(0) What is the QuadSPI controller?
The QuadSPI(Quad Serial Peripheral Interface) acts as an interface to
one single or two external serial flash devices, each with up to 4
bidirectional data lines.
(1) The QuadSPI controller is driven by the LUT(Look-up Table) registers.
The LUT registers are a look-up-table for sequences of instructions.
A valid sequence consists of four LUT registers.
(2) The definition of the LUT register shows below:
---------------------------------------------------
| INSTR1 | PAD1 | OPRND1 | INSTR0 | PAD0 | OPRND0 |
---------------------------------------------------
There are several types of INSTRx, such as:
CMD : the SPI NOR command.
ADDR : the address for the SPI NOR command.
DUMMY : the dummy cycles needed by the SPI NOR command.
....
There are several types of PADx, such as:
PAD1 : use a singe I/O line.
PAD2 : use two I/O lines.
PAD4 : use quad I/O lines.
....
(3) Test this driver with the JFFS2 and UBIFS:
For jffs2:
-------------
#flash_eraseall /dev/mtd0
#mount -t jffs2 /dev/mtdblock0 tmp
#bonnie++ -d tmp -u 0 -s 10 -r 5
For ubifs:
-------------
#flash_eraseall /dev/mtd0
#ubiattach /dev/ubi_ctrl -m 0
#ubimkvol /dev/ubi0 -N test -m
#mount -t ubifs ubi0:test tmp
#bonnie++ -d tmp -u 0 -s 10 -r 5
Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
This patch cloned most of the m25p80.c. In theory, it adds a new spi-nor layer.
Before this patch, the layer is like:
MTD
------------------------
m25p80
------------------------
spi bus driver
------------------------
SPI NOR chip
After this patch, the layer is like:
MTD
------------------------
spi-nor
------------------------
m25p80
------------------------
spi bus driver
------------------------
SPI NOR chip
With the spi-nor controller driver(Freescale Quadspi), it looks like:
MTD
------------------------
spi-nor
------------------------
fsl-quadspi
------------------------
SPI NOR chip
New APIs:
spi_nor_scan: used to scan a spi-nor flash.
Signed-off-by: Huang Shijie <b32955@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>
[Brian: rebased to include additional m25p_ids[] entry]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Brian Norris