mtd: rawnand: denali: optimize timing parameters for data interface

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>
Reviewed-by: Richard Weinberger <richard@nod.at>
Tested-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/mtd/nand/raw/denali_dt.c b/drivers/mtd/nand/raw/denali_dt.c
index afaae378c624..0faaad032e5f 100644
--- a/drivers/mtd/nand/raw/denali_dt.c
+++ b/drivers/mtd/nand/raw/denali_dt.c
@@ -150,6 +150,7 @@ static int denali_dt_probe(struct platform_device *pdev)
 		goto out_disable_clk_x;
 
 	if (dt->clk_x) {
+		denali->clk_rate = clk_get_rate(dt->clk);
 		denali->clk_x_rate = clk_get_rate(dt->clk_x);
 	} else {
 		/*
@@ -158,6 +159,7 @@ static int denali_dt_probe(struct platform_device *pdev)
 		 */
 		dev_notice(dev,
 			   "necessary clock is missing. default clock rates are used.\n");
+		denali->clk_rate = 50000000;
 		denali->clk_x_rate = 200000000;
 	}