[PATCH 2/2] clk: en7523: add support for .set_rate for en7581

[Christian Marangi <ansuelsmth@gmail.com>]

Add support for EN7523 driver to configure rate for Airoha EN7581 SoC.
The SoC expose both base clock selector and clock divisor hence it's
possible to change the rate.

This will be especially needed for new SoC AN7583 that require changes
for the MDIO and the eMMC.

The clock were assumed correctly configured by the bootloader but this
goes against the rule of "kernel should not depend on external
configuration".

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 drivers/clk/clk-en7523.c | 136 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)

diff --git a/drivers/clk/clk-en7523.c b/drivers/clk/clk-en7523.c
index 2f203c94f87e..832c43ae265f 100644
--- a/drivers/clk/clk-en7523.c
+++ b/drivers/clk/clk-en7523.c
@@ -777,8 +777,144 @@ static unsigned long en7581_recalc_rate(struct clk_hw *hw,
 	return rate / en7523_get_div(desc, val);
 }
 
+static int en7581_get_base_val_for_rate(const struct en_clk_desc *desc,
+					int div, unsigned long rate)
+{
+	int i;
+
+	/* Single base rate */
+	if (!desc->base_bits) {
+		if (rate != desc->base_value / div)
+			goto err;
+
+		return 0;
+	}
+
+	/* Check every base rate with provided divisor */
+	for (i = 0; i < desc->n_base_values; i++)
+		if (rate == desc->base_values[i] / div)
+			return i;
+
+err:
+	return -EINVAL;
+}
+
+static int en7581_get_vals_for_rate(const struct en_clk_desc *desc,
+				    unsigned long rate,
+				    u32 *base_val, u32 *div_val)
+{
+	int tmp_base_val = 0;
+	int tmp_div_val = 0;
+
+	if (!desc->base_bits && !desc->div_bits)
+		return -EINVAL;
+
+	/* Divisor not supported, just search in base rate */
+	if (!desc->div_bits) {
+		tmp_base_val = en7581_get_base_val_for_rate(desc, 1, rate);
+		if (tmp_base_val < 0) {
+			pr_err("Invalid rate for clock %s\n",
+			       desc->name);
+			return -EINVAL;
+		}
+
+		goto exit;
+	}
+
+	/* Check if div0 satisfy the request */
+	if (desc->div_val0) {
+		tmp_base_val = en7581_get_base_val_for_rate(desc,
+							    desc->div_val0,
+							    rate);
+		if (tmp_base_val >= 0)
+			goto exit;
+
+		/* Skip checking first divisor val */
+		tmp_div_val = 1;
+	}
+
+	/* Simulate rate with every divisor supported */
+	for (; tmp_div_val < BIT(desc->div_bits); tmp_div_val++) {
+		int div = (tmp_div_val + desc->div_offset) * desc->div_step;
+
+		tmp_base_val = en7581_get_base_val_for_rate(desc, div,
+							    rate);
+		if (tmp_base_val >= 0)
+			goto exit;
+	}
+
+	if (tmp_div_val == BIT(desc->div_bits)) {
+		pr_err("Invalid rate for clock %s\n",
+		       desc->name);
+		return -EINVAL;
+	}
+
+exit:
+	*base_val = tmp_base_val;
+	*div_val = tmp_div_val;
+
+	return 0;
+}
+
+static int en7581_determine_rate(struct clk_hw *hw,
+				 struct clk_rate_request *req)
+{
+	struct en_clk *en_clk = container_of(hw, struct en_clk, hw);
+	u32 div_val, base_val;
+
+	/* Just check if the rate is possible */
+	return en7581_get_vals_for_rate(en_clk->desc, req->rate,
+					&base_val, &div_val);
+}
+
+static int en7581_set_rate(struct clk_hw *hw, unsigned long rate,
+			   unsigned long parent_rate)
+{
+	struct en_clk *en_clk = container_of(hw, struct en_clk, hw);
+	const struct en_clk_desc *desc = en_clk->desc;
+	struct regmap *map = en_clk->map;
+	u32 base_val, div_val;
+	u32 reg, val, mask;
+	int err;
+
+	err = en7581_get_vals_for_rate(en_clk->desc, rate,
+				       &base_val, &div_val);
+	if (err)
+		return err;
+
+	if (desc->div_bits) {
+		reg = desc->div_reg ? desc->div_reg : desc->base_reg;
+
+		mask = (BIT(desc->div_bits) - 1) << desc->div_shift;
+		val = div_val << desc->div_shift;
+
+		err = regmap_update_bits(map, reg, mask, val);
+		if (err) {
+			pr_err("Failed to update div reg for clock %s\n",
+			       desc->name);
+			return -EINVAL;
+		}
+	}
+
+	if (desc->base_bits) {
+		mask = (BIT(desc->base_bits) - 1) << desc->base_shift;
+		val = base_val << desc->base_shift;
+
+		err = regmap_update_bits(map, desc->base_reg, mask, val);
+		if (err) {
+			pr_err("Failed to update reg for clock %s\n",
+			       desc->name);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
 static const struct clk_ops en7581_clk_ops = {
 	.recalc_rate = en7581_recalc_rate,
+	.determine_rate = en7581_determine_rate,
+	.set_rate = en7581_set_rate,
 };
 
 static int en7581_register_clocks(struct device *dev, struct clk_hw_onecell_data *clk_data,
-- 
2.55.0