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    SubjectRe: [PATCH 01/11] RTC subsystem, class
    Alessandro Zummo <a.zummo@towertech.it> wrote:
    >
    > This patch adds the basic RTC subsytem infrastructure
    > to the kernel.
    >
    > rtc/class.c - registration facilities for RTC drivers
    > rtc/interface.c - kernel/rtc interface functions
    > rtc/utils.c - misc rtc-related utility functions
    > rtc/hctosys.c - snippet of code that copies hw clock to sw clock
    > at bootup, if configured to do so.

    Couple of questions.

    a) Is all this code 100% compatible with existing kernel interfaces? No
    userspace-visible breakage? Right down the all the same -EFOO return
    codes for all the same errors?

    b) Will the kernel compile and run at each stage of your patch series?
    I hit a nasty no-compile half an hour through a git-bisect session
    yesterday and it's still smarting.

    Code looks nice and clean.

    > + if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
    > + err = -ENOMEM;
    > + goto exit;
    > + }
    > +
    > +
    > + mutex_lock(&idr_lock);
    > + err = idr_get_new(&rtc_idr, NULL, &id);
    > + mutex_unlock(&idr_lock);

    Oh the IDR API does suck. Not your fault though.

    > + if ((rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL)) == NULL) {

    You do a lot of

    if ((lhs = rhs) == something)

    But preferred kernel style is

    lhs = rhs;
    if (lhs == something)

    Generally, kernel style is to keep things as utterly simple as they can be.

    +config RTC_CLASS
    > + tristate "RTC class"
    > + depends on EXPERIMENTAL
    > + default y
    > + help
    > + Generic RTC class support. If you say yes here, you will
    > + be allowed to plug one or more RTCs to your system. You will
    > + probably want to enable one of more of the interfaces below.
    > +
    > + This driver can also be built as a module. If so, the module
    > + will be called rtc-class.
    > +
    > +config RTC_HCTOSYS
    > + bool "Set system time from RTC on startup"
    > + depends on RTC_CLASS = y
    > + default y
    > + help
    > + If you say yes here, the system time will be set using
    > + the value read from the specified RTC device. This is useful
    > + in order to avoid unnecessary fschk runs.
    > +
    > +config RTC_HCTOSYS_DEVICE
    > + string "The RTC to read the time from"
    > + depends on RTC_HCTOSYS = y
    > + default "rtc0"
    > + help
    > + The RTC device that will be used as the source for
    > + the system time, usually rtc0.

    hm. Doesn't the above disable RTC_HCTOSYS and RTC_HCTOSYS_DEVICE if
    RTC_CLASS=m?

    > --- /dev/null 1970-01-01 00:00:00.000000000 +0000
    > +++ linux-rtc/drivers/rtc/interface.c 2006-02-15 04:13:37.000000000 +0100
    > @@ -0,0 +1,274 @@
    > +/*
    > + * RTC subsystem, interface functions
    > + *
    > + * Copyright (C) 2005 Tower Technologies
    > + * Author: Alessandro Zummo <a.zummo@towertech.it>
    > + *
    > + * based on arch/arm/common/rtctime.c
    > + *
    > + * 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; version 2 of the License.
    > +*/
    > +
    > +#include <linux/rtc.h>
    > +
    > +extern struct class *rtc_class;
    Please always put extern declarations in a header file.

    > +}
    > +EXPORT_SYMBOL(rtc_set_alarm);
    > +
    > +void rtc_update_irq(struct class_device *class_dev,
    > + unsigned long num, unsigned long events)
    > +{
    > + struct rtc_device *rtc = to_rtc_device(class_dev);
    > +
    > + spin_lock(&rtc->irq_lock);
    > + rtc->irq_data = (rtc->irq_data + (num << 8)) | events;
    > + spin_unlock(&rtc->irq_lock);
    > +
    > + spin_lock(&rtc->irq_task_lock);
    > + if (rtc->irq_task)
    > + rtc->irq_task->func(rtc->irq_task->private_data);
    > + spin_unlock(&rtc->irq_task_lock);
    > +
    > + wake_up_interruptible(&rtc->irq_queue);
    > + kill_fasync(&rtc->async_queue, SIGIO, POLL_IN);
    > +}
    > +EXPORT_SYMBOL(rtc_update_irq);

    I don't know what this does.

    Please document all non-static functions. Preferably with kernel-doc
    format. Feel free to document static functions too..

    > +int rtc_irq_set_freq(struct class_device *class_dev, struct rtc_task *task, int freq)
    > +{
    > + int err = 0, tmp = 0;
    > + unsigned long flags;
    > + struct rtc_device *rtc = to_rtc_device(class_dev);
    > +
    > + /* allowed range is 2-8192 */
    > + if (freq < 2 || freq > 8192)
    > + return -EINVAL;
    > +
    > +/* if ((freq > rtc_max_user_freq) && (!capable(CAP_SYS_RESOURCE)))
    > + return -EACCES;
    > +*/

    What happened to rtc_max_user_freq?

    -
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