From 56a786838b7bf95dba205b88f2c6aa5bcc4c3085 Mon Sep 17 00:00:00 2001
From: Ziyuan Xu <xzy.xu@rock-chips.com>
Date: Thu, 12 Nov 2020 17:55:31 +0800
Subject: [PATCH] power: supply: gpio-charger: change current limit
 automatically by *USB_DCP*

The usb phy could update the state of the EXTCON_CHG_USB_DCP duly, so
that we can change the current limit to maximum within the USB dedicated
charging port.

Signed-off-by: Ziyuan Xu <xzy.xu@rock-chips.com>
Change-Id: I32f0361a2f0153424627bef0bd75c3b93e51ec03
---
 drivers/power/supply/gpio-charger.c | 41 +++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/drivers/power/supply/gpio-charger.c b/drivers/power/supply/gpio-charger.c
index a79e5f969b01..a2428d9699a7 100644
--- a/drivers/power/supply/gpio-charger.c
+++ b/drivers/power/supply/gpio-charger.c
@@ -13,6 +13,7 @@
  *
  */
 
+#include <linux/extcon-provider.h>
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
@@ -39,11 +40,13 @@ struct gpio_charger {
 
 	struct power_supply *charger;
 	struct power_supply_desc charger_desc;
+	struct extcon_dev *edev;
 	struct gpio_desc *gpiod;
 	struct gpio_desc *charge_status;
 
 	struct gpio_descs *current_limit_gpios;
 	struct gpio_mapping *current_limit_map;
+	struct notifier_block cable_cg_nb;
 	u32 current_limit_map_size;
 	u32 charge_current_limit;
 };
@@ -246,6 +249,22 @@ static int init_charge_current_limit(struct device *dev,
 	return 0;
 }
 
+static int gpio_charger_evt_notifier(struct notifier_block *nb,
+				     unsigned long event, void *ptr)
+{
+	int limit_ua;
+	struct gpio_charger *charger =
+		container_of(nb, struct gpio_charger, cable_cg_nb);
+
+	limit_ua = charger->current_limit_map[charger->current_limit_map_size - 1].limit_ua;
+	if (extcon_get_state(charger->edev, EXTCON_CHG_USB_DCP) > 0)
+		limit_ua = charger->current_limit_map[0].limit_ua;
+
+	set_charge_current_limit(charger, limit_ua);
+
+	return NOTIFY_DONE;
+}
+
 /*
  * The entries will be overwritten by driver's probe routine depending
  * on the available features. This list ensures, that the array is big
@@ -261,6 +280,7 @@ static int gpio_charger_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	const struct gpio_charger_platform_data *pdata = dev->platform_data;
+	struct extcon_dev *edev;
 	struct power_supply_config psy_cfg = {};
 	struct gpio_charger *gpio_charger;
 	struct power_supply_desc *charger_desc;
@@ -279,6 +299,27 @@ static int gpio_charger_probe(struct platform_device *pdev)
 		return -ENOMEM;
 	gpio_charger->dev = dev;
 
+	if (of_property_read_bool(dev->of_node, "extcon")) {
+		edev = extcon_get_edev_by_phandle(dev, 0);
+		if (IS_ERR(edev)) {
+			if (PTR_ERR(edev) != -EPROBE_DEFER)
+				dev_err(dev, "Invalid or missing extcon\n");
+			return PTR_ERR(edev);
+		}
+		gpio_charger->edev = edev;
+		gpio_charger->cable_cg_nb.notifier_call =
+			gpio_charger_evt_notifier;
+		ret = devm_extcon_register_notifier(dev, edev,
+						    EXTCON_CHG_USB_DCP,
+						    &gpio_charger->cable_cg_nb);
+		if (ret) {
+			dev_err(dev, "failed to register notifier for CDP\n");
+			return ret;
+		}
+	} else {
+		gpio_charger->edev = ERR_PTR(-ENODEV);
+	}
+
 	/*
 	 * This will fetch a GPIO descriptor from device tree, ACPI or
 	 * boardfile descriptor tables. It's good to try this first.