README: qspi usecase and testing documentation.

Contains documentation and testing details for qspi flash
interface.

Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>

2 files changed, 76 insertions, 0 deletions

diff --git a/README.dra_qspi_flash b/README.dra_qspi_flash
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+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.
+
+Usecase1
+-------
+
+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.
+
+
+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.
+
diff --git a/README.dra_qspi_test b/README.dra_qspi_test
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+-------------------------------------------------
+   Simple steps used to test the QSPI at U-Boot 
+-------------------------------------------------
+
+For #1, build the patched U-Boot and load MLO/u-boot.img
+
+----------------------------------
+Boot from another medium like MMC
+----------------------------------
+
+DRA752 EVM # mmc dev 0
+DRA752 EVM # fatload mmc 0 0x82000000 MLO
+DRA752 EVM # fatload mmc 0 0x82000000 u-boot.img
+
+--------------------------------------------------
+Commands to erase/write u-boot/mlo to flash device
+--------------------------------------------------
+
+DRA752 EVM # sf probe 0
+[should detect the S25FL256S serial flash device]
+
+DRA752 EVM # sf erase 0 10000
+DRA752 EVM # sf erase 10000 10000
+DRA752 EVM # sf erase 20000 10000
+DRA752 EVM # sf erase 30000 10000
+DRA752 EVM # sf erase 40000 10000
+DRA752 EVM # sf erase 50000 10000
+DRA752 EVM # sf erase 60000 10000
+
+DRA752 EVM # sf write 82000000 0 10000
+DRA752 EVM # sf write 83000000 80000 80000
+
+
+For #2, set sysboot to QSPI-1 boot mode and power on. ROM should find
+the GP header at offset 0 and load/execute SPL. SPL then detects that
+ROM was in QSPI-1 mode (boot code 10) and attempts to find a U-Boot
+image header at offset 0x80000 (set in the config file) and proceeds to
+load that image using the U-Boot image payload offset/size from the
+header. It will then start U-Boot.
+~