[PATCH V3 4/4] backlight: qcom-wled: Update auto calibration support for WLED5

[Kiran Gunda]

Currently, auto calibration logic checks only for OVP_FAULT bit
to be set in FAULT_STATUS register to detect OVP fault. This works
well for WLED4 type. However, WLED5 type has OVP_PRE_ALARM bit
which can indicate a potential OVP fault. Use that as well for
detecting OVP fault and run auto calibration to fix the sink
configuration.

Signed-off-by: Kiran Gunda <kgunda@xxxxxxxxxxxxxx>
---
 drivers/video/backlight/qcom-wled.c | 90 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 88 insertions(+), 2 deletions(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index edbbcb2..5079f1f 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -27,6 +27,7 @@
 #define  WLED3_CTRL_REG_ILIM_FAULT_BIT			BIT(0)
 #define  WLED3_CTRL_REG_OVP_FAULT_BIT			BIT(1)
 #define  WLED4_CTRL_REG_SC_FAULT_BIT			BIT(2)
+#define  WLED5_CTRL_REG_OVP_PRE_ALARM_BIT		BIT(4)
 
 #define WLED3_CTRL_REG_INT_RT_STS			0x10
 #define  WLED3_CTRL_REG_OVP_FAULT_STATUS		BIT(1)
@@ -104,6 +105,10 @@
 
 #define WLED4_SINK_REG_BRIGHT(n)			(0x57 + (n * 0x10))
 
+/* WLED5 specific control registers */
+#define WLED5_CTRL_REG_OVP_INT_CTL			0x5f
+#define  WLED5_CTRL_REG_OVP_INT_TIMER_MASK		GENMASK(2, 0)
+
 /* WLED5 specific sink registers */
 #define WLED5_SINK_REG_MOD_A_EN				0x50
 #define WLED5_SINK_REG_MOD_B_EN				0x60
@@ -394,11 +399,67 @@ static int wled4_ovp_fault_status(struct wled *wled, bool *fault_set)
 	return rc;
 }
 
+static int wled5_ovp_fault_status(struct wled *wled, bool *fault_set)
+{
+	int rc;
+	u32 int_rt_sts, fault_sts;
+
+	*fault_set = false;
+	rc = regmap_read(wled->regmap,
+			wled->ctrl_addr + WLED3_CTRL_REG_INT_RT_STS,
+			&int_rt_sts);
+	if (rc < 0) {
+		dev_err(wled->dev, "Failed to read INT_RT_STS rc=%d\n", rc);
+		return rc;
+	}
+
+	rc = regmap_read(wled->regmap,
+			wled->ctrl_addr + WLED3_CTRL_REG_FAULT_STATUS,
+			&fault_sts);
+	if (rc < 0) {
+		dev_err(wled->dev, "Failed to read FAULT_STATUS rc=%d\n", rc);
+		return rc;
+	}
+
+	if (int_rt_sts & WLED3_CTRL_REG_OVP_FAULT_STATUS)
+		*fault_set = true;
+
+	if (fault_sts & (WLED3_CTRL_REG_OVP_FAULT_BIT |
+			       WLED5_CTRL_REG_OVP_PRE_ALARM_BIT))
+		*fault_set = true;
+
+	if (*fault_set)
+		dev_dbg(wled->dev, "WLED OVP fault detected, int_rt_sts=0x%x fault_sts=0x%x\n",
+			int_rt_sts, fault_sts);
+
+	return rc;
+}
+
 static int wled4_ovp_delay(struct wled *wled)
 {
 	return WLED_SOFT_START_DLY_US;
 }
 
+static int wled5_ovp_delay(struct wled *wled)
+{
+	int rc, delay_us;
+	u32 val;
+	u8 ovp_timer_ms[8] = {1, 2, 4, 8, 12, 16, 20, 24};
+
+	/* For WLED5, get the delay based on OVP timer */
+	rc = regmap_read(wled->regmap, wled->ctrl_addr +
+			 WLED5_CTRL_REG_OVP_INT_CTL, &val);
+	if (rc < 0)
+		delay_us =
+		ovp_timer_ms[val & WLED5_CTRL_REG_OVP_INT_TIMER_MASK] * 1000;
+	else
+		delay_us = 2 * WLED_SOFT_START_DLY_US;
+
+	dev_dbg(wled->dev, "delay_time_us: %d\n", *delay_us);
+
+	return delay_us;
+}
+
 static int wled_update_status(struct backlight_device *bl)
 {
 	struct wled *wled = bl_get_data(bl);
@@ -736,9 +797,32 @@ static bool wled_auto_detection_required(struct wled *wled)
 	if (!wled->auto_detection_ovp_count) {
 		wled->start_ovp_fault_time = ktime_get();
 		wled->auto_detection_ovp_count++;
-	} else {
+		return false;
+	}
+
+	if (wled->version == 5) {
+		/*
+		 * WLED5 has OVP fault density interrupt configuration i.e. to
+		 * count the number of OVP alarms for a certain duration before
+		 * triggering OVP fault interrupt. By default, number of OVP
+		 * fault events counted before an interrupt is fired is 32 and
+		 * the time interval is 12 ms. If we see more than one OVP fault
+		 * interrupt, then that should qualify for a real OVP fault
+		 * condition to run auto calibration algorithm.
+		 */
+
+		if (wled->auto_detection_ovp_count > 1) {
+			elapsed_time_us = ktime_us_delta(ktime_get(),
+					wled->start_ovp_fault_time);
+			wled->auto_detection_ovp_count = 0;
+			dev_dbg(wled->dev, "Elapsed time: %lld us\n",
+				elapsed_time_us);
+			return true;
+		}
+		wled->auto_detection_ovp_count++;
+	} else if (wled->version == 4) {
 		elapsed_time_us = ktime_us_delta(ktime_get(),
-						 wled->start_ovp_fault_time);
+					 wled->start_ovp_fault_time);
 		if (elapsed_time_us > WLED_AUTO_DETECT_CNT_DLY_US)
 			wled->auto_detection_ovp_count = 0;
 		else
@@ -1424,6 +1508,8 @@ static int wled_configure(struct wled *wled)
 		wled->wled_set_brightness = wled5_set_brightness;
 		wled->wled_sync_toggle = wled5_sync_toggle;
 		wled->cabc_config = wled5_cabc_config;
+		wled->wled_ovp_fault_status = wled5_ovp_fault_status;
+		wled->wled_ovp_delay = wled5_ovp_delay;
 		wled->max_string_count = 4;
 
 		prop_addr = of_get_address(dev->of_node, 1, NULL, NULL);
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
 a Linux Foundation Collaborative Project