| Message ID | 1454704873-31066-1-git-send-email-stillcompiling@gmail.com |
|---|---|
| State | Accepted |
| Headers | show |
On Fri, 5 Feb 2016 12:41:11 -0800 Joshua Clayton <stillcompiling@gmail.com> wrote: Alexandre, in case you didn't see, I made the change you requested. The rtc_read_offset function checks for a read_offset function and returns -EINVAL if not there, instead of an offset of 0. I just didn't put together a cover letter this time around. > A number of rtc devices, such as the NXP pcf2123 include a facility > to adjust the clock in order to compensate for temperature or a > crystal, capacitor, etc, that results in the rtc clock not running > at exactly 32.768 kHz. > > Data sheets I have seen refer to this as a clock offset, and measure > it in parts per million, however they often reference ppm to 2 digits > of precision, which makes integer ppm less than ideal. > > We use parts per billion, which more than covers the precision needed > and works nicely within 32 bits > > Signed-off-by: Joshua Clayton <stillcompiling@gmail.com> > --- > drivers/rtc/interface.c | 54 > +++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/rtc.h | 4 ++++ 2 files changed, 58 insertions(+) > > diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c > index 5836751..9ef5f6f 100644 > --- a/drivers/rtc/interface.c > +++ b/drivers/rtc/interface.c > @@ -939,4 +939,58 @@ void > rtc_t4e40602412d61b7ef4162621a1a15be32126baeeimer_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 read_offset() is not implemented for the rtc, return -EINVAL > + */ > +int rtc_read_offset(struct rtc_device *rtc, long *offset) > +{ > + int ret; > + > + if (!rtc->ops) > + return -ENODEV; > + > + if (!rtc->ops->read_offset) > + return -EINVAL; > + > + 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; > + > + 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) Thanks, Joshua
Hi, On 23/02/2016 at 10:47:13 -0800, Joshua Clayton wrote : > On Fri, 5 Feb 2016 12:41:11 -0800 > Joshua Clayton <stillcompiling@gmail.com> wrote: > > Alexandre, > in case you didn't see, I made the change you requested. > The rtc_read_offset function checks for a read_offset function > and returns -EINVAL if not there, instead of an offset of 0. > I just didn't put together a cover letter this time around. > Sure, I was planning to review them tonight anyway. All applied, thanks!
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c index 5836751..9ef5f6f 100644 --- a/drivers/rtc/interface.c +++ b/drivers/rtc/interface.c @@ -939,4 +939,58 @@ 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 read_offset() is not implemented for the rtc, return -EINVAL + */ +int rtc_read_offset(struct rtc_device *rtc, long *offset) +{ + int ret; + + if (!rtc->ops) + return -ENODEV; + + if (!rtc->ops->read_offset) + return -EINVAL; + + 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; + + 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)
A number of rtc devices, such as the NXP pcf2123 include a facility to adjust the clock in order to compensate for temperature or a crystal, capacitor, etc, that results in the rtc clock not running at exactly 32.768 kHz. Data sheets I have seen refer to this as a clock offset, and measure it in parts per million, however they often reference ppm to 2 digits of precision, which makes integer ppm less than ideal. We use parts per billion, which more than covers the precision needed and works nicely within 32 bits Signed-off-by: Joshua Clayton <stillcompiling@gmail.com> --- drivers/rtc/interface.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/rtc.h | 4 ++++ 2 files changed, 58 insertions(+)