clk: renesas: rcar-gen3-cpg: Refactor checks for accessing the div table

Do the checks for accessing the SD divider table only when the rate gets
updated, namely on init and set_rate. In all other cases, reuse the last
value. This simplifies code, runtime load, and error reporting.

Signed-off-by: Wolfram Sang <[e-mail]>
Signed-off-by: Geert Uytterhoeven <[e-mail]>

drivers/clk/renesas/rcar-gen3-cpg.c

···
 	unsigned int div_num;
 	unsigned int div_min;
 	unsigned int div_max;
+	unsigned int cur_div_idx;
 };
 
 /* SDn divider
···
 static int cpg_sd_clock_enable(struct clk_hw *hw)
 {
 	struct sd_clock *clock = to_sd_clock(hw);
-	u32 val, sd_fc;
-	unsigned int i;
-
-	val = readl(clock->reg);
-
-	sd_fc = val & CPG_SD_FC_MASK;
-	for (i = 0; i < clock->div_num; i++)
-		if (sd_fc == (clock->div_table[i].val & CPG_SD_FC_MASK))
-			break;
-
-	if (i >= clock->div_num)
-		return -EINVAL;
+	u32 val = readl(clock->reg);
 
 	val &= ~(CPG_SD_STP_MASK);
-	val |= clock->div_table[i].val & CPG_SD_STP_MASK;
+	val |= clock->div_table[clock->cur_div_idx].val & CPG_SD_STP_MASK;
 
 	writel(val, clock->reg);
 
···
 						unsigned long parent_rate)
 {
 	struct sd_clock *clock = to_sd_clock(hw);
-	u32 val, sd_fc;
-	unsigned int i;
 
-	val = readl(clock->reg);
-
-	sd_fc = val & CPG_SD_FC_MASK;
-	for (i = 0; i < clock->div_num; i++)
-		if (sd_fc == (clock->div_table[i].val & CPG_SD_FC_MASK))
-			break;
-
-	if (i >= clock->div_num)
-		return -EINVAL;
-
-	return DIV_ROUND_CLOSEST(parent_rate, clock->div_table[i].div);
+	return DIV_ROUND_CLOSEST(parent_rate,
+				 clock->div_table[clock->cur_div_idx].div);
 }
 
 static unsigned int cpg_sd_clock_calc_div(struct sd_clock *clock,
···
 	if (i >= clock->div_num)
 		return -EINVAL;
 
+	clock->cur_div_idx = i;
+
 	val = readl(clock->reg);
 	val &= ~(CPG_SD_STP_MASK | CPG_SD_FC_MASK);
 	val |= clock->div_table[i].val & (CPG_SD_STP_MASK | CPG_SD_FC_MASK);
···
 	struct sd_clock *clock;
 	struct clk *clk;
 	unsigned int i;
+	u32 sd_fc;
 
 	clock = kzalloc(sizeof(*clock), GFP_KERNEL);
 	if (!clock)
···
 	clock->hw.init = &init;
 	clock->div_table = cpg_sd_div_table;
 	clock->div_num = ARRAY_SIZE(cpg_sd_div_table);
+
+	sd_fc = readl(clock->reg) & CPG_SD_FC_MASK;
+	for (i = 0; i < clock->div_num; i++)
+		if (sd_fc == (clock->div_table[i].val & CPG_SD_FC_MASK))
+			break;
+
+	if (WARN_ON(i >= clock->div_num)) {
+		kfree(clock);
+		return ERR_PTR(-EINVAL);
+	}
+
+	clock->cur_div_idx = i;
 
 	clock->div_max = clock->div_table[0].div;
 	clock->div_min = clock->div_max;