counter: 104-quad-8: Add Signal polarity component

The 104-quad-8 driver provides support for Index signal polarity modes
via the "index_polarity" Signal component. This patch exposes the same
functionality through the more standard "polarity" Signal component.

Link: https://lore.kernel.org/r/01d00c21873159833035cb6775d0d0e8ad55f2ef.1664204990.git.william.gray@linaro.org/
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/0bf840beee1665e9f04ea82368ecdde87c791a22.1664318353.git.william.gray@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/counter/104-quad-8.c

@@ -549,6 +549,32 @@ static int quad8_index_polarity_set(struct counter_device *counter,
 	return 0;
 }
 
+static int quad8_polarity_read(struct counter_device *counter,
+			       struct counter_signal *signal,
+			       enum counter_signal_polarity *polarity)
+{
+	int err;
+	u32 index_polarity;
+
+	err = quad8_index_polarity_get(counter, signal, &index_polarity);
+	if (err)
+		return err;
+
+	*polarity = (index_polarity) ? COUNTER_SIGNAL_POLARITY_POSITIVE :
+		COUNTER_SIGNAL_POLARITY_NEGATIVE;
+
+	return 0;
+}
+
+static int quad8_polarity_write(struct counter_device *counter,
+				struct counter_signal *signal,
+				enum counter_signal_polarity polarity)
+{
+	const u32 pol = (polarity == COUNTER_SIGNAL_POLARITY_POSITIVE) ? 1 : 0;
+
+	return quad8_index_polarity_set(counter, signal, pol);
+}
+
 static const char *const quad8_synchronous_modes[] = {
 	"non-synchronous",
 	"synchronous"
@@ -977,13 +1003,22 @@ static struct counter_comp quad8_signal_ext[] = {
 			       quad8_signal_fck_prescaler_write)
 };
 
+static const enum counter_signal_polarity quad8_polarities[] = {
+	COUNTER_SIGNAL_POLARITY_POSITIVE,
+	COUNTER_SIGNAL_POLARITY_NEGATIVE,
+};
+
+static DEFINE_COUNTER_AVAILABLE(quad8_polarity_available, quad8_polarities);
+
 static DEFINE_COUNTER_ENUM(quad8_index_pol_enum, quad8_index_polarity_modes);
 static DEFINE_COUNTER_ENUM(quad8_synch_mode_enum, quad8_synchronous_modes);
 
 static struct counter_comp quad8_index_ext[] = {
 	COUNTER_COMP_SIGNAL_ENUM("index_polarity", quad8_index_polarity_get,
 				 quad8_index_polarity_set,
 				 quad8_index_pol_enum),
+	COUNTER_COMP_POLARITY(quad8_polarity_read, quad8_polarity_write,
+			      quad8_polarity_available),
 	COUNTER_COMP_SIGNAL_ENUM("synchronous_mode", quad8_synchronous_mode_get,
 				 quad8_synchronous_mode_set,
 				 quad8_synch_mode_enum),