linux-kernel - [PATCH 05/10] soc: qcom: icc-bwmon: clear all registers on init

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Date:   Wed, 20 Jul 2022 21:28:02 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Georgi Djakov <djakov@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Rajendra Nayak <quic_rjendra@...cinc.com>
Subject: [PATCH 05/10] soc: qcom: icc-bwmon: clear all registers on init

The hardware programming guide recommends to clear all registers on
first initialization, through separate field in BWMON_CLEAR register.

This makes sense in general but especially if driver is rebound to avoid
spurious/early interrupts.

Cc: Rajendra Nayak <quic_rjendra@...cinc.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
---
 drivers/soc/qcom/icc-bwmon.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/soc/qcom/icc-bwmon.c b/drivers/soc/qcom/icc-bwmon.c
index 93c3cec84721..dcd445af6488 100644
--- a/drivers/soc/qcom/icc-bwmon.c
+++ b/drivers/soc/qcom/icc-bwmon.c
@@ -51,6 +51,7 @@
 
 #define BWMON_CLEAR				0x2a4
 #define BWMON_CLEAR_CLEAR			BIT(0)
+#define BWMON_CLEAR_CLEAR_ALL			BIT(1)
 
 #define BWMON_SAMPLE_WINDOW			0x2a8
 #define BWMON_THRESHOLD_HIGH			0x2ac
@@ -128,8 +129,12 @@ struct icc_bwmon {
 	unsigned int current_kbps;
 };
 
-static void bwmon_clear_counters(struct icc_bwmon *bwmon)
+static void bwmon_clear_counters(struct icc_bwmon *bwmon, bool clear_all)
 {
+	unsigned int val = BWMON_CLEAR_CLEAR;
+
+	if (clear_all)
+		val |= BWMON_CLEAR_CLEAR_ALL;
 	/*
 	 * Clear counters. The order and barriers are
 	 * important. Quoting downstream Qualcomm msm-4.9 tree:
@@ -138,7 +143,7 @@ static void bwmon_clear_counters(struct icc_bwmon *bwmon)
 	 * region. So, we need to make sure the counter clear is completed
 	 * before we try to clear the IRQ or do any other counter operations.
 	 */
-	writel(BWMON_CLEAR_CLEAR, bwmon->base + BWMON_CLEAR);
+	writel(val, bwmon->base + BWMON_CLEAR);
 }
 
 static void bwmon_clear_irq(struct icc_bwmon *bwmon)
@@ -209,7 +214,7 @@ static void bwmon_start(struct icc_bwmon *bwmon)
 	unsigned int thres_count;
 	int window;
 
-	bwmon_clear_counters(bwmon);
+	bwmon_clear_counters(bwmon, true);
 
 	window = mult_frac(bwmon->data->sample_ms, HW_TIMER_HZ, MSEC_PER_SEC);
 	/* Maximum sampling window: 0xfffff */
@@ -305,7 +310,7 @@ static irqreturn_t bwmon_intr_thread(int irq, void *dev_id)
 	bwmon_set_threshold(bwmon, BWMON_THRESHOLD_HIGH, up_kbps);
 	bwmon_set_threshold(bwmon, BWMON_THRESHOLD_MED, down_kbps);
 	/* Write barriers in bwmon_clear_counters() */
-	bwmon_clear_counters(bwmon);
+	bwmon_clear_counters(bwmon, false);
 	bwmon_clear_irq(bwmon);
 	bwmon_enable(bwmon, irq_enable);
 
-- 
2.34.1