Re: [PATCH v2 2/4] power: reset: add reboot mode driver

[Moritz Fischer]

Hi Andy,

On Tue, Jan 12, 2016 at 12:31 PM, Andy Yan <andy.yan@xxxxxxxxxxxxxx> wrote:
> 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 write interfae to store the boot
> mode in some persistent storage  like special register or ram,
> which can be read by the bootloader after system reboot, then
> the bootloader can take different action according to the mode
> stored.
>
> This is commonly used on Android based devices, which in order
> to reboot the device into fastboot or recovery mode.
>
> Signed-off-by: Andy Yan <andy.yan@xxxxxxxxxxxxxx>
>
> ---
>
> Changes in v2:
> - move to dir drivers/power/reset/
> - make syscon-reboot-mode a generic driver
>
> Changes in v1:
> - fix the embarrassed compile warning
> - correct the maskrom magic number
> - check for the normal reboot
>
>  drivers/power/reset/Kconfig              |  16 +++++
>  drivers/power/reset/Makefile             |   2 +
>  drivers/power/reset/reboot-mode.c        | 100 +++++++++++++++++++++++++++++++
>  drivers/power/reset/reboot-mode.h        |   6 ++
>  drivers/power/reset/syscon-reboot-mode.c |  62 +++++++++++++++++++
>  5 files changed, 186 insertions(+)
>  create mode 100644 drivers/power/reset/reboot-mode.c
>  create mode 100644 drivers/power/reset/reboot-mode.h
>  create mode 100644 drivers/power/reset/syscon-reboot-mode.c
>
> diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
> index 1131cf7..2e6d873 100644
> --- a/drivers/power/reset/Kconfig
> +++ b/drivers/power/reset/Kconfig
> @@ -173,5 +173,21 @@ config POWER_RESET_ZX
>         help
>           Reboot support for ZTE SoCs.
>
> +config REBOOT_MODE
> +       tristate
> +       depends on OF
> +       help
> +        This driver will help to pass the system reboot mode
> +        to bootloader
> +
> +config SYSCON_REBOOT_MODE
> +       bool "Generic SYSCON regmap reboot mode driver"
> +       select REBOOT_MODE
> +       help
> +        Say y here will enable reboot mode driver. This will
> +        get reboot mode arguments and store it in SYSCON mapped
> +        register, then the bootloader can read it to take different
> +        action according to the mode.
> +
>  endif
>
> diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
> index 096fa67..a63865b 100644
> --- a/drivers/power/reset/Makefile
> +++ b/drivers/power/reset/Makefile
> @@ -20,3 +20,5 @@ obj-$(CONFIG_POWER_RESET_SYSCON) += syscon-reboot.o
>  obj-$(CONFIG_POWER_RESET_SYSCON_POWEROFF) += syscon-poweroff.o
>  obj-$(CONFIG_POWER_RESET_RMOBILE) += rmobile-reset.o
>  obj-$(CONFIG_POWER_RESET_ZX) += zx-reboot.o
> +obj-$(CONFIG_REBOOT_MODE) += reboot-mode.o
> +obj-$(CONFIG_SYSCON_REBOOT_MODE) += syscon-reboot-mode.o
> diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
> new file mode 100644
> index 0000000..92b7b4d
> --- /dev/null
> +++ b/drivers/power/reset/reboot-mode.c
> @@ -0,0 +1,100 @@
> +/*
> + * Copyright (c) 2016, 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>
> +#include "reboot-mode.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)
> +{
> +       const char *normal = "normal";
> +       int magic = 0;
> +       struct mode_info *info;
> +
> +       if (!cmd)
> +               cmd = normal;
> +
> +       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);
> +       if (magic)
> +               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, "loader,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@xxxxxxxxxxxxxx");
> +MODULE_DESCRIPTION("System reboot mode driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/power/reset/reboot-mode.h b/drivers/power/reset/reboot-mode.h
> new file mode 100644
> index 0000000..76646e7
> --- /dev/null
> +++ b/drivers/power/reset/reboot-mode.h
> @@ -0,0 +1,6 @@
> +#ifndef __REBOOT_MODE_H__
> +#define __REBOOT_MODE_H__
> +
> +extern int reboot_mode_register(struct device *dev, int (*write)(int));
> +
> +#endif
> diff --git a/drivers/power/reset/syscon-reboot-mode.c b/drivers/power/reset/syscon-reboot-mode.c
> new file mode 100644
> index 0000000..b9370f3
> --- /dev/null
> +++ b/drivers/power/reset/syscon-reboot-mode.c
> @@ -0,0 +1,62 @@
> +/*
> + * Copyright (c) 2016, 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/init.h>
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +#include <linux/regmap.h>
> +#include <linux/mfd/syscon.h>
> +#include "reboot-mode.h"
> +
> +static struct regmap *map;
> +static u32 offset;
> +
> +static int syscon_reboot_mode_write(int magic)
> +{
> +       regmap_write(map, offset, magic);

See suggestion below. I think using regmap_update_bits() would be even
more useful for cases where you have other stuff in that register, too.

> +
> +       return 0;
> +}
> +
> +static int syscon_reboot_mode_probe(struct platform_device *pdev)
> +{
> +       int ret;
> +
> +       map = syscon_node_to_regmap(pdev->dev.parent->of_node);
> +       if (IS_ERR(map))
> +               return PTR_ERR(map);
> +       if (of_property_read_u32(pdev->dev.of_node, "offset", &offset))
> +               return -EINVAL;

I think it would be worthwhile to have a mask value here, that you can use
with regmap_update_bits()

+           if (of_property_read_u32(pdev->dev.of_node, "mask", &mask))
+                   return -EINVAL;


Cheers,

Moritz