Handle the short circuit interrupt and check if the short circuit
interrupt is valid. Re-enable the module to check if it goes
away. Disable the module altogether if the short circuit event
persists.

Signed-off-by: Kiran Gunda <redacted>
Reviewed-by: Bjorn Andersson <redacted>
---
Changes from V3:
	- Added Reviewed by tag.
	- Addressed minor comments from Vinod

  drivers/video/backlight/qcom-wled.c | 132 ++++++++++++++++++++++++++++++++++--
  1 file changed, 128 insertions(+), 4 deletions(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index 362d254..a14f1a6 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c

@@ -10,6 +10,9 @@
   * GNU General Public License for more details.
   */
  
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/ktime.h>
  #include <linux/kernel.h>
  #include <linux/backlight.h>
  #include <linux/module.h>

@@ -64,6 +67,16 @@
  #define WLED3_SINK_REG_STR_CABC(n)			(0x66 + (n * 0x10))
  #define  WLED3_SINK_REG_STR_CABC_MASK			BIT(7)
  
+/* WLED4 specific control registers */
+#define WLED4_CTRL_REG_SHORT_PROTECT			0x5e
+#define  WLED4_CTRL_REG_SHORT_EN_MASK			BIT(7)
+
+#define WLED4_CTRL_REG_SEC_ACCESS			0xd0
+#define  WLED4_CTRL_REG_SEC_UNLOCK			0xa5
+
+#define WLED4_CTRL_REG_TEST1				0xe2
+#define  WLED4_CTRL_REG_TEST1_EXT_FET_DTEST2		0x09
+
  /* WLED4 specific sink registers */
  #define WLED4_SINK_REG_CURR_SINK			0x46
  #define  WLED4_SINK_REG_CURR_SINK_MASK			GENMASK(7, 4)

@@ -113,17 +126,23 @@ struct wled_config {
  	bool cs_out_en;
  	bool ext_gen;
  	bool cabc;
+	bool external_pfet;
  };
  
  struct wled {
  	const char *name;
  	struct device *dev;
  	struct regmap *regmap;
+	struct mutex lock;	/* Lock to avoid race from thread irq handler */
+	ktime_t last_short_event;
  	u16 ctrl_addr;
  	u16 sink_addr;
  	u16 max_string_count;
  	u32 brightness;
  	u32 max_brightness;
+	u32 short_count;
+	bool disabled_by_short;
+	bool has_short_detect;
  
  	struct wled_config cfg;
  	int (*wled_set_brightness)(struct wled *wled, u16 brightness);

@@ -174,6 +193,9 @@ static int wled_module_enable(struct wled *wled, int val)
  {
  	int rc;
  
+	if (wled->disabled_by_short)
+		return -EFAULT;

+
  	rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
  				WLED_CTRL_REG_MOD_EN,
  				WLED_CTRL_REG_MOD_EN_MASK,

@@ -210,18 +232,19 @@ static int wled_update_status(struct backlight_device *bl)
  	    bl->props.state & BL_CORE_FBBLANK)
  		brightness = 0;
  
+	mutex_lock(&wled->lock);
  	if (brightness) {
  		rc = wled->wled_set_brightness(wled, brightness);
  		if (rc < 0) {
  			dev_err(wled->dev, "wled failed to set brightness rc:%d\n",
  				rc);
-			return rc;
+			goto unlock_mutex;
  		}
  
  		rc = wled_sync_toggle(wled);
  		if (rc < 0) {
  			dev_err(wled->dev, "wled sync failed rc:%d\n", rc);
-			return rc;
+			goto unlock_mutex;
  		}
  	}
  

@@ -229,15 +252,61 @@ static int wled_update_status(struct backlight_device *bl)
  		rc = wled_module_enable(wled, !!brightness);
  		if (rc < 0) {
  			dev_err(wled->dev, "wled enable failed rc:%d\n", rc);
-			return rc;
+			goto unlock_mutex;
  		}
  	}
  
  	wled->brightness = brightness;
  
+unlock_mutex:
+	mutex_unlock(&wled->lock);
+
  	return rc;
  }
  
+#define WLED_SHORT_DLY_MS			20
+#define WLED_SHORT_CNT_MAX			5
+#define WLED_SHORT_RESET_CNT_DLY_US		USEC_PER_SEC
+
+static irqreturn_t wled_short_irq_handler(int irq, void *_wled)
+{
+	struct wled *wled = _wled;
+	int rc;
+	s64 elapsed_time;
+
+	wled->short_count++;
+	mutex_lock(&wled->lock);
+	rc = wled_module_enable(wled, false);
+	if (rc < 0) {
+		dev_err(wled->dev, "wled disable failed rc:%d\n", rc);
+		goto unlock_mutex;
+	}
+
+	elapsed_time = ktime_us_delta(ktime_get(),
+				      wled->last_short_event);
+	if (elapsed_time > WLED_SHORT_RESET_CNT_DLY_US)
+		wled->short_count = 0;