[PATCH 4/5] power: supply: qcom_smbx: validate battery float voltage

[Robin Snyders via B4 Relay]

From: Robin Snyders <robin@xxxxxxxxxxx>

power_supply_get_battery_info() leaves absent optional properties at
-EINVAL. The driver uses voltage_max_design_uv without checking it, so a
missing or out-of-range value can become an invalid float-voltage
selector.

Prefer the constant-charge voltage because it describes the charger's CV
target, then fall back to the battery design voltage. Both properties are
optional in the simple-battery binding, so preserve the hardware setting
when neither is present. Reject a supplied target outside the SMB2 range.

smb_init_hw() enables charging before battery data is parsed and before
the remaining fallible probe steps. Save the initial charging-enable bit
and install a managed rollback before initialization. Keep the rollback
active across battery-info, voltage, IRQ and wake-IRQ setup, then remove it
only after probe can no longer fail.

Fixes: 8648aeb5d7b7 ("power: supply: add Qualcomm PMI8998 SMB2 Charger driver")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Robin Snyders <robin@xxxxxxxxxxx>
---
 drivers/power/supply/qcom_smbx.c | 61 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 58 insertions(+), 3 deletions(-)

diff --git a/drivers/power/supply/qcom_smbx.c b/drivers/power/supply/qcom_smbx.c
index e236b95c0ebf3..55ffe9857e494 100644
--- a/drivers/power/supply/qcom_smbx.c
+++ b/drivers/power/supply/qcom_smbx.c
@@ -353,6 +353,7 @@
 /* pmi8998 registers represent current in increments of 1/40th of an amp */
 #define CURRENT_SCALE_FACTOR				25000
 #define SMB2_FLOAT_VOLTAGE_MIN_UV			3487500
+#define SMB2_FLOAT_VOLTAGE_MAX_UV			4920000
 #define SMB2_FLOAT_VOLTAGE_STEP_UV			7500
 /* clang-format on */
 
@@ -380,6 +381,7 @@ struct smb_init_register {
  * @base:		Base address for smb registers
  * @regmap:		Register map
  * @batt_info:		Battery data from DT
+ * @initial_charge_enable: Charging enable state before hardware setup
  * @status_change_work: Worker to handle plug/unplug events
  * @cable_irq:		USB plugin IRQ
  * @wakeup_enabled:	If the cable IRQ will cause a wakeup
@@ -393,6 +395,7 @@ struct smb_chip {
 	unsigned int base;
 	struct regmap *regmap;
 	struct power_supply_battery_info *batt_info;
+	u8 initial_charge_enable;
 
 	struct delayed_work status_change_work;
 	int cable_irq;
@@ -905,6 +908,19 @@ static int smb_init_hw(struct smb_chip *chip)
 	return 0;
 }
 
+static void smb_restore_charge_enable(void *data)
+{
+	struct smb_chip *chip = data;
+	int rc;
+
+	rc = regmap_update_bits(chip->regmap,
+				chip->base + CHARGING_ENABLE_CMD,
+				CHARGING_ENABLE_CMD_BIT,
+				chip->initial_charge_enable);
+	if (rc < 0)
+		dev_err(chip->dev, "Couldn't restore charging state: %d\n", rc);
+}
+
 static int smb_init_irq(struct smb_chip *chip, int *irq, const char *name,
 			 irqreturn_t (*handler)(int irq, void *data))
 {
@@ -931,6 +947,9 @@ static int smb_probe(struct platform_device *pdev)
 	struct power_supply_config supply_config = {};
 	struct power_supply_desc *desc;
 	struct smb_chip *chip;
+	unsigned int charge_enable;
+	unsigned int float_voltage_sel;
+	int float_voltage_uv;
 	int rc, irq;
 
 	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
@@ -961,6 +980,18 @@ static int smb_probe(struct platform_device *pdev)
 				     "Couldn't get usbin_i IIO channel\n");
 	}
 
+	rc = regmap_read(chip->regmap, chip->base + CHARGING_ENABLE_CMD,
+			 &charge_enable);
+	if (rc < 0)
+		return dev_err_probe(chip->dev, rc,
+				     "Couldn't read charging state\n");
+
+	chip->initial_charge_enable = charge_enable & CHARGING_ENABLE_CMD_BIT;
+	rc = devm_add_action_or_reset(chip->dev, smb_restore_charge_enable, chip);
+	if (rc)
+		return dev_err_probe(chip->dev, rc,
+				     "Couldn't register charging state rollback\n");
+
 	rc = smb_init_hw(chip);
 	if (rc < 0)
 		return rc;
@@ -995,13 +1026,35 @@ static int smb_probe(struct platform_device *pdev)
 		return dev_err_probe(chip->dev, rc,
 				     "Failed to init status change work\n");
 
-	rc = (chip->batt_info->voltage_max_design_uv -
-	      SMB2_FLOAT_VOLTAGE_MIN_UV) / SMB2_FLOAT_VOLTAGE_STEP_UV;
+	if (power_supply_battery_info_has_prop(chip->batt_info,
+					       POWER_SUPPLY_PROP_CONSTANT_CHARGE_VOLTAGE_MAX)) {
+		float_voltage_uv =
+			chip->batt_info->constant_charge_voltage_max_uv;
+	} else if (power_supply_battery_info_has_prop(chip->batt_info,
+					      POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN)) {
+		float_voltage_uv = chip->batt_info->voltage_max_design_uv;
+	} else {
+		dev_warn(chip->dev, "No battery float voltage; preserving hardware setting\n");
+		goto skip_float_voltage;
+	}
+
+	if (float_voltage_uv < SMB2_FLOAT_VOLTAGE_MIN_UV ||
+	    float_voltage_uv > SMB2_FLOAT_VOLTAGE_MAX_UV)
+		return dev_err_probe(chip->dev, -EINVAL,
+				     "float voltage %d uV outside %d-%d uV\n",
+				     float_voltage_uv,
+				     SMB2_FLOAT_VOLTAGE_MIN_UV,
+				     SMB2_FLOAT_VOLTAGE_MAX_UV);
+
+	float_voltage_sel =
+		(float_voltage_uv - SMB2_FLOAT_VOLTAGE_MIN_UV) /
+		SMB2_FLOAT_VOLTAGE_STEP_UV;
 	rc = regmap_update_bits(chip->regmap, chip->base + FLOAT_VOLTAGE_CFG,
-				FLOAT_VOLTAGE_SETTING_MASK, rc);
+				FLOAT_VOLTAGE_SETTING_MASK, float_voltage_sel);
 	if (rc < 0)
 		return dev_err_probe(chip->dev, rc, "Couldn't set vbat max\n");
 
+skip_float_voltage:
 	rc = smb_init_irq(chip, &irq, "bat-ov", smb_handle_batt_overvoltage);
 	if (rc < 0)
 		return rc;
@@ -1025,6 +1078,8 @@ static int smb_probe(struct platform_device *pdev)
 	if (rc < 0)
 		return dev_err_probe(chip->dev, rc, "Couldn't set wake irq\n");
 
+	devm_remove_action(chip->dev, smb_restore_charge_enable, chip);
+
 	platform_set_drvdata(pdev, chip);
 
 	/* Initialise charger state */

-- 
2.54.0