From 2f24223ae150d9496694885cee401f4525b72acb Mon Sep 17 00:00:00 2001 From: "Poddar, Sourav" Date: Mon, 7 Oct 2013 15:53:04 +0530 Subject: README: qspi usecase and testing documentation. Contains documentation and testing details for qspi flash interface. Signed-off-by: Sourav Poddar Reviewed-by: Jagannadha Sutradharudu Teki --- doc/SPI/README.ti_qspi_flash | 47 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 doc/SPI/README.ti_qspi_flash (limited to 'doc/SPI/README.ti_qspi_flash') diff --git a/doc/SPI/README.ti_qspi_flash b/doc/SPI/README.ti_qspi_flash new file mode 100644 index 0000000..1b86d01 --- /dev/null +++ b/doc/SPI/README.ti_qspi_flash @@ -0,0 +1,47 @@ +QSPI U-boot support +------------------ + +Host processor is connected to serial flash device via qpsi +interface. QSPI is a kind of spi module that allows single, +dual and quad read access to external spi devices. The module +has a memory mapped interface which provide direct interface +for accessing data form external spi devices. + +The one QSPI in the device is primarily intended for fast booting +from Quad SPI flash devices. + +Usecase +------- + +MLO/u-boot.img will be flashed from SD/MMC to the flash device +using serial flash erase and write commands. Then, switch settings +will be changed to qspi boot. Then, the ROM code will read MLO +from the predefined location in the flash, where it was flashed and +execute it after storing it in SDRAM. Then, the MLO will read +u-boot.img from flash and execute it from SDRAM. + +SPI mode +------- +SPI mode uses mtd spi framework for transfer and reception of data. +Can be used in: +1. Normal mode: use single pin for transfers +2. Dual Mode: use two pins for transfers. +3. Quad mode: use four pin for transfer + +Memory mapped read mode +----------------------- +In this, SPI controller is configured using configuration port and then +controler is switched to memory mapped port for data read. + +Driver +------ +drivers/qspi/ti_qspi.c + - Newly created file which is responsible for configuring the + qspi controller and also for providing the low level api which + is responsible for transferring the datas from host controller + to flash device and vice versa. + +Testing +------- +A seperated file named README.dra_qspi_test has been created which gives all the +details about the commands required to test qspi at u-boot level. -- cgit v1.1