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Commit 79c6ab509558 (clk: divider: add CLK_DIVIDER_READ_ONLY flag) in
v3.16 introduced the CLK_DIVIDER_READ_ONLY flag which caused the
recalc_rate() and round_rate() clock callbacks to be omitted.
However using this flag has the unfortunate side effect of causing the
clock recalculation code when a clock rate change is attempted to always
treat it as a pass-through clock, i.e. with a fixed divide of 1, which
may not be the case. Child clock rates are then recalculated using the
wrong parent rate.
Therefore instead of dropping the recalc_rate() and round_rate()
callbacks, alter clk_divider_bestdiv() to always report the current
divider as the best divider so that it is never altered.
For me the read only clock was the system clock, which divided the PLL
rate by 2, from which both the UART and the SPI clocks were divided.
Initial setting of the UART rate set it correctly, but when the SPI
clock was set, the other child clocks were miscalculated. The UART clock
was recalculated using the PLL rate as the parent rate, resulting in a
UART new_rate of double what it should be, and a UART which spewed forth
garbage when the rate changes were propagated.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Thomas Abraham <thomas.ab@samsung.com>
Cc: Tomasz Figa <t.figa@samsung.com>
Cc: Max Schwarz <max.schwarz@online.de>
Cc: <stable@vger.kernel.org> # v3.16+
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Michael Turquette <mturquette@linaro.org>
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Commit c686078 ("clk: divider: Add round to closest divider") introduced
a helper function to check whether given divisor is the best one instead
of direct check. However due to int type used instead of unsigned long
for passing calculated rates to this function in certain cases an
overflow could occur, for example when trying to obtain maximum possible
clock rate by calling clk_round_rate(..., UINT_MAX).
This patch fixes this issue by changing the type of rate, now and best
arguments of the function to unsigned long, which is the type that
should be used for clock rates.
Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
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Commit 1d9fe6b97 ("clk: divider: Fix best div calculation for power-of-two and
table dividers") introduces a regression in its _table_round_up function.
When the divider passed to this function is greater than the max divider
available in the table, this function returns table's max divider.
Problem is that it causes an infinite loop in clk_divider_bestdiv() because
_next_div() will never return a value greater than maxdiv.
Instead of returning table's max divider, this patch returns INT_MAX.
Reported-by: Fabio Estevam <festevam@gmail.com>
Reported-by: Shawn Guo <shawn.guo@freescale.com>
Tested-by: Fabio Estevam <festevam@gmail.com>
Tested-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
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From: Heiko Stuebner <heiko@sntech.de>
Similar to muxes which already have a read-only flag there sometimes
exist dividers which should not be changed by the clock framework
but whose value still should be readable.
Therefore add a READ_ONLY flag similar to the mux-one to clk-divider
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
[changed flag bit to BIT(5) as suggested by Tomasz Figa]
Signed-off-by: Thomas Abraham <thomas.ab@samsung.com>
Acked-by: Tomasz Figa <t.figa@samsung.com>
Acked-by: Max Schwarz <max.schwarz@online.de>
Tested-by: Max Schwarz <max.schwarz@online.de>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
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Currently, the for-loop used to try all the different dividers to find the
one that best fit tries all the values from 1 to max_div, incrementing by one.
In case of power-of-two, or table based divider, the loop isn't optimal.
Instead of incrementing by one, this patch provides directly the next divider.
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
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In some cases, we want to be able to round the divider to the closest one,
instead than rounding up.
This patch adds a new CLK_DIVIDER_ROUND_CLOSEST flag to specify the divider
has to round to closest div, keeping rounding up as de default behaviour.
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
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The divider returned by clk_divider_bestdiv() is likely to be invalid in case
of power-of-two and table dividers when CLK_SET_RATE_PARENT flag isn't set.
Fixes boot on STiH416 platform.
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: trivial merge conflict & updated changelog]
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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>
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Commit 6d9252bd9a4bb (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>
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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>
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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]
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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>
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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>
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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>
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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]
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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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>
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