counter: ftm-quaddec: Convert to new counter registration

This fixes device lifetime issues where it was possible to free a live
struct device.

Fixes: a3b9a99980 ("counter: add FlexTimer Module Quadrature decoder counter driver")
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20211230150300.72196-19-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/counter/ftm-quaddec.c

@@ -26,7 +26,6 @@
 	})
 
 struct ftm_quaddec {
-	struct counter_device counter;
 	struct platform_device *pdev;
 	void __iomem *ftm_base;
 	bool big_endian;
@@ -259,15 +258,17 @@ static struct counter_count ftm_quaddec_counts = {
 
 static int ftm_quaddec_probe(struct platform_device *pdev)
 {
+	struct counter_device *counter;
 	struct ftm_quaddec *ftm;
 
 	struct device_node *node = pdev->dev.of_node;
 	struct resource *io;
 	int ret;
 
-	ftm = devm_kzalloc(&pdev->dev, sizeof(*ftm), GFP_KERNEL);
-	if (!ftm)
+	counter = devm_counter_alloc(&pdev->dev, sizeof(*ftm));
+	if (!counter)
 		return -ENOMEM;
+	ftm = counter_priv(counter);
 
 	io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!io) {
@@ -283,14 +284,13 @@ static int ftm_quaddec_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "Failed to map memory region\n");
 		return -EINVAL;
 	}
-	ftm->counter.name = dev_name(&pdev->dev);
-	ftm->counter.parent = &pdev->dev;
-	ftm->counter.ops = &ftm_quaddec_cnt_ops;
-	ftm->counter.counts = &ftm_quaddec_counts;
-	ftm->counter.num_counts = 1;
-	ftm->counter.signals = ftm_quaddec_signals;
-	ftm->counter.num_signals = ARRAY_SIZE(ftm_quaddec_signals);
-	ftm->counter.priv = ftm;
+	counter->name = dev_name(&pdev->dev);
+	counter->parent = &pdev->dev;
+	counter->ops = &ftm_quaddec_cnt_ops;
+	counter->counts = &ftm_quaddec_counts;
+	counter->num_counts = 1;
+	counter->signals = ftm_quaddec_signals;
+	counter->num_signals = ARRAY_SIZE(ftm_quaddec_signals);
 
 	mutex_init(&ftm->ftm_quaddec_mutex);
 
@@ -300,9 +300,9 @@ static int ftm_quaddec_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	ret = devm_counter_register(&pdev->dev, &ftm->counter);
+	ret = devm_counter_add(&pdev->dev, counter);
 	if (ret)
-		return ret;
+		return dev_err_probe(&pdev->dev, ret, "Failed to add counter\n");
 
 	return 0;
 }