[PATCH V1 2/4] qcom: spmi-wled: Add support for short circuit handling

[Kiran Gunda <kgunda@codeaurora.org>]

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

Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
---
 .../bindings/leds/backlight/qcom-spmi-wled.txt     |  22 ++++
 drivers/video/backlight/qcom-spmi-wled.c           | 126 ++++++++++++++++++++-
 2 files changed, 142 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/leds/backlight/qcom-spmi-wled.txt b/Documentation/devicetree/bindings/leds/backlight/qcom-spmi-wled.txt
index f1ea25b..768608c 100644
--- a/Documentation/devicetree/bindings/leds/backlight/qcom-spmi-wled.txt
+++ b/Documentation/devicetree/bindings/leds/backlight/qcom-spmi-wled.txt
@@ -74,6 +74,26 @@ The PMIC is connected to the host processor via SPMI bus.
 	Definition: Specify if cabc (content adaptive backlight control) is
 		    needed.
 
+- qcom,ext-pfet-sc-pro-en
+	Usage:      optional
+	Value type: <bool>
+	Definition: Specify if external PFET control for short circuit
+		    protection is needed.
+
+- interrupts
+	Usage:      optional
+	Value type: <prop encoded array>
+	Definition: Interrupts associated with WLED. Interrupts can be
+		    specified as per the encoding listed under
+		    Documentation/devicetree/bindings/spmi/
+		    qcom,spmi-pmic-arb.txt.
+
+- interrupt-names
+	Usage:      optional
+	Value type: <string>
+	Definition: Interrupt names associated with the interrupts.
+		    Must be "sc-irq".
+
 Example:
 
 qcom-wled@d800 {
@@ -82,6 +102,8 @@ qcom-wled@d800 {
 	reg-names = "qcom-wled-ctrl-base", "qcom-wled-sink-base";
 	label = "backlight";
 
+	interrupts = <0x3 0xd8 0x2 IRQ_TYPE_EDGE_RISING>;
+	interrupt-names = "sc-irq";
 	qcom,fs-current-limit = <25000>;
 	qcom,current-boost-limit = <970>;
 	qcom,switching-freq = <800>;
diff --git a/drivers/video/backlight/qcom-spmi-wled.c b/drivers/video/backlight/qcom-spmi-wled.c
index 14c3adc..7dbaaa7 100644
--- a/drivers/video/backlight/qcom-spmi-wled.c
+++ b/drivers/video/backlight/qcom-spmi-wled.c
@@ -11,6 +11,9 @@
  * 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>
@@ -23,7 +26,13 @@
 #define QCOM_WLED_DEFAULT_BRIGHTNESS		2048
 #define  QCOM_WLED_MAX_BRIGHTNESS		4095
 
+#define QCOM_WLED_SC_DLY_MS			20
+#define QCOM_WLED_SC_CNT_MAX			5
+#define QCOM_WLED_SC_RESET_CNT_DLY_US		1000000
+
 /* WLED control registers */
+#define QCOM_WLED_CTRL_FAULT_STATUS		0x08
+
 #define QCOM_WLED_CTRL_MOD_ENABLE		0x46
 #define  QCOM_WLED_CTRL_MOD_EN_MASK		BIT(7)
 #define  QCOM_WLED_CTRL_MODULE_EN_SHIFT		7
@@ -37,6 +46,15 @@
 #define QCOM_WLED_CTRL_ILIM			0x4e
 #define  QCOM_WLED_CTRL_ILIM_MASK		GENMASK(2, 0)
 
