sh: clkfwk: setup clock parent from current register value

Some clocks can select its parent clock by CPG register.
But it might have been modified by boot-loader or something.
This patch removed fixed initial parent clock,
and setup it from their current register settings.
It works on div6 reparent clocks for now.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 35 insertions, 0 deletions

diff --git a/drivers/sh/clk/cpg.c b/drivers/sh/clk/cpg.c
index 82dd6fb..5e4301b 100644
--- a/drivers/sh/clk/cpg.c
+++ b/drivers/sh/clk/cpg.c
@@ -167,6 +167,38 @@ static struct clk_ops sh_clk_div6_reparent_clk_ops = {
 	.set_parent	= sh_clk_div6_set_parent,
 };
 
+static int __init sh_clk_init_parent(struct clk *clk)
+{
+	u32 val;
+
+	if (clk->parent)
+		return 0;
+
+	if (!clk->parent_table || !clk->parent_num)
+		return 0;
+
+	if (!clk->src_width) {
+		pr_err("sh_clk_init_parent: cannot select parent clock\n");
+		return -EINVAL;
+	}
+
+	val  = (__raw_readl(clk->enable_reg) >> clk->src_shift);
+	val &= (1 << clk->src_width) - 1;
+
+	if (val >= clk->parent_num) {
+		pr_err("sh_clk_init_parent: parent table size failed\n");
+		return -EINVAL;
+	}
+
+	clk->parent = clk->parent_table[val];
+	if (!clk->parent) {
+		pr_err("sh_clk_init_parent: unable to set parent");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int __init sh_clk_div6_register_ops(struct clk *clks, int nr,
 					   struct clk_ops *ops)
 {
@@ -190,6 +222,9 @@ static int __init sh_clk_div6_register_ops(struct clk *clks, int nr,
 		clkp->ops = ops;
 		clkp->freq_table = freq_table + (k * freq_table_size);
 		clkp->freq_table[nr_divs].frequency = CPUFREQ_TABLE_END;
+		ret = sh_clk_init_parent(clkp);
+		if (ret < 0)
+			break;
 
 		ret = clk_register(clkp);
 	}