mtd: rawnand: denali: optimize timing parameters for data interface
authorMasahiro Yamada <yamada.masahiro@socionext.com>
Wed, 19 Dec 2018 11:03:18 +0000 (20:03 +0900)
committerMasahiro Yamada <yamada.masahiro@socionext.com>
Sat, 29 Dec 2018 02:38:37 +0000 (11:38 +0900)
commit8ccfbfb3e1c54caf67def3626ca046fafaa5092d
treeccb410f413d4e4cb1896664e22a24c314d9bb4ce
parenta13fe7afe9cd79060ecb8ac03265a27ceb7d91eb
mtd: rawnand: denali: optimize timing parameters for data interface

Based on Linux commit 1dfac31a5a63ac04a9b5fbc3f5105a586560f191

This commit improves the ->setup_data_interface() hook.

The denali_setup_data_interface() needs the frequency of clk_x
and the ratio of clk_x / clk.

The latter is currently hardcoded in the driver, like this:

  #define DENALI_CLK_X_MULT       6

The IP datasheet requires that clk_x / clk be 4, 5, or 6.  I just
chose 6 because it is the most defensive value, but it is not optimal.
By getting the clock rate of both "clk" and "clk_x", the driver can
compute the timing values more precisely.

To not break the existing platforms, the fallback value, 50 MHz is
provided.  It is true for all upstreamed platforms.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
drivers/mtd/nand/raw/denali.c
drivers/mtd/nand/raw/denali.h
drivers/mtd/nand/raw/denali_dt.c