[ARM] 4967/1: Adds functions to set clkout rate for Samsung S3C2410

This patch adds functions to set clkout rate for Samsung S3C2410
This patch supersedes 4884/1, that contained an error

Comments from Ben Dooks:

 Note, looks like this needs to be applied before 4882/1
Signed-off-by: Davide Rizzo <davide@elpa.it>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/plat-s3c24xx/clock.c

@@ -332,6 +332,58 @@ static int s3c24xx_dclk_setparent(struct clk *clk, struct clk *parent)
 	return 0;
 }
 
+static unsigned long s3c24xx_calc_div(struct clk *clk, unsigned long rate)
+{
+	unsigned long div;
+
+	if ((rate == 0) || !clk->parent)
+		return 0;
+
+	div = clk_get_rate(clk->parent) / rate;
+	if (div < 2)
+		div = 2;
+	else if (div > 16)
+		div = 16;
+
+	return div;
+}
+
+static unsigned long s3c24xx_round_dclk_rate(struct clk *clk,
+	unsigned long rate)
+{
+	unsigned long div = s3c24xx_calc_div(clk, rate);
+
+	if (div == 0)
+		return 0;
+
+	return clk_get_rate(clk->parent) / div;
+}
+
+static int s3c24xx_set_dclk_rate(struct clk *clk, unsigned long rate)
+{
+	unsigned long mask, data, div = s3c24xx_calc_div(clk, rate);
+
+	if (div == 0)
+		return -EINVAL;
+
+	if (clk == &s3c24xx_dclk0) {
+		mask = S3C2410_DCLKCON_DCLK0_DIV_MASK |
+			S3C2410_DCLKCON_DCLK0_CMP_MASK;
+		data = S3C2410_DCLKCON_DCLK0_DIV(div) |
+			S3C2410_DCLKCON_DCLK0_CMP((div + 1) / 2);
+	} else if (clk == &s3c24xx_dclk1) {
+		mask = S3C2410_DCLKCON_DCLK1_DIV_MASK |
+			S3C2410_DCLKCON_DCLK1_CMP_MASK;
+		data = S3C2410_DCLKCON_DCLK1_DIV(div) |
+			S3C2410_DCLKCON_DCLK1_CMP((div + 1) / 2);
+	} else
+		return -EINVAL;
+
+	clk->rate = clk_get_rate(clk->parent) / div;
+	__raw_writel(((__raw_readl(S3C24XX_DCLKCON) & ~mask) | data),
+		S3C24XX_DCLKCON);
+	return clk->rate;
+}
 
 static int s3c24xx_clkout_setparent(struct clk *clk, struct clk *parent)
 {
@@ -378,6 +430,8 @@ struct clk s3c24xx_dclk0 = {
 	.ctrlbit	= S3C2410_DCLKCON_DCLK0EN,
 	.enable	        = s3c24xx_dclk_enable,
 	.set_parent	= s3c24xx_dclk_setparent,
+	.set_rate	= s3c24xx_set_dclk_rate,
+	.round_rate	= s3c24xx_round_dclk_rate,
 };
 
 struct clk s3c24xx_dclk1 = {
@@ -386,6 +440,8 @@ struct clk s3c24xx_dclk1 = {
 	.ctrlbit	= S3C2410_DCLKCON_DCLK0EN,
 	.enable		= s3c24xx_dclk_enable,
 	.set_parent	= s3c24xx_dclk_setparent,
+	.set_rate	= s3c24xx_set_dclk_rate,
+	.round_rate	= s3c24xx_round_dclk_rate,
 };
 
 struct clk s3c24xx_clkout0 = {