From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- Documentation/fujitsu/frv/clock.txt | 65 +++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 Documentation/fujitsu/frv/clock.txt (limited to 'Documentation/fujitsu/frv/clock.txt') diff --git a/Documentation/fujitsu/frv/clock.txt b/Documentation/fujitsu/frv/clock.txt new file mode 100644 index 000000000000..c72d350e177a --- /dev/null +++ b/Documentation/fujitsu/frv/clock.txt @@ -0,0 +1,65 @@ +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. -- cgit v1.2.1