PM / devfreq: rockchip-dfi: Prepare for multiple users

When adding perf support later the DFI must be enabled when
either of devfreq-event or perf is active. Prepare for that
by adding a usage counter for the DFI. Also move enabling
and disabling of the clock away from the devfreq-event specific
functions to which the perf specific part won't have access.

Link: https://lore.kernel.org/all/[email protected]/
Reviewed-by: Jonathan Cameron <[email protected]>
Reviewed-by: Sebastian Reichel <[email protected]>
Acked-by: Chanwoo Choi <[email protected]>
Signed-off-by: Sascha Hauer <[email protected]>
Signed-off-by: Chanwoo Choi <[email protected]>

Author: saschahauer

drivers/devfreq/event/rockchip-dfi.c

@@ -68,14 +68,29 @@ struct rockchip_dfi {
 	void __iomem *regs;
 	struct regmap *regmap_pmu;
 	struct clk *clk;
+	int usecount;
+	struct mutex mutex;
 	u32 ddr_type;
 	unsigned int channel_mask;
 	unsigned int max_channels;
 };
 
-static void rockchip_dfi_start_hardware_counter(struct rockchip_dfi *dfi)
+static int rockchip_dfi_enable(struct rockchip_dfi *dfi)
 {
 	void __iomem *dfi_regs = dfi->regs;
+	int ret = 0;
+
+	mutex_lock(&dfi->mutex);
+
+	dfi->usecount++;
+	if (dfi->usecount > 1)
+		goto out;
+
+	ret = clk_prepare_enable(dfi->clk);
+	if (ret) {
+		dev_err(&dfi->edev->dev, "failed to enable dfi clk: %d\n", ret);
+		goto out;
+	}
 
 	/* clear DDRMON_CTRL setting */
 	writel_relaxed(HIWORD_UPDATE(0, DDRMON_CTRL_TIMER_CNT_EN | DDRMON_CTRL_SOFTWARE_EN |
@@ -100,14 +115,30 @@ static void rockchip_dfi_start_hardware_counter(struct rockchip_dfi *dfi)
 	/* enable count, use software mode */
 	writel_relaxed(HIWORD_UPDATE(DDRMON_CTRL_SOFTWARE_EN, DDRMON_CTRL_SOFTWARE_EN),
 		       dfi_regs + DDRMON_CTRL);
+out:
+	mutex_unlock(&dfi->mutex);
+
+	return ret;
 }
 
-static void rockchip_dfi_stop_hardware_counter(struct rockchip_dfi *dfi)
+static void rockchip_dfi_disable(struct rockchip_dfi *dfi)
 {
 	void __iomem *dfi_regs = dfi->regs;
 
+	mutex_lock(&dfi->mutex);
+
+	dfi->usecount--;
+
+	WARN_ON_ONCE(dfi->usecount < 0);
+
+	if (dfi->usecount > 0)
+		goto out;
+
 	writel_relaxed(HIWORD_UPDATE(0, DDRMON_CTRL_SOFTWARE_EN),
 		       dfi_regs + DDRMON_CTRL);
+	clk_disable_unprepare(dfi->clk);
+out:
+	mutex_unlock(&dfi->mutex);
 }
 
 static void rockchip_dfi_read_counters(struct rockchip_dfi *dfi, struct dmc_count *count)
@@ -125,29 +156,20 @@ static void rockchip_dfi_read_counters(struct rockchip_dfi *dfi, struct dmc_coun
 	}
 }
 
-static int rockchip_dfi_disable(struct devfreq_event_dev *edev)
+static int rockchip_dfi_event_disable(struct devfreq_event_dev *edev)
 {
 	struct rockchip_dfi *dfi = devfreq_event_get_drvdata(edev);
 
-	rockchip_dfi_stop_hardware_counter(dfi);
-	clk_disable_unprepare(dfi->clk);
+	rockchip_dfi_disable(dfi);
 
 	return 0;
 }
 
-static int rockchip_dfi_enable(struct devfreq_event_dev *edev)
+static int rockchip_dfi_event_enable(struct devfreq_event_dev *edev)
 {
 	struct rockchip_dfi *dfi = devfreq_event_get_drvdata(edev);
-	int ret;
-
-	ret = clk_prepare_enable(dfi->clk);
-	if (ret) {
-		dev_err(&edev->dev, "failed to enable dfi clk: %d\n", ret);
-		return ret;
-	}
 
-	rockchip_dfi_start_hardware_counter(dfi);
-	return 0;
+	return rockchip_dfi_enable(dfi);
 }
 
 static int rockchip_dfi_set_event(struct devfreq_event_dev *edev)
@@ -191,8 +213,8 @@ static int rockchip_dfi_get_event(struct devfreq_event_dev *edev,
 }
 
 static const struct devfreq_event_ops rockchip_dfi_ops = {
-	.disable = rockchip_dfi_disable,
-	.enable = rockchip_dfi_enable,
+	.disable = rockchip_dfi_event_disable,
+	.enable = rockchip_dfi_event_enable,
 	.get_event = rockchip_dfi_get_event,
 	.set_event = rockchip_dfi_set_event,
 };
@@ -280,6 +302,7 @@ static int rockchip_dfi_probe(struct platform_device *pdev)
 		return PTR_ERR(dfi->regmap_pmu);
 
 	dfi->dev = dev;
+	mutex_init(&dfi->mutex);
 
 	desc = &dfi->desc;
 	desc->ops = &rockchip_dfi_ops;