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Diffstat (limited to 'Platform/Marvell/Documentation/Drivers/SpiDriver.txt')
| -rw-r--r-- | Platform/Marvell/Documentation/Drivers/SpiDriver.txt | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/Platform/Marvell/Documentation/Drivers/SpiDriver.txt b/Platform/Marvell/Documentation/Drivers/SpiDriver.txt new file mode 100644 index 0000000000..42b5e3ce3b --- /dev/null +++ b/Platform/Marvell/Documentation/Drivers/SpiDriver.txt @@ -0,0 +1,116 @@ +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.
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