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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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