linux-kernel - [PATCH v2 2/6] clk: qcom: clk-alpha-pll: Update set

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Date: Tue, 2 Jul 2024 21:20:40 +0530
From: Satya Priya Kakitapalli <quic_skakitap@...cinc.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Abhishek Sahu <absahu@...eaurora.org>,
        "Rob
 Herring" <robh@...nel.org>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>
CC: Stephen Boyd <sboyd@...eaurora.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, Ajit Pandey <quic_ajipan@...cinc.com>,
        "Imran
 Shaik" <quic_imrashai@...cinc.com>,
        Taniya Das <quic_tdas@...cinc.com>,
        Jagadeesh Kona <quic_jkona@...cinc.com>,
        Satya Priya Kakitapalli
	<quic_skakitap@...cinc.com>
Subject: [PATCH v2 2/6] clk: qcom: clk-alpha-pll: Update set_rate for Zonda
 PLL

The Zonda PLL has a 16 bit signed alpha and in the cases where the alpha
value is greater than 0.5, the L value needs to be adjusted accordingly.
Thus update the logic for the same.

Also, fix zonda set_rate failure when PLL is disabled. Currently,
clk_zonda_pll_set_rate polls for the PLL to lock even if the PLL is
disabled. However, if the PLL is disabled then LOCK_DET will never
assert and we'll return an error. There is no reason to poll LOCK_DET
if the PLL is already disabled, so skip polling in this case.

Signed-off-by: Satya Priya Kakitapalli <quic_skakitap@...cinc.com>
---
 drivers/clk/qcom/clk-alpha-pll.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index 6107c144c0f5..d2bef078588f 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -2061,6 +2061,18 @@ static void clk_zonda_pll_disable(struct clk_hw *hw)
 	regmap_write(regmap, PLL_OPMODE(pll), 0x0);
 }
 
+static void zonda_pll_adjust_l_val(unsigned long rate, unsigned long prate, u32 *l)
+{
+	u64 remainder, quotient;
+
+	quotient = rate;
+	remainder = do_div(quotient, prate);
+	*l = quotient;
+
+	if ((remainder * 2) / prate)
+		*l = *l + 1;
+}
+
 static int clk_zonda_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 				  unsigned long prate)
 {
@@ -2077,9 +2089,15 @@ static int clk_zonda_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 	if (ret < 0)
 		return ret;
 
+	if (a & BIT(15))
+		zonda_pll_adjust_l_val(rate, prate, &l);
+
 	regmap_write(pll->clkr.regmap, PLL_ALPHA_VAL(pll), a);
 	regmap_write(pll->clkr.regmap, PLL_L_VAL(pll), l);
 
+	if (!clk_hw_is_enabled(hw))
+		return 0;
+
 	/* Wait before polling for the frequency latch */
 	udelay(5);
 

-- 
2.25.1