Documentation: rtc: add sysfs file permissions

Annotate the sysfs interface of rtc with file specific permissions
(RO/RW).

Signed-off-by: Aishwarya Pant <aishpant@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

Documentation/ABI/testing/sysfs-class-rtc

@@ -18,14 +18,14 @@ Date:		March 2006
 KernelVersion:	2.6.17
 Contact:	linux-rtc@vger.kernel.org
 Description:
-		RTC-provided date in YYYY-MM-DD format
+		(RO) RTC-provided date in YYYY-MM-DD format
 
 What:		/sys/class/rtc/rtcX/hctosys
 Date:		September 2009
 KernelVersion:	2.6.32
 Contact:	linux-rtc@vger.kernel.org
 Description:
-		1 if the RTC provided the system time at boot via the
+		(RO) 1 if the RTC provided the system time at boot via the
 		CONFIG_RTC_HCTOSYS kernel option, 0 otherwise
 
 What:		/sys/class/rtc/rtcX/max_user_freq
@@ -33,7 +33,7 @@ Date:		October 2007
 KernelVersion:	2.6.24
 Contact:	linux-rtc@vger.kernel.org
 Description:
-		The maximum interrupt rate an unprivileged user may request
+		(RW) The maximum interrupt rate an unprivileged user may request
 		from this RTC.
 
 What:		/sys/class/rtc/rtcX/name
@@ -41,49 +41,51 @@ Date:		March 2006
 KernelVersion:	2.6.17
 Contact:	linux-rtc@vger.kernel.org
 Description:
-		The name of the RTC corresponding to this sysfs directory
+		(RO) The name of the RTC corresponding to this sysfs directory
 
 What:		/sys/class/rtc/rtcX/since_epoch
 Date:		March 2006
 KernelVersion:	2.6.17
 Contact:	linux-rtc@vger.kernel.org
 Description:
-		RTC-provided time as the number of seconds since the epoch
+		(RO) RTC-provided time as the number of seconds since the epoch
 
 What:		/sys/class/rtc/rtcX/time
 Date:		March 2006
 KernelVersion:	2.6.17
 Contact:	linux-rtc@vger.kernel.org
 Description:
-		RTC-provided time in 24-hour notation (hh:mm:ss)
+		(RO) RTC-provided time in 24-hour notation (hh:mm:ss)
 
 What:		/sys/class/rtc/rtcX/*/nvmem
 Date:		February 2016
 KernelVersion:	4.6
 Contact:	linux-rtc@vger.kernel.org
 Description:
-		The non volatile storage exported as a raw file, as described in
+		(RW) The non volatile storage exported as a raw file, as
-		Documentation/nvmem/nvmem.txt
+		described in Documentation/nvmem/nvmem.txt
 
 What:		/sys/class/rtc/rtcX/offset
 Date:		February 2016
 KernelVersion:	4.6
 Contact:	linux-rtc@vger.kernel.org
 Description:
-		The amount which the rtc clock has been adjusted in firmware.
+		(RW) The amount which the rtc clock has been adjusted in
-		Visible only if the driver supports clock offset adjustment.
+		firmware. Visible only if the driver supports clock offset
-		The unit is parts per billion, i.e. The number of clock ticks
+		adjustment. The unit is parts per billion, i.e. The number of
-		which are added to or removed from the rtc's base clock per
+		clock ticks which are added to or removed from the rtc's base
-		billion ticks. A positive value makes a day pass more slowly,
+		clock per billion ticks. A positive value makes a day pass more
-		longer, and a negative value makes a day pass more quickly.
+		slowly, longer, and a negative value makes a day pass more
+		quickly.
 
 What:		/sys/class/rtc/rtcX/wakealarm
 Date:		February 2007
 KernelVersion:	2.6.20
 Contact:	linux-rtc@vger.kernel.org
 Description:
-		The time at which the clock will generate a system wakeup event.
+		(RW) The time at which the clock will generate a system wakeup
-		This is a one shot wakeup event, so must be reset after wake if
+		event. This is a one shot wakeup event, so must be reset after
-		a daily wakeup is required. Format is seconds since the epoch by
+		wake if a daily wakeup is required. Format is seconds since the
-		default, or if there's a leading +, seconds in the future, or if
+		epoch by default, or if there's a leading +, seconds in the
-		there is a leading +=, seconds ahead of the current alarm.
+		future, or if there is a leading +=, seconds ahead of the
+		current alarm.