linux-kernel - [PATCH] counter: microchip-tcb-capture: Handle Signal1 read and Synapse

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Date:   Mon, 17 Oct 2022 18:54:04 -0400
From:   William Breathitt Gray <william.gray@...aro.org>
To:     linux-iio@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        stable@...r.kernel.org,
        William Breathitt Gray <william.gray@...aro.org>,
        stable@...nel.org, Kamel Bouhara <kamel.bouhara@...tlin.com>
Subject: [PATCH] counter: microchip-tcb-capture: Handle Signal1 read and Synapse

The signal_read(), action_read(), and action_write() callbacks have been
assuming Signal0 is requested without checking. This results in requests
for Signal1 returning data for Signal0. This patch fixes these
oversights by properly checking for the Signal's id in the respective
callbacks and handling accordingly based on the particular Signal
requested. The trig_inverted member of the mchp_tc_data is removed as
superfluous.

Fixes: 106b104137fd ("counter: Add microchip TCB capture counter")
Cc: stable@...nel.org
Cc: Kamel Bouhara <kamel.bouhara@...tlin.com>
Signed-off-by: William Breathitt Gray <william.gray@...aro.org>
---
 drivers/counter/microchip-tcb-capture.c | 57 ++++++++++++++++---------
 1 file changed, 38 insertions(+), 19 deletions(-)

diff --git a/drivers/counter/microchip-tcb-capture.c b/drivers/counter/microchip-tcb-capture.c
index f9dee15d9777..438f82b07a03 100644
--- a/drivers/counter/microchip-tcb-capture.c
+++ b/drivers/counter/microchip-tcb-capture.c
@@ -28,7 +28,6 @@ struct mchp_tc_data {
 	int qdec_mode;
 	int num_channels;
 	int channel[2];
-	bool trig_inverted;
 };
 
 static const enum counter_function mchp_tc_count_functions[] = {
@@ -153,7 +152,7 @@ static int mchp_tc_count_signal_read(struct counter_device *counter,
 
 	regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], SR), &sr);
 
-	if (priv->trig_inverted)
+	if (signal->id == 1)
 		sigstatus = (sr & ATMEL_TC_MTIOB);
 	else
 		sigstatus = (sr & ATMEL_TC_MTIOA);
@@ -169,26 +168,46 @@ static int mchp_tc_count_action_read(struct counter_device *counter,
 				     enum counter_synapse_action *action)
 {
 	struct mchp_tc_data *const priv = counter_priv(counter);
+	const unsigned int cmr_reg = ATMEL_TC_REG(priv->channel[0], CMR);
+	enum counter_function function;
+	int err;
 	u32 cmr;
 
-	regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], CMR), &cmr);
+	err = mchp_tc_count_function_read(counter, count, &function);
+	if (err)
+		return err;
 
-	switch (cmr & ATMEL_TC_ETRGEDG) {
-	default:
-		*action = COUNTER_SYNAPSE_ACTION_NONE;
-		break;
-	case ATMEL_TC_ETRGEDG_RISING:
-		*action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
-		break;
-	case ATMEL_TC_ETRGEDG_FALLING:
-		*action = COUNTER_SYNAPSE_ACTION_FALLING_EDGE;
-		break;
-	case ATMEL_TC_ETRGEDG_BOTH:
+	/* Default action mode */
+	*action = COUNTER_SYNAPSE_ACTION_NONE;
+
+	switch (function) {
+	case COUNTER_FUNCTION_INCREASE:
+		/* TIOB signal is ignored */
+		if (synapse->signal->id == 1)
+			return 0;
+
+		regmap_read(priv->regmap, cmr_reg, &cmr);
+
+		switch (cmr & ATMEL_TC_ETRGEDG) {
+		case ATMEL_TC_ETRGEDG_RISING:
+			*action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
+			return 0;
+		case ATMEL_TC_ETRGEDG_FALLING:
+			*action = COUNTER_SYNAPSE_ACTION_FALLING_EDGE;
+			return 0;
+		case ATMEL_TC_ETRGEDG_BOTH:
+			*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
+			return 0;
+		default:
+			return 0;
+		}
+	case COUNTER_FUNCTION_QUADRATURE_X4:
 		*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
-		break;
+		return 0;
+	default:
+		/* should never reach this path */
+		return -EINVAL;
 	}
-
-	return 0;
 }
 
 static int mchp_tc_count_action_write(struct counter_device *counter,
@@ -199,8 +218,8 @@ static int mchp_tc_count_action_write(struct counter_device *counter,
 	struct mchp_tc_data *const priv = counter_priv(counter);
 	u32 edge = ATMEL_TC_ETRGEDG_NONE;
 
-	/* QDEC mode is rising edge only */
-	if (priv->qdec_mode)
+	/* QDEC mode is rising edge only; only TIOA handled in non-QDEC mode */
+	if (priv->qdec_mode || synapse->signal->id != 0)
 		return -EINVAL;
 
 	switch (action) {
-- 
2.37.3