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    SubjectRe: [PATCH v7 2/4] power: reset: add reboot mode driver
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    Date
    On 30.03.2016 11:20, 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 v7:
    > - address some suggestions from Krzysztof, make syscon-reboot-mode driver data self-contained.
    >

    Thanks for changes, few comments below.

    (...)

    > diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
    > new file mode 100644
    > index 0000000..ae6f931
    > --- /dev/null
    > +++ b/drivers/power/reset/reboot-mode.c
    > @@ -0,0 +1,115 @@
    > +/*
    > + * 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;
    > +};
    > +
    > +struct reboot_mode_driver {
    > + struct device *dev;
    > + struct list_head head;
    > + int (*write)(struct device *dev, 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(reboot->dev, magic);
    > +
    > + return NOTIFY_DONE;
    > +}
    > +
    > +int reboot_mode_register(struct device *dev, int (*write)(struct device *, int))
    > +{
    > + struct reboot_mode_driver *reboot;
    > + struct mode_info *info;
    > + struct property *prop;
    > + struct device_node *np;
    > + size_t len = strlen(PREFIX);
    > + int ret;
    > +
    > + reboot = devm_kzalloc(dev, sizeof(*reboot), GFP_KERNEL);
    > + if (!reboot)
    > + return -ENOMEM;
    > +
    > + reboot->dev = dev;
    > + reboot->write = write;
    > + INIT_LIST_HEAD(&reboot->head);
    > +
    > + np = of_node_get(dev->of_node);
    > + for_each_property_of_node(np, prop) {
    > + if (len > strlen(prop->name) || strncmp(prop->name, PREFIX, len))
    > + continue;
    > +
    > + info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
    > + if (!info)

    Clean up needed: of_node_put() and kfree_const() for items stored on the
    list from previous iterations.

    > + return -ENOMEM;
    > +
    > + info->mode = kstrdup_const(prop->name + len, GFP_KERNEL);
    > + if (of_property_read_u32(np, prop->name, &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);
    > + }
    > + of_node_put(np);

    If you of_node_put() here, there is no sense in getting it before. I
    mentioned of_node_get() only because I am not sure about life-cycle of
    nodes in case of DT overlays and you are storing the pointer to string
    from DT.

    The doubts I have are concerning only the case of freeing nodes from
    overlay.

    I don't know if of_node_get() is needed but of_node_get()+of_node_put()
    seems useless.

    > +
    > + 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 v2");
    > diff --git a/drivers/power/reset/reboot-mode.h b/drivers/power/reset/reboot-mode.h
    > new file mode 100644
    > index 0000000..c861129
    > --- /dev/null
    > +++ b/drivers/power/reset/reboot-mode.h
    > @@ -0,0 +1,6 @@
    > +#ifndef __REBOOT_MODE_H__
    > +#define __REBOOT_MODE_H__
    > +
    > +int reboot_mode_register(struct device *dev, int (*write)(struct device *, 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..f1b8072
    > --- /dev/null
    > +++ b/drivers/power/reset/syscon-reboot-mode.c
    > @@ -0,0 +1,86 @@
    > +/*
    > + * 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/platform_device.h>
    > +#include <linux/reboot.h>
    > +#include <linux/regmap.h>
    > +#include <linux/mfd/syscon.h>
    > +#include "reboot-mode.h"
    > +
    > +struct syscon_reboot_mode {
    > + struct device *dev;

    'dev' looks unused (only set).

    > + struct regmap *map;
    > + u32 offset;
    > + u32 mask;
    > +};
    > +
    > +static int syscon_reboot_mode_write(struct device *dev, int magic)
    > +{
    > + struct syscon_reboot_mode *syscon_rbm = dev_get_drvdata(dev);
    > + int ret;
    > +
    > + ret = regmap_update_bits(syscon_rbm->map, syscon_rbm->offset,
    > + syscon_rbm->mask, magic);
    > + if (ret < 0)
    > + dev_err(dev, "update reboot mode bits failed\n");
    > +
    > + return ret;
    > +}
    > +
    > +static int syscon_reboot_mode_probe(struct platform_device *pdev)
    > +{
    > + int ret;
    > + struct syscon_reboot_mode *syscon_rbm;
    > +
    > + syscon_rbm = devm_kzalloc(&pdev->dev, sizeof(*syscon_rbm), GFP_KERNEL);
    > + if (!syscon_rbm)
    > + return -ENOMEM;
    > +
    > + syscon_rbm->dev = &pdev->dev;
    > + syscon_rbm->mask = 0xffffffff;
    > +
    > + syscon_rbm->map = syscon_node_to_regmap(pdev->dev.parent->of_node);
    > + if (IS_ERR(syscon_rbm->map))
    > + return PTR_ERR(syscon_rbm->map);
    > +
    > + if (of_property_read_u32(pdev->dev.of_node, "offset", &syscon_rbm->offset))
    > + return -EINVAL;
    > +
    > + of_property_read_u32(pdev->dev.of_node, "mask", &syscon_rbm->mask);
    > +
    > + dev_set_drvdata(&pdev->dev, syscon_rbm);
    > +
    > + ret = reboot_mode_register(&pdev->dev, syscon_reboot_mode_write);
    > + if (ret)
    > + dev_err(&pdev->dev, "can't register reboot mode\n");
    > +
    > + return ret;
    > +}
    > +
    > +static const struct of_device_id syscon_reboot_mode_of_match[] = {
    > + { .compatible = "syscon-reboot-mode" },
    > + {}
    > +};
    > +
    > +static struct platform_driver syscon_reboot_mode_driver = {
    > + .probe = syscon_reboot_mode_probe,

    Cleanup needed. What will happen after device unbind? Memory will be
    released (devm-*()) but reboot notifier won't thus leading to OOPS on
    reboot.

    Best regards,
    Krzysztof

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