Hi,
On 03/02/2016 at 09:16:42 -0800, Joshua Clayton wrote :
> diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
> index 5836751..c064eb9 100644
> --- a/drivers/rtc/interface.c
> +++ b/drivers/rtc/interface.c
> @@ -939,4 +939,61 @@ void rtc_timer_cancel(struct rtc_device *rtc, struct
> rtc_timer *timer)
> mutex_unlock(&rtc->ops_lock);
> }
>
> +/**
> + * rtc_read_offset - Read the amount of rtc offset in parts per billion
> + * @ rtc: rtc device to be used
> + * @ offset: the offset in parts per billion
> + *
> + * see below for details.
> + *
> + * Kernel interface to read rtc clock offset
> + * Returns 0 on success, or a negative number on error.
> + * If the rtc offset is not setable (or not implemented), return 0 and put
> + * 0 in the offset value;
> + */
> +int rtc_read_offset(struct rtc_device *rtc, long *offset)
> +{
> + int ret = 0;
> +
> + if (!rtc->ops)
> + return -ENODEV;
> +
> + if (!rtc->ops->set_offset) {
> + *offset = 0;
> + return 0;
> + }
> +
I should have been clearer but this is not necessary anymore since the
sysfs interface will not always be present but you
should probably test rtc->ops->read_offset instead.
> + mutex_lock(&rtc->ops_lock);
> + ret = rtc->ops->read_offset(rtc->dev.parent, offset);
> + mutex_unlock(&rtc->ops_lock);
> + return ret;
> +}
>
> +/**
> + * rtc_set_offset - Adjusts the duration of the average second
> + * @ rtc: rtc device to be used
> + * @ offset: the offset in parts per billion
> + *
> + * Some rtc's allow an adjustment to the average duration of a second
> + * to compensate for differences in the actual clock rate due to temperature,
> + * the crystal, capacitor, etc.
> + *
> + * Kernel interface to adjust an rtc clock offset.
> + * Return 0 on success, or a negative number on error.
> + * If the rtc offset is not setable (or not implemented), return -EINVAL
> + */
> +int rtc_set_offset(struct rtc_device *rtc, long offset)
> +{
> + int ret = 0;
> +
> + if (!rtc->ops)
> + return -ENODEV;
> +
> + if (!rtc->ops->set_offset)
> + return -EINVAL;
> +
> + mutex_lock(&rtc->ops_lock);
> + ret = rtc->ops->set_offset(rtc->dev.parent, offset);
> + mutex_unlock(&rtc->ops_lock);
> + return ret;
> +}
> diff --git a/include/linux/rtc.h b/include/linux/rtc.h
> index 3359f04..b693ada 100644
> --- a/include/linux/rtc.h
> +++ b/include/linux/rtc.h
> @@ -89,6 +89,8 @@ struct rtc_class_ops {
> int (*set_mmss)(struct device *, unsigned long secs);
> int (*read_callback)(struct device *, int data);
> int (*alarm_irq_enable)(struct device *, unsigned int enabled);
> + int (*read_offset)(struct device *, long *offset);
> + int (*set_offset)(struct device *, long offset);
> };
>
> #define RTC_DEVICE_NAME_SIZE 20
> @@ -208,6 +210,8 @@ void rtc_timer_init(struct rtc_timer *timer, void
> (*f)(void *p), void *data);
> int rtc_timer_start(struct rtc_device *rtc, struct rtc_timer *timer,
> ktime_t expires, ktime_t period);
> void rtc_timer_cancel(struct rtc_device *rtc, struct rtc_timer *timer);
> +int rtc_read_offset(struct rtc_device *rtc, long *offset);
> +int rtc_set_offset(struct rtc_device *rtc, long offset);
> void rtc_timer_do_work(struct work_struct *work);
>
> static inline bool is_leap_year(unsigned int year)
> --
> 2.5.0
>
--
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
