[PATCH 3/6] misc: add reboot mode driver

[Andy Yan <andy.yan@rock-chips.com>]

This driver parse the reboot commands like "reboot loader"
and "reboot recovery" to get a boot mode described in the
device tree , then call the vendor specific write interfae
to store the boot mode in some place like special register
or sram , which can be read by the bootloader after system
reboot.

This is commonly done on Android based devices, in order to
reboot the device into fastboot or recovery mode.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
---

 drivers/misc/Kconfig        |  7 ++++
 drivers/misc/Makefile       |  1 +
 drivers/misc/reboot_mode.c  | 96 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/power/reset/Kconfig |  1 -
 include/linux/reboot.h      |  4 +-
 5 files changed, 107 insertions(+), 2 deletions(-)
 create mode 100644 drivers/misc/reboot_mode.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 22892c7..039be78 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -525,6 +525,13 @@ config VEXPRESS_SYSCFG
 	  bus. System Configuration interface is one of the possible means
 	  of generating transactions on this bus.
 
+config REBOOT_MODE
+	tristate
+	depends on OF
+	help
+	 This driver will help to communicate the system reboot mode
+	 to bootloader
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 537d7f3..6ada5de 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -56,3 +56,4 @@ obj-$(CONFIG_GENWQE)		+= genwqe/
 obj-$(CONFIG_ECHO)		+= echo/
 obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
 obj-$(CONFIG_CXL_BASE)		+= cxl/
+obj-$(CONFIG_REBOOT_MODE)       += reboot_mode.o
diff --git a/drivers/misc/reboot_mode.c b/drivers/misc/reboot_mode.c
new file mode 100644
index 0000000..39e3f9f
--- /dev/null
+++ b/drivers/misc/reboot_mode.c
@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2015, Fuzhou Rockchip Electronics Co., Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/reboot.h>
+
+struct mode_info {
+	const char *mode;
+	int magic;
+	struct list_head list;
+};
+
+struct reboot_mode_driver {
+	struct list_head head;
+	int (*write)(int magic);
+	struct notifier_block reboot_notifier;
+};
+
+static int get_reboot_mode_magic(struct reboot_mode_driver *reboot,
+				 const char *cmd)
+{
+	int magic = 0;
+	struct mode_info *info;
+
+	if (cmd) {
+		list_for_each_entry(info, &reboot->head, list) {
+			if (!strcmp(info->mode, cmd)) {
+				magic = info->magic;
+				break;
+			}
+		}
+	}
+
+	return magic;
+}
+
+static int reboot_mode_notify(struct notifier_block *this,
+				  unsigned long mode, void *cmd)
+{
+	struct reboot_mode_driver *reboot;
+	int magic;
+
+	reboot = container_of(this, struct reboot_mode_driver, reboot_notifier);
+	magic = get_reboot_mode_magic(reboot, cmd);
+	reboot->write(magic);
+
+	return NOTIFY_DONE;
+}
+
+int reboot_mode_register(struct device *dev, int (*write)(int))
+{
+	struct reboot_mode_driver *reboot;
+	struct mode_info *info;
+	struct device_node *child;
+	int ret;
+
+	reboot = devm_kzalloc(dev, sizeof(*reboot), GFP_KERNEL);
+	if (!reboot)
+		return -ENOMEM;
+
+	reboot->write = write;
+	INIT_LIST_HEAD(&reboot->head);
+	for_each_child_of_node(dev->of_node, child) {
+		info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+		if (!info)
+			return -ENOMEM;
+		info->mode = of_get_property(child, "linux,mode", NULL);
+		if (of_property_read_u32(child, "linux,magic", &info->magic)) {
+			dev_err(dev, "reboot mode %s without magic number\n",
+				info->mode);
+			devm_kfree(dev, info);
+			continue;
+		}
+		list_add_tail(&info->list, &reboot->head);
+	}
+	reboot->reboot_notifier.notifier_call = reboot_mode_notify;
+	ret = register_reboot_notifier(&reboot->reboot_notifier);
+	if (ret)
+		dev_err(dev, "can't register reboot notifier\n");
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(reboot_mode_register);
+
+MODULE_AUTHOR("Andy Yan <andy.yan@rock-chips.com");
+MODULE_DESCRIPTION("System reboot mode driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index 1131cf7..43521fd 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -172,6 +172,5 @@ config POWER_RESET_ZX
 	depends on HAS_IOMEM
 	help
 	  Reboot support for ZTE SoCs.
-
 endif
 
diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index a7ff409..f523c32 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -1,7 +1,7 @@
 #ifndef _LINUX_REBOOT_H
 #define _LINUX_REBOOT_H
 
-
+#include <linux/device.h>
 #include <linux/notifier.h>
 #include <uapi/linux/reboot.h>
 
@@ -42,6 +42,8 @@ extern int register_restart_handler(struct notifier_block *);
 extern int unregister_restart_handler(struct notifier_block *);
 extern void do_kernel_restart(char *cmd);
 
+extern int reboot_mode_register(struct device *dev, int (*write)(int));
+
 /*
  * Architecture-specific implementations of sys_reboot commands.
  */
-- 
1.9.1