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Commit | Line | Data |
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a187559e | 1 | QSPI U-Boot support |
2f24223a PS |
2 | ------------------ |
3 | ||
4 | Host processor is connected to serial flash device via qpsi | |
5 | interface. QSPI is a kind of spi module that allows single, | |
6 | dual and quad read access to external spi devices. The module | |
7 | has a memory mapped interface which provide direct interface | |
8 | for accessing data form external spi devices. | |
9 | ||
10 | The one QSPI in the device is primarily intended for fast booting | |
11 | from Quad SPI flash devices. | |
12 | ||
13 | Usecase | |
14 | ------- | |
15 | ||
16 | MLO/u-boot.img will be flashed from SD/MMC to the flash device | |
17 | using serial flash erase and write commands. Then, switch settings | |
18 | will be changed to qspi boot. Then, the ROM code will read MLO | |
19 | from the predefined location in the flash, where it was flashed and | |
20 | execute it after storing it in SDRAM. Then, the MLO will read | |
21 | u-boot.img from flash and execute it from SDRAM. | |
22 | ||
23 | SPI mode | |
24 | ------- | |
25 | SPI mode uses mtd spi framework for transfer and reception of data. | |
26 | Can be used in: | |
27 | 1. Normal mode: use single pin for transfers | |
28 | 2. Dual Mode: use two pins for transfers. | |
29 | 3. Quad mode: use four pin for transfer | |
30 | ||
31 | Memory mapped read mode | |
32 | ----------------------- | |
33 | In this, SPI controller is configured using configuration port and then | |
1cc0a9f4 | 34 | controller is switched to memory mapped port for data read. |
2f24223a PS |
35 | |
36 | Driver | |
37 | ------ | |
38 | drivers/qspi/ti_qspi.c | |
39 | - Newly created file which is responsible for configuring the | |
40 | qspi controller and also for providing the low level api which | |
41 | is responsible for transferring the datas from host controller | |
42 | to flash device and vice versa. | |
43 | ||
44 | Testing | |
45 | ------- | |
46 | A seperated file named README.dra_qspi_test has been created which gives all the | |
a187559e | 47 | details about the commands required to test qspi at U-Boot level. |