[PATCH RFC 07/11] power: supply: max77693: Add USB extcon detection for enabling charging

Artur Weber
2024-05-30T08:56:36Z

Add a device tree property, "maxim,usb-connector", that can be used to
specify a USB connector to use to detect whether a charging cable has
been plugged in/out, and enable/disable charging accordingly.

To accommodate this, also add an internal pointer to the CHARGER regulator,
which is used to enable/disable charging and set the input current limit
(which will be done in subsequent commits).

The extcon listener/worker implementation is inspired by the rt5033_charger
driver.

Signed-off-by: Artur Weber <aweber.kernel@gmail.com>
---
drivers/power/supply/Kconfig | 1 +
drivers/power/supply/max77693_charger.c | 125 ++++++++++++++++++++++++++++++++
2 files changed, 126 insertions(+)

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index 3e31375491d5..e4aeff9e7ad1 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -549,6 +549,7 @@ config CHARGER_MAX77650
config CHARGER_MAX77693
tristate "Maxim MAX77693 battery charger driver"
depends on MFD_MAX77693
+ depends on EXTCON || !EXTCON
help
Say Y to enable support for the Maxim MAX77693 battery charger.

diff --git a/drivers/power/supply/max77693_charger.c b/drivers/power/supply/max77693_charger.c
index d59b1524b0a4..c2e8ae367381 100644
--- a/drivers/power/supply/max77693_charger.c
+++ b/drivers/power/supply/max77693_charger.c
@@ -5,6 +5,8 @@
// Copyright (C) 2014 Samsung Electronics
// Krzysztof Kozlowski <krzk@kernel.org>

+#include <linux/devm-helpers.h>
+#include <linux/extcon.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
@@ -30,6 +32,13 @@ struct max77693_charger {
u32 batttery_overcurrent;
u32 fast_charge_current;
u32 charge_input_threshold_volt;
+
+ /* USB cable notifications */
+ struct {
+ struct extcon_dev *edev;
+ struct notifier_block nb;
+ struct work_struct work;
+ } cable;
};

static int max77693_get_charger_state(struct regmap *regmap, int *val)
@@ -711,16 +720,109 @@ static int max77693_reg_init(struct max77693_charger *chg)
chg->charge_input_threshold_volt);
}

+static int max77693_set_charging(struct max77693_charger *chg, bool enable)
+{
+ int is_enabled;
+ int ret = 0;
+
+ is_enabled = regulator_is_enabled(chg->regu);
+ if (is_enabled < 0)
+ return is_enabled;
+
+ if (enable && !is_enabled)
+ ret = regulator_enable(chg->regu);
+ else if (!enable && is_enabled)
+ ret = regulator_disable(chg->regu);
+
+ return ret;
+}
+
+static void max77693_charger_extcon_work(struct work_struct *work)
+{
+ struct max77693_charger *chg = container_of(work, struct max77693_charger,
+ cable.work);
+ struct extcon_dev *edev = chg->cable.edev;
+ int connector, state;
+ int ret;
+
+ for (connector = EXTCON_USB_HOST; connector <= EXTCON_CHG_USB_PD;
+ connector++) {
+ state = extcon_get_state(edev, connector);
+ if (state == 1)
+ break;
+ }
+
+ switch (connector) {
+ case EXTCON_CHG_USB_SDP:
+ case EXTCON_CHG_USB_DCP:
+ case EXTCON_CHG_USB_CDP:
+ case EXTCON_CHG_USB_ACA:
+ case EXTCON_CHG_USB_FAST:
+ case EXTCON_CHG_USB_SLOW:
+ case EXTCON_CHG_USB_PD:
+ ret = max77693_set_charging(chg, true);
+ if (ret) {
+ dev_err(chg->dev, "failed to enable charging\n");
+ break;
+ }
+ dev_info(chg->dev, "charging. connector type: %d\n",
+ connector);
+ break;
+ default:
+ ret = max77693_set_charging(chg, false);
+ if (ret) {
+ dev_err(chg->dev, "failed to disable charging\n");
+ break;
+ }
+ dev_info(chg->dev, "charging. connector type: %d\n",
+ connector);
+ break;
+ }
+
+ power_supply_changed(chg->charger);
+}
+
+static int max77693_charger_extcon_notifier(struct notifier_block *nb,
+ unsigned long event, void *param)
+{
+ struct max77693_charger *chg = container_of(nb, struct max77693_charger,
+ cable.nb);
+
+ schedule_work(&chg->cable.work);
+
+ return NOTIFY_OK;
+}
+
#ifdef CONFIG_OF
static int max77693_dt_init(struct device *dev, struct max77693_charger *chg)
{
struct device_node *np = dev->of_node;
+ struct device_node *np_conn, *np_edev;

if (!np) {
dev_err(dev, "no charger OF node\n");
return -EINVAL;
}

+ np_conn = of_parse_phandle(np, "maxim,usb-connector", 0);
+ np_edev = of_get_parent(np_conn);
+
+ chg->cable.edev = extcon_find_edev_by_node(np_edev);
+ if (IS_ERR(chg->cable.edev)) {
+ /*
+ * In case of deferred extcon probe, defer our probe as well
+ * until it appears.
+ */
+ if (PTR_ERR(chg->cable.edev) == -EPROBE_DEFER)
+ return PTR_ERR(chg->cable.edev);
+ /*
+ * Otherwise, ignore errors (the charger can run without a
+ * connector provided).
+ */
+ dev_warn(dev, "no extcon device found in device-tree (%ld)\n",
+ PTR_ERR(chg->cable.edev));
+ }
+
if (of_property_read_u32(np, "maxim,constant-microvolt",
&chg->constant_volt))
chg->constant_volt = DEFAULT_CONSTANT_VOLT;
@@ -787,6 +889,26 @@ static int max77693_charger_probe(struct platform_device *pdev)

psy_cfg.drv_data = chg;

+ /* Set up extcon if the USB connector node was found */
+ if (!IS_ERR(chg->cable.edev)) {
+ ret = devm_work_autocancel(&pdev->dev, &chg->cable.work,
+ max77693_charger_extcon_work);
+ if (ret) {
+ dev_err(&pdev->dev, "failed: initialize extcon work\n");
+ return ret;
+ }
+
+ chg->cable.nb.notifier_call = max77693_charger_extcon_notifier;
+
+ ret = devm_extcon_register_notifier_all(&pdev->dev,
+ chg->cable.edev,
+ &chg->cable.nb);
+ if (ret) {
+ dev_err(&pdev->dev, "failed: register extcon notifier\n");
+ return ret;
+ }
+ }
+
ret = device_create_file(&pdev->dev, &dev_attr_fast_charge_timer);
if (ret) {
dev_err(&pdev->dev, "failed: create fast charge timer sysfs entry\n");
@@ -822,6 +944,9 @@ static int max77693_charger_probe(struct platform_device *pdev)
device_remove_file(&pdev->dev, &dev_attr_top_off_threshold_current);
device_remove_file(&pdev->dev, &dev_attr_fast_charge_timer);

+ devm_extcon_unregister_notifier_all(&pdev->dev, chg->cable.edev,
+ &chg->cable.nb);
+
return ret;
}

--
2.45.1