diff options
author | Huang Shijie <b32955@freescale.com> | 2014-02-28 02:58:00 -0500 |
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committer | Brian Norris <computersforpeace@gmail.com> | 2014-04-14 14:22:58 -0400 |
commit | 1ef391084b22d75110171d34f565f57e4be9b2a6 (patch) | |
tree | 527d90e9cd4e05959fbb20b567c970f9723be49f /Documentation/mtd | |
parent | b199489d37b21c5e294f95bf265acc5dde3fc3a2 (diff) |
Documentation: add the document for the SPI NOR framework
This patch adds the document for the SPI NOR framework.
Signed-off-by: Huang Shijie <b32955@freescale.com>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Diffstat (limited to 'Documentation/mtd')
-rw-r--r-- | Documentation/mtd/spi-nor.txt | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/Documentation/mtd/spi-nor.txt b/Documentation/mtd/spi-nor.txt new file mode 100644 index 000000000000..294d5b06f892 --- /dev/null +++ b/Documentation/mtd/spi-nor.txt | |||
@@ -0,0 +1,59 @@ | |||
1 | SPI NOR framework | ||
2 | ============================================ | ||
3 | |||
4 | Part I - why we need this framework? | ||
5 | ------------------------------------- | ||
6 | |||
7 | The SPI bus controller only deals with the byte stream. | ||
8 | Some controller does not works like a SPI bus controller, it works | ||
9 | like a SPI NOR controller instead, such as the Freescale's QuadSPI controller. | ||
10 | |||
11 | The Freescale's QuadSPI controller should know the NOR commands to | ||
12 | find the right LUT sequence. Unfortunately, the old code can not meet | ||
13 | this requirement. | ||
14 | |||
15 | Part II - How does the framework work? | ||
16 | ------------------------------------- | ||
17 | |||
18 | This framework just adds a new layer between the MTD and the SPI bus driver. | ||
19 | With this new layer, the SPI NOR controller driver does not depend on the | ||
20 | m25p80 code anymore. | ||
21 | |||
22 | Before this framework, the layer is like: | ||
23 | |||
24 | MTD | ||
25 | ------------------------ | ||
26 | m25p80 | ||
27 | ------------------------ | ||
28 | SPI bus driver | ||
29 | ------------------------ | ||
30 | SPI NOR chip | ||
31 | |||
32 | After this framework, the layer is like: | ||
33 | MTD | ||
34 | ------------------------ | ||
35 | SPI NOR framework | ||
36 | ------------------------ | ||
37 | m25p80 | ||
38 | ------------------------ | ||
39 | SPI bus driver | ||
40 | ------------------------ | ||
41 | SPI NOR chip | ||
42 | |||
43 | With the SPI NOR controller driver(Freescale QuadSPI), it looks like: | ||
44 | MTD | ||
45 | ------------------------ | ||
46 | SPI NOR framework | ||
47 | ------------------------ | ||
48 | fsl-quadSPI | ||
49 | ------------------------ | ||
50 | SPI NOR chip | ||
51 | |||
52 | Part III - How can the drivers use the framework | ||
53 | ------------------------------------- | ||
54 | |||
55 | The main API is the spi_nor_scan(). Before you call the hook, you should | ||
56 | initialize the necessary fields for spi_nor{}. | ||
57 | Please see the drivers/mtd/spi-nor/spi-nor.c for detail. | ||
58 | Please also reference to the fsl-quadspi.c when you want to write a new driver | ||
59 | for a SPI NOR controller. | ||