clk: qcom: Allow clk_set_parent() to work on display clocks

Sometimes the display driver may want to change the parent PLL of
the display clocks (byte and pixel clocks) depending on the
use-case. Currently the parent is fixed by means of having a
frequency table with one entry that chooses a particular parent.
Remove this restriction and use the parent the clock is
configured for in the hardware during clk_set_rate(). This
requires consumers to rely on the default parent or to configure
the parent with clk_set_parent()/assigned-clock-parents on the
clocks before calling clk_set_rate().

Tested-by: Archit Taneja <architt@codeaurora.org>
Cc: Hai Li <hali@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

1 files changed, 83 insertions, 8 deletions

diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
index 9aec1761fd29..d941dea6f7c7 100644
--- a/drivers/clk/qcom/clk-rcg2.c
+++ b/drivers/clk/qcom/clk-rcg2.c
@@ -485,6 +485,76 @@ const struct clk_ops clk_byte_ops = {
 };
 EXPORT_SYMBOL_GPL(clk_byte_ops);
 
+static int clk_byte2_determine_rate(struct clk_hw *hw,
+				    struct clk_rate_request *req)
+{
+	struct clk_rcg2 *rcg = to_clk_rcg2(hw);
+	unsigned long parent_rate, div;
+	u32 mask = BIT(rcg->hid_width) - 1;
+	struct clk_hw *p;
+	unsigned long rate = req->rate;
+
+	if (rate == 0)
+		return -EINVAL;
+
+	p = req->best_parent_hw;
+	req->best_parent_rate = parent_rate = clk_hw_round_rate(p, rate);
+
+	div = DIV_ROUND_UP((2 * parent_rate), rate) - 1;
+	div = min_t(u32, div, mask);
+
+	req->rate = calc_rate(parent_rate, 0, 0, 0, div);
+
+	return 0;
+}
+
+static int clk_byte2_set_rate(struct clk_hw *hw, unsigned long rate,
+			 unsigned long parent_rate)
+{
+	struct clk_rcg2 *rcg = to_clk_rcg2(hw);
+	struct freq_tbl f = { 0 };
+	unsigned long div;
+	int i, num_parents = clk_hw_get_num_parents(hw);
+	u32 mask = BIT(rcg->hid_width) - 1;
+	u32 cfg;
+
+	div = DIV_ROUND_UP((2 * parent_rate), rate) - 1;
+	div = min_t(u32, div, mask);
+
+	f.pre_div = div;
+
+	regmap_read(rcg->clkr.regmap, rcg->cmd_rcgr + CFG_REG, &cfg);
+	cfg &= CFG_SRC_SEL_MASK;
+	cfg >>= CFG_SRC_SEL_SHIFT;
+
+	for (i = 0; i < num_parents; i++) {
+		if (cfg == rcg->parent_map[i].cfg) {
+			f.src = rcg->parent_map[i].src;
+			return clk_rcg2_configure(rcg, &f);
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int clk_byte2_set_rate_and_parent(struct clk_hw *hw,
+		unsigned long rate, unsigned long parent_rate, u8 index)
+{
+	/* Read the hardware to determine parent during set_rate */
+	return clk_byte2_set_rate(hw, rate, parent_rate);
+}
+
+const struct clk_ops clk_byte2_ops = {
+	.is_enabled = clk_rcg2_is_enabled,
+	.get_parent = clk_rcg2_get_parent,
+	.set_parent = clk_rcg2_set_parent,
+	.recalc_rate = clk_rcg2_recalc_rate,
+	.set_rate = clk_byte2_set_rate,
+	.set_rate_and_parent = clk_byte2_set_rate_and_parent,
+	.determine_rate = clk_byte2_determine_rate,
+};
+EXPORT_SYMBOL_GPL(clk_byte2_ops);
+
 static const struct frac_entry frac_table_pixel[] = {
 	{ 3, 8 },
 	{ 2, 9 },
@@ -496,14 +566,9 @@ static const struct frac_entry frac_table_pixel[] = {
 static int clk_pixel_determine_rate(struct clk_hw *hw,
 				    struct clk_rate_request *req)
 {
-	struct clk_rcg2 *rcg = to_clk_rcg2(hw);
 	unsigned long request, src_rate;
 	int delta = 100000;
-	const struct freq_tbl *f = rcg->freq_tbl;
 	const struct frac_entry *frac = frac_table_pixel;
-	int index = qcom_find_src_index(hw, rcg->parent_map, f->src);
-
-	req->best_parent_hw = clk_hw_get_parent_by_index(hw, index);
 
 	for (; frac->num; frac++) {
 		request = (req->rate * frac->den) / frac->num;
@@ -525,12 +590,23 @@ static int clk_pixel_set_rate(struct clk_hw *hw, unsigned long rate,
 		unsigned long parent_rate)
 {
 	struct clk_rcg2 *rcg = to_clk_rcg2(hw);
-	struct freq_tbl f = *rcg->freq_tbl;
+	struct freq_tbl f = { 0 };
 	const struct frac_entry *frac = frac_table_pixel;
 	unsigned long request;
 	int delta = 100000;
 	u32 mask = BIT(rcg->hid_width) - 1;
-	u32 hid_div;
+	u32 hid_div, cfg;
+	int i, num_parents = clk_hw_get_num_parents(hw);
+
+	regmap_read(rcg->clkr.regmap, rcg->cmd_rcgr + CFG_REG, &cfg);
+	cfg &= CFG_SRC_SEL_MASK;
+	cfg >>= CFG_SRC_SEL_SHIFT;
+
+	for (i = 0; i < num_parents; i++)
+		if (cfg == rcg->parent_map[i].cfg) {
+			f.src = rcg->parent_map[i].src;
+			break;
+		}
 
 	for (; frac->num; frac++) {
 		request = (rate * frac->den) / frac->num;
@@ -555,7 +631,6 @@ static int clk_pixel_set_rate(struct clk_hw *hw, unsigned long rate,
 static int clk_pixel_set_rate_and_parent(struct clk_hw *hw, unsigned long rate,
 		unsigned long parent_rate, u8 index)
 {
-	/* Parent index is set statically in frequency table */
 	return clk_pixel_set_rate(hw, rate, parent_rate);
 }