MLK-23195-2 perf/imx_ddr: add stop counter support for i.MX8MP

DDR perf driver now only supports free running counter, add stop counter
support which is compabile with free running counter, since i.MX8MP is
not free running.

Add spinlock for counter value update and clear.

Reviewed-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>

drivers/perf/fsl_imx8_ddr_perf.c

@@ -14,6 +14,7 @@
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
 #include <linux/perf_event.h>
+#include <linux/spinlock.h>
 #include <linux/slab.h>
 
 #define COUNTER_CNTL		0x0
@@ -82,6 +83,7 @@ struct ddr_pmu {
 	const struct fsl_ddr_devtype_data *devtype_data;
 	int irq;
 	int id;
+	spinlock_t lock;
 };
 
 enum ddr_perf_filter_capabilities {
@@ -368,16 +370,20 @@ static void ddr_perf_event_update(struct perf_event *event)
 	struct hw_perf_event *hwc = &event->hw;
 	u64 delta, prev_raw_count, new_raw_count;
 	int counter = hwc->idx;
+	unsigned long flags;
 
-	do {
-		prev_raw_count = local64_read(&hwc->prev_count);
-		new_raw_count = ddr_perf_read_counter(pmu, counter);
-	} while (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
-			new_raw_count) != prev_raw_count);
+	spin_lock_irqsave(&pmu->lock, flags);
+
+	prev_raw_count = local64_read(&hwc->prev_count);
+	new_raw_count = ddr_perf_read_counter(pmu, counter);
 
 	delta = (new_raw_count - prev_raw_count) & 0xFFFFFFFF;
 
 	local64_add(delta, &event->count);
+	local64_set(&hwc->prev_count, new_raw_count);
+
+	spin_unlock_irqrestore(&pmu->lock, flags);
+
 }
 
 static void ddr_perf_counter_enable(struct ddr_pmu *pmu, int config,
@@ -402,6 +408,15 @@ static void ddr_perf_counter_enable(struct ddr_pmu *pmu, int config,
 	}
 }
 
+static bool ddr_perf_counter_overflow(struct ddr_pmu *pmu, int counter)
+{
+	int val;
+
+	val = readl_relaxed(pmu->base + counter * 4 + COUNTER_CNTL);
+
+	return val & CNTL_OVER ? true : false;
+}
+
 static void ddr_perf_event_start(struct perf_event *event, int flags)
 {
 	struct ddr_pmu *pmu = to_ddr_pmu(event->pmu);
@@ -532,9 +547,9 @@ static int ddr_perf_init(struct ddr_pmu *pmu, void __iomem *base,
 
 static irqreturn_t ddr_perf_irq_handler(int irq, void *p)
 {
-	int i;
+	int i, ret;
 	struct ddr_pmu *pmu = (struct ddr_pmu *) p;
-	struct perf_event *event, *cycle_event = NULL;
+	struct perf_event *event;
 
 	/* all counter will stop if cycle counter disabled */
 	ddr_perf_counter_enable(pmu,
@@ -544,12 +559,7 @@ static irqreturn_t ddr_perf_irq_handler(int irq, void *p)
 	/*
 	 * When the cycle counter overflows, all counters are stopped,
 	 * and an IRQ is raised. If any other counter overflows, it
-	 * continues counting, and no IRQ is raised.
-	 *
-	 * Cycles occur at least 4 times as often as other events, so we
-	 * can update all events on a cycle counter overflow and not
-	 * lose events.
-	 *
+	 * will stop and no IRQ is raised.
 	 */
 	for (i = 0; i < NUM_COUNTERS; i++) {
 
@@ -559,17 +569,41 @@ static irqreturn_t ddr_perf_irq_handler(int irq, void *p)
 		event = pmu->events[i];
 
 		ddr_perf_event_update(event);
-
-		if (event->hw.idx == EVENT_CYCLES_COUNTER)
-			cycle_event = event;
 	}
 
+	spin_lock(&pmu->lock);
+
+	for (i = 0; i < NUM_COUNTERS; i++) {
+		if (!pmu->events[i])
+			continue;
+
+		if (i == EVENT_CYCLES_COUNTER)
+			continue;
+
+		event = pmu->events[i];
+
+		/* check non-cycle counters overflow */
+		ret = ddr_perf_counter_overflow(pmu, event->hw.idx);
+		if (ret)
+			dev_warn(pmu->dev, "Counter%d (not cycle counter) overflow happened, data incorrect!\n", i);
+
+		/* clear non-cycle counters */
+		ddr_perf_counter_enable(pmu, event->attr.config, event->hw.idx, true);
+
+		/* update the prev_conter */
+		local64_set(&event->hw.prev_count, 0);
+	}
+
+	if (pmu->events[EVENT_CYCLES_ID])
+		local64_set(&pmu->events[EVENT_CYCLES_ID]->hw.prev_count, 0);
+
+	/* enable cycle counter to start all counters */
 	ddr_perf_counter_enable(pmu,
 			      EVENT_CYCLES_ID,
 			      EVENT_CYCLES_COUNTER,
 			      true);
-	if (cycle_event)
-		ddr_perf_event_update(cycle_event);
+
+	spin_unlock(&pmu->lock);
 
 	return IRQ_HANDLED;
 }
@@ -617,6 +651,7 @@ static int ddr_perf_probe(struct platform_device *pdev)
 	num = ddr_perf_init(pmu, base, &pdev->dev);
 
 	platform_set_drvdata(pdev, pmu);
+	spin_lock_init(&pmu->lock);
 
 	name = devm_kasprintf(&pdev->dev, GFP_KERNEL, DDR_PERF_DEV_NAME "%d",
 			      num);