drivers: misc: power: implement usb fast charge mode

echo 0 /sys/kernel/fast_charge/force_fast_charge (disable)
echo 1 /sys/kernel/fast_charge/force_fast_charge (enable)

Force CDP mode for USB when available.
Not all power sources support it, use with care!

Signed-off-by: engstk <[email protected]>

drivers/misc/Kconfig

@@ -536,6 +536,12 @@ config ACCESS_RAMOOPS
 	  To compile this driver as a module, choose M here: the module will be
 	  called access_ramoops.
 
+config FORCE_FAST_CHARGE
+	bool "Force faster charge rate for USB"
+	default y
+	help
+	  This allows users to override default charge rate for USB
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"

drivers/misc/Makefile

@@ -66,3 +66,5 @@ obj-$(CONFIG_SBB_MUX)		+= sbb-mux/
 obj-$(CONFIG_SUBSYSTEM_COREDUMP)	+= sscoredump/
 obj-$(CONFIG_ACCESS_RAMOOPS)	+= access_ramoops.o
 obj-$(CONFIG_BCM_GPS_SPI_DRIVER)   += bbdpl/
+
+obj-$(CONFIG_FORCE_FAST_CHARGE) += fastchg.o

drivers/misc/fastchg.c

@@ -0,0 +1,78 @@
+/*
+ * Author (legacy sysfs): Chad Froebel <[email protected]>
+ *
+ * Additional fixes, port to raviole and power supply hooks: engstk <[email protected]>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+/*
+ * Possible values for "force_fast_charge" are :
+ *
+ *   0 - Disabled (default)
+ *   1 - Force faster charge
+ */
+
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/string.h>
+#include <linux/module.h>
+
+int force_fast_charge = 0;
+EXPORT_SYMBOL(force_fast_charge);
+
+static ssize_t force_fast_charge_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", force_fast_charge);
+}
+
+static ssize_t force_fast_charge_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	sscanf(buf, "%du", &force_fast_charge);
+	if (force_fast_charge < 0 || force_fast_charge > 1)
+		force_fast_charge = 0;
+	return count;
+}
+
+static struct kobj_attribute force_fast_charge_attribute =
+__ATTR(force_fast_charge, 0644, force_fast_charge_show, force_fast_charge_store);
+
+static struct attribute *attrs[] = {
+&force_fast_charge_attribute.attr,
+NULL,
+};
+
+static struct attribute_group attr_group = {
+.attrs = attrs,
+};
+
+static struct kobject *force_fast_charge_kobj;
+
+int force_fast_charge_init(void)
+{
+	int retval;
+        force_fast_charge_kobj = kobject_create_and_add("fast_charge", kernel_kobj);
+        if (!force_fast_charge_kobj) {
+                return -ENOMEM;
+        }
+        retval = sysfs_create_group(force_fast_charge_kobj, &attr_group);
+        if (retval)
+                kobject_put(force_fast_charge_kobj);
+        return retval;
+}
+
+void force_fast_charge_exit(void)
+{
+	kobject_put(force_fast_charge_kobj);
+}
+
+module_init(force_fast_charge_init);
+module_exit(force_fast_charge_exit);

drivers/usb/typec/tcpm/google/bc_max77759.c

@@ -19,6 +19,10 @@
 #include "../tcpci.h"
 #include "tcpci_max77759.h"
 
+#if IS_ENABLED(CONFIG_FORCE_FAST_CHARGE)
+extern bool force_fast_charge;
+#endif
+
 struct bc12_status {
 	struct workqueue_struct *wq;
 	struct max77759_plat *chip;
@@ -101,7 +105,14 @@ static void vendor_bc12_alert(struct work_struct *work)
 			logbuffer_log(plat->log, "BC12: nothing attached");
 			break;
 		case CHGTYP_SDP:
+#if IS_ENABLED(CONFIG_FORCE_FAST_CHARGE)
+			if (force_fast_charge == 0)
+				bc12->usb_type = POWER_SUPPLY_USB_TYPE_SDP;
+			else
+				bc12->usb_type = POWER_SUPPLY_USB_TYPE_CDP;
+#else
 			bc12->usb_type = POWER_SUPPLY_USB_TYPE_SDP;
+#endif
 			logbuffer_log(plat->log, "BC12: SDP detected");
 			break;
 		case CHGTYP_CDP: