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authorLinus Torvalds <torvalds@linux-foundation.org>2018-04-02 20:20:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-02 20:20:12 -0700
commitf5a8eb632b562bd9c16c389f5db3a5260fba4157 (patch)
tree82687234d772ff8f72a31e598fe16553885c56c9 /Documentation/frv/clock.txt
parentc9297d284126b80c9cfd72c690e0da531c99fc48 (diff)
parentdd3b8c329aa270027fba61a02a12600972dc3983 (diff)
Merge tag 'arch-removal' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic
Pul removal of obsolete architecture ports from Arnd Bergmann: "This removes the entire architecture code for blackfin, cris, frv, m32r, metag, mn10300, score, and tile, including the associated device drivers. I have been working with the (former) maintainers for each one to ensure that my interpretation was right and the code is definitely unused in mainline kernels. Many had fond memories of working on the respective ports to start with and getting them included in upstream, but also saw no point in keeping the port alive without any users. In the end, it seems that while the eight architectures are extremely different, they all suffered the same fate: There was one company in charge of an SoC line, a CPU microarchitecture and a software ecosystem, which was more costly than licensing newer off-the-shelf CPU cores from a third party (typically ARM, MIPS, or RISC-V). It seems that all the SoC product lines are still around, but have not used the custom CPU architectures for several years at this point. In contrast, CPU instruction sets that remain popular and have actively maintained kernel ports tend to all be used across multiple licensees. [ See the new nds32 port merged in the previous commit for the next generation of "one company in charge of an SoC line, a CPU microarchitecture and a software ecosystem" - Linus ] The removal came out of a discussion that is now documented at https://lwn.net/Articles/748074/. Unlike the original plans, I'm not marking any ports as deprecated but remove them all at once after I made sure that they are all unused. Some architectures (notably tile, mn10300, and blackfin) are still being shipped in products with old kernels, but those products will never be updated to newer kernel releases. After this series, we still have a few architectures without mainline gcc support: - unicore32 and hexagon both have very outdated gcc releases, but the maintainers promised to work on providing something newer. At least in case of hexagon, this will only be llvm, not gcc. - openrisc, risc-v and nds32 are still in the process of finishing their support or getting it added to mainline gcc in the first place. They all have patched gcc-7.3 ports that work to some degree, but complete upstream support won't happen before gcc-8.1. Csky posted their first kernel patch set last week, their situation will be similar [ Palmer Dabbelt points out that RISC-V support is in mainline gcc since gcc-7, although gcc-7.3.0 is the recommended minimum - Linus ]" This really says it all: 2498 files changed, 95 insertions(+), 467668 deletions(-) * tag 'arch-removal' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: (74 commits) MAINTAINERS: UNICORE32: Change email account staging: iio: remove iio-trig-bfin-timer driver tty: hvc: remove tile driver tty: remove bfin_jtag_comm and hvc_bfin_jtag drivers serial: remove tile uart driver serial: remove m32r_sio driver serial: remove blackfin drivers serial: remove cris/etrax uart drivers usb: Remove Blackfin references in USB support usb: isp1362: remove blackfin arch glue usb: musb: remove blackfin port usb: host: remove tilegx platform glue pwm: remove pwm-bfin driver i2c: remove bfin-twi driver spi: remove blackfin related host drivers watchdog: remove bfin_wdt driver can: remove bfin_can driver mmc: remove bfin_sdh driver input: misc: remove blackfin rotary driver input: keyboard: remove bf54x driver ...
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diff --git a/Documentation/frv/clock.txt b/Documentation/frv/clock.txt
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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.