_ACCESS_DENIED The SPI configuration interface is | |
| locked. | |
| return EFI_OUT_OF_RESOURCES Not enough resource available to | |
| initialize the device. | |
| return EFI_DEVICE_ERROR Device error, operation failed. | |
| ******** | |
| SPI devices (slaves) do not support any kind of automatic discovery or | |
| enumaration, so every device needs manual configuration, which may be done | |
| with SetupDevice function. | |
| ->SetupDevice() | |
| // | |
| //Allocate and zero all fields in the SPI_DEVICE struct. Set the chip | |
| //select, max frequency and transfer mode supported by slave device. | |
| // | |
| param[IN] Cs Chip select ID of the slave chip. | |
| param[IN] MaxFreq Maximum SCK rate in Hz. | |
| param[IN] Mode Clock polarity and clock phase. | |
| return *SPI_DEVICE Pointer to new allocated struct SPI_DEVICE. | |
| return NULL NULL pointer if any eroor occured. | |
| ******** | |
| Developers have to destroy all created SPI device structs (with FreeDevice | |
| function) in order to prevent from memory leak. | |
| ->FreeDevice() | |
| // | |
| //Free any memory associated with a SPI device. | |
| // | |
| param[in] SpiDev Pointer to the SPI_DEVICE struct. | |
| return EFI_SUCCESS Memory fried succesfully. | |
| return EFI_DEVICE_ERROR Device error, operation failed. | |
| ******** | |
| Transfer function allows write/read raw bytes over SPI bus. | |
| ->Transfer() | |
| // | |
| //Perform transfer over SPI bus | |
| // | |
| param[in] This Pointer to the MARVELL_SPI_MASTER_PROTOCOL | |
| instance. | |
| param[in] Slave Pointer to the SPI_DEVICE struct. | |
| param[in] DataByteCount Number of bytes in the data portion of | |
| the SPI cycle. | |
| param[in] DataOut Pointer to caller-allocated buffer | |
| containing the data to send. | |
| param[out] DataIn Pointer to caller-allocated buffer | |
| where received data will be placed. | |
| param[in] Flag Flags which indicate state of CS line | |
| during/after transfer (see file | |
| Drivers/Spi/Devices/A8kSpiFlash.h) | |
| return EFI_SUCCESS Memory fried succesfully. | |
| return EFI_DEVICE_ERROR Device error, operation failed. | |
| ********* | |
| When working with SPI devices it is often necessary to perform "command and | |
| address" transactions. It may be done via ReadWrite function. | |
| ->ReadWrite() | |
| // | |
| //Perform two steps transactions. First write Command, then read/write | |
| //buffer | |
| // | |
| param[in] This Pointer to the MARVELL_SPI_MASTER_PROTOCOL | |
| instance. | |
| param[in] Slave Pointer to the SPI_DEVICE struct. | |
| param[in] Cmd Pointer to caller-allocated buffer | |
| containing the command to send. | |
| param[in] CmdSize Size of command (in bytes). | |
| param[in] DataOut Pointer to caller-allocated buffer | |
| containing the data to send. | |
| param[out] DataIn Pointer to caller-allocated buffer | |
| where received data will be placed. | |
| param[in] DataSize Number of bytes in the data portion of | |
| the SPI cycle. |