clk: mediatek: clk-mux: Support custom parent indices for muxes

Add support for customized parent indices for MediaTek muxes: this is
necessary for the case in which we want to exclude some clocks from
a mux's parent clocks list, where the exclusions are not from the
very bottom of the list but either in the middle or the beginning.

Example:
- MUX1 (all parents)
  - parent1; idx=0
  - parent2; idx=1
  - parent3; idx=2

- MUX1 (wanted parents)
  - parent1; idx=0
  - parent3; idx=2

To achieve that add a `parent_index` array pointer to struct mtk_mux,
then in .set_parent(), .get_parent() callbacks check if this array
was populated and eventually get the index from that.

Also, to avoid updating all clock drivers for all SoCs, rename the
"main" macro to __GATE_CLR_SET_UPD_FLAGS (so, `__` was added) and
add the new member to it; furthermore, GATE_CLK_SET_UPD_FLAGS has
been reintroduced as being fully compatible with the older version.

The new parent_index can be specified with the new `_INDEXED`
variants of the MUX_GATE_CLR_SET_UPD_xxxx macros.

Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20231103102533.69280-2-angelogioacchino.delregno@collabora.com
Tested-by: Fei Shao <fshao@chromium.org>
Reviewed-by: Fei Shao <fshao@chromium.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/clk/mediatek/clk-mux.c b/drivers/clk/mediatek/clk-mux.c
index c93bc7f926e5..60990296450b 100644
--- a/drivers/clk/mediatek/clk-mux.c
+++ b/drivers/clk/mediatek/clk-mux.c
@@ -89,6 +89,17 @@ static u8 mtk_clk_mux_get_parent(struct clk_hw *hw)
 	regmap_read(mux->regmap, mux->data->mux_ofs, &val);
 	val = (val >> mux->data->mux_shift) & mask;
 
+	if (mux->data->parent_index) {
+		int i;
+
+		for (i = 0; i < mux->data->num_parents; i++)
+			if (mux->data->parent_index[i] == val)
+				return i;
+
+		/* Not found: return an impossible index to generate error */
+		return mux->data->num_parents + 1;
+	}
+
 	return val;
 }
 
@@ -104,6 +115,9 @@ static int mtk_clk_mux_set_parent_setclr_lock(struct clk_hw *hw, u8 index)
 	else
 		__acquire(mux->lock);
 
+	if (mux->data->parent_index)
+		index = mux->data->parent_index[index];
+
 	regmap_read(mux->regmap, mux->data->mux_ofs, &orig);
 	val = (orig & ~(mask << mux->data->mux_shift))
 			| (index << mux->data->mux_shift);