[PATCH v6 3/8] power: supply: max8997_charger: Set CHARGER current limit

[Timon Baetz <timon.baetz@protonmail.com>]

Register for extcon notification and set charging current depending on
the detected cable type. Current values are taken from vendor kernel,
where most charger types end up setting 650mA [0].

Also enable and disable the CHARGER regulator based on extcon events.

[0] https://github.com/krzk/linux-vendor-backup/blob/samsung/galaxy-s2-epic-4g-touch-sph-d710-exynos4210-dump/drivers/misc/max8997-muic.c#L1675-L1678

Signed-off-by: Timon Baetz <timon.baetz@protonmail.com>
---
v6: dev_info() instead of dev_err().
v5: Use devm_regulator_get_optional(), dev_err() on failure.
    dev_err() on extcon_get_edev_by_phandle() failure.
v4: Make extcon and charger-supply optional.
v3: Split MFD change.
    return on regulator_set_current_limit() failure.
v2: Split DTS changes.
    Add missing include.
    Rename charger_data members.
    Disable regulator on regulator_set_current_limit() failure.
    Fix ret declaration.
    Remove unneeded variables.
    Don't dev_err() on deferral.
    Get regulator and extcon from DTS.
    Use devm_regulator_get(). 
    Fix indentation.

 drivers/power/supply/max8997_charger.c | 96 ++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)

diff --git a/drivers/power/supply/max8997_charger.c b/drivers/power/supply/max8997_charger.c
index 1947af25879a..23df91ed2c72 100644
--- a/drivers/power/supply/max8997_charger.c
+++ b/drivers/power/supply/max8997_charger.c
@@ -6,12 +6,14 @@
 //  MyungJoo Ham <myungjoo.ham@samsung.com>
 
 #include <linux/err.h>
+#include <linux/extcon.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/platform_device.h>
 #include <linux/power_supply.h>
 #include <linux/mfd/max8997.h>
 #include <linux/mfd/max8997-private.h>
+#include <linux/regulator/consumer.h>
 
 /* MAX8997_REG_STATUS4 */
 #define DCINOK_SHIFT		1
@@ -31,6 +33,10 @@ struct charger_data {
 	struct device *dev;
 	struct max8997_dev *iodev;
 	struct power_supply *battery;
+	struct regulator *reg;
+	struct extcon_dev *edev;
+	struct notifier_block extcon_nb;
+	struct work_struct extcon_work;
 };
 
 static enum power_supply_property max8997_battery_props[] = {
@@ -88,6 +94,67 @@ static int max8997_battery_get_property(struct power_supply *psy,
 	return 0;
 }
 
+static void max8997_battery_extcon_evt_stop_work(void *data)
+{
+	struct charger_data *charger = data;
+
+	cancel_work_sync(&charger->extcon_work);
+}
+
+static void max8997_battery_extcon_evt_worker(struct work_struct *work)
+{
+	struct charger_data *charger =
+	    container_of(work, struct charger_data, extcon_work);
+	struct extcon_dev *edev = charger->edev;
+	int current_limit;
+
+	if (extcon_get_state(edev, EXTCON_CHG_USB_SDP) > 0) {
+		dev_dbg(charger->dev, "USB SDP charger is connected\n");
+		current_limit = 450000;
+	} else if (extcon_get_state(edev, EXTCON_CHG_USB_DCP) > 0) {
+		dev_dbg(charger->dev, "USB DCP charger is connected\n");
+		current_limit = 650000;
+	} else if (extcon_get_state(edev, EXTCON_CHG_USB_FAST) > 0) {
+		dev_dbg(charger->dev, "USB FAST charger is connected\n");
+		current_limit = 650000;
+	} else if (extcon_get_state(edev, EXTCON_CHG_USB_SLOW) > 0) {
+		dev_dbg(charger->dev, "USB SLOW charger is connected\n");
+		current_limit = 650000;
+	} else if (extcon_get_state(edev, EXTCON_CHG_USB_CDP) > 0) {
+		dev_dbg(charger->dev, "USB CDP charger is connected\n");
+		current_limit = 650000;
+	} else {
+		dev_dbg(charger->dev, "USB charger is diconnected\n");
+		current_limit = -1;
+	}
+
+	if (current_limit > 0) {
+		int ret = regulator_set_current_limit(charger->reg, current_limit, current_limit);
+
+		if (ret) {
+			dev_err(charger->dev, "failed to set current limit: %d\n", ret);
+			return;
+		}
+		ret = regulator_enable(charger->reg);
+		if (ret)
+			dev_err(charger->dev, "failed to enable regulator: %d\n", ret);
+	} else {
+		int ret  = regulator_disable(charger->reg);
+
+		if (ret)
+			dev_err(charger->dev, "failed to disable regulator: %d\n", ret);
+	}
+}
+
+static int max8997_battery_extcon_evt(struct notifier_block *nb,
+				unsigned long event, void *param)
+{
+	struct charger_data *charger =
+		container_of(nb, struct charger_data, extcon_nb);
+	schedule_work(&charger->extcon_work);
+	return NOTIFY_OK;
+}
+
 static const struct power_supply_desc max8997_battery_desc = {
 	.name		= "max8997_pmic",
 	.type		= POWER_SUPPLY_TYPE_BATTERY,
@@ -170,6 +237,35 @@ static int max8997_battery_probe(struct platform_device *pdev)
 		return PTR_ERR(charger->battery);
 	}
 
+	charger->reg = devm_regulator_get_optional(&pdev->dev, "charger");
+	if (IS_ERR(charger->reg)) {
+		if (PTR_ERR(charger->reg) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		dev_info(&pdev->dev, "couldn't get charger regulator\n");
+	}
+	charger->edev = extcon_get_edev_by_phandle(&pdev->dev, 0);
+	if (IS_ERR(charger->edev)) {
+		if (PTR_ERR(charger->edev) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		dev_info(charger->dev, "couldn't get extcon device\n");
+	}
+
+	if (!IS_ERR(charger->reg) && !IS_ERR(charger->edev)) {
+		INIT_WORK(&charger->extcon_work, max8997_battery_extcon_evt_worker);
+		ret = devm_add_action(&pdev->dev, max8997_battery_extcon_evt_stop_work, charger);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to add extcon evt stop action: %d\n", ret);
+			return ret;
+		}
+		charger->extcon_nb.notifier_call = max8997_battery_extcon_evt;
+		ret = devm_extcon_register_notifier_all(&pdev->dev, charger->edev,
+							&charger->extcon_nb);
+		if (ret) {
+			dev_err(&pdev->dev, "failed to register extcon notifier\n");
+			return ret;
+		};
+	}
+
 	return 0;
 }
 
-- 
2.25.1