+#define QCOM_WLED_CTRL_SHORT_PROTECT		0x5e
+#define  QCOM_WLED_CTRL_SHORT_EN_MASK		BIT(7)
+
+#define QCOM_WLED_CTRL_SEC_ACCESS		0xd0
+#define  QCOM_WLED_CTRL_SEC_UNLOCK		0xa5
+
+#define QCOM_WLED_CTRL_TEST1			0xe2
+#define  QCOM_WLED_EXT_FET_DTEST2		0x09
+
 /* WLED sink registers */
 #define QCOM_WLED_SINK_CURR_SINK_EN		0x46
 #define  QCOM_WLED_SINK_CURR_SINK_MASK		GENMASK(7, 4)
@@ -71,19 +89,23 @@ struct qcom_wled_config {
 	u32 switch_freq;
 	u32 fs_current;
 	u32 string_cfg;
+	int sc_irq;
 	bool en_cabc;
+	bool ext_pfet_sc_pro_en;
 };
 
 struct qcom_wled {
 	const char *name;
 	struct platform_device *pdev;
 	struct regmap *regmap;
+	struct mutex lock;
+	struct qcom_wled_config cfg;
+	ktime_t last_sc_event_time;
 	u16 sink_addr;
 	u16 ctrl_addr;
 	u32 brightness;
+	u32 sc_count;
 	bool prev_state;
-
-	struct qcom_wled_config cfg;
 };
 
 static int qcom_wled_module_enable(struct qcom_wled *wled, int val)
@@ -157,25 +179,26 @@ static int qcom_wled_update_status(struct backlight_device *bl)
 	    bl->props.state & BL_CORE_FBBLANK)
 		brightness = 0;
 
+	mutex_lock(&wled->lock);
 	if (brightness) {
 		rc = qcom_wled_set_brightness(wled, brightness);
 		if (rc < 0) {
 			pr_err("wled failed to set brightness rc:%d\n", rc);
-			return rc;
+			goto unlock_mutex;
 		}
 
 		if (!!brightness != wled->prev_state) {
 			rc = qcom_wled_module_enable(wled, !!brightness);
 			if (rc < 0) {
 				pr_err("wled enable failed rc:%d\n", rc);
-				return rc;
+				goto unlock_mutex;
 			}
 		}
 	} else {
 		rc = qcom_wled_module_enable(wled, brightness);
 		if (rc < 0) {
 			pr_err("wled disable failed rc:%d\n", rc);
-			return rc;
+			goto unlock_mutex;
 		}
 	}
 
@@ -184,19 +207,69 @@ static int qcom_wled_update_status(struct backlight_device *bl)
 	rc = qcom_wled_sync_toggle(wled);
 	if (rc < 0) {
 		pr_err("wled sync failed rc:%d\n", rc);
-		return rc;
+		goto unlock_mutex;
 	}
 
 	wled->brightness = brightness;
 
+unlock_mutex:
+	mutex_unlock(&wled->lock);
 	return rc;
 }
 
+static irqreturn_t qcom_wled_sc_irq_handler(int irq, void *_wled)
+{
+	struct qcom_wled *wled = _wled;
+	int rc;
+	u32 val;
+	s64 elapsed_time;
+
+	rc = regmap_read(wled->regmap,
+		wled->ctrl_addr + QCOM_WLED_CTRL_FAULT_STATUS, &val);
+	if (rc < 0) {
+		pr_err("Error in reading WLED_FAULT_STATUS rc=%d\n", rc);
+		return IRQ_HANDLED;
+	}
+
+	wled->sc_count++;
+	pr_err("WLED short circuit detected %d times fault_status=%x\n",
+		wled->sc_count, val);
+	mutex_lock(&wled->lock);
+	rc = qcom_wled_module_enable(wled, false);
+	if (rc < 0) {
+		pr_err("wled disable failed rc:%d\n", rc);
+		goto unlock_mutex;
+	}
+
+	elapsed_time = ktime_us_delta(ktime_get(),
+				wled->last_sc_event_time);
+	if (elapsed_time > QCOM_WLED_SC_RESET_CNT_DLY_US) {
+		wled->sc_count = 0;
+	} else if (wled->sc_count > QCOM_WLED_SC_CNT_MAX) {
+		pr_err("SC trigged %d times, disabling WLED forever!\n",
+			wled->sc_count);
+		goto unlock_mutex;
+	}
+
+	wled->last_sc_event_time = ktime_get();
+
+	msleep(QCOM_WLED_SC_DLY_MS);
+	rc = qcom_wled_module_enable(wled, true);
+	if (rc < 0)
+		pr_err("wled enable failed rc:%d\n", rc);
+
+unlock_mutex:
+	mutex_unlock(&wled->lock);
+
+	return IRQ_HANDLED;
+}
+
 static int qcom_wled_setup(struct qcom_wled *wled)
 {
 	int rc, temp, i;
 	u8 sink_en = 0;
 	u8 string_cfg = wled->cfg.string_cfg;
+	int sc_irq = wled->cfg.sc_irq;
 
