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@quicinc.com>
Cc: Sibi Sankar <quic_sibis@quicinc.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Tested-by: Steev Klimaszewski <steev@kali.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220728113748.170548-6-krzysztof.kozlowski@linaro.org

drivers/soc/qcom/icc-bwmon.c

@@ -50,6 +50,7 @@
 
 #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
@@ -127,8 +128,12 @@ 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:
@@ -137,7 +142,7 @@ 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)
@@ -208,7 +213,7 @@ 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 */
@@ -304,7 +309,7 @@ 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);