wctdm24xxp: Use time range for debouncing polarity.

Eliminate the assumption that the check function is going to be called
for every frame. Also, use a state machine to make polarity debouncing
similar to the other debouncing code.

Signed-off-by: Shaun Ruffell <sruffell@digium.com>

2 files changed, 68 insertions, 30 deletions

diff --git a/drivers/dahdi/wctdm24xxp/base.c b/drivers/dahdi/wctdm24xxp/base.c
index 05637a0..eaad245 100644
--- a/drivers/dahdi/wctdm24xxp/base.c
+++ b/drivers/dahdi/wctdm24xxp/base.c
@@ -1985,6 +1985,62 @@ wctdm_check_battery_present(struct wctdm *wc, struct wctdm_module *const mod)
 }
 
 static void
+wctdm_fxo_check_polarity(struct wctdm *wc, struct wctdm_module *const mod,
+			 const bool positive_polarity)
+{
+	struct fxo *const fxo = &mod->mod.fxo;
+
+	switch (fxo->polarity_state) {
+	case UNKNOWN_POLARITY:
+		fxo->polarity_state = (positive_polarity) ? POLARITY_POSITIVE :
+							    POLARITY_NEGATIVE;
+		break;
+	case POLARITY_DEBOUNCE_POSITIVE:
+		if (!positive_polarity) {
+			fxo->polarity_state = POLARITY_NEGATIVE;
+		} else if (time_after(wc->framecount, fxo->poldebounce_timer)) {
+			fxo->polarity_state = POLARITY_POSITIVE;
+			dahdi_qevent_lock(&mod->chan->chan,
+					  DAHDI_EVENT_POLARITY);
+			if (debug & DEBUG_CARD) {
+				dev_info(&wc->vb.pdev->dev,
+					 "%s: Polarity NEGATIVE -> POSITIVE\n",
+					 mod->chan->chan.name);
+			}
+		}
+		break;
+	case POLARITY_POSITIVE:
+		if (!positive_polarity) {
+			fxo->polarity_state = POLARITY_DEBOUNCE_NEGATIVE;
+			fxo->poldebounce_timer = wc->framecount +
+							POLARITY_DEBOUNCE;
+		}
+		break;
+	case POLARITY_DEBOUNCE_NEGATIVE:
+		if (positive_polarity) {
+			fxo->polarity_state = POLARITY_POSITIVE;
+		} else if (time_after(wc->framecount, fxo->poldebounce_timer)) {
+			dahdi_qevent_lock(&mod->chan->chan,
+					  DAHDI_EVENT_POLARITY);
+			if (debug & DEBUG_CARD) {
+				dev_info(&wc->vb.pdev->dev,
+					 "%s: Polarity POSITIVE -> NEGATIVE\n",
+					 mod->chan->chan.name);
+			}
+			fxo->polarity_state = POLARITY_NEGATIVE;
+		}
+		break;
+	case POLARITY_NEGATIVE:
+		if (positive_polarity) {
+			fxo->polarity_state = POLARITY_DEBOUNCE_POSITIVE;
+			fxo->poldebounce_timer = wc->framecount +
+							POLARITY_DEBOUNCE;
+		}
+		break;
+	};
+}
+
+static void
 wctdm_voicedaa_check_hook(struct wctdm *wc, struct wctdm_module *const mod)
 {
 	signed char b;
@@ -2033,35 +2089,10 @@ wctdm_voicedaa_check_hook(struct wctdm *wc, struct wctdm_module *const mod)
 		wctdm_check_battery_lost(wc, mod);
 	} else {
 		wctdm_check_battery_present(wc, mod);
-
-		if (fxo->lastpol >= 0) {
-			if (b < 0) {
-				fxo->lastpol = -1;
-				fxo->polaritydebounce = POLARITY_DEBOUNCE / MS_PER_CHECK_HOOK;
-			}
-		} 
-		if (fxo->lastpol <= 0) {
-			if (b > 0) {
-				fxo->lastpol = 1;
-				fxo->polaritydebounce = POLARITY_DEBOUNCE / MS_PER_CHECK_HOOK;
-			}
-		}
+		wctdm_fxo_check_polarity(wc, mod,
+					 (fxo->line_voltage_status > 0));
 	}
 
-	if (fxo->polaritydebounce) {
-	        fxo->polaritydebounce--;
-		if (fxo->polaritydebounce < 1) {
-		    if (fxo->lastpol != fxo->polarity) {
-			if (debug & DEBUG_CARD)
-				dev_info(&wc->vb.pdev->dev, "%lu Polarity reversed (%d -> %d)\n", jiffies, 
-				       fxo->polarity, 
-				       fxo->lastpol);
-			if (fxo->polarity)
-				dahdi_qevent_lock(&mod->chan->chan, DAHDI_EVENT_POLARITY);
-			fxo->polarity = fxo->lastpol;
-		    }
-		}
-	}
 	/* Look for neon mwi pulse */
 	if (neonmwi_monitor && !fxo->offhook) {
 		/* Look for 4 consecutive voltage readings
diff --git a/drivers/dahdi/wctdm24xxp/wctdm24xxp.h b/drivers/dahdi/wctdm24xxp/wctdm24xxp.h
index 16dd8c7..21235f5 100644
--- a/drivers/dahdi/wctdm24xxp/wctdm24xxp.h
+++ b/drivers/dahdi/wctdm24xxp/wctdm24xxp.h
@@ -129,6 +129,14 @@ enum ring_detector_state {
 	DEBOUNCING_RINGOFF,
 };
 
+enum polarity_state {
+	UNKNOWN_POLARITY = 0,
+	POLARITY_DEBOUNCE_POSITIVE,
+	POLARITY_POSITIVE,
+	POLARITY_DEBOUNCE_NEGATIVE,
+	POLARITY_NEGATIVE,
+};
+
 struct wctdm_cmd {
 	struct list_head node;
 	struct completion *complete;
@@ -165,13 +173,11 @@ struct wctdm_chan {
 struct fxo {
 	enum ring_detector_state ring_state:4;
 	enum battery_state battery_state:4;
+	enum polarity_state polarity_state:4;
 	u8 ring_polarity_change_count:4;
 	u8 hook_ring_shadow;
 	s8 line_voltage_status;
 	int offhook;
-	int lastpol;
-	int polarity;
-	int polaritydebounce;
 	int neonmwi_state;
 	int neonmwi_last_voltage;
 	unsigned int neonmwi_debounce;
@@ -179,6 +185,7 @@ struct fxo {
 	unsigned long display_fxovoltage;
 	unsigned long ringdebounce_timer;
 	unsigned long battdebounce_timer;
+	unsigned long poldebounce_timer;
 };
 
 struct fxs {