mfd: da9053: Ensure the FAULT_LOG is cleared during MFD driver probe

The function da9052_clear_fault_log() is added to mitigate the case of
persistent data being transferred between reboots.

Clearance of any the persistent information within the DA9053 FAULT_LOG
register must be completed during start-up so the fault-log does not
continue with previous values. A clearance function has been added here in
the kernel driver because wiping the fault-log cannot be counted on outside
the Linux kernel.
Signed-off-by: Steve Twiss <stwiss.opensource@diasemi.com>
Reviewed-by: Adam Thomson <adam.thomson.opensource@diasemi.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/da9052-core.c

@@ -167,6 +167,7 @@ static bool da9052_reg_writeable(struct device *dev, unsigned int reg)
 	case DA9052_EVENT_B_REG:
 	case DA9052_EVENT_C_REG:
 	case DA9052_EVENT_D_REG:
+	case DA9052_FAULTLOG_REG:
 	case DA9052_IRQ_MASK_A_REG:
 	case DA9052_IRQ_MASK_B_REG:
 	case DA9052_IRQ_MASK_C_REG:
@@ -541,6 +542,52 @@ const struct regmap_config da9052_regmap_config = {
 };
 EXPORT_SYMBOL_GPL(da9052_regmap_config);
 
+static int da9052_clear_fault_log(struct da9052 *da9052)
+{
+	int ret = 0;
+	int fault_log = 0;
+
+	fault_log = da9052_reg_read(da9052, DA9052_FAULTLOG_REG);
+	if (fault_log < 0) {
+		dev_err(da9052->dev,
+			"Cannot read FAULT_LOG %d\n", fault_log);
+		return fault_log;
+	}
+
+	if (fault_log) {
+		if (fault_log & DA9052_FAULTLOG_TWDERROR)
+			dev_dbg(da9052->dev,
+				"Fault log entry detected: TWD_ERROR\n");
+		if (fault_log & DA9052_FAULTLOG_VDDFAULT)
+			dev_dbg(da9052->dev,
+				"Fault log entry detected: VDD_FAULT\n");
+		if (fault_log & DA9052_FAULTLOG_VDDSTART)
+			dev_dbg(da9052->dev,
+				"Fault log entry detected: VDD_START\n");
+		if (fault_log & DA9052_FAULTLOG_TEMPOVER)
+			dev_dbg(da9052->dev,
+				"Fault log entry detected: TEMP_OVER\n");
+		if (fault_log & DA9052_FAULTLOG_KEYSHUT)
+			dev_dbg(da9052->dev,
+				"Fault log entry detected: KEY_SHUT\n");
+		if (fault_log & DA9052_FAULTLOG_NSDSET)
+			dev_dbg(da9052->dev,
+				"Fault log entry detected: nSD_SHUT\n");
+		if (fault_log & DA9052_FAULTLOG_WAITSET)
+			dev_dbg(da9052->dev,
+				"Fault log entry detected: WAIT_SHUT\n");
+
+		ret = da9052_reg_write(da9052,
+					DA9052_FAULTLOG_REG,
+					0xFF);
+		if (ret < 0)
+			dev_err(da9052->dev,
+				"Cannot reset FAULT_LOG values %d\n", ret);
+	}
+
+	return ret;
+}
+
 int da9052_device_init(struct da9052 *da9052, u8 chip_id)
 {
 	struct da9052_pdata *pdata = dev_get_platdata(da9052->dev);
@@ -549,6 +596,10 @@ int da9052_device_init(struct da9052 *da9052, u8 chip_id)
 	mutex_init(&da9052->auxadc_lock);
 	init_completion(&da9052->done);
 
+	ret = da9052_clear_fault_log(da9052);
+	if (ret < 0)
+		dev_warn(da9052->dev, "Cannot clear FAULT_LOG\n");
+
 	if (pdata && pdata->init != NULL)
 		pdata->init(da9052);