TCB hardware is capable of capturing the timer value to registers RA and
RB. On top, it is capable of triggering on compare against a third
register, RC. Add these registers as extensions.

Signed-off-by: Bence Csókás <csokas.bence@prolan.hu>
---

Notes:
    Changes in v2:
    * Add IRQs
    Changes in v3:
    * Move IRQs to previous patch
    Changes in v4:
    * Return the status of the regmap_*() operations
    * Add names for the extension numbers

 drivers/counter/microchip-tcb-capture.c       | 62 +++++++++++++++++++
 .../linux/counter/microchip-tcb-capture.h     |  9 +++
 2 files changed, 71 insertions(+)

diff --git a/drivers/counter/microchip-tcb-capture.c b/drivers/counter/microchip-tcb-capture.c
index cc12c2e2113a..369f69aaf14f 100644
--- a/drivers/counter/microchip-tcb-capture.c
+++ b/drivers/counter/microchip-tcb-capture.c
@@ -254,6 +254,66 @@ static int mchp_tc_count_read(struct counter_device *counter,
 	return 0;
 }
 
+static int mchp_tc_count_cap_read(struct counter_device *counter,
+				  struct counter_count *count, size_t idx, u64 *val)
+{
+	struct mchp_tc_data *const priv = counter_priv(counter);
+	u32 cnt;
+	int ret;
+
+	switch (idx) {
+	case COUNTER_MCHP_EXCAP_RA:
+		ret = regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], RA), &cnt);
+		break;
+	case COUNTER_MCHP_EXCAP_RB:
+		ret = regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], RB), &cnt);
+		break;
+	case COUNTER_MCHP_EXCAP_RC:
+		ret = regmap_read(priv->regmap, ATMEL_TC_REG(priv->channel[0], RC), &cnt);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (!ret)
+		*val = cnt;
+
+	return ret;
+}
+
+static int mchp_tc_count_cap_write(struct counter_device *counter,
+				   struct counter_count *count, size_t idx, u64 val)
+{
+	struct mchp_tc_data *const priv = counter_priv(counter);
+	int ret;
+
+	if (val > U32_MAX)
+		return -ERANGE;
+
+	switch (idx) {
+	case COUNTER_MCHP_EXCAP_RA:
+		ret = regmap_write(priv->regmap, ATMEL_TC_REG(priv->channel[0], RA), val);
+		break;
+	case COUNTER_MCHP_EXCAP_RB:
+		ret = regmap_write(priv->regmap, ATMEL_TC_REG(priv->channel[0], RB), val);
+		break;
+	case COUNTER_MCHP_EXCAP_RC:
+		ret = regmap_write(priv->regmap, ATMEL_TC_REG(priv->channel[0], RC), val);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static DEFINE_COUNTER_ARRAY_CAPTURE(mchp_tc_cnt_cap_array, 3);
+
+static struct counter_comp mchp_tc_count_ext[] = {
+	COUNTER_COMP_ARRAY_CAPTURE(mchp_tc_count_cap_read, mchp_tc_count_cap_write,
+				   mchp_tc_cnt_cap_array),
+};
+
 static struct counter_count mchp_tc_counts[] = {
 	{
 		.id = 0,
@@ -262,6 +322,8 @@ static struct counter_count mchp_tc_counts[] = {
 		.num_functions = ARRAY_SIZE(mchp_tc_count_functions),
 		.synapses = mchp_tc_count_synapses,
 		.num_synapses = ARRAY_SIZE(mchp_tc_count_synapses),
+		.ext = mchp_tc_count_ext,
+		.num_ext = ARRAY_SIZE(mchp_tc_count_ext),
 	},
 };
 
diff --git a/include/uapi/linux/counter/microchip-tcb-capture.h b/include/uapi/linux/counter/microchip-tcb-capture.h
index b91d8954f06e..0bef1c9d1535 100644
--- a/include/uapi/linux/counter/microchip-tcb-capture.h
+++ b/include/uapi/linux/counter/microchip-tcb-capture.h
@@ -12,6 +12,9 @@
  * Count 0
  * \__  Synapse 0 -- Signal 0 (Channel A, i.e. TIOA)
  * \__  Synapse 1 -- Signal 1 (Channel B, i.e. TIOB)
+ * \__  Extension capture0    (RA register)
+ * \__  Extension capture1    (RB register)
+ * \__  Extension capture2    (RC register)
  * 
  * It also supports the following events:
  *
@@ -30,6 +33,12 @@ enum counter_mchp_signals {
 	COUNTER_MCHP_SIG_TIOB,
 };
 
+enum counter_mchp_capture_extensions {
+	COUNTER_MCHP_EXCAP_RA,
+	COUNTER_MCHP_EXCAP_RB,
+	COUNTER_MCHP_EXCAP_RC,
+};
+
 enum counter_mchp_event_channels {
 	COUNTER_MCHP_EVCHN_CV = 0,
 	COUNTER_MCHP_EVCHN_RA = 0,
-- 
2.48.1