Re: [PATCH v5 13/25] clk: mediatek: pll: Add ops for PLLs using set/clr regs

MT8189 SoC uses a new combination of status and set/clr registers to
control its PLL enable state and perform BAR reset, that are different
than the current default clock prepare/unprepare operations are using.

Add new set of PLL clock operations to support this logic that relies
on the following registers for prepare/unprepare operations:
  - en/en_set/en_clr, rather than en register, for PLL enable
    control
  - rst_bar/rst_bar_set/rst_bar_clr, rather than default rst_bar
    register for BAR reset control

Also, handle rst_bar register setting/clearing with a timeout, to
verify the operation was correctly performed.

Signed-off-by: Louis-Alexis Eyraud <redacted>
---
 drivers/clk/mediatek/clk-pll.c | 66 ++++++++++++++++++++++++++++++++++++++++++
 drivers/clk/mediatek/clk-pll.h |  5 ++++
 2 files changed, 71 insertions(+)

diff --git a/drivers/clk/mediatek/clk-pll.c b/drivers/clk/mediatek/clk-pll.c
index 9a197a657dce..3118f68aa9ac 100644
--- a/drivers/clk/mediatek/clk-pll.c
+++ b/drivers/clk/mediatek/clk-pll.c

@@ -9,6 +9,7 @@
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/of_address.h>
 #include <linux/platform_device.h>

@@ -32,6 +33,7 @@
 #define INTEGER_BITS		7
 
 #define PLL_STABILIZATION_DELAY	20 /* in us */
+#define RST_BAR_TIMEOUT		20 /* in us */
 
 int mtk_pll_is_prepared(struct clk_hw *hw)
 {

@@ -301,6 +303,60 @@ void mtk_pll_unprepare(struct clk_hw *hw)
 	mtk_pll_power_off(pll);
 }
 
+int mtk_pll_prepare_setclr(struct clk_hw *hw)
+{
+	struct mtk_clk_pll *pll = to_mtk_clk_pll(hw);
+	u32 val = 0;
+	int ret;
+
+	mtk_pll_power_on(pll);
+
+	writel(BIT(pll->data->pll_en_bit), pll->en_set_addr);
+
+	__mtk_pll_tuner_enable(pll);
+
+	udelay(PLL_STABILIZATION_DELAY);
+
+	if (pll->data->flags & HAVE_RST_BAR) {
+		writel(pll->data->rst_bar_mask, pll->rst_bar_set_addr);
+
+		ret = readl_poll_timeout(pll->rst_bar_addr, val,
+					(val & pll->data->rst_bar_mask), 1,
+					RST_BAR_TIMEOUT);
+		if (ret) {
+			mtk_pll_unprepare_setclr(hw);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mtk_pll_prepare_setclr);
+
+void mtk_pll_unprepare_setclr(struct clk_hw *hw)
+{
+	struct mtk_clk_pll *pll = to_mtk_clk_pll(hw);
+	u32 val = 0;
+
+	if (pll->data->flags & HAVE_RST_BAR) {
+		writel(pll->data->rst_bar_mask, pll->rst_bar_clr_addr);
+
+		/* ignore return code to continue unpreparing the PLL if
+		 * a error occurs on register read poll.