This patch adds a new rate rounding algorithm for DPLL clocks on the
OMAP2/3 architecture.
For a desired DPLL target rate, there may be several
multiplier/divider (M, N) values which will generate a sufficiently
close rate. Lower N values result in greater power economy. However,
lower N values can cause the difference between the rounded rate and
the target rate ("rate error") to be larger than it would be with a
higher N. This can cause downstream devices to run more slowly than
they otherwise would.
This DPLL rate rounding algorithm:
- attempts to find the lowest possible N (DPLL divider) to reach the
target_rate (since, according to Richard Woodruff <r-woodruff@ti.com>,
lower N values save more power than higher N values).
- allows developers to set an upper bound on the error between the
rounded rate and the desired target rate ("rate tolerance"), so an
appropriate balance between rate fidelity and power savings can be
set. This maximum rate error tolerance is set via
omap2_set_dpll_rate_tolerance().
- never returns a rounded rate higher than the target rate.
The rate rounding algorithm caches the last rounded M, N, and rate
computation to avoid rounding the rate twice for each clk_set_rate()
call. (This patch does not yet implement set_rate for DPLLs; that
follows in a future patch.)
The algorithm trades execution speed for rate accuracy. It will find
the (M, N) set that results in the least rate error, within a
specified rate tolerance. It does this by evaluating each divider
setting - on OMAP3, this involves 128 steps. Another approach to DPLL
rate rounding would be to bail out as soon as a valid rate is found
within the rate tolerance, which would trade rate accuracy for
execution speed. Alternate implementations welcome.
This code is not yet used by the OMAP24XX DPLL clock, since it
is currently defined as a composite clock, fusing the DPLL M,N and the
M2 output divider. This patch also renames the existing OMAP24xx DPLL
programming functions to highlight that they program both the DPLL and
the DPLL's output multiplier.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This patch adds support for DPLL autoidle control to the OMAP3 clock
framework. These functions will be used by the noncore DPLL enable
and disable code - this is because, according to the CDP code, the
DPLL autoidle status must be saved and restored across DPLL
lock/bypass/off transitions.
N.B.: the CORE DPLL (DPLL3) has three autoidle mode options, rather
than just two. This code currently does not support the third option,
low-power bypass autoidle.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
debugfs can provide the infrastructure to trace the dependencies of
clock tree hierarchy quite visibly. This patch enables to keep track
of clock tree hierarchy and expose their attributes under each clock
directry as below:
omap:~# tree -d -L 2 /debug/clock/omap_32k_fck/
/debug/clock/omap_32k_fck/
|-- gpt10_fck
|-- gpt11_fck
|-- gpt1_fck
|-- per_32k_alwon_fck
| |-- gpio2_fck
| |-- gpio3_fck
| |-- gpio4_fck
| |-- gpio5_fck
| |-- gpio6_fck
| `-- wdt3_fck
|-- ts_fck
`-- wkup_32k_fck
|-- gpio1_fck
`-- wdt2_fck
14 directories
omap:~# tree /debug/clock/omap_32k_fck/gpt10_fck/
/debug/clock/omap_32k_fck/gpt10_fck/
|-- flags
|-- rate
`-- usecount
0 directories, 3 files
Although, compared with David Brownell's small patch, this may look
bit overkilling, I expect that this debugfs can deal with other PRCM
complexities at the same time. For example, powerdomain dependencies
can be expressed by using symbolic links of these clocks if
powerdomain supports dubgfs as well.
Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
arch/arm/plat-omap/clock.c:397: warning: "struct cpufreq_frequency_table" declared inside parameter list
arch/arm/plat-omap/clock.c:397: warning: its scope is only this definition or declaration, which is probably not what you want
arch/arm/plat-omap/clock.c: In function `clk_init_cpufreq_table':
arch/arm/plat-omap/clock.c:402: error: structure has no member named `clk_init_cpufreq_table'
arch/arm/plat-omap/clock.c:403: error: structure has no member named `clk_init_cpufreq_table'
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
These changes is the result of the discussion with Paul Walmsley.
His ideas are included into this patch.
Remove DPLL output divider handling from DPLLs and CLKOUTX2 clocks,
and place it into specific DPLL output divider clocks (e.g., dpll3_m2_clk).
omap2_get_dpll_rate() now returns the correct DPLL rate, as represented
by the DPLL's CLKOUT output. Also add MPU and IVA2 subsystem clocks, along
with high-frequency bypass support.
Add support for DPLLs function in locked and bypass clock modes.
Signed-off-by: Roman Tereshonkov <roman.tereshonkov@nokia.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This patch changes 24xx to use shared clock code and new register
access.
Note that patch adds some temporary OLD_CK defines to keep patch
more readable. These temporary defines will be removed in the next
patch. Also not all clocks are changed in this patch to limit the
size.
Also, the patch fixes few incorrect clock defines in clock24xx.h.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
This patch changes 24xx to use new register access, except for clock
framework. Clock framework register access will get updates in the
next patch.
Note that board-*.c files change GPMC (General Purpose Memory Controller)
access to use gpmc_cs_write_reg() instead of accessing the registers
directly. The code also uses gpmc_fck instead of it's parent clock
core_l3_ck for GPMC clock.
The H4 board file also adds h4_init_flash() function, which specify the
flash start and end addresses.
Also note that sleep.S removes some unused registers addresses.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Mostly clean up CONFIG_OMAP_RESET_CLOCKS. Also includes a
patch from Imre Deak to make McSPI clocks use id.
Signed-off-by: Tony Lindgren <tony@atomide.com>
Patch from Tony Lindgren
"clocks" is only needed only for CONFIG_OMAP_RESET_CLOCKS,
which turns of all unused clocks in with late_initcall. This is to kill
clocks that may have been left on by the bootloader. Having static and
non-static declaration of clocks makes omap_h2_1610_defconfig build fail.
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Patch from Tony Lindgren
Update OMAP clock framework from linux-omap tree.
The highlights of the patch are:
- Add support for omap730 clocks by Andrzej Zaborowski
- Fix compile warnings by Dirk Behme
- Add support for using dev id by Tony Lindgren and Komal Shah
- Move memory timings and PRCM into separate files by Tony Lindgren
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch fixes OMAP clock framework to use clk_enable/disable
instead of clk_use/unuse as specified in include/linux/clk.h.
Instances of clk_use/unuse are renamed to clk_enable/disable,
and references clk_use/unuse are removed.
Signed-off-by: Tony Lindgren <tony@atomide.com>
Patch from Tony Lindgren
This patch syncs the mainline kernel with linux-omap tree.
This patch contains changes to common header files for
omap1xxx and omap24xx by various omap developers, and
improved cpu detection by Imre Deak
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
