Custom approximation of fractional-divider may not need parent clock
rate checking. For example Rockchip SoCs work fine using grand parent
clock rate even if target rate is greater than parent.
This patch checks parent clock rate only if CLK_SET_RATE_PARENT flag
is set.
For detailed example, clock tree of Rockchip I2S audio hardware.
- Clock rate of CPLL is 1.2GHz, GPLL is 491.52MHz.
- i2s1_div is integer divider can divide N (N is 1~128).
Input clock is CPLL or GPLL. Initial divider value is N = 1.
Ex) PLL = CPLL, N = 10, i2s1_div output rate is
CPLL / 10 = 1.2GHz / 10 = 120MHz
- i2s1_frac is fractional divider can divide input to x/y, x and
y are 16bit integer.
CPLL --> | selector | ---> i2s1_div -+--> | selector | --> I2S1 MCLK
GPLL --> | | ,--------------' | |
`--> i2s1_frac ---> | |
Clock mux system try to choose suitable one from i2s1_div and
i2s1_frac for master clock (MCLK) of I2S1.
Bad scenario as follows:
- Try to set MCLK to 8.192MHz (32kHz audio replay)
Candidate setting is
- i2s1_div: GPLL / 60 = 8.192MHz
i2s1_div candidate is exactly same as target clock rate, so mux
choose this clock source. i2s1_div output rate is changed
491.52MHz -> 8.192MHz
- After that try to set to 11.2896MHz (44.1kHz audio replay)
Candidate settings are
- i2s1_div : CPLL / 107 = 11.214945MHz
- i2s1_frac: i2s1_div = 8.192MHz
This is because clk_fd_round_rate() thinks target rate
(11.2896MHz) is higher than parent rate (i2s1_div = 8.192MHz)
and returns parent clock rate.
Above is current upstreamed behavior. Clock mux system choose
i2s1_div, but this clock rate is not acceptable for I2S driver, so
users cannot replay audio.
Expected behavior is:
- Try to set master clock to 11.2896MHz (44.1kHz audio replay)
Candidate settings are
- i2s1_div : CPLL / 107 = 11.214945MHz
- i2s1_frac: i2s1_div * 147/6400 = 11.2896MHz
Change i2s1_div to GPLL / 1 = 491.52MHz at same
time.
If apply this commit, clk_fd_round_rate() calls custom approximate
function of Rockchip even if target rate is higher than parent.
Custom function changes both grand parent (i2s1_div) and parent
(i2s_frac) settings at same time. Clock mux system can choose
i2s1_frac and audio works fine.
Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
[sboyd@kernel.org: Make function into a macro instead]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Adding CLK_FRAC_DIVIDER_ZERO_BASED flag to indicate the numerator and
denominator value in register are start from 0.
This can be used to support frac dividers like below:
Divider output clock = Divider input clock x [(frac +1) / (div +1)]
where frac/div in register is:
000b - Divide by 1.
001b - Divide by 2.
010b - Divide by 3.
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Michael Turquette <mturquette@baylibre.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Fractional dividers may have special requirements concerning numerator
and denominator selection that differ from just getting the best
approximation.
For example on Rockchip socs the denominator must be at least 20 times
larger than the numerator to generate precise clock frequencies.
Therefore add the ability to provide custom approximation functions.
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Add registration APIs in the clk fractional divider code to
return struct clk_hw pointers instead of struct clk pointers.
This way we hide the struct clk pointer from providers unless
they need to use consumer facing APIs.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
to_clk_*(_hw) macros have been repeatedly defined in many places.
This patch moves all the to_clk_*(_hw) definitions in the common
clock framework to public header clk-provider.h, and drop the local
definitions.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
This patch converts the code to use rational best approximation algorithm which
is much more precise.
Suggested-by: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
The patch adds mwidth and nwidth fields to the struct clk_fractional_divider
for further usage. While here, use GENMASK() instead of open coding this
functionality.
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Rename function parameter to be more explicit what it is for. This also makes
it in align with struct clk_ops.
There is no functional change.
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
The basic clock types use conditional locking for the register
accessor spinlocks. Add __acquire() and __release() markings in
the right locations so that sparse isn't tripped up on the
conditional locking.
drivers/clk/clk-mux.c:68:12: warning: context imbalance in 'clk_mux_set_parent' - different lock contexts for basic block
drivers/clk/clk-divider.c:379:12: warning: context imbalance in 'clk_divider_set_rate' - different lock contexts for basic block
drivers/clk/clk-gate.c:71:9: warning: context imbalance in 'clk_gate_endisable' - different lock contexts for basic block
drivers/clk/clk-fractional-divider.c:36:9: warning: context imbalance in 'clk_fd_recalc_rate' - different lock contexts for basic block
drivers/clk/clk-fractional-divider.c:68:12: warning: context imbalance in 'clk_fd_set_rate' - different lock contexts for basic block
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Printing an error on kmalloc() failures is unnecessary. Remove
the print and use *ptr in sizeof() for future-proof code.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
If the divider or multiplier values are 0 in the register, bypassing the
divider and returning the parent clock rate in clk_fd_recalc_rate().
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@linaro.org>
[mturquette@linaro.org: fixed commitlog typo]
On 32bit architectures, like ARM calculating the fractional rate will
do the multiplication before converting the value to u64 when it gets
assigned to ret, which can produce overflows.
The error in question happened with a parent_rate of 386MHz, m = 3000,
n = 60000, which resulted in a wrong rate value of 15812Hz.
Therefore cast parent_rate to u64 to make sure the multiplication
happens in a 64bit space and produces the correct 192MHz in the example.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
Fractional divider clocks are fairly common. This adds basic
type for them.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Katsuhiro Suzuki