clk-divider.c does not calculate the rates consistently at the moment.
As an example, on OMAP3 we have a clock divider with a source clock of
864000000 Hz. With dividers 6, 7 and 8 the theoretical rates are:
6: 144000000
7: 123428571.428571...
8: 108000000
Calling clk_round_rate() with the rate in the first column will give the
rate in the second column:
144000000 -> 144000000
143999999 -> 123428571
123428572 -> 123428571
123428571 -> 108000000
Note how clk_round_rate() returns 123428571 for rates from 123428572 to
143999999, which is mathematically correct, but when clk_round_rate() is
called with 123428571, the returned value is surprisingly 108000000.
This means that the following code works a bit oddly:
rate = clk_round_rate(clk, 123428572);
clk_set_rate(clk, rate);
As clk_set_rate() also does clock rate rounding, the result is that the
clock is set to the rate of 108000000, not 123428571 returned by the
clk_round_rate.
This patch changes the clk-divider.c to use DIV_ROUND_UP when
calculating the rate. This gives the following behavior which fixes the
inconsistency:
144000000 -> 144000000
143999999 -> 123428572
123428572 -> 123428572
123428571 -> 108000000
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Commit 6d9252bd9a (clk: Add support for power of two type dividers)
merged in v3.6 added the _get_val function to convert a divisor value to
a register field value depending on the flags. However it used the type
u8 for the div field, causing divisors larger than 255 to be masked
and the resultant clock rate to be too high.
E.g. in my case an 11bit divider was supposed to divide 24.576 MHz down
to 32.768KHz. The divisor was correctly calculated as 750 (0x2ee). This
was masked to 238 (0xee) resulting in a frequency of 103.26KHz.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: stable@vger.kernel.org
Signed-off-by: Mike Turquette <mturquette@linaro.org>
the common clock drivers were motivated/initiated by ARM development
and apparently assume little endian peripherals
wrap register/peripherals access in the common code (div, gate, mux)
in preparation of adding COMMON_CLK support for other platforms
Signed-off-by: Gerhard Sittig <gsi@denx.de>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
clk_register_divider() needs to be exported so that it could be used
in a module driver, otherwise we get the following error:
ERROR: "clk_register_divider" [sound/soc/mxs/snd-soc-mxs.ko] undefined!
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: also export clk_register_divider_table]
In both Hisilicon & Rockchip Cortex-A9 based chips, they don't use the
paradigm of reading-changing-writing the register contents.
Instead they use a hiword mask to indicate the changed bits.
When b01 should be set as setting divider, it also needs to indicate
the change by setting hiword mask (b11 << 16).
The patch adds divider flag for this usage.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
If the current rate of parent clock is sufficient to provide child a
requested rate with a proper divider setting, the rate change request
should not be propagated. Instead, changing the divider setting is good
enough to get child clock run at the requested rate.
On an imx6q clock configuration illustrated below,
ahb --> ipg --> ipg_per
132M 66M 66M
calling clk_set_rate(ipg_per, 22M) with the current
clk_divider_bestdiv() implementation will result in the rate change up
to ahb level like the following, because of the unnecessary/incorrect
rate change propagation.
ahb --> ipg --> ipg_per
66M 22M 22M
Fix the problem by trying to see if the requested rate can be achieved
by simply changing the divider value, and in that case return the
divider immediately from function clk_divider_bestdiv() as the best
one, so that all those unnecessary rate change propagation can be saved.
Reported-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Dividers which have CLK_DIVIDER_ONE_BASED set have a redundant state,
being a divider value of zero. Some hardware implementations allow a
zero divider which simply doesn't alter the frequency. I.e. it acts like
a divide by one or bypassing the divider.
This flag is used to handle such HW in the clk-divider model.
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
The macro is_power_of_two() in clk-divider.c was defined as !(i & ~i)
which is always true. Instead use is_power_of_2() from log2.h.
Also add brackets around the macro arguments in div_mask to avoid any
future operator precedence problems.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: use log2.h per Joe Perches; update changelog]
Most platforms end up using a mix of basic clock types and
some which use clk_hw_foo struct for filling in custom platform
information when the clocks don't fit into basic types supported.
In platform code, its useful to know if a clock is using a basic
type or clk_hw_foo, which helps platforms know if they can
safely use to_clk_hw_foo to derive the clk_hw_foo pointer from
clk_hw.
