clk: mediatek: clk-mtk: Introduce mtk_clk_get_hwv_regmap()

On MT8196, some clock controllers use a separate regmap for hardware
voting via set/clear/status registers. Add mtk_clk_get_hwv_regmap() to
retrieve this optional regmap, avoiding duplicated lookup code in 
mtk_clk_register_muxes() and mtk_clk_register_gate().

Reviewed-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Laura Nao <laura.nao@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: laura-nao

drivers/clk/mediatek/clk-mtk.c

@@ -685,4 +685,20 @@ void mtk_clk_simple_remove(struct platform_device *pdev)
 }
 EXPORT_SYMBOL_GPL(mtk_clk_simple_remove);
 
+struct regmap *mtk_clk_get_hwv_regmap(struct device_node *node)
+{
+	struct device_node *hwv_node;
+	struct regmap *regmap_hwv;
+
+	hwv_node = of_parse_phandle(node, "mediatek,hardware-voter", 0);
+	if (!hwv_node)
+		return NULL;
+
+	regmap_hwv = device_node_to_regmap(hwv_node);
+	of_node_put(hwv_node);
+
+	return regmap_hwv;
+}
+EXPORT_SYMBOL_GPL(mtk_clk_get_hwv_regmap);
+
 MODULE_LICENSE("GPL");

drivers/clk/mediatek/clk-mtk.h

@@ -245,5 +245,6 @@ int mtk_clk_pdev_probe(struct platform_device *pdev);
 void mtk_clk_pdev_remove(struct platform_device *pdev);
 int mtk_clk_simple_probe(struct platform_device *pdev);
 void mtk_clk_simple_remove(struct platform_device *pdev);
+struct regmap *mtk_clk_get_hwv_regmap(struct device_node *node);
 
 #endif /* __DRV_CLK_MTK_H */