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RSB-4210 User Manual 78

You can use open/close/write/read functions to control this storage.

3.11.6 LAN

Refer to Socket Programming (http://www.tenouk.com/cnlinuxsockettutorials.html)

3.11.7 RTC

Because Linux supports many non-ACPI and non-PC platforms, some of which have

more than one RTC style clock, it needed a more portable solution than expecting a

single battery-backed MC146818 clone on every system. Accordingly, a new "RTC

Class" framework has been defined. It offers three different userspace interfaces:

* /dev/rtcN ... much the same as the older /dev/rtc interface

*/sys/class/rtc/rtcN...sysfs attributes support readonly access to some RTC attri-

butes.

* /proc/driver/rtc ... the first RTC (rtc0) may expose itself using a procfs interface.

More information is (currently) shown here than through sysfs.

The RTC Class framework supports a wide variety of RTCs, ranging from those inte-

grated into embeddable system-on-chip (SOC) processors to discrete chips using

I2C, SPI, or some other bus to communicate with the host CPU. There's even sup-

port for PC-style RTCs ... including the features exposed on newer PCs through

ACPI.

The new framework also removes the "one RTC per system" restriction. For exam-

ple, maybe the low-power battery-backed RTC is a discrete I2C chip, but a high func-

tionality RTC is integrated into the SOC. That system might read the system clock

from the discrete RTC, but use the integrated one for all other tasks, because of its

greater functionality.

3.11.7.1 SYSFS INTERFACE

The sysfs interface under /sys/class/rtc/rtcN provides access to various rtc attributes

without requiring the use of ioctls. All dates and times are in the RTC's timezone,

rather than in system time.

date: RTC-provided date

hctosys: 1 if the RTC provided the system time at boot via the

CONFIG_RTC_HCTOSYS kernel option, 0 otherwise

max_user_freq: The maximum interrupt rate an unprivileged user may request

from this RTC.

name: The name of the RTC corresponding to this sysfs directory

since_epoch: The number of seconds since the epoch according to the RTC

time: RTC-provided time

SD card /dev/mmcblk1

iNand /dev/mmcblk0

USB Disk /dev/sdx

SATA Disk /dev/sdx

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