linux-kernel - [PATCH v4 2/9] clk: qcom: clk-alpha-pll: introduce stromer plus ops

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Message-ID: <5e1c2ff9522dd29e69f286dbbe1c867433763629.1697694811.git.quic_varada@quicinc.com>
Date:   Thu, 19 Oct 2023 14:10:36 +0530
From:   Varadarajan Narayanan <quic_varada@...cinc.com>
To:     <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...aro.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <mturquette@...libre.com>, <sboyd@...nel.org>, <rafael@...nel.org>,
        <viresh.kumar@...aro.org>, <ilia.lin@...nel.org>,
        <sivaprak@...eaurora.org>, <quic_kathirav@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-clk@...r.kernel.org>,
        <linux-pm@...r.kernel.org>
CC:     Varadarajan Narayanan <quic_varada@...cinc.com>
Subject: [PATCH v4 2/9] clk: qcom: clk-alpha-pll: introduce stromer plus ops

Stromer plus APSS PLL does not support dynamic frequency scaling.
To switch between frequencies, we have to shut down the PLL,
configure the L and ALPHA values and turn on again. So introduce the
separate set of ops for Stromer Plus PLL.

Signed-off-by: Kathiravan T <quic_kathirav@...cinc.com>
Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
---
v4:	Ensure PLL is enabled before re-enabling
v3:	Use prepare/unprepare instead of disable/enable in clk_alpha_pll_stromer_plus_ops
v2:	Use clk_alpha_pll_stromer_determine_rate, instead of adding new
	clk_alpha_pll_stromer_plus_determine_rate as the alpha pll width
	is same for both

	Fix review comments
		udelay(50) -> usleep_range(50, 60)
		Remove SoC-specific from print message
---
 drivers/clk/qcom/clk-alpha-pll.c | 63 ++++++++++++++++++++++++++++++++++++++++
 drivers/clk/qcom/clk-alpha-pll.h |  1 +
 2 files changed, 64 insertions(+)

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index 4edbf77..05898d2 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -2508,3 +2508,66 @@ const struct clk_ops clk_alpha_pll_stromer_ops = {
 	.set_rate = clk_alpha_pll_stromer_set_rate,
 };
 EXPORT_SYMBOL_GPL(clk_alpha_pll_stromer_ops);
+
+static int clk_alpha_pll_stromer_plus_set_rate(struct clk_hw *hw,
+					       unsigned long rate,
+					       unsigned long prate)
+{
+	struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
+	u32 l, alpha_width = pll_alpha_width(pll);
+	int ret, pll_mode;
+	u64 a;
+
+	rate = alpha_pll_round_rate(rate, prate, &l, &a, alpha_width);
+
+	ret = regmap_read(pll->clkr.regmap, PLL_MODE(pll), &pll_mode);
+	if (ret)
+		return ret;
+
+	regmap_write(pll->clkr.regmap, PLL_MODE(pll), 0);
+
+	/* Delay of 2 output clock ticks required until output is disabled */
+	udelay(1);
+
+	regmap_write(pll->clkr.regmap, PLL_L_VAL(pll), l);
+
+	if (alpha_width > ALPHA_BITWIDTH)
+		a <<= alpha_width - ALPHA_BITWIDTH;
+
+	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), a);
+	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL_U(pll),
+					a >> ALPHA_BITWIDTH);
+
+	regmap_write(pll->clkr.regmap, PLL_MODE(pll), PLL_BYPASSNL);
+
+	/* Wait five micro seconds or more */
+	udelay(5);
+	regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll), PLL_RESET_N,
+			   PLL_RESET_N);
+
+	/* The lock time should be less than 50 micro seconds worst case */
+	usleep_range(50, 60);
+
+	ret = wait_for_pll_enable_lock(pll);
+	if (ret) {
+		pr_err("Wait for PLL enable lock failed [%s] %d\n",
+		       clk_hw_get_name(hw), ret);
+		return ret;
+	}
+
+	if (pll_mode & PLL_OUTCTRL)
+		regmap_update_bits(pll->clkr.regmap, PLL_MODE(pll), PLL_OUTCTRL,
+				   PLL_OUTCTRL);
+
+	return 0;
+}
+
+const struct clk_ops clk_alpha_pll_stromer_plus_ops = {
+	.prepare = clk_alpha_pll_enable,
+	.unprepare = clk_alpha_pll_disable,
+	.is_enabled = clk_alpha_pll_is_enabled,
+	.recalc_rate = clk_alpha_pll_recalc_rate,
+	.determine_rate = clk_alpha_pll_stromer_determine_rate,
+	.set_rate = clk_alpha_pll_stromer_plus_set_rate,
+};
+EXPORT_SYMBOL_GPL(clk_alpha_pll_stromer_plus_ops);
diff --git a/drivers/clk/qcom/clk-alpha-pll.h b/drivers/clk/qcom/clk-alpha-pll.h
index 3b24a66..a1a75bb 100644
--- a/drivers/clk/qcom/clk-alpha-pll.h
+++ b/drivers/clk/qcom/clk-alpha-pll.h
@@ -152,6 +152,7 @@ extern const struct clk_ops clk_alpha_pll_postdiv_ops;
 extern const struct clk_ops clk_alpha_pll_huayra_ops;
 extern const struct clk_ops clk_alpha_pll_postdiv_ro_ops;
 extern const struct clk_ops clk_alpha_pll_stromer_ops;
+extern const struct clk_ops clk_alpha_pll_stromer_plus_ops;
 
 extern const struct clk_ops clk_alpha_pll_fabia_ops;
 extern const struct clk_ops clk_alpha_pll_fixed_fabia_ops;
-- 
2.7.4