A5D3_PMC(8)

NAME
a5d3_pmc - Power Management Controller (PMC) utility

SYNOPSIS
a5d3_tc_freq [-a ACRON] [-d DIV] [-D] [-e] [-E] [-h] [-p] [-s] [-v] [-V] [-w WPEN]

DESCRIPTION

Atmel's SAMA5D3 family of SoCs contains a Power Management Controller (PMC) which achieves power reduction by allowing clocks that run other macrocells to be slowed down or stopped.

The clocks are divider into two groups: systems clocks and peripheral clocks.

The default action of this utility (i.e. when no options are given) is to list peripheral clocks that are enabled.

OPTIONS

-a ACRON
    ACRON is an acronym for a system or peripheral clock. To enumerate the available acronyms, use the -e option. Alternatively a number may be given which is interpreted as an identifier; in which case the -p or -s oprion must be given to indicate whether the identifier is for a system or peripheral clock.

-d DIV
    in most cases, the master clock (MCK) going to the peripheral macrocell identified by ACRON can be divided by 2, 4 or 8. DIV may be 1, 2, 4 or 8. The default is a value of 1 .

-D  disable (turn off) the clock going to the system or peripheral macrocell identified by ACRON. If a Linux driver is using the associated macrocell then the kernel may freeze so use with care. All peripheral clocks are disabled at reset, however the boostrap and kernel will almost always turn some on. The kernel may only turn on a peripheral clock when the corresponding device is in use (e.g. serial ports (i.e. usarts or uarts) clocks only enabled while the corresponding serial port (e.g. /dev/ttyS2) is open).

-e  enumerate the available system and peripheral clocks. A separate table for each is shown. Each table contains an ID, acronym and description column.

-E  enable (turn on) the clock going to the system or peripheral macrocell identified by ACRON.

-h  print out usage message then exit.

-p  if ACRON is not given then this option will list peripheral clocks that are enabled. If ACRON is a number then this option indicates that it refers to a peripheral clock.

-s  if ACRON is not given then this option will list system clocks that are enabled. If ACRON is a number then this option indicates that it refers to a system clock.

-v  increase the level of verbosity, (i.e. debug output). Additional output caused by this option is sent to stderr.

-V  print the version string and then exit.

-w WPEN
    if WPEN is 0 then this utility will attempt to disable the write protect feature on the TCB associated with PIO_TIO. If WPEN is 1 then this utility will attempt to enable the write protect feature on the TCB associated with PIO_TIO. If WPEN is -1 then this utility will attempt to show the current state of the write protect feature on this TCB. This utility will exit immediately after the actions associated with this option.

NOTES
The SAMA5D3 Power Management Controller (PMC) reduces power by turning off the master clock going to various macrocells. At power up almost all macrocells are turned off. During boot up the kernel turns on those macrocell clocks that it needs.

EXAMPLES
To view the available system and peripheral clocks:

   a5d3_pmc -e
     System clocks:
             ID Acronym Description
     -------------------------------------------------
             0 PCK Processor clock
             2 DDRCK DDR clock
             ...
     Peripheral clocks:
             ID Acronym Description
     -------------------------------------------------
             2 DBGU Debug unit
             3 PIT Periodic interval timer
             4 WDT watchdog timer
             ...

To view the peripheral clocks that are currently enabled:

   a5d3_pmc
     Peripheral clocks enabled:
         DBGU: Debug unit
         HSMC: Multi-bit ECC
         PIOA: Parallel I/O controller A
         PIOB: Parallel I/O controller B
         ...

To view the system clocks that are currently enabled:

   a5d3_pmc -s
     System clocks enabled:
         PCK: Processor clock
         DDRCK: DDR clock
         UHP: The UHP48M and UHP12M OHCI clocks

EXIT STATUS
The exit status of a5d3_pmc is 0 when it is successful. Otherwise it is most likely to be 1.

AUTHORS
Written by Douglas Gilbert.

REPORTING BUGS
Report bugs to <dgilbert at interlog dot com>.

COPYRIGHT
Copyright © 2013 Douglas Gilbert
This software is distributed under a FreeBSD license. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO
a5d3_tc_freq(sama5d3_utils)