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-Clock scaling
--------------
-
-The kernel supports scaling of CLCK.CMODE, CLCK.CM and CLKC.P0 clock
-registers. If built with CONFIG_PM and CONFIG_SYSCTL options enabled, four
-extra files will appear in the directory /proc/sys/pm/. Reading these files
-will show:
-
- p0 -- current value of the P0 bit in CLKC register.
- cm -- current value of the CM bits in CLKC register.
- cmode -- current value of the CMODE bits in CLKC register.
-
-On all boards, the 'p0' file should also be writable, and either '1' or '0'
-can be rewritten, to set or clear the CLKC_P0 bit respectively, hence
-controlling whether the resource bus rate clock is halved.
-
-The 'cm' file should also be available on all boards. '0' can be written to it
-to shift the board into High-Speed mode (normal), and '1' can be written to
-shift the board into Medium-Speed mode. Selecting Low-Speed mode is not
-supported by this interface, even though some CPUs do support it.
-
-On the boards with FR405 CPU (i.e. CB60 and CB70), the 'cmode' file is also
-writable, allowing the CPU core speed (and other clock speeds) to be
-controlled from userspace.
-
-
-Determining current and possible settings
------------------------------------------
-
-The current state and the available masks can be found in /proc/cpuinfo. For
-example, on the CB70:
-
- # cat /proc/cpuinfo
- CPU-Series: fr400
- CPU-Core: fr405, gr0-31, BE, CCCR
- CPU: mb93405
- MMU: Prot
- FP-Media: fr0-31, Media
- System: mb93091-cb70, mb93090-mb00
- PM-Controls: cmode=0xd31f, cm=0x3, p0=0x3, suspend=0x9
- PM-Status: cmode=3, cm=0, p0=0
- Clock-In: 50.00 MHz
- Clock-Core: 300.00 MHz
- Clock-SDRAM: 100.00 MHz
- Clock-CBus: 100.00 MHz
- Clock-Res: 50.00 MHz
- Clock-Ext: 50.00 MHz
- Clock-DSU: 25.00 MHz
- BogoMips: 300.00
-
-And on the PDK, the PM lines look like the following:
-
- PM-Controls: cm=0x3, p0=0x3, suspend=0x9
- PM-Status: cmode=9, cm=0, p0=0
-
-The PM-Controls line, if present, will indicate which /proc/sys/pm files can
-be set to what values. The specification values are bitmasks; so, for example,
-"suspend=0x9" indicates that 0 and 3 can be written validly to
-/proc/sys/pm/suspend.
-
-The PM-Controls line will only be present if CONFIG_PM is configured to Y.
-
-The PM-Status line indicates which clock controls are set to which value. If
-the file can be read, then the suspend value must be 0, and so that's not
-included.