Re: [PATCH v8 2/4] power: reset: add reboot mode driver

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

Hi Krzysztof:

On 2016年04月25日 20:48, Krzysztof Kozlowski wrote:
> On 04/25/2016 01:29 PM, Andy Yan wrote:
>> Hi Krzysztof:
>>
>> On 2016年04月25日 18:42, Krzysztof Kozlowski wrote:
>>> On 04/25/2016 08:55 AM, Andy Yan wrote:
>>>> This driver parses the reboot commands like "reboot bootloader"
>>>> 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 place like special register or sram, 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, in order to
>>>> reboot the device into fastboot or recovery mode.
>>>>
>>>> Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
>>>> Reviewed-by: Moritz Fischer <moritz.fischer@ettus.com>
>>>> Tested-by: John Stultz <john.stultz@linaro.org>
>>>> Acked-by: John Stultz <john.stultz@linaro.org>
>>>> Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
>>>>
>>>> ---
>>>>
>>>> Changes in v8:
>>>> - do some cleanup when driver ubind
>>>>
>>>> Changes in v7:
>>>> - address some suggestions from Krzysztof, make syscon-reboot-mode
>>>> driver data self-contained.
>>>>
>>>> Changes in v6: None
>>>> Changes in v5:
>>>> - use two blank space under help in Kconfig
>>>> - use unsigned int instead of int for member magic in struct mode_info
>>>>
>>>> Changes in v4:
>>>> - make this driver depends on OF to avoid kbuild test error
>>>>
>>>> Changes in v3:
>>>> - scan multi properities
>>>> - add mask value for some platform which only use some bits of the
>>>> register
>>>>     to store boot mode magic value
>>>>
>>>> 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              |  13 ++++
>>>>    drivers/power/reset/Makefile             |   2 +
>>>>    drivers/power/reset/reboot-mode.c        | 118
>>>> +++++++++++++++++++++++++++++++
>>>>    drivers/power/reset/reboot-mode.h        |  14 ++++
>>>>    drivers/power/reset/syscon-reboot-mode.c |  99
>>>> ++++++++++++++++++++++++++
>>>>    5 files changed, 246 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..cf50630 100644
>>>> --- a/drivers/power/reset/Kconfig
>>>> +++ b/drivers/power/reset/Kconfig
>>>> @@ -173,5 +173,18 @@ config POWER_RESET_ZX
>>>>        help
>>>>          Reboot support for ZTE SoCs.
>>>>    +config REBOOT_MODE
>>>> +    tristate
>>>> +
>>>> +config SYSCON_REBOOT_MODE
>>>> +    bool "Generic SYSCON regmap reboot mode driver"
>>>> +    depends on OF
>>>> +    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..cdc4d72
>>>> --- /dev/null
>>>> +++ b/drivers/power/reset/reboot-mode.c
>>>> @@ -0,0 +1,118 @@
>>>> +/*
>>>> + * 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"
>>>> +
>>>> +#define PREFIX "mode-"
>>>> +
>>>> +struct mode_info {
>>>> +    const char *mode;
>>>> +    unsigned int magic;
>>>> +    struct list_head list;
>>>> +};
>>>> +
>>>> +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(reboot, magic);
>>>> +
>>>> +    return NOTIFY_DONE;
>>>> +}
>>>> +
>>>> +int reboot_mode_register(struct reboot_mode_driver *reboot)
>>>> +{
>>>> +    struct mode_info *info;
>>>> +    struct property *prop;
>>>> +    struct device_node *np = reboot->dev->of_node;
>>>> +    size_t len = strlen(PREFIX);
>>>> +    int ret;
>>>> +
>>>> +    INIT_LIST_HEAD(&reboot->head);
>>>> +
>>>> +    for_each_property_of_node(np, prop) {
>>>> +        if (len > strlen(prop->name) || strncmp(prop->name, PREFIX,
>>>> len))
>>>> +            continue;
>>>> +
>>>> +        info = devm_kzalloc(reboot->dev, sizeof(*info), GFP_KERNEL);
>>>> +        if (!info) {
>>>> +            ret = -ENOMEM;
>>>> +            goto error;
>>>> +        }
>>>> +
>>>> +        info->mode = kstrdup_const(prop->name + len, GFP_KERNEL);
>>>> +        if (of_property_read_u32(np, prop->name, &info->magic)) {
>>>> +            dev_err(reboot->dev, "reboot mode %s without magic
>>>> number\n",
>>>> +                info->mode);
>>>> +            devm_kfree(reboot->dev, info);
>>> kfree_const(). The duplicated string won't be added to the list so it
>>> won't be freed in error path or in unregister().
>>     Each mode has a mode_info,  if one of them gets an error whith
>> devm_kzalloc, they other mode_info add to the list before should be freed.
> Please, write it again. I don't understand.
>
> You are allocating 'info'. Then you are const-allocating 'info->mode'.
> In this error path you are freeing 'info'. Where is the kfree_const()
> for 'info->mode'?
>
>>>> +            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(reboot->dev, "can't register reboot notifier\n");
>>> I don't understand your error paths. In previous patches they were
>>> buggy... they still look buggy, I think. It's 8th iteration and such
>>> basic things are still present.
>>>
>>> If this is an error then shouldn't everything be cleaned up? You are
>>> returning error code thus the reboot_mode_register() caller will fail.
>>> This means the probe will fail. So you need to clean up - go to error?
>>      If this is an error, I think only the duplicated string should be
>> clean up,because other resources allocated by devm. If there is
>> something else, please let me know.
> Just goto error...

     I check the code of register_reboot_notifier, this function only  
return 0. So
Maybe I don't need to check the return value here.
>
> Best regards,
> Krzysztof
>
>
>