 	rc = regmap_update_bits(wled->regmap,
 			wled->ctrl_addr + QCOM_WLED_CTRL_OVP,
@@ -261,6 +334,39 @@ static int qcom_wled_setup(struct qcom_wled *wled)
 		return rc;
 	}
 
+	if (sc_irq >= 0) {
+		rc = devm_request_threaded_irq(&wled->pdev->dev, sc_irq,
+				NULL, qcom_wled_sc_irq_handler, IRQF_ONESHOT,
+				"qcom_wled_sc_irq", wled);
+		if (rc < 0) {
+			pr_err("Unable to request sc(%d) IRQ(err:%d)\n",
+				sc_irq, rc);
+			return rc;
+		}
+
+		rc = regmap_update_bits(wled->regmap,
+				wled->ctrl_addr + QCOM_WLED_CTRL_SHORT_PROTECT,
+				QCOM_WLED_CTRL_SHORT_EN_MASK,
+				QCOM_WLED_CTRL_SHORT_EN_MASK);
+		if (rc < 0)
+			return rc;
+
+		if (wled->cfg.ext_pfet_sc_pro_en) {
+			/* unlock the secure access regisetr */
+			rc = regmap_write(wled->regmap, wled->ctrl_addr +
+					QCOM_WLED_CTRL_SEC_ACCESS,
+					QCOM_WLED_CTRL_SEC_UNLOCK);
+			if (rc < 0)
+				return rc;
+
+			rc = regmap_write(wled->regmap,
+					wled->ctrl_addr + QCOM_WLED_CTRL_TEST1,
+					QCOM_WLED_EXT_FET_DTEST2);
+			if (rc < 0)
+				return rc;
+		}
+	}
+
 	return 0;
 }
 
@@ -271,6 +377,7 @@ static int qcom_wled_setup(struct qcom_wled *wled)
 	.switch_freq = 11,
 	.string_cfg = 0xf,
 	.en_cabc = 0,
+	.ext_pfet_sc_pro_en = 1,
 };
 
 struct qcom_wled_var_cfg {
@@ -376,6 +483,7 @@ static int qcom_wled_configure(struct qcom_wled *wled, struct device *dev)
 		bool *val_ptr;
 	} bool_opts[] = {
 		{ "qcom,en-cabc", &cfg->en_cabc, },
+		{ "qcom,ext-pfet-sc-pro", &cfg->ext_pfet_sc_pro_en, },
 	};
 
 	prop_addr = of_get_address(dev->of_node, 0, NULL, NULL);
@@ -427,6 +535,10 @@ static int qcom_wled_configure(struct qcom_wled *wled, struct device *dev)
 			*bool_opts[i].val_ptr = true;
 	}
 
+	wled->cfg.sc_irq = platform_get_irq_byname(wled->pdev, "sc-irq");
+	if (wled->cfg.sc_irq < 0)
+		dev_dbg(&wled->pdev->dev, "sc irq is not used\n");
+
 	return 0;
 }
 
@@ -469,6 +581,8 @@ static int qcom_wled_probe(struct platform_device *pdev)
 		return rc;
 	}
 
+	mutex_init(&wled->lock);
+
 	val = QCOM_WLED_DEFAULT_BRIGHTNESS;
 	of_property_read_u32(pdev->dev.of_node, "default-brightness", &val);
 	wled->brightness = val;
-- 
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