Lines Matching +full:soc +full:- +full:rtc

2 Real Time Clock (RTC) Drivers for Linux
8 the local time zone or daylight savings time -- unless they dual boot
9 with MS-Windows -- but will instead be set to Coordinated Universal Time
12 The newest non-PC hardware tends to just count seconds, like the time(2)
16 Linux has two largely-compatible userspace RTC API families you may
19     *	/dev/rtc ... is the RTC provided by PC compatible systems,
20 	so it's not very portable to non-x86 systems.
23 	supported by a wide variety of RTC chips on all systems.
27 RTCs use the same API to make requests in both RTC frameworks (using
29 same functionality.  For example, not every RTC is hooked up to an
35 Old PC/AT-Compatible driver:  /dev/rtc
36 --------------------------------------
44 a few ways (enabling longer alarm periods, and wake-from-hibernate).
57 The interrupts are reported via /dev/rtc (major 10, minor 135, read only
59 the type of interrupt (update-done, alarm-rang, or periodic) that was
61 the last read.  Status information is reported through the pseudo-file
62 /proc/driver/rtc if the /proc filesystem was enabled.  The driver has
63 built in locking so that only one process is allowed to have the /dev/rtc
67 select(2) on /dev/rtc -- either will block/stop the user process until
75 typical 486-33 running a tight read loop on /dev/rtc will start to suffer
83 an evil user generating lots of IRQs on a slow 386sx-16, where it might have
85 a different value to /proc/sys/dev/rtc/max-user-freq. Note that the
91 the process of doing this, the kernel briefly turns off RTC periodic 
94 whatever) then the kernel will keep its hands off the RTC, allowing you
97 The alarm and/or interrupt frequency are programmed into the RTC via
98 various ioctl(2) calls as listed in ./include/linux/rtc.h
105 (The original /dev/rtc driver was written by Paul Gortmaker.)
108 New portable "RTC Class" drivers:  /dev/rtcN
109 --------------------------------------------
111 Because Linux supports many non-ACPI and non-PC platforms, some of which
112 have more than one RTC style clock, it needed a more portable solution
113 than expecting a single battery-backed MC146818 clone on every system.
114 Accordingly, a new "RTC Class" framework has been defined.  It offers
117     *	/dev/rtcN ... much the same as the older /dev/rtc interface
119     *	/sys/class/rtc/rtcN ... sysfs attributes support readonly
120 	access to some RTC attributes.
122     *	/proc/driver/rtc ... the system clock RTC may expose itself
123 	using a procfs interface. If there is no RTC for the system clock,
127 The RTC Class framework supports a wide variety of RTCs, ranging from those
128 integrated into embeddable system-on-chip (SOC) processors to discrete chips
130 even support for PC-style RTCs ... including the features exposed on newer PCs
133 The new framework also removes the "one RTC per system" restriction.  For
134 example, maybe the low-power battery-backed RTC is a discrete I2C chip, but
135 a high functionality RTC is integrated into the SOC.  That system might read
136 the system clock from the discrete RTC, but use the integrated one for all
139 Check out tools/testing/selftests/rtc/rtctest.c for an example usage of the