[U-Boot] [UBOOT][PATCHv4 6/6] README: qspi usecase and testing documentation.

[Sourav Poddar]

Contains documentation and testing details for qspi flash
interface.

Signed-off-by: Sourav Poddar <sourav.poddar at ti.com>
---
 doc/README.ti_qspi_dra_test |   38 ++++++++++++++++++++++++++++++++++
 doc/README.ti_qspi_flash    |   47 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 85 insertions(+), 0 deletions(-)
 create mode 100644 doc/README.ti_qspi_dra_test
 create mode 100644 doc/README.ti_qspi_flash

diff --git a/doc/README.ti_qspi_dra_test b/doc/README.ti_qspi_dra_test
new file mode 100644
index 0000000..c4540ea
--- /dev/null
+++ b/doc/README.ti_qspi_dra_test
@@ -0,0 +1,38 @@
+-------------------------------------------------
+   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 0x83000000 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 20000 70000
+
+For #2, set sysboot to QSPI-1 boot mode(SYSBOOT[5:0] = 100110) 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 0x20000 (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.
diff --git a/doc/README.ti_qspi_flash b/doc/README.ti_qspi_flash
new file mode 100644
index 0000000..1b86d01
--- /dev/null
+++ b/doc/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.
-- 
1.7.1