Mark all basic clocks with a CLK_IS_BASIC flag.
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Some divider clks do not have any obvious relationship
between the divider and the value programmed in the
register. For instance, say a value of 1 could signify divide
by 6 and a value of 2 could signify divide by 4 etc.
Also there are dividers where not all values possible
based on the bitfield width are valid. For instance
a 3 bit wide bitfield can be used to program a value
from 0 to 7. However its possible that only 0 to 4
are valid values.
All these cases need the platform code to pass a simple
table of divider/value tuple, so the framework knows
the exact value to be written based on the divider
calculation and can also do better error checking.
This patch adds support for such rate table based
dividers and as part of the support adds a new
registration function 'clk_register_divider_table()'
and a new macro for static definition
'DEFINE_CLK_DIVIDER_TABLE'.
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Quite often dividers and the value programmed in the
register have a relation of 'power of two', something like
value div
0 1
1 2
2 4
3 8...
Add support for such dividers as part of clk-divider.
The clk-divider flag 'CLK_DIVIDER_POWER_OF_TWO' should be used
to define such clocks.
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Create a struct clk_init_data to hold all data that needs to be passed from
the platfrom specific driver to the common clock framework during clock
registration. Add a pointer to this struct inside clk_hw.
This has several advantages:
* Completely hides struct clk from many clock platform drivers and static
clock initialization code that don't care for static initialization of
the struct clks.
* For platforms that want to do complete static initialization, it removed
the need to directly mess with the struct clk's fields while still
allowing to statically allocate struct clk. This keeps the code more
future proof even if they include clk-private.h.
* Simplifies the generic clk_register() function and allows adding optional
fields in the future without modifying the function signature.
* Simplifies the static initialization of clocks on all platforms by
removing the need for forward delcarations or convoluted macros.
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
[mturquette@linaro.org: kept DEFINE_CLK_* macros and __clk_init]
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Jeremy Kerr <jeremy.kerr@canonical.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergman <arnd.bergmann@linaro.org>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Shawn Guo <shawn.guo@freescale.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Jamie Iles <jamie@jamieiles.com>
Cc: Richard Zhao <richard.zhao@linaro.org>
Cc: Saravana Kannan <skannan@codeaurora.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Amit Kucheria <amit.kucheria@linaro.org>
Cc: Deepak Saxena <dsaxena@linaro.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
For most of .set_rate implementation, parent_rate will be used, so just
like passing parent_rate into .recalc_rate, let's pass parent_rate into
.set_rate too.
It also updates the kernel doc for .set_rate ops.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
The parent_rate will likely be used by most .round_rate implementation
no matter whether flag CLK_SET_RATE_PARENT is set or not, so let's
always pass parent_rate into .round_rate.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
This patch is the basic clk version of 'clk: core: copy parent_names &
return error codes'.
The registration functions are changed to allow the core code to copy
the array of strings and allow platforms to declare those arrays as
__initdata.
This patch also converts all of the basic clk registration functions to
return error codes which better aligns them with the existing clk.h api.
Signed-off-by: Mike Turquette <mturquette@linaro.org>
The clk_ops of basic clks should have "const" to match the definition
in "struct clk" and clk_register prototype.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
It makes no sense to have EXPORT_SYMBOL_GPL on static functions.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Many platforms support simple gateable clocks, fixed-rate clocks,
adjustable divider clocks and multi-parent multiplexer clocks.
This patch introduces basic clock types for the above-mentioned hardware
which share some common characteristics.
Based on original work by Jeremy Kerr and contribution by Jamie Iles.
Dividers and multiplexor clocks originally contributed by Richard Zhao &
Sascha Hauer.
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Mike Turquette <mturquette@ti.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Rob Herring <rob.herring@calxeda.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Jeremy Kerr <jeremy.kerr@canonical.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergman <arnd.bergmann@linaro.org>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Shawn Guo <shawn.guo@freescale.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Jamie Iles <jamie@jamieiles.com>
Cc: Richard Zhao <richard.zhao@linaro.org>
Cc: Saravana Kannan <skannan@codeaurora.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Linus Walleij <linus.walleij@stericsson.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Amit Kucheria <amit.kucheria@linaro.org>
Cc: Deepak Saxena <dsaxena@linaro.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
