[v2 4/4] regulator: qcom: labibb: Add SC interrupt handling

[Sumit Semwal <sumit.semwal@linaro.org>]

From: Nisha Kumari <nishakumari@codeaurora.org>

Add Short circuit interrupt handling and recovery for the lab and
ibb regulators on qcom platforms.

The client panel drivers need to register for REGULATOR_EVENT_OVER_CURRENT
notification which will be triggered on short circuit. They should
try to enable the regulator once, and if it doesn't get enabled,
handle shutting down the panel accordingly.

Signed-off-by: Nisha Kumari <nishakumari@codeaurora.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>

--
v2: sumits: reworked handling to user regmap_read_poll_timeout, and handle it
    per-regulator instead of clearing both lab and ibb errors on either irq
    triggering. Also added REGULATOR_EVENT_OVER_CURRENT handling and
    notification to clients.
---
 drivers/regulator/qcom-labibb-regulator.c | 103 +++++++++++++++++++++-
 1 file changed, 100 insertions(+), 3 deletions(-)

diff --git a/drivers/regulator/qcom-labibb-regulator.c b/drivers/regulator/qcom-labibb-regulator.c
index a9dc7c060375..3539631c9f96 100644
--- a/drivers/regulator/qcom-labibb-regulator.c
+++ b/drivers/regulator/qcom-labibb-regulator.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2019, The Linux Foundation. All rights reserved.
 
+#include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/of_irq.h>
 #include <linux/of.h>
@@ -18,11 +19,15 @@
 #define REG_LABIBB_ENABLE_CTL		0x46
 #define LABIBB_STATUS1_VREG_OK_BIT	BIT(7)
 #define LABIBB_CONTROL_ENABLE		BIT(7)
+#define LABIBB_STATUS1_SC_DETECT_BIT	BIT(6)
 
 #define LAB_ENABLE_CTL_MASK		BIT(7)
 #define IBB_ENABLE_CTL_MASK		(BIT(7) | BIT(6))
 
 #define POWER_DELAY			8000
+#define POLLING_SCP_DONE_INTERVAL_US	5000
+#define POLLING_SCP_TIMEOUT		16000
+
 
 struct labibb_regulator {
 	struct regulator_desc		desc;
@@ -30,6 +35,8 @@ struct labibb_regulator {
 	struct regmap			*regmap;
 	struct regulator_dev		*rdev;
 	u16				base;
+	int				sc_irq;
+	int				vreg_enabled;
 	u8				type;
 };
 
@@ -112,9 +119,10 @@ static int qcom_labibb_regulator_enable(struct regulator_dev *rdev)
 		return ret;
 	}
 
-	if (ret)
+	if (ret) {
+		reg->vreg_enabled = 1;
 		return 0;
-
+	}
 
 	dev_err(reg->dev, "Can't enable %s\n", reg->desc.name);
 	return -EINVAL;
@@ -140,8 +148,10 @@ static int qcom_labibb_regulator_disable(struct regulator_dev *rdev)
 		return ret;
 	}
 
-	if (!ret)
+	if (!ret) {
+		reg->vreg_enabled = 0;
 		return 0;
+	}
 
 	dev_err(reg->dev, "Can't disable %s\n", reg->desc.name);
 	return -EINVAL;
@@ -153,6 +163,70 @@ static struct regulator_ops qcom_labibb_ops = {
 	.is_enabled		= qcom_labibb_regulator_is_enabled,
 };
 
+
+static irqreturn_t labibb_sc_err_handler(int irq, void *_reg)
+{
+	int ret, count;
+	u16 reg;
+	u8 sc_err_mask;
+	unsigned int val;
+	struct labibb_regulator *labibb_reg = (struct labibb_regulator *)_reg;
+	bool in_sc_err, reg_en, scp_done = false;
+
+	if (irq == labibb_reg->sc_irq)
+		reg = labibb_reg->base + REG_LABIBB_STATUS1;
+	else
+		return IRQ_HANDLED;
+
+	sc_err_mask = LABIBB_STATUS1_SC_DETECT_BIT;
+
+	ret = regmap_bulk_read(labibb_reg->regmap, reg, &val, 1);
+	if (ret < 0) {
+		dev_err(labibb_reg->dev, "Read failed, ret=%d\n", ret);
+		return IRQ_HANDLED;
+	}
+	dev_dbg(labibb_reg->dev, "%s SC error triggered! STATUS1 = %d\n",
+		labibb_reg->desc.name, val);
+
+	in_sc_err = !!(val & sc_err_mask);
+
+	/*
+	 * The SC(short circuit) fault would trigger PBS(Portable Batch
+	 * System) to disable regulators for protection. This would
+	 * cause the SC_DETECT status being cleared so that it's not
+	 * able to get the SC fault status.
+	 * Check if the regulator is enabled in the driver but
+	 * disabled in hardware, this means a SC fault had happened
+	 * and SCP handling is completed by PBS.
+	 */
+	if (!in_sc_err) {
+
+		reg = labibb_reg->base + REG_LABIBB_ENABLE_CTL;
+
+		ret = regmap_read_poll_timeout(labibb_reg->regmap,
+					reg, val,
+					!(val & LABIBB_CONTROL_ENABLE),
+					POLLING_SCP_DONE_INTERVAL_US,
+					POLLING_SCP_TIMEOUT);
+
+		if (!ret && labibb_reg->vreg_enabled) {
+			dev_dbg(labibb_reg->dev,
+				"%s has been disabled by SCP\n",
+				labibb_reg->desc.name);
+			scp_done = true;
+		}
+	}
+
+	if (in_sc_err || scp_done) {
+		regulator_lock(labibb_reg->rdev);
+		regulator_notifier_call_chain(labibb_reg->rdev,
+						REGULATOR_EVENT_OVER_CURRENT,
+						NULL);
+		regulator_unlock(labibb_reg->rdev);
+	}
+	return IRQ_HANDLED;
+}
+
 static int register_labibb_regulator(struct qcom_labibb *labibb,
 				const struct labibb_regulator_data *reg_data,
 				struct device_node *of_node)
@@ -181,6 +255,29 @@ static int register_labibb_regulator(struct qcom_labibb *labibb,
 	reg->desc.type = REGULATOR_VOLTAGE;
 	reg->desc.ops = &qcom_labibb_ops;
 
+	reg->sc_irq = -EINVAL;
+	ret = of_irq_get_byname(of_node, reg_data->irq_name);
+	if (ret < 0)
+		dev_dbg(labibb->dev,
+			"Unable to get %s, ret = %d\n",
+			reg_data->irq_name, ret);
+	else
+		reg->sc_irq = ret;
+
+	if (reg->sc_irq > 0) {
+		ret = devm_request_threaded_irq(labibb->dev,
+						reg->sc_irq,
+						NULL, labibb_sc_err_handler,
+						IRQF_ONESHOT |
+						IRQF_TRIGGER_RISING,
+						reg_data->irq_name, labibb);
+		if (ret) {
+			dev_err(labibb->dev, "Failed to register '%s' irq ret=%d\n",
+				reg_data->irq_name, ret);
+			return ret;
+		}
+	}
+
 	cfg.dev = labibb->dev;
 	cfg.driver_data = reg;
 	cfg.regmap = labibb->regmap;
-- 
2.26.2