clk: sunxi: Support factor clocks with N factor starting not from 0

commit 9a5e6c7e upstream.

The PLLs on newer Allwinner SoC's, such as the A31 and A23, have a
N multiplier factor that starts from 1, not 0.

This patch adds an option to the factor clk driver's config data
structures to specify the base value of N.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

drivers/clk/sunxi/clk-factors.c

@@ -70,7 +70,7 @@ static unsigned long clk_factors_recalc_rate(struct clk_hw *hw,
 		p = FACTOR_GET(config->pshift, config->pwidth, reg);
 
 	/* Calculate the rate */
-	rate = (parent_rate * n * (k + 1) >> p) / (m + 1);
+	rate = (parent_rate * (n + config->n_start) * (k + 1) >> p) / (m + 1);
 
 	return rate;
 }

drivers/clk/sunxi/clk-factors.h

@@ -15,6 +15,7 @@ struct clk_factors_config {
 	u8 mwidth;
 	u8 pshift;
 	u8 pwidth;
+	u8 n_start;
 };
 
 struct clk *clk_register_factors(struct device *dev, const char *name,