drivers/misc: Introduce kernelspace battery saver mode

Change-Id: I4ed95be27f8059804ad6a90dc928f30ce84c679f
Signed-off-by: K A R T H I K <karthik.lal558@gmail.com>

Author: adithya2306

drivers/misc/Kconfig

@@ -606,6 +606,19 @@ config FORCE_FAST_CHARGE
 	help
 	  This allows users to override default charge rate for USB
 
+config BATTERY_SAVER
+	bool "Battery saver mode for kernelspace"
+	help
+	  This driver creates a sysfs toggle that can be enabled when
+	  battery saver mode is activated in userspace, and provides
+	  functions to check the status of battery saver and to activate
+	  it from anywhere in the kernel.
+
+	  The former can be used to disable features that may otherwise
+	  drain battery faster, such as CPU and DDR boosting.
+
+	  If in doubt, say N.
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"

drivers/misc/Makefile

@@ -66,6 +66,7 @@ obj-$(CONFIG_UID_SYS_STATS)	+= uid_sys_stats.o
 obj-$(CONFIG_MEMORY_STATE_TIME)	+= memory_state_time.o
 obj-$(CONFIG_QPNP_MISC) 	+= qpnp-misc.o
 obj-$(CONFIG_ANT_CHECK)		+= ant_check.o
+obj-$(CONFIG_BATTERY_SAVER)	+= battery_saver.o
 
 obj-$(CONFIG_OKL4_USER_VIRQ)	+= okl4-virq.o
 obj-$(CONFIG_OKL4_RINGBUF)	+= okl4-ringbuf.o

drivers/misc/battery_saver.c

@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Adithya R <gh0strider.2k18.reborn@gmail.com>.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/battery_saver.h>
+
+static bool enabled = false;
+module_param(enabled, bool, 0644);
+
+// returns whether battery saver is enabled or disabled
+bool is_battery_saver_on(void)
+{
+	return enabled;
+}
+
+// enable or disable battery saver mode
+void update_battery_saver(bool status)
+{
+	enabled = status;
+}

include/linux/battery_saver.h

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Adithya R <gh0strider.2k18.reborn@gmail.com>.
+ */
+
+#ifndef _BATTERY_SAVER_H_
+#define _BATTERY_SAVER_H_
+
+#include <linux/types.h>
+
+#ifdef CONFIG_BATTERY_SAVER
+bool is_battery_saver_on(void);
+void enable_battery_saver(bool status);
+#else
+static inline bool is_battery_saver_on()
+{
+	return false;
+}
+static inline void update_battery_saver(bool status)
+{
+}
+#endif
+
+#endif /* _BATTERY_SAVER_H_ */