clk: mediatek: pll: Implement unregister API

The PLL clk type within the MediaTek clk driver library only has a
register function, and no corresponding unregister function. This
means there is no way for its users to properly implement cleanup
and removal.

Add a matching unregister function for the PLL type clk.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Miles Chen <miles.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220208124034.414635-14-wenst@chromium.org
Reviewed-by: Chun-Jie Chen <chun-jie.chen@mediatek.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/mediatek/clk-pll.c

@@ -360,6 +360,21 @@ static struct clk *mtk_clk_register_pll(const struct mtk_pll_data *data,
 	return clk;
 }
 
+static void mtk_clk_unregister_pll(struct clk *clk)
+{
+	struct clk_hw *hw;
+	struct mtk_clk_pll *pll;
+
+	hw = __clk_get_hw(clk);
+	if (!hw)
+		return;
+
+	pll = to_mtk_clk_pll(hw);
+
+	clk_unregister(clk);
+	kfree(pll);
+}
+
 void mtk_clk_register_plls(struct device_node *node,
 		const struct mtk_pll_data *plls, int num_plls, struct clk_onecell_data *clk_data)
 {
@@ -388,4 +403,44 @@ void mtk_clk_register_plls(struct device_node *node,
 }
 EXPORT_SYMBOL_GPL(mtk_clk_register_plls);
 
+static __iomem void *mtk_clk_pll_get_base(struct clk *clk,
+					  const struct mtk_pll_data *data)
+{
+	struct clk_hw *hw = __clk_get_hw(clk);
+	struct mtk_clk_pll *pll = to_mtk_clk_pll(hw);
+
+	return pll->base_addr - data->reg;
+}
+
+void mtk_clk_unregister_plls(const struct mtk_pll_data *plls, int num_plls,
+			     struct clk_onecell_data *clk_data)
+{
+	__iomem void *base = NULL;
+	int i;
+
+	if (!clk_data)
+		return;
+
+	for (i = num_plls; i > 0; i--) {
+		const struct mtk_pll_data *pll = &plls[i - 1];
+
+		if (IS_ERR_OR_NULL(clk_data->clks[pll->id]))
+			continue;
+
+		/*
+		 * This is quite ugly but unfortunately the clks don't have
+		 * any device tied to them, so there's no place to store the
+		 * pointer to the I/O region base address. We have to fetch
+		 * it from one of the registered clks.
+		 */
+		base = mtk_clk_pll_get_base(clk_data->clks[pll->id], pll);
+
+		mtk_clk_unregister_pll(clk_data->clks[pll->id]);
+		clk_data->clks[pll->id] = ERR_PTR(-ENOENT);
+	}
+
+	iounmap(base);
+}
+EXPORT_SYMBOL_GPL(mtk_clk_unregister_plls);
+
 MODULE_LICENSE("GPL");

drivers/clk/mediatek/clk-pll.h

@@ -51,5 +51,7 @@ struct mtk_pll_data {
 void mtk_clk_register_plls(struct device_node *node,
 			   const struct mtk_pll_data *plls, int num_plls,
 			   struct clk_onecell_data *clk_data);
+void mtk_clk_unregister_plls(const struct mtk_pll_data *plls, int num_plls,
+			     struct clk_onecell_data *clk_data);
 
 #endif /* __DRV_CLK_MTK_PLL_H */